nLIGHT (LASR) S-1 4 Sep 18 IPO registration Financial data

Document and Entity Information

Document and Entity Information Document	6 Months Ended
	Jun. 30, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	NLIGHT, INC.
Entity Central Index Key	1,124,796
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	S1
Document Period End Date	Jun. 30, 2018
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 129,725	$ 36,687	$ 13,500
Accounts receivable, net of allowances of $527, $438 and $1,608	21,664	13,353	9,697
Inventory	35,269	29,570	18,805
Prepaid expenses and other current assets	8,363	4,973	4,117
Total current assets	195,021	84,583	46,119
Property and equipment, net	19,528	17,968	17,323
Intangible assets, net	2,440	1,836	1,485
Goodwill	1,387	1,387	1,387
Other assets	4,644	4,374	4,745
Total assets	223,020	110,148	71,059
Current liabilities:
Accounts payable	16,064	12,920	9,380
Accrued liabilities	11,918	12,650	8,347
Customer advances	674	575	203
Deferred revenue	778	386	13
Current portion of long-term debt	4,597	2,363	1,287
Total current liabilities	34,031	28,894	19,230
Non-current income taxes payable	4,470	3,930	2,572
Long-term debt	12,797	15,108	18,380
Other long-term liabilities	1,486	933	1,186
Total liabilities	52,784	48,865	41,368
Stockholders' equity:
Common stock-$0.0001 par value; 190,000 shares authorized, 34,792 shares issued and outstanding at June 30, 2018 (unaudited). 190,000 shares authorized, 2,979 shares issued and outstanding at December 31, 2017 and 150,000 shares authorized, 2,539 shares issued and outstanding at December 31, 2016	15	2	1
Additional paid-in capital	282,678	180,657	153,195
Accumulated other comprehensive loss	(1,357)	(719)	(3,009)
Accumulated deficit	(111,100)	(118,669)	(120,506)
Total stockholders' equity	170,236	61,283	29,691
Total liabilities and stockholders' equity	223,020	110,148	71,059
Convertible preferred stock
Stockholders' equity:
Preferred stock - $0.0001 par value		12	10
Preferred stock
Stockholders' equity:
Preferred stock - $0.0001 par value

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts receivable, allowances	$ 527	$ 438	$ 1,608
Convertible preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001	$ 0.0001
Convertible preferred stock, shares authorized (in shares)	5,000,000	0	0
Convertible preferred stock, shares issued (in shares)	0	0	0
Convertible preferred stock, shares outstanding (in shares)	0	0	0
Convertible preferred stock, liquidation preference		$ 148,452	$ 119,669
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	190,000,000	190,000,000	150,000,000
Common stock, shares issued (in shares)	34,792,000	2,979,000	2,539,000
Common stock, shares outstanding (in shares)	34,792,000	2,979,000	2,539,000
Convertible preferred stock
Convertible preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001	$ 0.0001
Convertible preferred stock, shares authorized (in shares)	0	129,478,000	100,255,000
Convertible preferred stock, shares issued (in shares)	0	24,642,000	19,836,000
Convertible preferred stock, shares outstanding (in shares)	0	24,642,000	19,836,000
Convertible preferred stock, liquidation preference		$ 148,452	$ 119,669

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Revenues	$ 94,172	$ 64,551	$ 138,580	$ 101,325
Cost of revenues	61,764	44,904	94,306	78,159
Gross profit	32,408	19,647	44,274	23,166
Operating expenses:
Research and development	9,181	7,736	15,123	15,239
Sales, general, and administrative	13,470	9,403	19,353	17,265
Total operating expenses	22,651	17,139	34,476	32,504
Income (loss) from operations	9,757	2,508	9,798	(9,338)
Other income (expense):
Interest expense, net	(225)	(971)	(1,269)	(2,229)
Other income (expense)	34	(797)	(1,834)	(753)
Income (loss) before income taxes	9,566	740	6,695	(12,320)
Income tax expense	1,997	2,240	4,858	1,882
Net income (loss)	7,569	(1,500)	1,837	(14,202)
Less: Income allocated to participating securities	(4,415)	0	(1,837)	0
Net income (loss) attributable to common stockholders	$ 3,154	$ (1,500)	$ 0	$ (14,202)
Net income (loss) per share, basic (in dollars per share)	$ 0.23	$ (0.57)	$ 0	$ (5.68)
Net income (loss) per share, diluted (in dollars per share)	$ 0.17	$ (0.57)	$ 0	$ (5.68)
Shares used in per share calculations:
Basic (in shares)	13,761	2,613	2,735	2,500
Diluted (in shares)	18,797	2,613	2,735	2,500

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 7,569	$ (1,500)	$ 1,837	$ (14,202)
Other comprehensive income (loss):
Foreign currency translation adjustments, net of tax	(638)	(627)	2,290	(627)
Comprehensive income (loss)	$ 6,931	$ (2,127)	$ 4,127	$ (14,829)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Convertible preferred stockSeries F convertible preferred stock	Convertible preferred stockSeries G convertible preferred stock	Convertible preferred stock	Common stockIPO	Common stock	Additional paid-in capitalSeries F convertible preferred stock	Additional paid-in capitalSeries G convertible preferred stock	Additional paid-in capitalIPO	Additional paid-in capital	Accumulated other comprehensive loss	Accumulated deficit	Series F convertible preferred stock	Series G convertible preferred stock	IPO	Total
Balance at Dec. 31, 2015			$ 9		$ 1				$ 140,763	$ (2,382)	$ (106,304)				$ 32,087
Balance (in shares) at Dec. 31, 2015			17,505		2,470
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)											(14,202)				(14,202)
Net proceeds from issuance of stock	$ 1					$ 11,963						$ 11,964
Net proceeds from issuance of stock (in shares)	2,332
Exercise of stock options									52						52
Exercise of stock options (in shares)					69
Stock based compensation									308						308
Stock options issued in exchange for liability settlement									153						153
Other financing costs									(44)						(44)
Cumulative translation adjustment										(627)					(627)
Balance at Dec. 31, 2016			$ 10		$ 1				153,195	(3,009)	(120,506)				29,691
Balance (in shares) at Dec. 31, 2016			19,837		2,539
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)											1,837				1,837
Net proceeds from issuance of stock		$ 2					$ 27,479						$ 27,481
Net proceeds from issuance of stock (in shares)		4,805
Exercise of stock options					$ 1				335						$ 336
Exercise of stock options (in shares)					440										440
Stock based compensation									369						$ 369
Other deferred offering costs									(721)						(721)
Cumulative translation adjustment										2,290					2,290
Balance at Dec. 31, 2017			$ 12		$ 2				180,657	(719)	(118,669)				61,283
Balance (in shares) at Dec. 31, 2017			24,642		2,979
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)											7,569				7,569
Net proceeds from issuance of stock				$ 1				$ 100,930						$ 100,931
Net proceeds from issuance of stock (in shares)				6,900
Exercise of stock options									123						$ 123
Exercise of stock options (in shares)					256										141
Conversion of convertible preferred stock to common stock			$ (12)		$ 12
Shares of common stock issued upon conversion (in shares)			(24,642)		24,642
Issuance of warrants					15
Stock based compensation									968						$ 968
Cumulative translation adjustment										(638)					(638)
Balance at Jun. 30, 2018					$ 15				$ 282,678	$ (1,357)	$ (111,100)				$ 170,236
Balance (in shares) at Jun. 30, 2018					34,792

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income (loss)	$ 7,569	$ (1,500)	$ 1,837	$ (14,202)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	4,118	3,909	7,922	8,099
Provision for losses on accounts receivable	183	143	232	340
Stock-based compensation	968	148	369	308
Deferred income taxes			(424)	226
(Gain)/Loss on disposal of property and equipment	11	7	9	(9)
Loss on debt extinguishment			911
Changes in operating assets and liabilities:
Accounts receivable	(8,711)	(602)	(3,523)	569
Inventory	(5,644)	(3,402)	(9,875)	8,975
Prepaid expenses and other current assets	(3,458)	(579)	(639)	933
Other assets	(1,226)	(486)	(1,148)	(3,069)
Accounts payable	3,539	1,723	2,491	601
Accrued and other long-term liabilities	(736)	1,440	3,160	3,038
Customer advances	110	189	358	(223)
Deferred revenue	392	156	373	(243)
Non-current income taxes payable	540	169	1,358	616
Net cash provided by (used in) operating activities	(2,345)	1,315	3,411	5,959
Cash flows from investing activities:
Purchases of property, equipment and intangibles	(5,789)	(1,767)	(5,483)	(4,063)
Proceeds from sale of property and equipment	8	6	6	36
Net cash used in investing activities	(5,781)	(1,761)	(5,477)	(4,027)
Cash flows from financing activities:
Principal payments on debt and capital leases	(74)	(2,652)	(15,318)	(8,331)
Proceeds from public offering, net of offering costs	101,486
Net proceeds from debt financing			12,499
Cash paid on debt extinguishment			(388)
Net proceeds from issuance of convertible preferred stock		27,582	27,481	11,964
Payments of other financing costs			(191)	(44)
Proceeds from stock option exercises	123	66	336	52
Net cash provided by financing activities	101,535	24,996	24,419	3,641
Effect of exchange rate changes on cash	(371)	757	834	1,072
Net increase in cash and cash equivalents	93,038	25,307	23,187	6,645
Cash and cash equivalents, beginning of period	36,687	13,500	13,500	6,855
Cash and cash equivalents, end of period	129,725	38,807	36,687	13,500
Supplemental disclosures:
Cash paid for interest	506	914	1,437	2,060
Cash paid for income taxes	2,119	901	3,493	$ 1,271
Accrued purchases of property, equipment and intangibles	675	86	969
Accrued deferred offering costs	$ 1,087	$ 105	$ 530

