Coherent 10-Q 14 May 15 2015 Q2 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	6 Months Ended
	Apr. 04, 2015	11-May-15
DEI [Abstract]
Entity Registrant Name	COHERENT INC
Trading Symbol	COHR
Entity Central Index Key	21510
Document Type	10-Q
Document Period End Date	4-Apr-15
Amendment Flag	FALSE
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	7
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		23,831,252

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (unaudited) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Apr. 04, 2015	Mar. 29, 2014	Apr. 04, 2015	Mar. 29, 2014
Income Statement [Abstract]
Net sales	$203,721	$199,222	$404,336	$392,778
Cost of sales	120,417	118,557	238,713	234,567
Gross profit	83,304	80,665	165,623	158,211
Operating expenses:
Research and development	21,024	20,413	40,197	41,350
Selling, general and administrative	39,482	39,296	77,623	79,187
Amortization of intangible assets	666	916	1,362	1,850
Total operating expenses	61,172	60,625	119,182	122,387
Income from operations	22,132	20,040	46,441	35,824
Other income (expense):
Interest and dividend income	161	58	257	117
Interest expense	-14	-8	-25	-31
Other - net	1,843	990	1,073	734
Total other income (expense), net	1,990	1,040	1,305	820
Income before income taxes	24,122	21,080	47,746	36,644
Provision for income taxes	5,709	5,773	11,903	9,634
Net income	$18,413	$15,307	$35,843	$27,010
Net income per share:
Basic	$0.75	$0.62	$1.44	$1.10
Diluted	$0.74	$0.61	$1.43	$1.08
Shares used in computation:
Basic	24,709	24,782	24,823	24,662
Diluted	24,891	25,044	25,042	24,980

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (unaudited) (USD $)	3 Months Ended				6 Months Ended
In Thousands, unless otherwise specified	Apr. 04, 2015		Mar. 29, 2014		Apr. 04, 2015		Mar. 29, 2014
Statement of Comprehensive Income [Abstract]
Net income	$18,413		$15,307		$35,843		$27,010
Other comprehensive income (loss):
Translation adjustment, net of taxes	-33,280	[1]	2,867	[1]	-47,799	[1]	4,015	[1]
Net gain (loss) on derivatives instruments, net of taxes	175	[2]	0	[2]	550	[2]	0	[2]
Changes in unrealized gains (losses) on available-for-sale securities, net of taxes	274	[3]	-6	[3]	201	[3]	-17	[3]
Other comprehensive income (loss), net of tax	-32,831	[4]	2,861	[4]	-47,048	[4]	3,998	[4]
Comprehensive income (loss)	-14,418		18,168		-11,205		31,008
Translation Adjustment Functional to Reporting Currency, Tax Benefit (Expense)	1,110		-153		1,862		-1,339
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	$102				$319
[1]	Tax benefit of $1,110 and $1,862 was provided on translation adjustments during the three and six months ended April 4, 2015, respectively. Tax expense of $153 and $1,339 was provided on translation adjustments during the three and six months ended March 29, 2014, respectively.
[2]	Tax expense of $102 and $319 was provided on net gains (losses) on derivative instruments during the three and six months ended April 4, 2015.
[3]	Tax expense (benefit) on changes in unrealized gains (losses) on available-for-sale securities was insignificant.
[4]	Reclassification adjustments were not significant during the three and six months ended April 4, 2015 and March 29, 2014.