Organization and Operations of

Organization and Operations of the Company	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Operations of the Company	(1) Organization and Operations of the Company nLIGHT, Inc. (the "Company") is a leading provider of high-power semiconductor and fiber lasers used in a variety of end applications in the industrial, microfabrication, and aerospace and defense markets. The Company, a Delaware corporation, is headquartered in Vancouver, Washington and is vertically integrated with manufacturing in Vancouver, Washington; Hillsboro, Oregon; Shanghai, China; and Lohja, Finland.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2018
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	(2) Summary of Significant Accounting Policies (a) Use of Estimates The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates, including those related to inventory valuation, allowances for doubtful accounts, warranty, sales return reserves and the recoverability of long‑lived assets. Management of the Company bases its estimates on historical experience and on various other assumptions. Actual results could differ from those estimates. (b) Unaudited Interim Financial Information The accompanying interim consolidated balance sheet as of June 30, 2018, the interim consolidated statements of operations, comprehensive income and cash flows for the six months ended June 30, 2017 and 2018 and the interim consolidated statement of stockholders’ equity for the six months ended June 30, 2018 are unaudited. The financial data and information disclosed in these notes to the consolidated financial statements related to that date and these periods are also unaudited. The unaudited interim consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly our financial position as of June 30, 2018 and the results of our operations and cash flows for the six months ended June 30, 2017 and 2018. The consolidated results of operations for the six months ended June 30, 2018 are not necessarily indicative of the results to be expected for the entire year ending December 31, 2018, or for any other future annual or interim period. (c) Initial Public Offering (unaudited) On April 30, 2018, the Company closed its IPO of 6.9 million shares of common stock at an initial price to the public of $16.00 per share, including 0.9 million shares of common stock pursuant to the exercise in full of the underwriters’ option to purchase additional shares, resulting in aggregate estimated net proceeds to the Company of $100.2 million after deducting underwriting discounts and commissions and offering costs. Immediately prior to the closing of the IPO on April 30, 2018, all of the outstanding shares of convertible preferred stock converted into 24.6 million shares of common stock. (d) Reverse Stock Split On April 12, 2018, the Company’s Board of Directors approved a one‑for‑five reverse stock split of its issued and outstanding shares of common and convertible preferred stock. The par value of the Company’s common stock and the par value of the Company’s convertible preferred stock were not adjusted as a result of the reverse stock split. Accordingly, all share and per share amounts for all periods presented in the accompanying financial statements and notes thereto have been retroactively adjusted, where applicable, to reflect the reverse stock split. The reverse stock split became effective on April 13, 2018. (e) Revenue Recognition Revenues are recognized when there is persuasive evidence of an arrangement, product delivery has occurred, the sales price is fixed or determinable, and collectability is reasonably assured. Title and risk of loss generally pass to the customer at the time of delivery of the product as indicated by the shipping terms. Revenues are recognized upon such delivery. In limited circumstances when customer‑specified acceptance criteria exist, revenue is deferred until customer acceptance if the Company cannot demonstrate the product meets the specifications prior to shipment. If installation is included with the sale of a product, installation revenues are deferred until installation is complete. Taxes collected on behalf of a governmental entity are excluded from revenues. The recognition of revenues on arrangements with multiple elements is consistent with guidance provided by FASB ASC Subtopic 605‑25, Revenue Recognition‑Multiple‑Element Arrangements . For arrangements with multiple elements, revenues are allocated across the separately identified deliverables and may be recognized or deferred. When vendor‑specific objective evidence does not exist for undelivered elements, revenues are allocated to the elements based on third‑party evidence, if available, or management’s best estimate of fair value. The Company also has a limited number of design and development contracts, principally with governmental customers, which are accounted for in accordance with the provisions of FASB ASC Subtopic 605‑35, Revenue Recognition‑Construction‑Type and Production‑Type Contracts , using the percentage‑of‑completion method. The Company utilizes a cost‑to‑cost methodology whereby it estimates the percent complete by calculating the ratio of costs incurred to the Company’s estimate of total anticipated costs. (f) Product Warranty The Company’s products are sold with warranty provisions that require the Company to remedy deficiencies in quality or performance over a specified period of time, generally three to 36 months, at no cost to its customers. A provision for the estimated future costs of warranty, based upon historical cost and product performance experience, is recorded when revenues are recognized. The following is a reconciliation of the changes in the aggregate product warranty accrual: Six Months Year Ended Ended December 31, (in thousands) June 30, 2018 2017 2016 (Unaudited) Product warranty accrual, beginning $ 4,186 $ 2,677 $ 1,691 Warranty charges incurred, net (1,335) (2,278) (1,789) Provision for warranty charges 1,773 3,787 2,775 Product warranty accrual, ending $ 4,624 $ 4,186 $ 2,677 Warranty costs are included in the consolidated statement of operations within the cost of revenues. The warranty accrual is presented in accrued liabilities and other long-term liabilities within the consolidated balance sheet. (g) Sales Returns and Allowances The Company’s customers generally do not have a stated right to return product except for replacement of defective products under the warranty program. However, the Company has accepted customer returns on a case‑by‑case basis as customer accommodations in the past. As a result, the Company provides for these returns in the reserves for sales returns and allowances. The reserve is estimated at the end of each reporting period based on historical experience and knowledge of any applicable events or transactions. The return reserve was $8 thousand and $75 thousand at December 31, 2017 and 2016, respectively and is presented as a reduction of accounts receivables in the consolidated financial statements. (h) Cash and Cash Equivalents The Company considers all highly liquid investments with a maturity of three months or less when acquired to be cash equivalents. Cash equivalents included $126 thousand and $58 thousand of highly liquid investments at December 31, 2017 and 2016, respectively. The Company maintains the majority of its cash balance at a financial institution in the United States, which it believes to be high‑credit quality financial institution with the Company’s balance often exceeding the insurance limit set by the Federal Deposit Insurance Corporation (FDIC) of $250 thousand per bank. The Company has not historically experienced any losses due to such concentration of credit risk. As of December 31, 2017, the balance of restricted cash was $55 thousand and consisted of surety bonds and performance guarantees in the United States. As of December 31, 2016 the balance of restricted cash was $776 thousand, including $721 thousand of frozen funds related to a customer non‑payment litigation in China that was released in July 2017 after conclusion of litigation. (i) Accounts Receivable Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The allowance for doubtful accounts is the Company’s best estimate of the amount of probable credit losses in the Company’s existing accounts receivable. The Company determines the allowance based on historical write-off experience and knowledge of any applicable circumstances. Activity related to the allowance for doubtful accounts was as follows: (in thousands) 2017 2016 Allowance for doubtful accounts, beginning $ 1,608 $ 1,477 Provision for bad debts 232 340 Write offs and recoveries (1,402) (82) Allowance for doubtful accounts, ending $ 438 $ 1,608 Included in the write offs and recoveries for 2017 is a $1.0 million recovery related to a receivable fully reserved in 2015 and included in the allowance for doubtful accounts in the consolidated financial statements as of December 31, 2016. The amount noted above was recovered in July 2017 after extensive litigation with the customer and was recognized as a reduction in bad debt expense within the sales, general and administrative caption on the consolidated statement of operations. The Company also received $175 thousand in interest income as a result of this litigation which the Company recognized within the interest expense, net caption in the consolidated statement of operations. (j) Inventory Inventory is stated at the lower of cost (average cost) or net realizable value. The Company periodically reviews the quantities and carrying values of its inventory to assess recoverability. The costs associated with write-downs for excess quantities, technological obsolescence, or component rejections are charged to cost of revenues as incurred and result in a new cost basis for that item in inventory. The components of inventory at June 30, 2018 and December 31, 2017 and 2016 are as follows: December 31, (in thousands) June 30, 2018 2017 2016 (Unaudited) Raw materials $ 13,499 $ 11,326 $ 7,705 Work in process and semi-finished goods 12,497 6,039 3,762 Finished goods 9,273 12,205 7,338 $ 35,269 $ 29,570 $ 18,805 (k) Risks and Uncertainties including Business and Credit Concentrations Financial instruments that potentially expose the Company to concentrations of credit risk consist principally of accounts receivable. Ten customers represented 71% (unaudited), 67% and 62% of accounts receivable at June 30, 2018 and December 31, 2017 and 2016, respectively. Seven of the ten customers were included in both December 31, 2017 and 2016. The Company generates a significant portion of its revenues from a relatively small number of customers. One customer accounted for 16% (unaudited) and 14% of revenues during the six months and twelve months ended June 30, 2018 and December 31, 2017, respectively. The same customer as well as an additional customer accounted for 11% and 10%, respectively, of revenues during the year ended December 31, 2016. Included in the consolidated balance sheets are the net assets of the Company’s foreign manufacturing operations located primarily in China which totaled approximately $14.3 million (unaudited), $13.3 million and $5.8 million at June 30, 2018 and December 31, 2017 and 2016, respectively. The market for the Company’s products is rapidly changing and evolving. The Company believes its future success will depend, in part, on its ability to increase sales of its existing products, penetrate new vertical markets, and to remain competitive in the marketplace. An inability of the Company to manage growth and generate increased demand for its products could have a material adverse impact on the Company’s financial position, results of operations and liquidity. It is the Company’s belief that existing cash resources will be sufficient to support operations and meet its debt service requirements at least through February 15, 2019, twelve months from the date on which the consolidated financial statements were available for issuance. (l) Property and Equipment Property and equipment are stated at cost. Improvements and replacements are capitalized. Repair and maintenance costs are expensed as incurred. Depreciation is computed using the straight-line method over the estimated useful life of each asset, generally two to 10 years. (m) Income Taxes The Company accounts for income taxes using the asset and liability approach under which deferred income taxes are provided based upon enacted tax laws and rates applicable to the periods in which taxes become payable. The Company recognizes the effect of income tax positions only if those positions are more likely than not of being sustained. Recognized income tax positions are measured at the largest amount that is greater than 50% likely to be realized. Changes in recognition or measurement are reflected in the period in which the change in judgment occurs. (n) Stock-Based Compensation Stock‑based compensation is recognized for the fair value of the portion of the award that is ultimately expected to vest and is recognized as expense over the requisite service period. The Company recognizes stock‑based compensation expense on a straight‑line basis. The fair value of options granted in 2017 was determined to be approximately $1.0 million. The expenses recognized in 2017 and 2016 were $369 thousand and $308 thousand, respectively. Employee and non‑employee stock options were granted by the Compensation Committee in 2016 on April 27, July 1, September 13, October 26, and December 31. In 2017, the Compensation Committee granted stock options on May 26, June 2, July 30, August 3, August 31, and December 14. For determining the fair value of stock options granted, the Company used the Black‑Scholes option pricing model with the following assumptions: 2017 2016 Expected volatility ‑ 40.1 % ‑ 40.9 % Expected option term ‑ 6.5 years ‑ 6.6 years Risk ‑ free interest rate ‑ 2.2 % ‑ 1.6 % Expected dividend yield None None Included in the option pricing model is the fair value of the underlying common stock at the time of grant. Determining the fair value of the Company’s common stock requires complex and subjective judgments and estimates. There is inherent uncertainty in making these judgments and estimates. The absence of an active market for the Company’s common stock required the board of directors to estimate the fair value of the common stock for purposes of setting the exercise price of the options and estimating the fair value of the common stock at each meeting at which options were granted based on a number of objective and subjective factors, including valuations of comparable companies, operating and financial performance, lack of liquidity of the common stock and general and industry‑specific economic outlook, among other factors. Since 2012, the Company has obtained valuations prepared by an independent third‑party valuation firm to assist in determining the fair market value of its common stock. The board of directors and management of the Company considered these valuation reports when determining the fair market value of the Company’s common stock and related option exercise price on the dates such awards were granted. The valuations determined as of the dates below are as follows: Fair Market Value November 13, 2014 $ 0.75 January 1, 2016 $ 1.10 May 1, 2017 $ 1.45 September 1, 2017 $ 6.65 The average expected option term for awards granted reflects the application of the simplified method. The simplified method is based on the vesting period and the contractual term for each grant. The midpoint between the vesting date and the expiration date is used as the expected term under this method. The Company uses the historical stock price volatility for comparable publicly‑traded competitors as the basis for its expected volatility assumption. The Company has assessed that the calculated volatility is representative of expected future stock price trends. The risk‑free interest rate assumption is based upon observed U.S. Treasury rates consistent with the expected term of the award. The dividend yield assumption is based on the Company’s history of no dividend payouts and an expectation that no dividends will be paid in the foreseeable future. The Company accounts for stock options issued to non‑employees in accordance with the provisions of FASB ASC Topic 718 and FASB ASC Subtopic 505‑50, Equity Based Payments to Non‑Employees . Under FASB ASC Topic 718 and FASB ASC Subtopic 505‑50, the Company uses the Black‑Scholes option pricing model to measure the fair value of stock options granted to non‑employees on the measurement date. (o) Research and Development Costs Research and development is defined as activities aimed at developing or significantly improving a product or a process or technique whether the product or process is intended for sale or use. A process also may be used internally as a part of a manufacturing activity. Research and development costs are expensed as incurred. (p) Principles of Consolidation The accompanying consolidated financial statements include the accounts of nLIGHT, Inc. and its wholly owned subsidiaries. The wholly owned subsidiaries are Arbor Photonics, LLC, nLIGHT Cayman Ltd., nLIGHT Laser Technology (Shanghai) Co. Ltd, nLIGHT Oy (Finland), and nLIGHT Korea Inc. All intercompany balances have been eliminated. (q) Impairment of Long-Lived Assets Long‑lived assets, such as property and equipment, and intangibles subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated future cash flows, an impairment charge is recognized for the amount by which the carrying amount of the asset exceeds the fair value of the asset. There was no impairment of long‑lived assets recorded for the years ended December 31, 2017 and 2016. (r) Commitments and Contingencies Liabilities for loss contingencies are recorded when it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. In July 2017, the Company received notification of a claim related to a quality dispute with a vendor alleging that the Company owed payment for future non-cancelable order quantities. The Company believes it is probable that a partial settlement of this claim will occur and recorded a $196 thousand liability related to this matter within the accrued liabilities on the consolidated balance sheet as of December 31, 2017. This amount remains outstanding as of June 30, 2018 (unaudited). In December 2013, the Company submitted a disclosure letter to the Office of the Inspector General of the Department of Defense advising that it might not have been eligible for certain contracts it was awarded under the Small Business Innovation Research (“SBIR”) Program, notwithstanding its prior representations that the Company was eligible. The matter was referred to the Small Business Administration and the US Department of Justice (“DOJ”) for investigation of potential violations of the False Claims Act. In March 2015, a civil settlement agreement related to the SBIR matter was signed. A liability of $420 thousand was recorded at December 31, 2014 and subsequently paid in full. In October 2014, the Company received a request for information related to the SBIR matter from the U.S. Attorney’s Office, Criminal Division. The Company provided documentation and an explanation of why a criminal investigation was unwarranted. In March 2015, the Company received an additional request, to which it also responded. Although the Company is unable to predict the final outcome of this matter, it intends to vigorously defend against any future claims. The Company becomes involved in various legal proceedings and claims incidental to normal business activities. As of June 30, 2018, the Company believes these matters will not have a material adverse effect on the consolidated financial statements. (s) Goodwill and Intangible Assets Goodwill and intangible assets with indefinite lives are not amortized; rather, they are tested for impairment on at least an annual basis. Intangible assets with finite lives are amortized over their useful lives. External costs incurred to file new patent applications, and extend the term of or defend the existing patents are capitalized and amortized over the estimated useful life. (t) Prepaid Expenses and Other Current Assets The components of prepaid expenses and other current assets at June 30, 2018 and December 31, 2017 and 2016 are as follows: December 31, (in thousands) June 30, 2018 2017 2016 (Unaudited) Prepaid expenses $ 2,617 $ 1,248 $ 769 Value ‑ added tax receivable, net 2,480 1,291 994 Vendor prepayments 1,154 1,391 1,117 Prepaid taxes and duties 2,049 946 413 Restricted cash — — 721 Other 63 97 103 $ 8,363 $ 4,973 $ 4,117 (u) Translation of Foreign Currencies The Company’s international subsidiaries use their local currency as their functional currency. The financial statements of the international subsidiaries are translated to their U.S. dollar equivalents at end‑of‑period currency exchange rates for assets and liabilities and at average currency exchange rates for revenues and expenses. Translation adjustments are recorded as a component of accumulated other comprehensive loss within stockholders’ equity. Realized and unrealized foreign currency gains or losses, net are recorded in other expense within the consolidated statement of operations. Realized and unrealized foreign currency losses were $0.9 million and $36 thousand, respectively, in the year ended December 31, 2017. Realized and unrealized foreign currency losses were $1.0 million and $53 thousand, respectively, in the year ended December 31, 2016. During the six months ended June 30, 2018 realized foreign currency gains were $533 thousand (unaudited) and unrealized foreign currency losses were $850 thousand. During the six months ended June 30, 2017 realized and unrealized foreign currency losses were $686 thousand (unaudited) and $96 thousand (unaudited), respectively. (v) Fair Value of Financial Instruments The carrying amounts of certain of the Company’s financial instruments, including cash equivalents, accounts receivable and accounts payable, are shown at cost which approximates fair value due to the short term nature of these instruments. The fair value of the Company’s term and revolving loans with Pacific Western Bank, also described in Note 8, approximates the carrying value due to the variable market rate used to calculate interest payments. The Company considers the fair value of its term loan with Multiplier Growth Partners SPV I, LP to be equal to the costs incurred to extinguish the liability subsequent to December 31, 2016. Refer to Note 8 for further information. The Company does not have any other significant financial assets or liabilities that are measured at fair value. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The standard describes a fair value hierarchy based on three levels of inputs, of which the first two are considered observable and the last unobservable, that may be used to measure fair value which are the following: Level 1 Inputs: Observable inputs, such as quoted prices (unadjusted) in active markets for identical assets or liabilities at the measurement date. Level 2 Inputs: Observable inputs, other than Level 1 prices, such as quoted prices in active markets for similar assets and liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 Inputs: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The Company’s financial instruments that are carried at fair value consist of Level 1 assets and Level 2 and Level 3 liabilities. Level 1 assets include highly liquid bank drafts classified as cash equivalents. Level 2 liabilities consist of the Company’s loan with Pacific Western Bank while Level 3 liabilities are the Company’s term loan with Multiplier Growth Partners SPV I, L.P. (w) Revision of Prior Period Financial Statement Disclosures Deferred income taxes and other adjustment to reconcile net income (loss) to net cash provided by operating activities has been corrected in the consolidated statements of cash flows to present deferred income taxes and the change in non-current income taxes payable separately. Amortization of debt issuance costs as disclosed in Note 8 has been corrected to $194 thousand from $108 thousand, for the year ended December 31, 2016. Stock options to purchase common stock disclosed in Note 14 have been corrected from being presented net under the treasury stock method to gross options outstanding. (x) Recently Issued Accounting Standards The FASB issued ASU No. 2014‑09, Revenue from Contracts with Customers, in May 2014. ASU 2014‑09 requires an entity to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The ASU No. 2014‑09 is effective for annual reporting periods beginning after December 15, 2018. The Company expects to implement the provisions of ASU 2014‑09 as of January 1, 2019. While the Company continues to assess the potential impacts of ASU 2014‑09, and anticipates ASU 2014‑09 could have an impact on the consolidated financial statements, the Company cannot reasonably estimate the quantitative impact on the financial statements at this time. The FASB issued ASU No. 2015‑11, Inventory (Topic 330): Simplifying the Measurement of Inventory, in July 2015. ASU 2015‑11 requires that inventory within the scope of this standard be measured at the lower of cost and net realizable value. Net realizable value is the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. The amendments in this update do not apply to inventory that is measured using last‑in, first‑out (LIFO) or the retail inventory method. The amendments apply to all other inventory, including inventory that is measured using first‑in, first‑out (FIFO) or average cost. ASU 2015‑11 is effective for the Company’s annual reporting periods beginning January 1, 2017. The adoption of the standard did not have a material impact on the consolidated financial statements, financial condition or results of operations. The FASB issued ASU No. 2016‑02, Leases (Topic 842), in February 2016. ASU 2016‑02 requires a lessee to recognize a right of use asset and a lease liability for virtually all leases, other than leases that meet the definition of short‑term. The standard is effective for annual reporting periods beginning after December 15, 2019. The Company expects to implement the provisions of ASU 2016‑02 as of January 1, 2020. The Company is currently evaluating the impact of this ASU and cannot reasonably estimate the quantitative impact on the financial statements at this time. The FASB issued ASU No. 2016‑09, Compensation‑Stock Compensation (Topic 842), in March 2016. ASU 2016‑09 amends the guidelines for share‑based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The standard is effective for annual and interim periods beginning January 1, 2018. The Company does not expect the implementation of this guidance to have a material impact on its consolidated financial statements. The FASB issued ASU No. 2016‑15, Classification of Certain Cash Receipts and Cash Payments (Topic 230), in August 2016. ASU 2016‑15 provides guidance on eight different issues, intended to reduce diversity in practice on how certain cash receipts and cash payments are presented and classified in the statement of cash flows. The standard is effective for annual and interim periods beginning January 1, 2019, and early adoption is permitted. The Company is currently evaluating the impact the adoption of this ASU; however the Company does not expect that the adoption of ASU 2016‑09 will have a material impact on its consolidated financial statements. The FASB issued ASU No. 2016‑16, Intra‑Entity Transfers of Assets Other Than Inventory (Topic 740), in November 2016. ASU 2016‑16 requires entities to recognize the current and deferred income taxes for an intra‑entity transfer of an asset other than inventory when the transfer occurs, as opposed to deferring the recognition of the income tax consequences until the asset has been sold to an outside party. The amendments in this ASU are effective for annual reporting periods beginning January 1, 2018, including interim reporting periods within those annual reporting periods. The amendments in this ASU should be applied on a modified retrospective basis through a cumulative‑effect adjustment directly to retained earnings as of the beginning of the period of adoption. The Company does not expect the adoption of the amendments in this ASU to have a material impact on the consolidated financial statements. The FASB issued ASU No. 2016‑18, Restricted Cash (Topic 230), in November 2016. ASU 2016‑18 requires entities to show the changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. As a result, entities will no longer present transfers between cash and cash equivalents and restricted cash and restricted cash equivalents in the statement of cash flows. The update amends the guidance in ASC 230, which is principles‑based and often requires judgment to determine the appropriate classification of cash flows as operating, investing or financing activities. The guidance is effective for annual and interim reporting periods beginning January 1, 2019, and requires retrospective application. Early adoption is permitted as of the beginning of an annual period. The Company does not expect the adoption to have a material impact on the consolidated financial statements. The FASB issued ASU No. 2017‑04, Simplifying the Test for Goodwill Impairment (Topic 350), in January 2017. ASU 2017‑04 simplifies the test for goodwill impairment and removes step 2 from the goodwill impairment test. Early adoption is permitted, but will be effective for annual or any interim goodwill impairment tests for fiscal years beginning January 1, 2020. The Company does not expect the adoption to have a material impact on the consolidated financial statements. The FASB issued ASU No. 2017‑11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), Derivatives and Hedging (Topic 815), in July 2017. ASU 2017‑11 was issued to address the complexity associated with applying U.S. GAAP for certain financial instruments with characteristics of liabilities and equity. The ASU, among other things, eliminates the need to consider the effects of down round features when analyzing convertible debt, warrants and other financial instruments. As a result, a freestanding equity‑linked financial feature (or embedded conversion option) no longer would be accounted for as a derivative liability at fair value as a result of the existence of a down round feature. The guidance is effective for annual and interim periods beginning January 1, 2019. The Company does not expect the adoption of this ASU to have a material impact on the consolidated financial statements. The SEC issued Staff Accounting Bulletin No. 118 in December 2017, which provides SEC staff guidance for the application of ASC Topic 740, Income Taxes, in the reporting period in which the 2017 Tax Act was signed into law. The Company applied the guidance for the purposes of the 2017 consolidated financial statements. Refer to Note 9 for further information.

Property and Equipment

Property and Equipment	6 Months Ended
	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
Property and Equipment	(3) Property and Equipment Property and equipment consisted of the following: Useful life As of June 30, As of December 31, (in thousands) (years) 2018 2017 2016 (Unaudited) Computer hardware and software 3 ‐ 5 $ 3,866 $ 3,732 $ 3,344 Manufacturing and lab equipment 2 ‐ 7 47,048 43,432 37,805 Office equipment and furniture 5 ‐ 7 1,122 1,053 942 Leasehold improvements 2 ‐ 12 18,987 18,580 18,299 71,023 66,797 60 Accumulated depreciation (51,495) (48,829) (43,067) $ 19,528 $ 17,968 $ 17,323 Total depreciation expense for the years ended December 31, 2017 and 2016 was $5.3 million and $5.4 million, respectively. Depreciation expense for the six months ended June 30, 2018 and 2017 was $2.9 million (unaudited) and $2.5 million (unaudited), respectively.

Intangible Assets and Goodwill

Intangible Assets and Goodwill	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets and Goodwill	(4) Intangible Assets and Goodwill (a) Intangibles Through the purchases of Liekki Oy and Arbor Photonics, Inc., intangible assets were acquired. In addition, the Company capitalizes certain patent expenses as disclosed in Note 2(s). The details of the intangibles are as follows: June 30, 2018 (Unaudited) Average Gross amortization carrying Accumulated (in thousands) (unaudited) period amount amortization Net value Amortizing intangible assets: Patents 5 yrs $ 4,163 $ (1,723) $ 2,440 Arbor acquired technology 3 yrs 670 (670) — Direct nanoparticle deposition technology 6 yrs 528 (528) — $ 5,361 $ (2,921) $ 2,440 December 31, 2017 Average Gross amortization carrying Accumulated (in thousands) period amount amortization Net value Amortizing intangible assets: Direct nanoparticle deposition technology 6 yrs $ 543 $ (543) $ — Patents 5 yrs 3,310 (1,474) 1,836 Arbor acquired technology 3 yrs 670 (670) — $ 4,523 $ (2,687) $ 1,836 December 31, 2016 Average Gross amortization carrying Accumulated (in thousands) period amount amortization Net value Amortizing intangible assets: Direct nanoparticle deposition technology 6 yrs $ 478 $ (478) $ — Patents 5 yrs 2,447 (962) 1,485 Arbor acquired technology 3 yrs 670 (670) — $ 3,595 $ (2,110) $ 1,485 During 2016 the Company evaluated the remaining useful life of the Arbor acquired technology, and revised the remaining period of amortization to one year. As a result, the asset was fully amortized as of December 31, 2016. Amortization expense for intangible assets was $472 thousand and $779 thousand for the years ended December 31, 2017 and 2016, respectively. Amortization expense for intangible assets was $259 thousand (unaudited) and $219 thousand (unaudited) for the six months ended June 30, 2018 and 2017, respectively. Estimated amortization expense for the remainder of 2018 and subsequent years is as follows: (in thousands) (unaudited) 2018 $ 344 2019 654 2020 581 2021 454 2022 309 Thereafter 98 $ 2,440 (b) Goodwill The Company’s goodwill originated with the acquisition of Arbor Photonics, Inc. in December 2012. The Company reviews its goodwill for impairment annually during the fourth quarter, or more frequently if events or circumstances indicate that the carrying value of a reporting unit exceeds its fair value. The Company completed its annual review of goodwill as of December 31, 2017 and determined that no impairment of its recorded goodwill was necessary. There were no changes in the carrying amount of goodwill during the years ended December 31, 2017 and 2016 or during the six months ended June 30, 2018 (unaudited).

Other Assets

Other Assets	6 Months Ended
	Jun. 30, 2018
Other Assets [Abstract]
Other Assets	(5) Other Assets Other assets consisted of the following: As of As of June 30, December 31, (in thousands) 2018 2017 2016 (Unaudited) Demonstration assets, net $ 2,410 $ 2,224 $ 2,981 Deferred tax assets, net 1,807 1,807 1,383 Other 427 343 381 $ 4,644 $ 4,374 $ 4,745 Demonstration (demo) assets are equipment that is used for demonstration and other purposes with existing and prospective customers. Demo assets are recorded at cost and amortized over an estimated useful life of two years. Amortization expense for demo assets totaled $2.1 million and $1.8 million for the years ended December 31, 2017 and 2016, respectively. Amortization expense was $938 thousand (unaudited) and $1.1 million (unaudited) for the six months ended June 30, 2018 and 2017, respectively.

Accrued Liabilities

Accrued Liabilities	6 Months Ended
	Jun. 30, 2018
Payables and Accruals [Abstract]
Accrued Liabilities	(6) Accrued Liabilities Accrued liabilities consisted of the following: As of June 30, As of December 31, (in thousands) 2018 2017 2016 (unaudited) Accrued payroll $ 6,495 $ 6,201 $ 5,075 Product warranty, current 3,480 3,589 2,146 Income tax payable 786 931 8 Other accrued expenses 1,157 1,929 1,118 $ 11,918 $ 12,650 $ 8,347

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	(7) Commitments The Company leases its facilities in Vancouver, Washington; Hillsboro, Oregon; China, Finland, and South Korea as well as certain equipment under operating leases that expire at various dates through 2024. The Company had deposits of $301 thousand and $235 thousand as of December 31, 2017 and 2016, respectively, relating primarily to rent deposits on the China and Vancouver, Washington facility leases. Rent expense, before sublease income, totaled $2.7 million and $2.5 million for the years ended December 31, 2017 and 2016, respectively. Sublease income totaled $86 thousand and $50 thousand for the years ended December 31, 2017 and 2016, respectively. The minimum future rent payments under noncancelable operating leases as of December 31, 2017 are as follows: (in thousands) 2018 $ 2,751 2019 1,907 2020 1,379 2021 1,383 2022 641 Thereafter 998 Total $ 9,059 Minimum rent payments under operating leases are recognized on a straight‑line basis over the term of the lease, including any periods of free rent. Deferred rent liability associated with operating leases was $254 thousand and $180 thousand as of December 31, 2017 and 2016, respectively. Lease Extension (Unaudited) On May 10, 2018, the Company entered into an amendment (the “Amendment”) to a lease covering a portion of its Vancouver, Washington office space and production facility. The Amendment extends the original term of the lease to July 31, 2025, with an option to renew for an additional five years. Total commitments under this lease extension are approximately $1.9 million and are not included in the minimum future rent payments table above.

Long-Term Debt

Long-Term Debt	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Long-Term Debt	(8) Long‑Term Debt Term and Revolving Loans In March 2018, the Company entered into an Amended and Restated Loan and Security Agreement with Pacific Western Bank (successor in interest to Square 1 Bank) (unaudited). The agreement amends and restates in its entirety the Company’s previous Loan and Security Agreement with Pacific Western Bank, dated March 13, 2014 (unaudited). The loan facility provides for up to $25.0 million in aggregate commitments, including a term loan of up to $15.0 million and a revolving loan facility equal to the lesser of (i) $25.0 million minus the unpaid principal amount of the term loan and the amount of any reserves for ancillary banking services, or (ii) a borrowing base equal to 85% of eligible accounts receivable plus the lesser of $5.5 million or 35% of eligible inventory. The principal amount of the term loan will be repaid in thirty‑six equal monthly installments beginning on July 14, 2018 with all outstanding principal and interest on the revolving loan due and payable on July 14, 2019. The term and revolving loans bear interest at a rate equal to the bank’s prime rate plus 0.50% per annum, subject to a floor of 5.00% per annum (unaudited). Interest is due and payable monthly in arrears. The Company’s loan with Pacific Western Bank is secured by liens, subject to certain exceptions, on substantially all of the Company’s existing and future assets, including but not limited to accounts receivable, inventory, property and equipment, and intellectual property. In relation to the Pacific Western Bank loan, the Company is required to comply with, among other covenants, a minimum revenue covenant and to stay below a maximum capital expenditure level. The Company was in compliance with all of its financial covenants as of June 30, 2018 (unaudited) and December 31, 2017. The term loan balance was $13.5 million at June 30, 2018 (unaudited) and December 31, 2017 and $17.9 million at December 31, 2016. The revolving loan balance was $3.7 million at June 30, 2018 and December 31, 2017 and $2.0 million at December 31, 2016, respectively. In 2015, the Company entered into a Loan and Security Agreement with Multiplier Growth Partners SPV I, LP, or Multiplier, agreeing to a term loan with a principal amount of up to $15.0 million, an interest rate of 11% per annum, and a maturity date of July 16, 2020. The initial borrowing consisted of $12.5 million in principal including $150 thousand in fees. In conjunction with the term loan, the Company granted a stock warrant to Multiplier, see Note 10 for details. In July 2017, and concurrent with the increase in the borrowing base of the Company’s loan facility with Pacific Western Bank noted above, the Company extinguished all debt outstanding with Multiplier. The transaction qualified as a debt extinguishment under FASB ASC Subtopic 470‑50, Debt , and a loss of $911 thousand, associated with an early prepayment penalty of $375 thousand, write‑down of debt issuance costs of $523 thousand, and other miscellaneous costs of $13 thousand, was recorded in other expense during the year ended December 31, 2017 as a result. Subordinated Finnish Capital Loans Under the Finnish Companies Act, companies may use a subordinated loan, referred to as a capital loan, which is subordinated to all other debts of a company. At the time of acquisition, Liekki Oy had three capital loans through Tekes, the Finnish Funding Agency for Technology and Innovation. The interest for these loans is Finnish State Bank prime rate minus 1% with a minimum of 3%. In accordance with the Finnish Companies Act, the loan principal and accrued interest became payable as the Finnish entity had a positive equity balance starting December 31, 2014. The payment schedule was adjusted annually based on the entity’s net income. The loans were paid in full as of December 31, 2016. Long‑term debt at June 30, 2018, December 31, 2017 and 2016 consists of the following: June 30, December 31, (in thousands) 2018 2017 2016 (Unaudited) 2014 Pacific Western Bank, Term and Revolving Loans $ 17,200 $ 17,200 $ 7,400 2015 Multiplier, Term Loan — — 12,512 2014 Finland equipment loans, Danske Bank, 3 - 5 year terms, EURIBOR plus 1.7% 60 80 104 Capital leases, various 149 191 236 Total debt 17,409 17,471 20,252 Less: debt issuance costs (15) — (571) Less: current portion of long-term debt (4,597) (2,363) (1,287) Noncurrent portion of long-term debt $ 12,797 $ 15,108 $ 18,380 Amortization of debt issuance costs was $96 thousand and $194 thousand for the years ended December 31, 2017 and 2016. Amortization of debt issuance costs was $3 thousand (unaudited) and $95 thousand (unaudited) for the six months ended June 30, 2018 and 2017, respectively. The Company has minimum payment schedules as of December 31, 2017 that call for future principal payments summarized as follows: (in thousands) 2018 $ 2,363 2019 15,061 2020 47 $ 17,471