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (unaudited) (USD $)	Apr. 04, 2015	Sep. 27, 2014
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$115,081	$91,217
Short-term investments	229,353	227,058
Accounts receivable—net of allowances of $996 and $1,155, respectively	124,227	137,324
Inventories	153,659	170,483
Prepaid expenses and other assets	38,538	27,839
Deferred tax assets	23,832	27,134
Total current assets	684,690	681,055
Property and equipment, net	100,903	107,424
Goodwill	99,388	109,513
Intangible assets, net	23,896	31,666
Other assets	66,116	69,717
Total assets	974,993	999,375
Current liabilities:
Accounts payable	31,949	32,784
Income taxes payable	1,036	2,029
Other current liabilities	99,159	82,506
Total current liabilities	132,144	117,319
Other long-term liabilities	52,364	62,407
Commitments and contingencies
Common stock, par value $.01 per share:
Authorized—500,000 shares, Outstanding—24,763 shares and 24,950 shares, respectively	246	248
Additional paid-in capital	166,085	184,042
Accumulated other comprehensive income (loss)	-12,366	34,682
Retained earnings	636,520	600,677
Total stockholders’ equity	790,485	819,649
Total liabilities and stockholders’ equity	$974,993	$999,375

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Apr. 04, 2015	Sep. 27, 2014
In Thousands, except Share data, unless otherwise specified
Condensed Consolidated Balance Sheets (Parenthetical) [Abstract]
Allowance for Doubtful Accounts Receivable	$996	$1,155
Common Stock, Par or Stated Value Per Share	$0.01	$0.01
Common Stock, Shares Authorized	500,000,000	500,000,000
Common Stock, Shares, Outstanding	24,763,000	24,950,000

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (unaudited) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Apr. 04, 2015	Mar. 29, 2014
Cash flows from operating activities:
Net income	$35,843	$27,010
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	12,436	13,524
Amortization of intangible assets	4,216	4,879
Deferred income taxes	6,483	-2,078
Stock-based compensation	9,172	9,540
Other non-cash (income) expense	384	-22
Changes in assets and liabilities, net of effect of acquisitions:
Accounts receivable	6,441	-1,574
Inventories	6,114	-7,142
Prepaid expenses and other assets	-13,921	-8,139
Other assets	582	-2,067
Accounts payable	557	-2,070
Income taxes payable/receivable	-9,871	-4,474
Other current liabilities	21,894	14,330
Other long-term liabilities	84	2,701
Net cash provided by operating activities	80,414	44,418
Cash flows from investing activities:
Purchases of property and equipment	-12,210	-13,995
Proceeds from dispositions of property and equipment	974	500
Purchases of available-for-sale securities	-177,704	-89,900
Proceeds from sales and maturities of available-for-sale securities	175,436	86,346
Net cash used in investing activities	-13,504	-17,049
Cash flows from financing activities:
Short-term borrowings	19,485	36,768
Repayments of short-term borrowing	-19,485	-36,768
Net change in capital lease obligations	0	-2
Issuance of common stock under employee stock option and purchase plans	3,701	7,038
Repurchase of common stock	-25,009	0
Net settlement of restricted common stock	-5,235	-7,689
Net cash used in financing activities	-26,543	-653
Effect of exchange rate changes on cash and cash equivalents	-16,503	3,091
Net increase in cash and cash equivalents	23,864	29,807
Cash and cash equivalents, beginning of period	91,217	110,444
Cash and cash equivalents, end of period	115,081	140,251
Unpaid property and equipment purchases	$828	$614

Basis_of_Presentation

Basis of Presentation	6 Months Ended
	Apr. 04, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	BASIS OF PRESENTATION
	The accompanying unaudited condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted pursuant to such rules and regulations. These interim condensed consolidated financial statements and notes thereto should be read in conjunction with the Coherent, Inc. (referred to herein as the “Company,” “we,” “our,” “us” or “Coherent”) condensed consolidated financial statements and notes thereto filed on Form 10-K for the fiscal year ended September 27, 2014. In the opinion of management, all adjustments necessary for a fair presentation of financial condition and results of operation as of and for the periods presented have been made and include only normal recurring adjustments. Interim results of operations are not necessarily indicative of results to be expected for the year or any other interim periods. Our fiscal year ends on the Saturday closest to September 30 and our second fiscal quarters include 14 and 13 weeks of operations in fiscal 2015 and 2014, respectively. Fiscal year 2015 includes 53 weeks and fiscal year 2014 includes 52 weeks.

Recent_Accounting_Standards

Recent Accounting Standards	6 Months Ended
	Apr. 04, 2015
Accounting Policies [Abstract]
Recent Accounting Standards	RECENT ACCOUNTING STANDARDS
	Adoption of New Accounting Pronouncements
	In July 2013, the FASB issued amended guidance that resolves the diversity in practice for the presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. This new accounting guidance requires the netting of unrecognized tax benefits ("UTBs") against a deferred tax asset for a loss or other carryforward that would apply in settlement of the uncertain tax positions. Under the new standard, UTBs will be netted against all available same-jurisdiction losses or other tax carryforwards that would be utilized, rather than only against carryforwards that are created by the UTBs. The standard requires prospective adoption but allows retrospective adoption for all periods presented. In the first quarter of fiscal year 2015, we adopted the FASB’s amended guidance prospectively in accordance with the standard. As a result of this adoption, both long-term income taxes payable and noncurrent deferred tax assets decreased by approximately $7.9 million on our condensed consolidated balance sheet.
	Recently Issued Accounting Pronouncement
	In May 2014, the FASB amended the Accounting Standards Codification and created a new Topic 606, Revenue from Contracts with Customers. The new guidance establishes a single comprehensive contract-based model for entities to use in accounting for revenue arising from contracts with customers. The new model significantly changes existing GAAP, requires substantial judgment in its application, and will generally require companies to make more disclosures about revenue. The core principle of the amendment is that an entity recognizes 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. In applying the new guidance, an entity will (1) identify the contract(s) with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the contract’s performance obligations; and (5) recognize revenue when (or as) the entity satisfies a performance obligation. The new standard provides for two alternative implementation methods. The first is to apply the new standard retrospectively to each prior reporting period presented. This method does allow the use of certain practical expedients. The second method is to apply the new standard retrospectively in the year of initial adoption and record a cumulative effect adjustment for the impact of adjusting contracts open at the date of adoption. Under this transition method, we would apply this guidance retrospectively only to contracts that are not completed contracts at the date of initial application. We would then recognize the cumulative effect of initially applying the standard as an adjustment to the opening balance of retained earnings. This method also requires us to disclose comparative information for the year of adoption. We will adopt the FASB’s amended guidance for our fiscal year beginning October 1, 2017; early adoption is not permitted. However, in April 2015, the FASB tentatively proposed a one-year deferral of the effective date. If the proposed deferral is approved, the new standard will become effective for our fiscal year beginning September 30, 2018.
	We are currently evaluating the new guidance and have not determined the impact this standard may have on our financial statements nor have we decided upon the method of adoption.