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2018
Income Taxes
Income Taxes	(9) Income Taxes In December 2017, the Tax Cuts and Jobs Act (2017 Tax Act) was enacted. The 2017 Tax Act includes a number of changes to existing U.S. tax laws that impact the Company, most notably a reduction of the U.S. corporate income tax rate from 34% to 21% for tax years beginning after December 31, 2017. The 2017 Tax Act also provides for a one‑time transition tax on certain foreign earnings and the acceleration of depreciation for certain assets placed into service after September 27, 2017 as well as prospective changes beginning in 2018, including repeal of the domestic manufacturing deduction, acceleration of tax revenue recognition, capitalization of research and development expenditures, additional limitations on executive compensation and limitations on the deductibility of interest. The Company recognized the income tax effects of the 2017 Tax Act in its 2017 financial statements in accordance with Staff Accounting Bulletin No. 118, which provides SEC staff guidance for the application of ASC Topic 740, Income Taxes , in the reporting period in which the 2017 Tax Act was signed into law. As such, the Company’s financial results reflect the income tax effects of the 2017 Tax Act for which the accounting under ASC Topic 740 is complete and provisional amounts for those specific income tax effects of the 2017 Tax Act for which the accounting under ASC Topic 740 is incomplete but a reasonable estimate could be determined. The changes to existing U.S. tax laws as a result of the 2017 Tax Act, which we believe have the most significant impact on the Company’s federal income taxes are as follows: Reduction of the U.S. Corporate Income Tax Rate The Company measures deferred tax assets and liabilities using enacted tax rates that will apply in the years in which the temporary differences are expected to be recovered or paid. Accordingly, the Company’s deferred tax assets and liabilities were remeasured to reflect the reduction in the U.S. corporate income tax rate from 34% to 21%, resulting in a $16.1 million increase in income tax expense for the year ended December 31, 2017 and a corresponding decrease in net deferred tax assets as of December 31, 2017. These adjustments were fully offset with a corresponding adjustment to the valuation allowance. Transition Tax on Foreign Earnings The Company recognized a provisional income tax expense of $1.1 million for the year ended December 31, 2017 related to the one‑time transition tax on certain foreign earnings. This resulted in a corresponding decrease in deferred tax assets due to the utilization of net operating loss carryforwards. The final determination of the transition tax requires further analysis regarding the amount and composition of the Company’s historical foreign earnings, and is expected to be completed during the year ending December 31, 2018. Net income (loss) before income tax expense for the years ended December 31 was as follows: (in thousands) 2017 2016 Domestic $ (9,064) $ (19,006) Foreign 15,759 6,686 Net income (loss) before income tax $ 6,695 $ (12,320) Income tax provision for the year ended December 31 was as follows: (in thousands) 2017 2016 Current tax expense: Federal $ — $ — State — 8 Foreign 5,200 1,632 Current tax expense 5,200 1,640 Deferred tax expense Federal — — State — — Foreign (342) 242 Deferred tax expense (342) 242 Income tax expense $ 4,858 $ 1,882 The income tax provision differs from the amount computed by applying the statutory federal income tax rate to the loss before income tax as a result of the following differences: (in thousands) 2017 2016 Tax computed at federal statutory rate $ 2,276 $ (4,189) State tax, net of federal tax benefit (102) (125) Permanent items 1,078 662 Foreign dividends and unremitted earnings 796 586 Foreign rate differential (1,897) (991) Rate change due to tax reform 17,176 — Federal credits (302) (363) Tax contingencies, net of reversals 592 663 Other 109 302 Valuation allowance (14,868) 5,337 Income tax expense $ 4,858 $ 1,882 The income tax expense recorded for 2017 and 2016 primarily relates to operations in China and Finland, which have income tax rates of 25% and 20%, respectively. The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and deferred tax liabilities at December 31, 2017 and 2016 are approximately as follows: (in thousands) 2017 2016 Deferred tax assets: Net operating loss carryforwards $ 21,626 $ 35,803 Research and alternative minimum tax credits 3,635 3,373 Accrued expenses and other 1,891 2,466 Inventory 2,280 2,155 Property and equipment 1,644 2,351 Total gross deferred tax assets 31,076 46,148 Less valuation allowance (28,873) (43,741) Total deferred tax assets 2,203 2,407 Deferred tax liabilities Intangible assets (396) (503) Unremitted foreign earnings — (521) Total deferred tax liabilities (396) (1,024) Net deferred tax assets $ 1,807 $ 1,383 Net deferred tax assets of $1.8 million and $1.4 million as of December 31, 2017 and 2016, respectively, are included in other assets within the consolidated balance sheet. In evaluating its valuation allowance, the Company considers all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax planning strategies, and recent financial performance. Due to uncertainty with respect to ultimate realizability of deferred tax assets, the Company has provided a valuation allowance against the U.S. deferred tax assets. The net change in the total valuation allowance during the years ended December 31, 2017 and 2016 was a decrease of $14.9 million and an increase of $5.3 million, respectively. At December 31, 2017, the Company has U.S. and state net operating loss carryforwards of $104.5 million and $13.7 million, respectively. These net operating losses will expire between 2020 and 2037 if not used by the Company to reduce income taxes payable in future periods. The Company has U.S. and state research and development credits of $4.2 million and $59 thousand, respectively. These credits will begin to expire between 2018 and 2037 if not used by the Company to reduce income taxes payable in future periods. Utilization of net operating loss carryforwards, credit carryforwards and certain deductions have been subject to annual limitations due to ownership change limitations provided by the Internal Revenue Code of 1986, as amended, and similar state provisions. Under Sections 382 and 383 of the Internal Revenue Code of 1986, as amended, substantial changes in the Company’s ownership have required the Company to limit the amount of net operating loss and research and development credit carryforwards that were previously available to offset future taxable income. The Company has had three “change in ownership” events that limit the utilization of net operating loss carryforwards. The “change in ownership” events occurred twice in August of 2000 and in January of 2001, and resulted in net operating loss carryforward limitations of $17 thousand, $52 thousand, and $459 thousand. Additional limitations on the use of these tax attributes could occur in the event of possible disputes arising in examination from various taxing authorities. The following table presents a reconciliation of the changes in the unrecognized tax benefit: (in thousands) Balance at December 31, 2015 $ 1,528 Additions based on tax positions related to the current year 570 Additions for tax positions of prior years 3 Other (51) Balance at December 31, 2016 $ 2,050 Additions based on tax positions related to the current year 365 Additions for tax positions of prior years 99 Other 3 Balance at December 31, 2017 $ 2,517 At December 31, 2017, the Company has recognized $1.5 million unrecognized tax benefits in non‑current income taxes payable and $1.0 million of unrecognized tax benefits in noncurrent deferred tax assets on the accompanying consolidated balance sheet. $2.5 million of the Company’s unrecognized tax benefits, if recognized, would impact the effective tax rate. At December 31, 2016, the Company has recorded $1.3 million of unrecognized tax benefits in non‑current income taxes payable and $759 thousand of unrecognized tax benefits recognized as an offset to noncurrent deferred tax assets on the accompanying consolidated balance sheet. The Company does not expect a significant decrease to the total amount of unrecognized tax benefits within the next twelve months. The Company will recognize interest and penalties related to unrecognized tax benefits as a component of income tax expense. The Company has recognized penalties and interest during the years ended December 31, 2017 and 2016, of $367 thousand and $145 thousand, respectively. At December 31, 2017 and 2016 interest and penalties associated with unrecognized tax benefits were $939 thousand and $572 thousand, respectively. In addition, the Company recorded a tax benefit of $127 thousand and $75 thousand related to foreign currency translation adjustments during the year ended December 31, 2017 and 2016, respectively. At December 31, 2017, the Company’s tax years 2014 through 2017, 2013 through 2017, and 2007 through 2017, remain open for examination in the federal, state and foreign jurisdictions, respectively. However, to the extent allowed by law, the taxing authorities may have the right to examine prior periods where net operating losses and credits were generated and carried forward, and to make adjustments up to the net operating loss and credit carryforward amounts. The Company is not currently under federal, state, or foreign examination.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Shareholders' Equity	(10) Stockholders’ Equity (a) Authorized Shares As of June 30, 2018 and December 31, 2017 and 2016, the Company was authorized to issue a total of 190.0 million (unaudited), 319.5 million and 250.3 million shares respectively, with a par value of $0.0001 per share. (b) Preferred Stock (unaudited) In April 2018, the Company’s Board of Directors approved an increase to the amount of authorized preferred stock to become effective on the closing of the Company’s IPO. As of June 30, 2018 there were 5.0 million shares of preferred stock, par value $0.0001, authorized and no shares of preferred stock issues and outstanding. (c) Common Stock At June 30, 2018, December 31, 2017 and 2016 there were 34.8 million (unaudited), 3.0 million and 2.5 million shares of common stock issued and outstanding. (d) Series A and Series B Convertible Preferred Stock In August and November 2000, the Company sold a total of 1.8 million shares of Series A convertible preferred stock at $5.15 per share to investors. In January 2001, the Company sold an additional 40 thousand shares of Series A convertible preferred stock for the same price. In January 2001, the Company sold 3.3 million shares of its Series B convertible preferred stock for $13.30 per share to investors. All of the outstanding shares of Series A convertible preferred stock and Series B convertible preferred stock were converted to Series C convertible preferred stock and common stock in 2004. (e) Series C, Series D, Series E, Series F and Series G Convertible Preferred Stock In January, March, and October 2004, the Company sold a total of 1.6 million shares of Series C convertible preferred stock at $8.490 per share to investors for a net consideration of $13.1 million (net of offering costs of $129 thousand). Holders of Series A and Series B convertible preferred stock were provided an opportunity to participate in the Series C convertible preferred stock financing. Those investors that elected to participate in the Series C convertible preferred stock financing exchanged their Series A convertible preferred stock and Series B convertible preferred stock for a total of 3.0 million shares of Series C convertible preferred stock. All remaining shares of Series A and Series B convertible preferred stock were converted to common stock on a one‑for‑one basis. At June 30, 2018 there were zero shares (unaudited) of Series C convertible preferred stock issued and outstanding. At December 31, 2017 and 2016 there were 4.6 million shares of Series C convertible preferred stock issued and outstanding. In March and May 2007, the Company sold a total of 3.3 million shares of Series D convertible preferred stock at $4.590 per share to investors for a net consideration of $15.2 million (net of offering costs of $14 thousand). In January and June 2009, the Company sold a total of 2.3 million shares of Series D convertible preferred stock at $4.590 per share to investors for a net consideration of $10.7 million (net of offering costs of $55 thousand). At June 30, 2018 there were zero shares (unaudited) of Series D convertible preferred stock issued and outstanding. At December 31, 2017 and 2016 there were 5.7 million shares of Series D convertible preferred stock issued and outstanding. In February and July 2011, the Company sold a total of 2.3 million shares of Series E convertible preferred stock at $7.4695 per share to investors for a net consideration of $17.4 million (net of offering costs of $135 thousand). At June 30, 2018 there were zero shares (unaudited) of Series E convertible preferred stock issued and outstanding. At December 31, 2017 and 2016 there were 2.3 million shares of Series E convertible preferred stock issued and outstanding. In November 2014, the Company sold a total of 1.0 million shares of Series F convertible preferred stock at $5.145 per share to investors for a net consideration of $4.9 million (net of offering costs of $127 thousand). In January and April 2015, the Company sold a total of 4.0 million shares of Series F convertible preferred stock at $5.145 per share to investors for a net consideration of $20.3 million (net of offering costs of $71 thousand). In January and February 2016, the Company sold a total of 2.3 million shares of Series F convertible preferred stock at $5.145 per share to investors for a net consideration of $12.0 million (net of offering costs of $36 thousand). At June 30, 2018 there were zero shares (unaudited) of Series F convertible preferred stock issued and outstanding. At December 31, 2017 and 2016 there were 7.3 million shares of Series F convertible preferred stock issued and outstanding. In April and May 2017, the Company sold a total of 4.8 million shares of Series G convertible preferred stock at $5.9885 per share to investors for a gross consideration of $28.8 million. Total offering costs incurred in connection with the financing were $1.3 million, of which $45 thousand was incurred in 2016. At June 30, 2018 there were zero shares (unaudited) of Series G convertible preferred stock issued and outstanding. At December 31, 2017 and 2016 there were 4.8 million and no shares of Series G convertible preferred stock issued and outstanding, respectively. The rights and privileges of the Series C, Series D, Series E, Series F, and Series G convertible preferred stock are as follows: Dividends The holders of shares of Series F and Series G convertible preferred stock are entitled to receive dividends out of any assets legally available in preference to any declaration or payment of any dividend on the Series C, Series D, or Series E convertible preferred stock or common stock. The dividend rate for the Series F and Series G convertible preferred stock is equal to $0.206 and $0.240 per annum (as adjusted for any stock splits, stock dividends or distributions, recapitalizations, and similar events) on each outstanding share of Series G and Series F convertible preferred stock, respectively. The holders of Series C convertible preferred stock, Series D convertible preferred stock and Series E convertible preferred stock are entitled to receive dividends payable out of any assets legally available in preference to any declaration or payment of any dividend (payable other than in common stock or other securities and rights convertible into or entitling the holder thereof to receive, directly or indirectly, additional shares of common stock) on the common stock, at the rate of $0.340, in the case of the Series C convertible preferred stock, $0.184 in the case of the Series D convertible preferred stock, and $0.300 in the case of the Series E convertible preferred stock, per share per annum (as adjusted for any stock splits, stock dividends or distributions, recapitalizations, and similar events) on the preferred stock, payable annually. Such dividends are payable only if declared by the board of directors, and are not cumulative. As of June 30, 2018 no dividends have been declared (unaudited). Liquidation Preference In the event of liquidation the holders of Series F and Series G convertible preferred stock will be entitled to receive, in preference to the holders of Series C, D, and E convertible preferred stock and the holders of common stock, a per share amount equal to $5.145 and $5.9885, respectively, plus any declared but unpaid dividends. Upon the completion of distribution to holders of Series G and Series F convertible preferred stock, the holders of Series C, D, and E convertible preferred stock will be entitled to receive, in preference to the holders of common stock, a per share amount equal to $8.490, $4.590, and $7.469, respectively, plus any declared but unpaid dividends. After payment of the Liquidation Preference to the holders of Series C, D, and E convertible preferred stock, any remaining assets of the Company legally available for distribution to stockholders will be distributed among the holders of common stock on a pro‑rata basis. As of December 31, the aggregate liquidation preference to the preferred stockholders was as follows: (in thousands) 2017 2016 Series C $ 38,819 $ 38,819 Series D 25,980 25,980 Series E 17,536 17,536 Series F 37,334 37,334 Series G 28,783 — $ 148,452 $ 119,669 Conversion Each share of Series C, D, E, F and G convertible preferred stock is convertible, at the option of the holder, at any time into shares of the Company’s common stock. Each share of Series C, D, E, F and G convertible preferred stock is initially convertible into one share of the Company’s common stock. Shares of Series C, D, E, F and G convertible preferred stock automatically convert to shares of common stock upon the earlier of an initial public offering of the Company’s equity securities of not less than $7.185 per share and gross aggregate cash proceeds of $50.0 million or the written consent of the holders of a majority of the then‑outstanding shares of convertible preferred stock, voting together as a single class on an as‑converted basis, and the holders of a majority of the then‑outstanding shares of Series G convertible preferred stock, voting together as a separate class. Voting Rights The holders of each share of Series C, D, E, F and G convertible preferred stock are entitled to a number of votes equal to the number of shares of common stock into which such shares could be converted. In addition, the consent of the holders of a majority of the convertible preferred stock, voting as a separate class, is required for certain corporate actions. The holders of Series E, F and G convertible preferred stock have additional voting rights, which require the consent of the holders of a majority of the then‑outstanding shares of Series E, F or G convertible preferred stock, each voting as a separate class, to consent to certain corporate actions as the case may be. Warrants In conjunction with the Loan and Security Agreement with Pacific Western Bank, the Company granted 20 thousand warrants to purchase Series E convertible preferred stock at an exercise price of $7.4695 per share in 2014. The warrants expire on March 13, 2024. The fair value of the warrants was recorded as a debt discount and was not material to the consolidated financial statements. In conjunction with the Loan and Security Agreement with Multiplier, the Company granted 194 thousand warrants to purchase Series F convertible preferred stock at an exercise price of $5.145 per share in 2015. The warrants expire on July 16, 2025. The warrants were measured at fair value using the Black‑Scholes option pricing model, with assumptions of expected term of five years, volatility of 39.0%, and risk free rate of 1.7%. The relative fair value of the warrants of $360 thousand was accounted for as debt discount, and was initially included in debt issuance costs before being expensed in the current year as a result of the debt extinguishment described in Note 8. The warrant was net settled and 15 thousand shares were issued on May 2018 (unaudited). (f) 2000, 2001 and 2018 Stock Plans On August 29, 2000, the board of directors adopted the 2000 Stock Plan (the 2000 Plan). As of December 31, 2000, the Company had reserved 17.2 million shares of common stock for issuance under the 2000 Plan to employees, directors, and consultants of the Company. The Company is no longer issuing options under the 2000 Plan. On April 24, 2001, the board of directors adopted the 2001 Stock Option Plan (the 2001 Plan). Under the 2001 Plan, either incentive or nonqualified options to purchase the Company’s common stock may be granted at prices determined by the board of directors. Options granted under the 2001 Plan typically vest over 4 ‑ 5 years and have terms of up to 10 years from the date of grant. All vested options must be exercised within three months of termination of employment. In April 2018, the Board of Directors adopted the 2018 Plan, which stockholders approved in April 2018 (unaudited). The 2018 Plan became effective on April 24, 2018, the effective date of the Company’s IPO, and serves as the successor to the 2001 Plan (unaudited). There are no shares reserved for future awards under the 2001 Plan (unaudited). Outstanding awards under the 2001 Plan continue to be subject to the terms and conditions of the 2001 Plan (unaudited). In April 2018, the Company adopted the 2018 Plan with a reserve of 3.4 million shares of common stock for issuance under the 2018 Plan, plus, on and after the effective date of the 2018 Plan, shares subject to awards under the 2001 Plan that, on or after the termination of the 2001 Plan, expire or terminate and shares previously issued pursuant to the 2001 Plan, as applicable, that, on or after the termination of the 2001 Plan, are forfeited or repurchased by the Company (provided that the maximum number of shares that may be added to the 2018 Plan from the 2001 plan is 5.6 million shares) (unaudited). The number of shares reserved for issuance under the 2018 Plan will increase automatically on the first day of January of each calendar year during the term of the 2018 Plan by a number of shares of common stock equal to the lesser of (i) 5% of the total outstanding shares of the Company’s common stock as of the immediately preceding December 31st or (ii) a number of shares determined by the Board of Directors (unaudited). As of June 30, 2018, December 31, 2017 and December 31, 2016 the Company had reserved 9.0 million, 9.0 million and 6.3 million shares of common stock for issuance under the two plans to employees, directors, and consultants of the Company. Of these shares, a total of 2.9 million (unaudited), 1.7 million and 149 thousand shares, respectively were available for issuance as of June 30, 2018, December 31, 2017 and 2016. The following table summarizes the Company’s stock option activity: Weighted average Weighted remaining average contractual Aggregate Number exercise term intrinsic (in thousands) of shares price (years) value Outstanding, December 31, 2016 4,602 $ 0.87 8.2 $ 1,214 Options granted 1,458 $ 1.69 Options exercised (440) $ 0.76 Options canceled (251) $ 1.15 Outstanding, December 31, 2017 5,369 $ 1.09 7.4 $ 29,863 Options granted (unaudited) 357 $ 9.71 Options exercised (unaudited) (141) $ 0.88 Options canceled (unaudited) (18) $ 1.50 Outstanding, June 30, 2018 (unaudited) 5,567 $ 1.65 7.2 $ 174,883 Options exercisable at June 30, 2018 (unaudited) 2,707 $ 0.88 6.6 $ 87,093 Options vested as of June 30, 2018 and expected to vest after June 30, 2018 (unaudited) 4,624 $ 1.65 7.7 $ 145,939 The aggregate intrinsic value in the table above represents the total pretax value, based on the Company’s closing value of $33.06 at June 30, 2018 that would have been received by the option holders had all option holders exercised their in‑the‑money options on June 30, 2018 (unaudited). Total intrinsic value of options exercised for the six months ended June 30, 2018 and 2017 was $1.9 million (unaudited) and $38 thousand (unaudited), respectively. Total intrinsic value for the years ended December 31, 2017 and 2016 was $751 thousand and $32 thousand, respectively. Restricted stock award activity during the six months ended June 30, 2018 was as follows: Weighted Number of average restricted grant date (in thousands) stock awards fair value Outstanding, December 31, 2017 — $ — Awards granted (unaudited) 115 $ 37.15 Awards vested (unaudited) — $ — Awards canceled (unaudited) — $ — Outstanding, June 30, 2018 (unaudited) 115 $ 37.15 Restricted stock unit activity during the six months ended June 30, 2018 was as follows: Weighted Number of average restricted grant date (in thousands) stock units fair value Outstanding, December 31, 2017 — $ — Units granted (unaudited) 443 $ 36.28 Units vested (unaudited) — $ — Units canceled (unaudited) — $ — Outstanding, June 30, 2018 (unaudited) 443 $ 36.28 Of the 558 thousand non‑vested restricted stock awards and restricted stock units outstanding under the 2018 Plan as of June 30, 2018, 206 thousand awards represent the expected number of awards whereby vesting is contingent on meeting certain performance conditions (unaudited). Total compensation cost related to nonvested options, restricted stock units and restricted stock awards not yet recognized is $22.8 million (unaudited), which will be recognized during the remainder of 2018 and subsequent years as follows: (in thousands) (unaudited) 2018 $ 3,683 2019 7,023 2020 6,051 2021 4,344 2022 1,652 2023 9 $ 22,762 (g) 2018 Employee Stock Purchase Plan (unaudited) The Company’s Employee Stock Purchase Plan, or 2018 ESPP, became effective on April 24, 2018. A total of 0.9 million shares of common stock are available for sale under the ESPP. The number of shares of common stock that are available for sale under the ESPP also includes an annual increase on the first day of each fiscal year following the fiscal year in which the first offering period enrollment date (if any) occurs, equal to the least of: 0.9 million shares; two percent 2% of the outstanding shares of common stock as of the last day of the immediately preceding fiscal year; or such other amount as the administrator may determine. No offerings have been authorized to date by the Board of Directors under the 2018 ESPP.

401(k) Plan

401(k) Plan	6 Months Ended
	Jun. 30, 2018
Retirement Benefits [Abstract]
401(k) Plan	(11) 401(k) Plan The Company has a 401(k) Profit Sharing Plan and Trust (the Plan). Participation in the Plan is voluntary and is available to all employees. Employees are eligible to participate in the Plan on the first day of the month after their first day of employment. Participants may elect to contribute part of their annual salary to the Plan up to the statutorily prescribed limit. The Company may make discretionary matching or qualified nonelective contributions to the Plan. The Company maintains a match of 40% of each dollar up to the first 5% of compensation that is contributed to the Plan. The match for the years ended December 31, 2017 and 2016 was $462 thousand and $376 thousand, respectively.

Related-Party Transactions

Related-Party Transactions	6 Months Ended
	Jun. 30, 2018
Related Party Transactions [Abstract]
Related-Party Transactions	(12) Related‑Party Transactions The Company has incurred costs related to consulting services provided by a member of the board of directors of $102 thousand and $54 thousand during the years ended December 31, 2017 and 2016 and $80 thousand (unaudited) for the six months ended June 30, 2018, respectively. These costs were included in sales, general and administrative expense on the consolidated statement of operations. As of December 31, 2017 and 2016, a customer owned 1.1 million and 1.2 million shares of Series E preferred stock, respectively. There was $1.3 million of revenue recognized related to this customer in the year ended December 31, 2017. The Company recognized $1.4 million of revenue directly related to this customer in the year ended December 31, 2016. As of December 31, 2017 and 2016, there was a balance of accounts receivable related to the above of $1 thousand and zero, respectively.

Segment and Geographic Informat

Segment and Geographic Information	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment and Geographic Information	(13) Segment and Geographic Information The Company operates in one segment which involves the design, development, production and distribution of fiber lasers, semiconductor lasers, and other related products. Our chief operating decision‑maker (CODM) is our Chief Executive Officer. The CODM regularly reviews financial information presented on a total company basis, accompanied by information about revenue and direct costs by product family for purposes of monitoring our product mix impact on total gross margin. Throughout the year, the CODM allocates capital resources on a project‑by‑project basis across the Company’s entire asset base to maximize profitability regardless of the legal entity, product or end market basis. The Company markets and sells its products throughout the world through both direct sales and distribution channels. For the years ended December 31 and six months ended June 30, 2018, the geographic sources of the Company’s revenues based on the customer’s location are as follows: Six Months Ended Year Ended June 30, December 31, (in thousands) 2018 2017 2017 2016 (Unaudited) China $ 38,793 $ 26,843 $ 55,344 $ 38,309 North America 32,551 19,939 46,489 36,200 Other 22,828 17,769 36,747 26,816 $ 94,172 $ 64,551 $ 138,580 $ 101,325 The geographic locations of the Company’s long‑lived assets, net, based on location of the assets, as of June 30, 2018 and December 31, 2017 and December 31, 2016 are as follows: June 30, December 31, (in thousands) 2018 2017 2016 (Unaudited) United States $ 16,228 $ 13,991 $ 13,811 China 8,691 8,433 8,341 Other 847 991 1,053 $ 25,766 $ 23,415 $ 23,205

Net Income (Loss) per Share

Net Income (Loss) per Share	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Net Income (Loss) per Share	(14) Net Income (Loss) per Share Net income (loss) per share is presented in conformity with the two‑class method required for multiple classes of common stock and participating securities. The participating securities include Series C, D, E, F and G convertible preferred stock, as the holders of these series of preferred stock are entitled to receive a noncumulative dividend in preference to the common stockholders in the event that a dividend is declared on common stock. In the year ended December 31, 2017 the amount of income generated by the Company was less than the stated annual dividend amount that would have been allocated to the preferred stockholders in the event that a dividend had been declared and thus no income has been allocated to the common stockholders. The holders of Series C, D, E, F and G preferred stock do not have a contractual obligation to share in the losses. As such, net loss for the six months ended June 30, 2017 and year ended December 31, 2016 was not allocated to these participating securities. The convertible preferred stock converted to common stock upon the closing of the Company’s IPO on April 30, 2018 (unaudited). As such only the income earned during the period prior to their conversion is allocated to these shares during the six months ended June 30, 2018 (unaudited). Basic income (loss) per share is computed using the weighted average number of common shares outstanding during the period, and excludes any dilutive effects of common stock equivalent shares such as stock options, restricted stock, warrants, and convertible preferred stock. Diluted income (loss) per share is computed using the weighted average number of common shares outstanding and potentially dilutive common stock options, restricted stock, warrants, and convertible preferred stock. The following table sets forth the calculation of basic and diluted net income (loss) per share attributable to common stockholders during the periods presented: Six Months Ended Year Ended June 30, December 31, (in thousands, except per share data) 2018 2017 2017 2016 (Unaudited) Numerator: Net income (loss) $ 7,569 $ (1,500) $ 1,837 $ (14,202) Participating securities: Income allocated to preferred stockholders (4,415) — (1,837) — Net income (loss) attributable to common stockholders 3,154 (1,500) - (14,202) Denominator: Weighted-average shares, basic 13,761 2,613 2,735 2,500 Dilutive effect of warrant 137 — — — Dilutive effect of restricted stock units and awards 1 — — — Dilutive effect of common stock options 4,898 — — — Weighted-average common shares outstanding, diluted 18,797 2,613 2,735 2,500 Net income (loss) per share attributable to common stockholders: Basic $ 0.23 $ (0.57) $ — $ (5.68) Diluted $ 0.17 $ (0.57) $ — $ (5.68) The following potentially dilutive shares of convertible preferred stock, preferred stock warrants, restricted stock awards and units, and stock options were not included in the calculation of diluted shares above as the effect would have been anti‑dilutive: Six Months Ended Year Ended June 30, December 31, (in thousands) 2018 2017 2017 2016 (Unaudited) Convertible preferred stock — 24,642 23,095 19,774 Preferred stock warrants — 214 214 214 Restricted stock units and awards 541 — — — Stock options to purchase common stock — 5,150 5,369 4,602 Total 541 30,006 28,678 24,590

Summary of Significant Accoun22

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2018
Summary of Significant Accounting Policies
Use of Estimates	(a) Use of Estimates The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates, including those related to inventory valuation, allowances for doubtful accounts, warranty, sales return reserves and the recoverability of long‑lived assets. Management of the Company bases its estimates on historical experience and on various other assumptions. Actual results could differ from those estimates.
Unaudited Interim Financial Information	(b) Unaudited Interim Financial Information The accompanying interim consolidated balance sheet as of June 30, 2018, the interim consolidated statements of operations, comprehensive income and cash flows for the six months ended June 30, 2017 and 2018 and the interim consolidated statement of stockholders’ equity for the six months ended June 30, 2018 are unaudited. The financial data and information disclosed in these notes to the consolidated financial statements related to that date and these periods are also unaudited. The unaudited interim consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly our financial position as of June 30, 2018 and the results of our operations and cash flows for the six months ended June 30, 2017 and 2018. The consolidated results of operations for the six months ended June 30, 2018 are not necessarily indicative of the results to be expected for the entire year ending December 31, 2018, or for any other future annual or interim period.
Initial Public Offering	(c) Initial Public Offering (unaudited) On April 30, 2018, the Company closed its IPO of 6.9 million shares of common stock at an initial price to the public of $16.00 per share, including 0.9 million shares of common stock pursuant to the exercise in full of the underwriters’ option to purchase additional shares, resulting in aggregate estimated net proceeds to the Company of $100.2 million after deducting underwriting discounts and commissions and offering costs. Immediately prior to the closing of the IPO on April 30, 2018, all of the outstanding shares of convertible preferred stock converted into 24.6 million shares of common stock.
Reverse Stock Split	(d) Reverse Stock Split On April 12, 2018, the Company’s Board of Directors approved a one‑for‑five reverse stock split of its issued and outstanding shares of common and convertible preferred stock. The par value of the Company’s common stock and the par value of the Company’s convertible preferred stock were not adjusted as a result of the reverse stock split. Accordingly, all share and per share amounts for all periods presented in the accompanying financial statements and notes thereto have been retroactively adjusted, where applicable, to reflect the reverse stock split. The reverse stock split became effective on April 13, 2018.
Revenue Recognition	(e) Revenue Recognition Revenues are recognized when there is persuasive evidence of an arrangement, product delivery has occurred, the sales price is fixed or determinable, and collectability is reasonably assured. Title and risk of loss generally pass to the customer at the time of delivery of the product as indicated by the shipping terms. Revenues are recognized upon such delivery. In limited circumstances when customer‑specified acceptance criteria exist, revenue is deferred until customer acceptance if the Company cannot demonstrate the product meets the specifications prior to shipment. If installation is included with the sale of a product, installation revenues are deferred until installation is complete. Taxes collected on behalf of a governmental entity are excluded from revenues. The recognition of revenues on arrangements with multiple elements is consistent with guidance provided by FASB ASC Subtopic 605‑25, Revenue Recognition‑Multiple‑Element Arrangements . For arrangements with multiple elements, revenues are allocated across the separately identified deliverables and may be recognized or deferred. When vendor‑specific objective evidence does not exist for undelivered elements, revenues are allocated to the elements based on third‑party evidence, if available, or management’s best estimate of fair value. The Company also has a limited number of design and development contracts, principally with governmental customers, which are accounted for in accordance with the provisions of FASB ASC Subtopic 605‑35, Revenue Recognition‑Construction‑Type and Production‑Type Contracts , using the percentage‑of‑completion method. The Company utilizes a cost‑to‑cost methodology whereby it estimates the percent complete by calculating the ratio of costs incurred to the Company’s estimate of total anticipated costs.
Product Warranty	(f) Product Warranty The Company’s products are sold with warranty provisions that require the Company to remedy deficiencies in quality or performance over a specified period of time, generally three to 36 months, at no cost to its customers. A provision for the estimated future costs of warranty, based upon historical cost and product performance experience, is recorded when revenues are recognized. The following is a reconciliation of the changes in the aggregate product warranty accrual: Six Months Year Ended Ended December 31, (in thousands) June 30, 2018 2017 2016 (Unaudited) Product warranty accrual, beginning $ 4,186 $ 2,677 $ 1,691 Warranty charges incurred, net (1,335) (2,278) (1,789) Provision for warranty charges 1,773 3,787 2,775 Product warranty accrual, ending $ 4,624 $ 4,186 $ 2,677 Warranty costs are included in the consolidated statement of operations within the cost of revenues. The warranty accrual is presented in accrued liabilities and other long-term liabilities within the consolidated balance sheet.
Sales Returns and Allowances	(g) Sales Returns and Allowances The Company’s customers generally do not have a stated right to return product except for replacement of defective products under the warranty program. However, the Company has accepted customer returns on a case‑by‑case basis as customer accommodations in the past. As a result, the Company provides for these returns in the reserves for sales returns and allowances. The reserve is estimated at the end of each reporting period based on historical experience and knowledge of any applicable events or transactions. The return reserve was $8 thousand and $75 thousand at December 31, 2017 and 2016, respectively and is presented as a reduction of accounts receivables in the consolidated financial statements.
Cash and Cash Equivalents	(h) Cash and Cash Equivalents The Company considers all highly liquid investments with a maturity of three months or less when acquired to be cash equivalents. Cash equivalents included $126 thousand and $58 thousand of highly liquid investments at December 31, 2017 and 2016, respectively. The Company maintains the majority of its cash balance at a financial institution in the United States, which it believes to be high‑credit quality financial institution with the Company’s balance often exceeding the insurance limit set by the Federal Deposit Insurance Corporation (FDIC) of $250 thousand per bank. The Company has not historically experienced any losses due to such concentration of credit risk. As of December 31, 2017, the balance of restricted cash was $55 thousand and consisted of surety bonds and performance guarantees in the United States. As of December 31, 2016 the balance of restricted cash was $776 thousand, including $721 thousand of frozen funds related to a customer non‑payment litigation in China that was released in July 2017 after conclusion of litigation.
Accounts Receivable	(i) Accounts Receivable Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The allowance for doubtful accounts is the Company’s best estimate of the amount of probable credit losses in the Company’s existing accounts receivable. The Company determines the allowance based on historical write-off experience and knowledge of any applicable circumstances. Activity related to the allowance for doubtful accounts was as follows: (in thousands) 2017 2016 Allowance for doubtful accounts, beginning $ 1,608 $ 1,477 Provision for bad debts 232 340 Write offs and recoveries (1,402) (82) Allowance for doubtful accounts, ending $ 438 $ 1,608 Included in the write offs and recoveries for 2017 is a $1.0 million recovery related to a receivable fully reserved in 2015 and included in the allowance for doubtful accounts in the consolidated financial statements as of December 31, 2016. The amount noted above was recovered in July 2017 after extensive litigation with the customer and was recognized as a reduction in bad debt expense within the sales, general and administrative caption on the consolidated statement of operations. The Company also received $175 thousand in interest income as a result of this litigation which the Company recognized within the interest expense, net caption in the consolidated statement of operations.
Inventory	(j) Inventory Inventory is stated at the lower of cost (average cost) or net realizable value. The Company periodically reviews the quantities and carrying values of its inventory to assess recoverability. The costs associated with write-downs for excess quantities, technological obsolescence, or component rejections are charged to cost of revenues as incurred and result in a new cost basis for that item in inventory. The components of inventory at June 30, 2018 and December 31, 2017 and 2016 are as follows: December 31, (in thousands) June 30, 2018 2017 2016 (Unaudited) Raw materials $ 13,499 $ 11,326 $ 7,705 Work in process and semi-finished goods 12,497 6,039 3,762 Finished goods 9,273 12,205 7,338 $ 35,269 $ 29,570 $ 18,805
Risks and Uncertainties including Business and Credit Concentrations	(k) Risks and Uncertainties including Business and Credit Concentrations Financial instruments that potentially expose the Company to concentrations of credit risk consist principally of accounts receivable. Ten customers represented 71% (unaudited), 67% and 62% of accounts receivable at June 30, 2018 and December 31, 2017 and 2016, respectively. Seven of the ten customers were included in both December 31, 2017 and 2016. The Company generates a significant portion of its revenues from a relatively small number of customers. One customer accounted for 16% (unaudited) and 14% of revenues during the six months and twelve months ended June 30, 2018 and December 31, 2017, respectively. The same customer as well as an additional customer accounted for 11% and 10%, respectively, of revenues during the year ended December 31, 2016. Included in the consolidated balance sheets are the net assets of the Company’s foreign manufacturing operations located primarily in China which totaled approximately $14.3 million (unaudited), $13.3 million and $5.8 million at June 30, 2018 and December 31, 2017 and 2016, respectively. The market for the Company’s products is rapidly changing and evolving. The Company believes its future success will depend, in part, on its ability to increase sales of its existing products, penetrate new vertical markets, and to remain competitive in the marketplace. An inability of the Company to manage growth and generate increased demand for its products could have a material adverse impact on the Company’s financial position, results of operations and liquidity. It is the Company’s belief that existing cash resources will be sufficient to support operations and meet its debt service requirements at least through February 15, 2019, twelve months from the date on which the consolidated financial statements were available for issuance.
Property and Equipment	(l) Property and Equipment Property and equipment are stated at cost. Improvements and replacements are capitalized. Repair and maintenance costs are expensed as incurred. Depreciation is computed using the straight-line method over the estimated useful life of each asset, generally two to 10 years.
Income Taxes	(m) Income Taxes The Company accounts for income taxes using the asset and liability approach under which deferred income taxes are provided based upon enacted tax laws and rates applicable to the periods in which taxes become payable. The Company recognizes the effect of income tax positions only if those positions are more likely than not of being sustained. Recognized income tax positions are measured at the largest amount that is greater than 50% likely to be realized. Changes in recognition or measurement are reflected in the period in which the change in judgment occurs.
StockBased Compensation	(n) Stock-Based Compensation Stock‑based compensation is recognized for the fair value of the portion of the award that is ultimately expected to vest and is recognized as expense over the requisite service period. The Company recognizes stock‑based compensation expense on a straight‑line basis. The fair value of options granted in 2017 was determined to be approximately $1.0 million. The expenses recognized in 2017 and 2016 were $369 thousand and $308 thousand, respectively. Employee and non‑employee stock options were granted by the Compensation Committee in 2016 on April 27, July 1, September 13, October 26, and December 31. In 2017, the Compensation Committee granted stock options on May 26, June 2, July 30, August 3, August 31, and December 14. For determining the fair value of stock options granted, the Company used the Black‑Scholes option pricing model with the following assumptions: 2017 2016 Expected volatility ‑ 40.1 % ‑ 40.9 % Expected option term ‑ 6.5 years ‑ 6.6 years Risk ‑ free interest rate ‑ 2.2 % ‑ 1.6 % Expected dividend yield None None Included in the option pricing model is the fair value of the underlying common stock at the time of grant. Determining the fair value of the Company’s common stock requires complex and subjective judgments and estimates. There is inherent uncertainty in making these judgments and estimates. The absence of an active market for the Company’s common stock required the board of directors to estimate the fair value of the common stock for purposes of setting the exercise price of the options and estimating the fair value of the common stock at each meeting at which options were granted based on a number of objective and subjective factors, including valuations of comparable companies, operating and financial performance, lack of liquidity of the common stock and general and industry‑specific economic outlook, among other factors. Since 2012, the Company has obtained valuations prepared by an independent third‑party valuation firm to assist in determining the fair market value of its common stock. The board of directors and management of the Company considered these valuation reports when determining the fair market value of the Company’s common stock and related option exercise price on the dates such awards were granted. The valuations determined as of the dates below are as follows: Fair Market Value November 13, 2014 $ 0.75 January 1, 2016 $ 1.10 May 1, 2017 $ 1.45 September 1, 2017 $ 6.65 The average expected option term for awards granted reflects the application of the simplified method. The simplified method is based on the vesting period and the contractual term for each grant. The midpoint between the vesting date and the expiration date is used as the expected term under this method. The Company uses the historical stock price volatility for comparable publicly‑traded competitors as the basis for its expected volatility assumption. The Company has assessed that the calculated volatility is representative of expected future stock price trends. The risk‑free interest rate assumption is based upon observed U.S. Treasury rates consistent with the expected term of the award. The dividend yield assumption is based on the Company’s history of no dividend payouts and an expectation that no dividends will be paid in the foreseeable future. The Company accounts for stock options issued to non‑employees in accordance with the provisions of FASB ASC Topic 718 and FASB ASC Subtopic 505‑50, Equity Based Payments to Non‑Employees . Under FASB ASC Topic 718 and FASB ASC Subtopic 505‑50, the Company uses the Black‑Scholes option pricing model to measure the fair value of stock options granted to non‑employees on the measurement date.
Research and Development Costs	(o) Research and Development Costs Research and development is defined as activities aimed at developing or significantly improving a product or a process or technique whether the product or process is intended for sale or use. A process also may be used internally as a part of a manufacturing activity. Research and development costs are expensed as incurred.
Principles of Consolidation	(p) Principles of Consolidation The accompanying consolidated financial statements include the accounts of nLIGHT, Inc. and its wholly owned subsidiaries. The wholly owned subsidiaries are Arbor Photonics, LLC, nLIGHT Cayman Ltd., nLIGHT Laser Technology (Shanghai) Co. Ltd, nLIGHT Oy (Finland), and nLIGHT Korea Inc. All intercompany balances have been eliminated.
Impairment of Long-Lived Assets	(q) Impairment of Long-Lived Assets Long‑lived assets, such as property and equipment, and intangibles subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated future cash flows, an impairment charge is recognized for the amount by which the carrying amount of the asset exceeds the fair value of the asset. There was no impairment of long‑lived assets recorded for the years ended December 31, 2017 and 2016.
Commitments and Contingencies	(r) Commitments and Contingencies Liabilities for loss contingencies are recorded when it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. In July 2017, the Company received notification of a claim related to a quality dispute with a vendor alleging that the Company owed payment for future non-cancelable order quantities. The Company believes it is probable that a partial settlement of this claim will occur and recorded a $196 thousand liability related to this matter within the accrued liabilities on the consolidated balance sheet as of December 31, 2017. This amount remains outstanding as of June 30, 2018 (unaudited). In December 2013, the Company submitted a disclosure letter to the Office of the Inspector General of the Department of Defense advising that it might not have been eligible for certain contracts it was awarded under the Small Business Innovation Research (“SBIR”) Program, notwithstanding its prior representations that the Company was eligible. The matter was referred to the Small Business Administration and the US Department of Justice (“DOJ”) for investigation of potential violations of the False Claims Act. In March 2015, a civil settlement agreement related to the SBIR matter was signed. A liability of $420 thousand was recorded at December 31, 2014 and subsequently paid in full. In October 2014, the Company received a request for information related to the SBIR matter from the U.S. Attorney’s Office, Criminal Division. The Company provided documentation and an explanation of why a criminal investigation was unwarranted. In March 2015, the Company received an additional request, to which it also responded. Although the Company is unable to predict the final outcome of this matter, it intends to vigorously defend against any future claims. The Company becomes involved in various legal proceedings and claims incidental to normal business activities. As of June 30, 2018, the Company believes these matters will not have a material adverse effect on the consolidated financial statements.
Goodwill and Intangible Assets	(s) Goodwill and Intangible Assets Goodwill and intangible assets with indefinite lives are not amortized; rather, they are tested for impairment on at least an annual basis. Intangible assets with finite lives are amortized over their useful lives. External costs incurred to file new patent applications, and extend the term of or defend the existing patents are capitalized and amortized over the estimated useful life.
Prepaid Expenses and Other Current Assets	(t) Prepaid Expenses and Other Current Assets The components of prepaid expenses and other current assets at June 30, 2018 and December 31, 2017 and 2016 are as follows: December 31, (in thousands) June 30, 2018 2017 2016 (Unaudited) Prepaid expenses $ 2,617 $ 1,248 $ 769 Value ‑ added tax receivable, net 2,480 1,291 994 Vendor prepayments 1,154 1,391 1,117 Prepaid taxes and duties 2,049 946 413 Restricted cash — — 721 Other 63 97 103 $ 8,363 $ 4,973 $ 4,117
Foreign Currency Transactions and Translations Policy [Policy Text Block]	(u) Translation of Foreign Currencies The Company’s international subsidiaries use their local currency as their functional currency. The financial statements of the international subsidiaries are translated to their U.S. dollar equivalents at end‑of‑period currency exchange rates for assets and liabilities and at average currency exchange rates for revenues and expenses. Translation adjustments are recorded as a component of accumulated other comprehensive loss within stockholders’ equity. Realized and unrealized foreign currency gains or losses, net are recorded in other expense within the consolidated statement of operations. Realized and unrealized foreign currency losses were $0.9 million and $36 thousand, respectively, in the year ended December 31, 2017. Realized and unrealized foreign currency losses were $1.0 million and $53 thousand, respectively, in the year ended December 31, 2016. During the six months ended June 30, 2018 realized foreign currency gains were $533 thousand (unaudited) and unrealized foreign currency losses were $850 thousand. During the six months ended June 30, 2017 realized and unrealized foreign currency losses were $686 thousand (unaudited) and $96 thousand (unaudited), respectively.
Fair Value of Financial Instruments	foreign currency gains or losses, net are recorded in other expense within the consolidated statement of operations. Realized and unrealized foreign currency losses were $0.9 million and $36 thousand, respectively, in the year ended December 31, 2017. Realized and unrealized foreign currency losses were $1.0 million and $53 thousand, respectively, in the year ended December 31, 2016. During the six months ended June 30, 2018 realized foreign currency gains were $533 thousand (unaudited) and unrealized foreign currency losses were $850 thousand. During the six months ended June 30, 2017 realized and unrealized foreign currency losses were $686 thousand (unaudited) and $96 thousand (unaudited), respectively. (v) Fair Value of Financial Instruments The carrying amounts of certain of the Company’s financial instruments, including cash equivalents, accounts receivable and accounts payable, are shown at cost which approximates fair value due to the short term nature of these instruments. The fair value of the Company’s term and revolving loans with Pacific Western Bank, also described in Note 8, approximates the carrying value due to the variable market rate used to calculate interest payments. The Company considers the fair value of its term loan with Multiplier Growth Partners SPV I, LP to be equal to the costs incurred to extinguish the liability subsequent to December 31, 2016. Refer to Note 8 for further information. The Company does not have any other significant financial assets or liabilities that are measured at fair value. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The standard describes a fair value hierarchy based on three levels of inputs, of which the first two are considered observable and the last unobservable, that may be used to measure fair value which are the following: Level 1 Inputs: Observable inputs, such as quoted prices (unadjusted) in active markets for identical assets or liabilities at the measurement date. Level 2 Inputs: Observable inputs, other than Level 1 prices, such as quoted prices in active markets for similar assets and liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 Inputs: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The Company’s financial instruments that are carried at fair value consist of Level 1 assets and Level 2 and Level 3 liabilities. Level 1 assets include highly liquid bank drafts classified as cash equivalents. Level 2 liabilities consist of the Company’s loan with Pacific Western Bank while Level 3 liabilities are the Company’s term loan with Multiplier Growth Partners SPV I, L.P.
Revision of Prior Period Financial Statement Disclosures	(w) Revision of Prior Period Financial Statement Disclosures Deferred income taxes and other adjustment to reconcile net income (loss) to net cash provided by operating activities has been corrected in the consolidated statements of cash flows to present deferred income taxes and the change in non-current income taxes payable separately. Amortization of debt issuance costs as disclosed in Note 8 has been corrected to $194 thousand from $108 thousand, for the year ended December 31, 2016. Stock options to purchase common stock disclosed in Note 14 have been corrected from being presented net under the treasury stock method to gross options outstanding.
Recently Issued Accounting Standards	(x) Recently Issued Accounting Standards The FASB issued ASU No. 2014‑09, Revenue from Contracts with Customers, in May 2014. ASU 2014‑09 requires an entity to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The ASU No. 2014‑09 is effective for annual reporting periods beginning after December 15, 2018. The Company expects to implement the provisions of ASU 2014‑09 as of January 1, 2019. While the Company continues to assess the potential impacts of ASU 2014‑09, and anticipates ASU 2014‑09 could have an impact on the consolidated financial statements, the Company cannot reasonably estimate the quantitative impact on the financial statements at this time. The FASB issued ASU No. 2015‑11, Inventory (Topic 330): Simplifying the Measurement of Inventory, in July 2015. ASU 2015‑11 requires that inventory within the scope of this standard be measured at the lower of cost and net realizable value. Net realizable value is the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. The amendments in this update do not apply to inventory that is measured using last‑in, first‑out (LIFO) or the retail inventory method. The amendments apply to all other inventory, including inventory that is measured using first‑in, first‑out (FIFO) or average cost. ASU 2015‑11 is effective for the Company’s annual reporting periods beginning January 1, 2017. The adoption of the standard did not have a material impact on the consolidated financial statements, financial condition or results of operations. The FASB issued ASU No. 2016‑02, Leases (Topic 842), in February 2016. ASU 2016‑02 requires a lessee to recognize a right of use asset and a lease liability for virtually all leases, other than leases that meet the definition of short‑term. The standard is effective for annual reporting periods beginning after December 15, 2019. The Company expects to implement the provisions of ASU 2016‑02 as of January 1, 2020. The Company is currently evaluating the impact of this ASU and cannot reasonably estimate the quantitative impact on the financial statements at this time. The FASB issued ASU No. 2016‑09, Compensation‑Stock Compensation (Topic 842), in March 2016. ASU 2016‑09 amends the guidelines for share‑based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The standard is effective for annual and interim periods beginning January 1, 2018. The Company does not expect the implementation of this guidance to have a material impact on its consolidated financial statements. The FASB issued ASU No. 2016‑15, Classification of Certain Cash Receipts and Cash Payments (Topic 230), in August 2016. ASU 2016‑15 provides guidance on eight different issues, intended to reduce diversity in practice on how certain cash receipts and cash payments are presented and classified in the statement of cash flows. The standard is effective for annual and interim periods beginning January 1, 2019, and early adoption is permitted. The Company is currently evaluating the impact the adoption of this ASU; however the Company does not expect that the adoption of ASU 2016‑09 will have a material impact on its consolidated financial statements. The FASB issued ASU No. 2016‑16, Intra‑Entity Transfers of Assets Other Than Inventory (Topic 740), in November 2016. ASU 2016‑16 requires entities to recognize the current and deferred income taxes for an intra‑entity transfer of an asset other than inventory when the transfer occurs, as opposed to deferring the recognition of the income tax consequences until the asset has been sold to an outside party. The amendments in this ASU are effective for annual reporting periods beginning January 1, 2018, including interim reporting periods within those annual reporting periods. The amendments in this ASU should be applied on a modified retrospective basis through a cumulative‑effect adjustment directly to retained earnings as of the beginning of the period of adoption. The Company does not expect the adoption of the amendments in this ASU to have a material impact on the consolidated financial statements. The FASB issued ASU No. 2016‑18, Restricted Cash (Topic 230), in November 2016. ASU 2016‑18 requires entities to show the changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. As a result, entities will no longer present transfers between cash and cash equivalents and restricted cash and restricted cash equivalents in the statement of cash flows. The update amends the guidance in ASC 230, which is principles‑based and often requires judgment to determine the appropriate classification of cash flows as operating, investing or financing activities. The guidance is effective for annual and interim reporting periods beginning January 1, 2019, and requires retrospective application. Early adoption is permitted as of the beginning of an annual period. The Company does not expect the adoption to have a material impact on the consolidated financial statements. The FASB issued ASU No. 2017‑04, Simplifying the Test for Goodwill Impairment (Topic 350), in January 2017. ASU 2017‑04 simplifies the test for goodwill impairment and removes step 2 from the goodwill impairment test. Early adoption is permitted, but will be effective for annual or any interim goodwill impairment tests for fiscal years beginning January 1, 2020. The Company does not expect the adoption to have a material impact on the consolidated financial statements. The FASB issued ASU No. 2017‑11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), Derivatives and Hedging (Topic 815), in July 2017. ASU 2017‑11 was issued to address the complexity associated with applying U.S. GAAP for certain financial instruments with characteristics of liabilities and equity. The ASU, among other things, eliminates the need to consider the effects of down round features when analyzing convertible debt, warrants and other financial instruments. As a result, a freestanding equity‑linked financial feature (or embedded conversion option) no longer would be accounted for as a derivative liability at fair value as a result of the existence of a down round feature. The guidance is effective for annual and interim periods beginning January 1, 2019. The Company does not expect the adoption of this ASU to have a material impact on the consolidated financial statements. The SEC issued Staff Accounting Bulletin No. 118 in December 2017, which provides SEC staff guidance for the application of ASC Topic 740, Income Taxes, in the reporting period in which the 2017 Tax Act was signed into law. The Company applied the guidance for the purposes of the 2017 consolidated financial statements. Refer to Note 9 for further information.

Summary of Significant Accoun23

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2018
Summary of Significant Accounting Policies
Reconciliation of Changes in Aggregate Product Warranty Accrual	Six Months Year Ended Ended December 31, (in thousands) June 30, 2018 2017 2016 (Unaudited) Product warranty accrual, beginning $ 4,186 $ 2,677 $ 1,691 Warranty charges incurred, net (1,335) (2,278) (1,789) Provision for warranty charges 1,773 3,787 2,775 Product warranty accrual, ending $ 4,624 $ 4,186 $ 2,677
Schedule of allowance for doubtful accounts	(in thousands) 2017 2016 Allowance for doubtful accounts, beginning $ 1,608 $ 1,477 Provision for bad debts 232 340 Write offs and recoveries (1,402) (82) Allowance for doubtful accounts, ending $ 438 $ 1,608
Schedule of Components of Inventory	December 31, (in thousands) June 30, 2018 2017 2016 (Unaudited) Raw materials $ 13,499 $ 11,326 $ 7,705 Work in process and semi-finished goods 12,497 6,039 3,762 Finished goods 9,273 12,205 7,338 $ 35,269 $ 29,570 $ 18,805
Schedule of assumptions used in option pricing model	2017 2016 Expected volatility ‑ 40.1 % ‑ 40.9 % Expected option term ‑ 6.5 years ‑ 6.6 years Risk ‑ free interest rate ‑ 2.2 % ‑ 1.6 % Expected dividend yield None None
Schedule of valuation dates fair market value	Fair Market Value November 13, 2014 $ 0.75 January 1, 2016 $ 1.10 May 1, 2017 $ 1.45 September 1, 2017 $ 6.65
Schedule of components of prepaid expenses and other current assets	December 31, (in thousands) June 30, 2018 2017 2016 (Unaudited) Prepaid expenses $ 2,617 $ 1,248 $ 769 Value ‑ added tax receivable, net 2,480 1,291 994 Vendor prepayments 1,154 1,391 1,117 Prepaid taxes and duties 2,049 946 413 Restricted cash — — 721 Other 63 97 103 $ 8,363 $ 4,973 $ 4,117

Property and Equipment (Tables)

Property and Equipment (Tables)	6 Months Ended
	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment	Useful life As of June 30, As of December 31, (in thousands) (years) 2018 2017 2016 (Unaudited) Computer hardware and software 3 ‐ 5 $ 3,866 $ 3,732 $ 3,344 Manufacturing and lab equipment 2 ‐ 7 47,048 43,432 37,805 Office equipment and furniture 5 ‐ 7 1,122 1,053 942 Leasehold improvements 2 ‐ 12 18,987 18,580 18,299 71,023 66,797 60 Accumulated depreciation (51,495) (48,829) (43,067) $ 19,528 $ 17,968 $ 17,323

Intangible Assets and Goodwill

Intangible Assets and Goodwill (Tables)	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets	June 30, 2018 (Unaudited) Average Gross amortization carrying Accumulated (in thousands) (unaudited) period amount amortization Net value Amortizing intangible assets: Patents 5 yrs $ 4,163 $ (1,723) $ 2,440 Arbor acquired technology 3 yrs 670 (670) — Direct nanoparticle deposition technology 6 yrs 528 (528) — $ 5,361 $ (2,921) $ 2,440 December 31, 2017 Average Gross amortization carrying Accumulated (in thousands) period amount amortization Net value Amortizing intangible assets: Direct nanoparticle deposition technology 6 yrs $ 543 $ (543) $ — Patents 5 yrs 3,310 (1,474) 1,836 Arbor acquired technology 3 yrs 670 (670) — $ 4,523 $ (2,687) $ 1,836 December 31, 2016 Average Gross amortization carrying Accumulated (in thousands) period amount amortization Net value Amortizing intangible assets: Direct nanoparticle deposition technology 6 yrs $ 478 $ (478) $ — Patents 5 yrs 2,447 (962) 1,485 Arbor acquired technology 3 yrs 670 (670) — $ 3,595 $ (2,110) $ 1,485
Schedule of Estimated Future Amortization Expense	(in thousands) (unaudited) 2018 $ 344 2019 654 2020 581 2021 454 2022 309 Thereafter 98 $ 2,440

Other Assets (Tables)

Other Assets (Tables)	6 Months Ended
	Jun. 30, 2018
Other Assets [Abstract]
Schedule of Other Assets	As of As of June 30, December 31, (in thousands) 2018 2017 2016 (Unaudited) Demonstration assets, net $ 2,410 $ 2,224 $ 2,981 Deferred tax assets, net 1,807 1,807 1,383 Other 427 343 381 $ 4,644 $ 4,374 $ 4,745

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	6 Months Ended
	Jun. 30, 2018
Payables and Accruals [Abstract]
Summary of Accrued Liabilities	As of June 30, As of December 31, (in thousands) 2018 2017 2016 (unaudited) Accrued payroll $ 6,495 $ 6,201 $ 5,075 Product warranty, current 3,480 3,589 2,146 Income tax payable 786 931 8 Other accrued expenses 1,157 1,929 1,118 $ 11,918 $ 12,650 $ 8,347

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of minimum future rent payments under noncancelable operating leases	(in thousands) 2018 $ 2,751 2019 1,907 2020 1,379 2021 1,383 2022 641 Thereafter 998 Total $ 9,059

Long-Term Debt (Tables)

Long-Term Debt (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Schedule of Long-term Debt	June 30, December 31, (in thousands) 2018 2017 2016 (Unaudited) 2014 Pacific Western Bank, Term and Revolving Loans $ 17,200 $ 17,200 $ 7,400 2015 Multiplier, Term Loan — — 12,512 2014 Finland equipment loans, Danske Bank, 3 - 5 year terms, EURIBOR plus 1.7% 60 80 104 Capital leases, various 149 191 236 Total debt 17,409 17,471 20,252 Less: debt issuance costs (15) — (571) Less: current portion of long-term debt (4,597) (2,363) (1,287) Noncurrent portion of long-term debt $ 12,797 $ 15,108 $ 18,380
Schedule of Minimum Future Principal Payments of Long-term Debt	(in thousands) 2018 $ 2,363 2019 15,061 2020 47 $ 17,471

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2018
Income Taxes
Schedule of net income (loss) before income tax expense	: (in thousands) 2017 2016 Domestic $ (9,064) $ (19,006) Foreign 15,759 6,686 Net income (loss) before income tax $ 6,695 $ (12,320)
Schedule of income tax provision	(in thousands) 2017 2016 Current tax expense: Federal $ — $ — State — 8 Foreign 5,200 1,632 Current tax expense 5,200 1,640 Deferred tax expense Federal — — State — — Foreign (342) 242 Deferred tax expense (342) 242 Income tax expense $ 4,858 $ 1,882
Reconciliation of statutory federal income tax rate to the loss before income tax	(in thousands) 2017 2016 Tax computed at federal statutory rate $ 2,276 $ (4,189) State tax, net of federal tax benefit (102) (125) Permanent items 1,078 662 Foreign dividends and unremitted earnings 796 586 Foreign rate differential (1,897) (991) Rate change due to tax reform 17,176 — Federal credits (302) (363) Tax contingencies, net of reversals 592 663 Other 109 302 Valuation allowance (14,868) 5,337 Income tax expense $ 4,858 $ 1,882
Schedule of deferred tax assets and deferred tax liabilities	(in thousands) 2017 2016 Deferred tax assets: Net operating loss carryforwards $ 21,626 $ 35,803 Research and alternative minimum tax credits 3,635 3,373 Accrued expenses and other 1,891 2,466 Inventory 2,280 2,155 Property and equipment 1,644 2,351 Total gross deferred tax assets 31,076 46,148 Less valuation allowance (28,873) (43,741) Total deferred tax assets 2,203 2,407 Deferred tax liabilities Intangible assets (396) (503) Unremitted foreign earnings — (521) Total deferred tax liabilities (396) (1,024) Net deferred tax assets $ 1,807 $ 1,383
Schedule of reconciliation of the changes in the unrecognized tax benefit	(in thousands) Balance at December 31, 2015 $ 1,528 Additions based on tax positions related to the current year 570 Additions for tax positions of prior years 3 Other (51) Balance at December 31, 2016 $ 2,050 Additions based on tax positions related to the current year 365 Additions for tax positions of prior years 99 Other 3 Balance at December 31, 2017 $ 2,517

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Schedule of Liquidation Preference	(in thousands) 2017 2016 Series C $ 38,819 $ 38,819 Series D 25,980 25,980 Series E 17,536 17,536 Series F 37,334 37,334 Series G 28,783 — $ 148,452 $ 119,669
Summary of Stock Option Activity	Weighted average Weighted remaining average contractual Aggregate Number exercise term intrinsic (in thousands) of shares price (years) value Outstanding, December 31, 2016 4,602 $ 0.87 8.2 $ 1,214 Options granted 1,458 $ 1.69 Options exercised (440) $ 0.76 Options canceled (251) $ 1.15 Outstanding, December 31, 2017 5,369 $ 1.09 7.4 $ 29,863 Options granted (unaudited) 357 $ 9.71 Options exercised (unaudited) (141) $ 0.88 Options canceled (unaudited) (18) $ 1.50 Outstanding, June 30, 2018 (unaudited) 5,567 $ 1.65 7.2 $ 174,883 Options exercisable at June 30, 2018 (unaudited) 2,707 $ 0.88 6.6 $ 87,093 Options vested as of June 30, 2018 and expected to vest after June 30, 2018 (unaudited) 4,624 $ 1.65 7.7 $ 145,939
Summary of Restricted Stock and Restricted Stock Unit Activity	Weighted Number of average restricted grant date (in thousands) stock awards fair value Outstanding, December 31, 2017 — $ — Awards granted (unaudited) 115 $ 37.15 Awards vested (unaudited) — $ — Awards canceled (unaudited) — $ — Outstanding, June 30, 2018 (unaudited) 115 $ 37.15 Restricted stock unit activity during the six months ended June 30, 2018 was as follows: Weighted Number of average restricted grant date (in thousands) stock units fair value Outstanding, December 31, 2017 — $ — Units granted (unaudited) 443 $ 36.28 Units vested (unaudited) — $ — Units canceled (unaudited) — $ — Outstanding, June 30, 2018 (unaudited) 443 $ 36.28
Total Compensation Cost Related to Nonvested Awards Not Yet Recognized	(in thousands) (unaudited) 2018 $ 3,683 2019 7,023 2020 6,051 2021 4,344 2022 1,652 2023 9 $ 22,762

Segment and Geographic Inform32

Segment and Geographic Information (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Schedule of geographic sources of revenues based on the customer's location	Six Months Ended Year Ended June 30, December 31, (in thousands) 2018 2017 2017 2016 (Unaudited) China $ 38,793 $ 26,843 $ 55,344 $ 38,309 North America 32,551 19,939 46,489 36,200 Other 22,828 17,769 36,747 26,816 $ 94,172 $ 64,551 $ 138,580 $ 101,325
Schedule of geographic locations of long lived assets, net,	June 30, December 31, (in thousands) 2018 2017 2016 (Unaudited) United States $ 16,228 $ 13,991 $ 13,811 China 8,691 8,433 8,341 Other 847 991 1,053 $ 25,766 $ 23,415 $ 23,205

Net Income (Loss) per Share (Ta

Net Income (Loss) per Share (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Income (Loss) per Share	Six Months Ended Year Ended June 30, December 31, (in thousands, except per share data) 2018 2017 2017 2016 (Unaudited) Numerator: Net income (loss) $ 7,569 $ (1,500) $ 1,837 $ (14,202) Participating securities: Income allocated to preferred stockholders (4,415) — (1,837) — Net income (loss) attributable to common stockholders 3,154 (1,500) - (14,202) Denominator: Weighted-average shares, basic 13,761 2,613 2,735 2,500 Dilutive effect of warrant 137 — — — Dilutive effect of restricted stock units and awards 1 — — — Dilutive effect of common stock options 4,898 — — — Weighted-average common shares outstanding, diluted 18,797 2,613 2,735 2,500 Net income (loss) per share attributable to common stockholders: Basic $ 0.23 $ (0.57) $ — $ (5.68) Diluted $ 0.17 $ (0.57) $ — $ (5.68)
Schedule of Potentially Dilutive Shares Not Included in Calculation of Diluted Shares	Six Months Ended Year Ended June 30, December 31, (in thousands) 2018 2017 2017 2016 (Unaudited) Convertible preferred stock — 24,642 23,095 19,774 Preferred stock warrants — 214 214 214 Restricted stock units and awards 541 — — — Stock options to purchase common stock — 5,150 5,369 4,602 Total 541 30,006 28,678 24,590

Summary of Significant Accoun34

Summary of Significant Accounting Policies - Narrative (Details) $ / shares in Units, shares in Millions, $ in Millions	Apr. 30, 2018USD ($)$ / sharesshares	Apr. 13, 2018
Class of Stock [Line Items]
Shares of common stock issued upon conversion (in shares)	24.6
Reverse stock split ratio		0.2
IPO
Class of Stock [Line Items]
Number of shares issued (in shares)	6.9
Initial price per share in IPO (in USD per share) | $ / shares	$ 16
Net proceeds received from IPO | $	$ 100.2
IPO - Over-Allotment Option
Class of Stock [Line Items]
Number of shares issued (in shares)	0.9

Summary of Significant Accoun35

Summary of Significant Accounting Policies - Product Warranty (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Movement in Standard Product Warranty Accrual [Roll Forward]
Product warranty accrual, beginning	$ 4,186	$ 2,677	$ 1,691
Warranty charges incurred, net	(1,335)	(2,278)	(1,789)
Provision for warranty charges	1,773	3,787	2,775
Product warranty accrual, ending	$ 4,624	$ 4,186	$ 2,677
Minimum
Product Warranty Liability [Line Items]
Product warranty period	3 months
Maximum
Product Warranty Liability [Line Items]
Product warranty period	36 years

Summary of Significant Accoun36

Summary of Significant Accounting Policies - Sales Returns and Allowances and Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Summary of Significant Accounting Policies
Return reserve	$ 8	$ 75
Cash equivalents	126	58
Restricted cash	$ 55	776
Frozen funds related to customer non payment litigation		$ 721

Summary of Significant Accoun37

Summary of Significant Accounting Policies - Accounts Receivable and Inventory (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for doubtful accounts
Allowance for doubtful accounts, beginning	$ 438	$ 1,608	$ 1,608	$ 1,477
Provision for bad debts	183	$ 143	232	340
Write offs and recoveries			(1,402)	(82)	$ 1,000
Allowance for doubtful accounts, ending			438	1,608	$ 1,477
Interest income on litigation			175
Inventory
Raw materials	13,499		11,326	7,705
Work in process and semi-finished goods	12,497		6,039	3,762
Finished goods	9,273		12,205	7,338
Inventory	$ 35,269		$ 29,570	$ 18,805

Summary of Significant Accoun38

Summary of Significant Accounting Policies - Risks and Uncertainties including Business and Credit Concentrations (Details) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018USD ($)customer	Dec. 31, 2017USD ($)customer	Dec. 31, 2016USD ($)customer
Concentration Risk [Line Items]
Net assets | $	$ 223,020	$ 110,148	$ 71,059
China
Concentration Risk [Line Items]
Net assets | $	$ 14,300	$ 13,300	$ 5,800
Accounts receivable | Credit Concentration Risk [Member]
Concentration Risk [Line Items]
Number of customers | customer	10	10	10
Concentration risk, percentage	71.00%	67.00%	62.00%
Revenues | Credit Concentration Risk [Member]
Concentration Risk [Line Items]
Number of customers | customer	1	1
Concentration risk, percentage	16.00%	14.00%	11.00%
Revenues | Credit Concentration Risk [Member] | Additional customer
Concentration Risk [Line Items]
Concentration risk, percentage			10.00%

Summary of Significant Accoun39

Summary of Significant Accounting Policies - Property and Equipment (Details)	6 Months Ended
	Jun. 30, 2018
Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life of each asset	P2Y
Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life of each asset	P10Y

Summary of Significant Accoun40

Summary of Significant Accounting Policies - Stock Based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 01, 2017	May 01, 2017	Jan. 01, 2016	Nov. 13, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Fair value of options granted	$ 1,000
Stock-based compensation expense	$ 369	$ 308
Options
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected dividend yield	0.00%	0.00%
Exercise price			$ 6.65	$ 1.45	$ 1.10	$ 0.75
Options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected volatility	30.20%	34.10%
Expected option term	6 years 2 months 12 days	5 years 7 months 6 days
Riskfree interest rate	1.90%	1.20%
Options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected volatility	40.10%	40.90%
Expected option term	6 years 6 months	6 years 7 months 6 days
Riskfree interest rate	2.20%	1.60%

Summary of Significant Accoun41

Summary of Significant Accounting Policies - Impairment of Long-Lived Assets and Commitments and Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2018	Dec. 31, 2014
Summary of Significant Accounting Policies
Impairment of long lived assets	$ 0	$ 0
Partial settlement liability	$ 196		$ 196
Civil settlement liability				$ 420

Summary of Significant Accoun42

Summary of Significant Accounting Policies - Prepaid expenses and Translation of Foreign Currencies (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Prepaid expenses and other current assets
Prepaid expenses	$ 2,617		$ 1,248	$ 769
Valueadded tax receivable, net	2,480		1,291	994
Vendor prepayments	1,154		1,391	1,117
Prepaid taxes and duties	2,049		946	413
Restricted cash				721
Other	63		97	103
Prepaid expenses and other current assets	8,363		4,973	4,117
Translation of Foreign Currencies
Realized foreign currency gains (losses)	533	$ (686)	(900)	(1,000)
unrealized foreign currency gains (losses)	$ (850)	$ (96)	$ (36)	$ (53)

Summary of Significant Accoun43

Summary of Significant Accounting Policies - Revision of Prior Period Statement Disclosures (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Revision of Prior Period Financial Statement Disclosures
Amortization of debt issuance costs	$ 3	$ 95	$ 96	$ 194
Revision of prior period financial statement
Revision of Prior Period Financial Statement Disclosures
Amortization of debt issuance costs				$ 108

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 71,023		$ 66,797	$ 60
Accumulated depreciation	(51,495)		(48,829)	(43,067)
Property and equipment, net	19,528		17,968	17,323
Depreciation expense	2,900	$ 2,500	5,300	5,400
Computer hardware and software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 3,866		3,732	3,344
Computer hardware and software | Minimum
Property, Plant and Equipment [Line Items]
Useful life (years)	3 years
Computer hardware and software | Maximum
Property, Plant and Equipment [Line Items]
Useful life (years)	5 years
Manufacturing and lab equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 47,048		43,432	37,805
Manufacturing and lab equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful life (years)	2 years
Manufacturing and lab equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful life (years)	7 years
Office equipment and furniture
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,122		1,053	942
Office equipment and furniture | Minimum
Property, Plant and Equipment [Line Items]
Useful life (years)	5 years
Office equipment and furniture | Maximum
Property, Plant and Equipment [Line Items]
Useful life (years)	7 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 18,987		$ 18,580	$ 18,299
Leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Useful life (years)	2 years
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Useful life (years)	12 years

Intangible Assets and Goodwil45

Intangible Assets and Goodwill - Intangible Assets (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 5,361	$ 4,523	$ 3,595
Accumulated amortization	(2,921)	(2,687)	(2,110)
Net value	$ 2,440	$ 1,836	$ 1,485
Patents
Finite-Lived Intangible Assets [Line Items]
Average amortization period	5 years	5 years	5 years
Gross carrying amount	$ 4,163	$ 3,310	$ 2,447
Accumulated amortization	(1,723)	(1,474)	(962)
Net value	$ 2,440	$ 1,836	$ 1,485
Arbor acquired technology
Finite-Lived Intangible Assets [Line Items]
Average amortization period	3 years	3 years	3 years
Gross carrying amount	$ 670	$ 670	$ 670
Accumulated amortization	(670)	(670)	(670)
Net value	$ 0	$ 0	$ 0
Direct nanoparticle deposition technology
Finite-Lived Intangible Assets [Line Items]
Average amortization period	6 years	6 years	6 years
Gross carrying amount	$ 528	$ 543	$ 478
Accumulated amortization	(528)	(543)	(478)
Net value	$ 0	$ 0	$ 0

Intangible Assets and Goodwil46

Intangible Assets and Goodwill - Amortization of Intangible Assets (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Remaining period of amortization (in years)				1 year
Amortization expense	$ 259	$ 219	$ 472	$ 779
2,018	344
2,019	654
2,020	581
2,021	454
2,022	309
Thereafter	98
Net value	$ 2,440		1,836	$ 1,485
Goodwill impairment			$ 0

Other Assets (Details)

Other Assets (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Other Assets [Abstract]
Demonstration assets, net	$ 2,410		$ 2,224	$ 2,981
Deferred tax assets, net	1,807		1,807	1,383
Other	427		343	381
Total other assets	$ 4,644		4,374	4,745
Useful life of demonstration assets	2 years
Amortization expense for demonstration assets	$ 938	$ 1,100	$ 2,100	$ 1,800

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Accrued payroll	$ 6,495	$ 6,201	$ 5,075
Product warranty, current	3,480	3,589	2,146
Income tax payable	786	931	8
Other accrued expenses	1,157	1,929	1,118
Total accrued liabilities	$ 11,918	$ 12,650	$ 8,347

Commitments and Contingencies49

Commitments and Contingencies (Details) - USD ($) $ in Thousands	May 10, 2018	Dec. 31, 2017	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Rent deposits		$ 301	$ 235
Rent expense		2,700	2,500
Sublease income		86	50
Minimum future rent payments under noncancelable operating leases
2,018		2,751
2,019		1,907
2,020		1,379
2,021		1,383
2,022		641
Thereafter		998
Total		9,059
Deferred Rent Credit		$ 254	$ 180
Lease renewal term (in years)	5 years
Commitments under lease extension	$ 1,900

Long-Term Debt - Narrative (Det

Long-Term Debt - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended	6 Months Ended		12 Months Ended
	Mar. 31, 2018	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Outstanding balance		$ 17,409		$ 17,471	$ 20,252
Loss on debt extinguishment				911
Early prepayment penalty				388
Write down of debt issuance costs		3	$ 95	96	194
2014 Pacific Western Bank, Term and Revolving Loans
Debt Instrument [Line Items]
Debt instrument, face amount	$ 25,000
Outstanding balance		17,200		17,200	7,400
2014 Pacific Western Bank, Term and Revolving Loans | Term Loan
Debt Instrument [Line Items]
Debt instrument, face amount	$ 15,000
Outstanding balance		13,500		13,500	17,900
2014 Pacific Western Bank, Term and Revolving Loans | Term Loan | Prime Rate
Debt Instrument [Line Items]
Basis on variable rate	0.50%
Variable rate floor	5.00%
2014 Pacific Western Bank, Term and Revolving Loans | Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Outstanding balance		3,700		3,700	2,000
2014 Pacific Western Bank, Term and Revolving Loans | Revolving Credit Facility | Line of Credit | Borrowing Capacity less Unpaid Principal Amount
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 25,000
2014 Pacific Western Bank, Term and Revolving Loans | Revolving Credit Facility | Line of Credit | Borrowing Capacity as a Percentage of Accounts Receivable
Debt Instrument [Line Items]
Borrowing base as a percentage of eligible accounts receivable	85.00%
Borrowing base, basis spread, amount	$ 5,500
Borrowing base, basis spread, percentage of eligible inventory	35.00%
2015 Multiplier, Term Loan
Debt Instrument [Line Items]
Outstanding balance		$ 0		0	$ 12,512
2015 Multiplier, Term Loan | Warrants
Debt Instrument [Line Items]
Loss on debt extinguishment				911
Early prepayment penalty				375
Write down of debt issuance costs				523
other miscellaneous costs				$ 13
2015 Multiplier, Term Loan | Term Loan
Debt Instrument [Line Items]
Debt instrument, face amount						$ 15,000
Maximum borrowing capacity						$ 12,500
Interest rate (as a percentage)						11.00%
Fees						$ 150,000
Subordinated Finnish Capital Loans | Prime Rate
Debt Instrument [Line Items]
Basis on variable rate		1.00%
Variable rate floor		3.00%

Long-Term Debt - Schedule of Lo

Long-Term Debt - Schedule of Long-term Debt (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Total long-term debt	$ 17,409	$ 17,471	$ 20,252
Less: debt issuance costs	(15)	0	(571)
Less: current portion of long-term debt	(4,597)	(2,363)	(1,287)
Non-current portion of long-term debt	12,797	15,108	18,380
Capital Lease Obligations
Debt Instrument [Line Items]
Total long-term debt	149	191	236
2014 Pacific Western Bank, Term and Revolving Loans
Debt Instrument [Line Items]
Total long-term debt	$ 17,200	17,200	7,400
2014 Pacific Western Bank, Term and Revolving Loans | Equipment Loans | Minimum
Debt Instrument [Line Items]
Debt term	3 years
2014 Pacific Western Bank, Term and Revolving Loans | Equipment Loans | Maximum
Debt Instrument [Line Items]
Debt term	5 years
2015 Multiplier, Term Loan
Debt Instrument [Line Items]
Total long-term debt	$ 0	0	12,512
2014 Finland equipment loans, Danske Bank, 3-5 year terms, EURIBOR plus 1.7%
Debt Instrument [Line Items]
Total long-term debt	$ 60	$ 80	$ 104
2014 Finland equipment loans, Danske Bank, 3-5 year terms, EURIBOR plus 1.7% | Equipment Loans | EURIBOR
Debt Instrument [Line Items]
Basis on variable rate	1.70%

Long-Term Debt - Future princip

Long-Term Debt - Future principal payments (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
Amortization of debt issuance costs	$ 3	$ 95	$ 96	$ 194
Future principal payments
2,018			2,363
2,019			15,061
2,020			47
Total long-term debt	$ 17,409		$ 17,471	$ 20,252

Income Taxes (Details)

Income Taxes (Details) $ in Thousands	Jan. 01, 2018	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)item	Dec. 31, 2016USD ($)
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				34.00%
Increase in income tax				$ 16,100
Provisional income tax expense				1,100
Net income (loss) before income tax expense
Domestic				(9,064)	$ (19,006)
Foreign				15,759	6,686
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest, Total				6,695	(12,320)
Current tax expense:
State					8
Foreign				5,200	1,632
Current tax expense				5,200	1,640
Deferred tax expense
Foreign				(342)	242
Deferred tax expense				(342)	242
Income tax expense		$ 1,997	$ 2,240	4,858	1,882
Effective Income Tax Rate Reconciliation, Amount
Tax computed at federal statutory rate				2,276	(4,189)
State tax, net of federal tax benefit				(102)	(125)
Permanent items				1,078	662
Foreign dividends and unremitted earnings				796	586
Foreign rate differential				(1,897)	(991)
Rate change due to tax reform				17,176
Federal credits				(302)	(363)
Tax contingencies, net of reversals				592	663
Other				109	302
Valuation allowance				(14,868)	5,337
Income tax expense		$ 1,997	$ 2,240	4,858	1,882
Deferred tax assets:
Net operating loss carryforwards				21,626	35,803
Research and alternative minimum tax credits				3,635	3,373
Accrued expenses and other				1,891	2,466
Inventory				2,280	2,155
Property and equipment				1,644	2,351
Total gross deferred tax assets				31,076	46,148
Less valuation allowance				(28,873)	(43,741)
Total deferred tax assets				2,203	2,407
Deferred tax liabilities
Intangible assets				(396)	(503)
Unremitted foreign earnings					(521)
Total deferred tax liabilities				(396)	(1,024)
Net deferred tax assets				1,807	1,383
Increase/decrease in valuation allowance				$ (14,900)	5,300
Number of changes in ownership | item				3
Forecast
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%
August of 2000 one
Deferred tax liabilities
Net operating loss carryforward limitations				$ 17
August of 2000 two
Deferred tax liabilities
Net operating loss carryforward limitations				52
January 2,001
Deferred tax liabilities
Net operating loss carryforward limitations				459
US
Deferred tax assets:
Net operating loss carryforwards				104,500
US | Research and development credits
Deferred tax liabilities
Tax credits				4,200
State
Deferred tax assets:
Net operating loss carryforwards				13,700
State | Research and development credits
Deferred tax liabilities
Tax credits				59
Other assets
Deferred tax liabilities
Net deferred tax assets				$ 1,800	$ 1,400
China
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				25.00%	25.00%
Finland
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				20.00%	20.00%

Income Taxes - Unrecognized tax

Income Taxes - Unrecognized tax benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Unrecognized tax benefit
Balance at beginning of the period	$ 2,050	$ 1,528
Additions based on tax positions related to the current year	365	570
Additions for tax positions of prior years	99	3
Other	3	(51)
Balance at end of the period	2,517	2,050
Unrecognized tax benefits that would impact effective tax rate	2,500
Interest and penalties	367	145
Interest and penalties related to unrecognized tax benefits	939	572
tax benefit related to foreign currency translation adjustments	127	75
Non current income taxes payable
Unrecognized tax benefit
Balance at beginning of the period	1,300
Balance at end of the period	1,500	1,300
Noncurrent deferred tax assets
Unrecognized tax benefit
Balance at beginning of the period	759
Balance at end of the period	$ 1,000	$ 759

Stockholders' Equity - Narrativ

Stockholders' Equity - Narrative (Details) $ / shares in Units, $ in Thousands	Apr. 24, 2001	Nov. 30, 2014USD ($)$ / sharesshares	Jan. 31, 2001$ / sharesshares	May 31, 2017USD ($)$ / sharesshares	Feb. 29, 2016USD ($)$ / sharesshares	May 31, 2007USD ($)$ / sharesshares	Apr. 30, 2015USD ($)$ / sharesshares	Nov. 30, 2000$ / sharesshares	Jun. 30, 2018USD ($)ShareBasedCompensationPlan$ / sharesshares	Jun. 30, 2017USD ($)	Jul. 31, 2011USD ($)$ / sharesshares	Jun. 30, 2009USD ($)$ / sharesshares	Oct. 31, 2004USD ($)$ / sharesshares	Dec. 31, 2017USD ($)ShareBasedCompensationPlan$ / sharesshares	Dec. 31, 2016USD ($)ShareBasedCompensationPlan$ / sharesshares	Dec. 31, 2015$ / sharesshares	Dec. 31, 2014$ / sharesshares	May 31, 2018shares	Apr. 24, 2018shares	Dec. 31, 2000shares
Class of Stock [Line Items]
Shares authorized (in shares)									190,000,000					319,500,000	250,300,000
Par value (in dollars per share) | $ / shares									$ 0.0001					$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)									5,000,000					0	0
Preferred stock, par value (in dollars per share) | $ / shares									$ 0.0001					$ 0.0001	$ 0.0001
Preferred stock, shares issued (in shares)									0					0	0
Preferred stock, shares outstanding (in shares)									0					0	0
Common stock, shares issued (in shares)									34,792,000					2,979,000	2,539,000
Common stock, shares outstanding (in shares)									34,792,000					2,979,000	2,539,000
Net consideration received (net of offering costs) | $										$ 27,582				$ 27,481	$ 11,964
Offering costs | $									$ 15					0	571
Liquidation preference | $														$ 148,452	$ 119,669
Gross aggregate cash proceeds | $									$ 101,486
Number of shares authorized for issuance (in shares)									9,000,000					9,000,000	6,300,000
Number of stock-based compensation plans | ShareBasedCompensationPlan									2					2	2
Number of shares available for issuance (in shares)									2,900,000					1,700,000	149,000
Intrinsic value of options exercised | $									$ 1,900	38				$ 751	$ 32
Proceeds from the exercise of options | $									123	$ 66				$ 336	$ 52
Compensation cost related to nonvested awards not yet recognized | $									$ 22,762
IPO
Class of Stock [Line Items]
Share price (in dollars per share) | $ / shares									$ 7.185
Gross aggregate cash proceeds | $									$ 50,000
Warrants
Class of Stock [Line Items]
Expected term (in years)									5 years
Volatility rate (as a percent)									39.00%
Risk free rate (as a percent)									1.70%
Fair value of warrants | $									$ 360
Shares issued for warrants (in shares)																		15,000
Restricted stock awards and restricted stock units
Class of Stock [Line Items]
Forecasted number of non-vested contingent awards (in shares)									558,000
Restricted stock awards
Class of Stock [Line Items]
Forecasted number of non-vested contingent awards (in shares)									115,000					0
Performance-Based Awards
Class of Stock [Line Items]
Forecasted number of non-vested contingent awards (in shares)									206,000
2000 Plan
Class of Stock [Line Items]
Number of shares authorized for issuance (in shares)																				17,200,000
2001 Plan
Class of Stock [Line Items]
Number of shares available for issuance (in shares)																			0
2001 Plan | Options
Class of Stock [Line Items]
Term of options (in years)	10 years
Term of exercise of vested options after termination of employment (in months)	3 months
2001 Plan | Options | Minimum
Class of Stock [Line Items]
Vesting period (in years)	4 years
2001 Plan | Options | Maximum
Class of Stock [Line Items]
Vesting period (in years)	5 years
2018 Plan
Class of Stock [Line Items]
Number of shares authorized for issuance (in shares)																			3,400,000
Maximum number of shares to be added to Plan																			5,600,000
Percentage of shares of common stock on last day of fiscal year that can be added upon annual increase																			5.00%
2018 ESPP
Class of Stock [Line Items]
Number of shares authorized for issuance (in shares)																			900,000
Percentage of shares of common stock on last day of fiscal year that can be added upon annual increase																			2.00%
Number of shares that can be added upon annual increase (in shares)																			900,000
Convertible preferred stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)									0					129,478,000	100,255,000
Preferred stock, par value (in dollars per share) | $ / shares									$ 0.0001					$ 0.0001	$ 0.0001
Preferred stock, shares issued (in shares)									0					24,642,000	19,836,000
Preferred stock, shares outstanding (in shares)									0					24,642,000	19,836,000
Shares issued upon conversion of preferred stock (in shares)									1
Dividends declared (in dollars per share) | $ / shares									$ 0
Liquidation preference | $														$ 148,452	$ 119,669
Series A convertible preferred stock
Class of Stock [Line Items]
Number of shares sold (in shares)			40,000					1,800,000
Share price (in dollars per share) | $ / shares								$ 5.15
Series B convertible preferred stock
Class of Stock [Line Items]
Number of shares sold (in shares)			3,300,000
Share price (in dollars per share) | $ / shares			$ 13.30
Series A and Series B convertible preferred stock
Class of Stock [Line Items]
Shares issued upon conversion of preferred stock (in shares)									3,000,000
Conversion ratio									1
Series C convertible preferred stock
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)									0					4,600,000	4,600,000
Preferred stock, shares outstanding (in shares)									0					4,600,000	4,600,000
Number of shares sold (in shares)													1,600,000
Share price (in dollars per share) | $ / shares													$ 8.490
Net consideration received (net of offering costs) | $													$ 13,100
Offering costs | $													$ 129
Dividend entitlement per annum (in dollars per share) | $ / shares									$ 0.340
Liquidation preference (in dollars per share) | $ / shares									$ 8.490
Liquidation preference | $														$ 38,819	$ 38,819
Series D convertible preferred stock
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)									0					5,700,000	5,700,000
Preferred stock, shares outstanding (in shares)									0					5,700,000	5,700,000
Number of shares sold (in shares)						3,300,000						2,300,000
Share price (in dollars per share) | $ / shares						$ 4.590						$ 4.590
Net consideration received (net of offering costs) | $						$ 15,200						$ 10,700
Offering costs | $						$ 14						$ 55
Dividend entitlement per annum (in dollars per share) | $ / shares									$ 0.184
Liquidation preference (in dollars per share) | $ / shares									$ 4.590
Liquidation preference | $														$ 25,980	$ 25,980
Series E convertible preferred stock
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)									0					2,300,000	2,300,000
Preferred stock, shares outstanding (in shares)									0					2,300,000	2,300,000
Number of shares sold (in shares)											2,300,000
Share price (in dollars per share) | $ / shares											$ 7.4695
Net consideration received (net of offering costs) | $											$ 17,400
Offering costs | $											$ 135
Dividend entitlement per annum (in dollars per share) | $ / shares									$ 0.300
Liquidation preference (in dollars per share) | $ / shares									$ 7.469
Liquidation preference | $														$ 17,536	$ 17,536
Series E convertible preferred stock | Warrants
Class of Stock [Line Items]
Warrants granted to purchase convertible preferred stock (in shares)																	20,000
Exercise price (in dollars per share) | $ / shares																	$ 7.4695
Series F convertible preferred stock
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)									0					7,300,000	7,300,000
Preferred stock, shares outstanding (in shares)									0					7,300,000	7,300,000
Number of shares sold (in shares)		1,000,000			2,300,000		4,000,000
Share price (in dollars per share) | $ / shares		$ 5.145			$ 5.145		$ 5.145
Net consideration received (net of offering costs) | $		$ 4,900			$ 12,000		$ 20,300
Offering costs | $		$ 127			$ 36		$ 71
Dividend entitlement per annum (in dollars per share) | $ / shares									$ 0.206
Liquidation preference (in dollars per share) | $ / shares									$ 5.145
Liquidation preference | $														$ 37,334	$ 37,334
Series F convertible preferred stock | Warrants
Class of Stock [Line Items]
Warrants granted to purchase convertible preferred stock (in shares)																194,000
Exercise price (in dollars per share) | $ / shares																$ 5.145
Series G convertible preferred stock
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)									0					4,800,000	0
Preferred stock, shares outstanding (in shares)									0					4,800,000	0
Number of shares sold (in shares)				4,800,000
Share price (in dollars per share) | $ / shares				$ 5.9885
Net consideration received (net of offering costs) | $				$ 28,800
Offering costs | $				$ 1,300											$ 45
Dividend entitlement per annum (in dollars per share) | $ / shares									$ 0.240
Liquidation preference (in dollars per share) | $ / shares									$ 5.9885
Liquidation preference | $														$ 28,783

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of shares
Outstanding, beginning of period (in shares)	5,369	4,602
Options granted (in shares)	357	1,458
Options exercised (in shares)	(141)	(440)
Options canceled (in shares)	(18)	(251)
Outstanding, end of period (in shares)	5,567	5,369	4,602
Weighted average exercise price
Outstanding, beginning of period (in dollars per share)	$ 1.09	$ 0.87
Options granted (in dollars per share)	9.71	1.69
Options exercised (in dollars per share)	0.88	0.76
Options canceled (in dollars per share)	1.50	1.15
Outstanding, end of period (in dollars per share)	$ 1.65	$ 1.09	$ 0.87
Outstanding, Weighted average remaining contractual term (years)	7 years 2 months 12 days	7 years 4 months 24 days	8 years 2 months 12 days
Outstanding, Aggregate intrinsic value	$ 174,883	$ 29,863	$ 1,214
Aggregate intrinsic value (in dollars per share)	$ 33.06
Options exercisable at end of period
Number of shares	2,707
Weighted average exercise price (in dollars per share)	$ 0.88
Weighted average remaining contractual term (years)	6 years 7 months 6 days
Aggregate intrinsic value	$ 87,093
Options vested as of end of period and expected to vest after end of period
Number of shares	4,624
Weighted average exercise price (in dollars per share)	$ 1.65
Weighted average remaining contractual term (years)	7 years 8 months 12 days
Aggregate intrinsic value	$ 145,939

Stockholders' Equity - Summar57

Stockholders' Equity - Summary of Restricted Stock and Restricted Stock Unit Activity (Details) shares in Thousands	6 Months Ended
	Jun. 30, 2018$ / sharesshares
Restricted stock awards
Number of restricted shares
Balance, Beginning (in shares) | shares	0
Granted (in shares) | shares	115
Vested (in shares) | shares	0
Forfeited (in shares) | shares	0
Balance, Ending (in shares) | shares	115
Weighted average exercise price
Balance, Beginning (in dollars per share) | $ / shares	$ 0
Granted (in dollars per share) | $ / shares	37.15
Vested (in dollars per share) | $ / shares	0
Forfeited (in dollars per share) | $ / shares	0
Balance, Ending (in dollars per share) | $ / shares	$ 37.15
Restricted stock units
Number of restricted shares
Balance, Beginning (in shares) | shares	0
Granted (in shares) | shares	443
Vested (in shares) | shares	0
Forfeited (in shares) | shares	0
Balance, Ending (in shares) | shares	443
Weighted average exercise price
Balance, Beginning (in dollars per share) | $ / shares	$ 0
Granted (in dollars per share) | $ / shares	36.28
Vested (in dollars per share) | $ / shares	0
Forfeited (in dollars per share) | $ / shares	0
Balance, Ending (in dollars per share) | $ / shares	$ 36.28

Stockholders' Equity - Total Co

Stockholders' Equity - Total Compensation Cost Related to Nonvested Awards Not Yet Recognized (Details) $ in Thousands	Jun. 30, 2018USD ($)
Equity [Abstract]
2,018	$ 3,683
2,019	7,023
2,020	6,051
2,021	4,344
2,022	1,652
2,023	9
Total compensation cost	$ 22,762

401(k) Plan (Details)

401(k) Plan (Details) - 401(k) Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
401(k) Plan
Employer matching contribution (as a percent)	40.00%	40.00%
Employer first contribution to the plan (as a percent)	5.00%	5.00%
Employer matching contribution	$ 462	$ 376

Related-Party Transactions (Det

Related-Party Transactions (Details) - USD ($) shares in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Convertible preferred stock, shares outstanding (in shares)	0	0	0
Series E convertible preferred stock
Related Party Transaction [Line Items]
Convertible preferred stock, shares outstanding (in shares)	0	2,300	2,300
Member of the Board of Directors | Consulting services
Related Party Transaction [Line Items]
Related party sales, general and administrative expense	$ 80	$ 102	$ 54
Customer owning Series E preferred stock
Related Party Transaction [Line Items]
Revenue recognized related to customer		1,300	1,400
Balance of accounts receivable		$ 1	$ 0
Customer owning Series E preferred stock | Series E convertible preferred stock
Related Party Transaction [Line Items]
Convertible preferred stock, shares outstanding (in shares)		1,100	1,200

Segment and Geographic Inform61

Segment and Geographic Information (Details) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2018USD ($)segment	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Revenues and Long-Lived Assets
Number of operating segment | segment	1
Revenues	$ 94,172	$ 64,551	$ 138,580	$ 101,325
Long-lived assets	25,766		23,415	23,205
China
Revenues and Long-Lived Assets
Revenues	38,793	26,843	55,344	38,309
Long-lived assets	8,691		8,433	8,341
North America
Revenues and Long-Lived Assets
Revenues	32,551	19,939	46,489	36,200
United States
Revenues and Long-Lived Assets
Long-lived assets	16,228		13,991	13,811
Other
Revenues and Long-Lived Assets
Revenues	22,828	$ 17,769	36,747	26,816
Long-lived assets	$ 847		$ 991	$ 1,053

Net Income (Loss) per Share - C

Net Income (Loss) per Share - Calculation of Basic and Diluted Net Income (Loss) per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Numerator:
Net income (loss)	$ 7,569	$ (1,500)	$ 1,837	$ (14,202)
Less: Income allocated to participating securities	(4,415)	0	(1,837)	0
Net income (loss) attributable to common stockholders	$ 3,154	$ (1,500)	$ 0	$ (14,202)
Denominator:
Weighted-average shares, basic (in shares)	13,761	2,613	2,735	2,500
Dilutive effect of warrant (in shares)	137	0	0	0
Weighted-average common shares outstanding, diluted (in shares)	18,797	2,613	2,735	2,500
Net income (loss) per share attributable to common stockholders:
Basic (in dollars per share)	$ 0.23	$ (0.57)	$ 0	$ (5.68)
Diluted (in dollars per share)	$ 0.17	$ (0.57)	$ 0	$ (5.68)
Restricted stock awards and restricted stock units
Denominator:
Diluted effect of share-based payment arrangements (in shares)	1	0	0	0
Stock options to purchase common stock
Denominator:
Diluted effect of share-based payment arrangements (in shares)	4,898	0	0	0

Net Income (Loss) per Share - A

Net Income (Loss) per Share - Antidilutive Securities Excluded from Dilutive Shares (Details) - shares shares in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	541	30,006	28,678	24,590
Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	24,642	23,095	19,774
Preferred stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	214	214	214
Restricted stock awards and restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	541	0	0	0
Stock options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	5,150	5,369	4,602