Fair_Values

Fair Values	6 Months Ended
	Apr. 04, 2015
Fair Value Disclosures [Abstract]
Fair Values	IR VALUES
	We have not changed our valuation techniques in measuring the fair value of any financial assets and liabilities during the period. We recognize transfers between levels within the fair value hierarchy, if any, at the end of each quarter. There were no transfers between levels during the periods presented. As of April 4, 2015 and September 27, 2014, we did not have any assets or liabilities valued based on Level 3 valuations.
	Financial assets and liabilities measured at fair value as of April 4, 2015 and September 27, 2014 are summarized below (in thousands):
			Aggregate Fair Value			Quoted Prices		Significant			Aggregate Fair Value			Quoted Prices		Significant
						in		Other						in		Other
						Active Markets		Observable						Active Markets		Observable
						for Identical		Inputs						for Identical		Inputs
						Assets								Assets
			4-Apr-15								27-Sep-14
						(Level 1)		(Level 2)						(Level 1)		(Level 2)
	Assets:
	Cash equivalents:
	Money market fund deposits		$	8,315		$	8,315	$	—		$	5,975		$	5,975	$	—
	Certificates of deposit		17,600			—		17,600			12,084			—		12,084
	Commercial paper (1)		9,297			—		9,297			1,400			—		1,400
	Short-term investments:
	U.S. Treasury and agency obligations (1)		155,539			—		155,539			150,088			—		150,088
	Corporate notes and obligations (1)		41,261			—		41,261			52,987			—		52,987
	Commercial paper (1)		16,985			—		16,985			23,983			—		23,983
	Equity securities (1)		15,568			—		15,568			—			—		—
	Prepaid and other assets:
	Foreign currency contracts (2)		331			—		331			366			—		366
	Mutual funds — Deferred comp and supplemental plan (3)		14,040			14,040		—			15,000			15,000		—
	Total		$	278,936		$	22,355	$	256,581		$	261,883		$	20,975	$	240,908
	Liabilities:
	Other current liabilities:
	Foreign currency contracts (2)		$	(2,437	)	$	—	$	(2,437	)	$	(2,196	)	$	—	$	(2,196	)
	Total		$	276,499		$	22,355	$	254,144		$	259,687		$	20,975	$	238,712
	___________________________________________________
	-1	Valuations are based upon quoted market prices in active markets involving similar assets. The market inputs used to value these instruments generally consist of market yields, reported trades, broker/dealer quotes or alternative pricing sources with reasonable levels of price transparency. Pricing sources include industry standard data providers, security master files from large financial institutions, and other third party sources which are input into a distribution-curve-based algorithm to determine a daily market value. This creates a “consensus price” or a weighted average price for each security.
	-2	The principal market in which we execute our foreign currency contracts is the institutional market in an over-the-counter environment with a relatively high level of price transparency. The market participants usually are large commercial banks. Our foreign currency contracts’ valuation inputs are based on quoted prices and quoted pricing intervals from public data sources and do not involve management judgment. At September 27, 2014, prepaid expenses and other assets include $303 non-designated forward contracts and $63 foreign currency contracts designated for cash flow hedges, respectively; other current liabilities include $1,246 non-designated forward contracts and $950 cash flow contracts, respectively. At April 4, 2015, prepaid expenses and other assets include $331 non-designated forward contracts and zero cash flow contracts, respectively; other current liabilities include $2,400 non-designated forward contracts and $37 cash flow contracts, respectively. See Note 5, "Derivative Instruments and Hedging Activities".
	-3	The fair value of mutual funds is determined based on quoted market prices. Securities traded on a national exchange are stated at the last reported sales price on the day of valuation; other securities traded in over-the-counter markets and listed securities for which no sale was reported on that date are stated as the last quoted bid price.

Derivative_Instruments_and_Hed

Derivative Instruments and Hedging Activities	6 Months Ended
	Apr. 04, 2015
Offsetting Assets [Line Items]
Offsetting Assets [Table Text Block]	Offsetting of Financial Assets/Liabilities under Master Netting Agreements with Derivative Counterparties as of April 4, 2015 and September 27, 2014 (in thousands):
															Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets
			Gross Amounts of Recognized Derivative Assets				Gross Amounts Offset in the Condensed Consolidated Balance Sheets				Net Amounts of Derivative Assets Presented in the Condensed Consolidated Balance Sheets				Financial Instruments (1)			Cash Collateral Received		Net Amounts
	As of April 4, 2015:
	Foreign exchange contracts		$	331			$	—			$	331			$	(316	)	$	—	$	15
	As of September 27, 2014:
	Foreign exchange contracts		$	367			$	—			$	367			$	(367	)	$	—	$	—
	(1) The balances at April 4, 2015 and September 27, 2014 were related to derivative liabilities which are allowed to be net settled against derivative assets in accordance with the master netting agreements.
Derivative Instruments and Hedging Activities	DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES
	We maintain operations in various countries outside of the United States and have foreign subsidiaries that manufacture and sell our products in various global markets. The majority of our sales are transacted in U.S. dollars. However, we do generate revenues in other currencies, primarily the Euro, Japanese Yen (JPY), Korean Won and Chinese Renminbi (RMB). As a result, our earnings, cash flows and cash balances are exposed to fluctuations in foreign currency exchange rates. We attempt to limit these exposures through financial market instruments. We utilize derivative instruments, primarily forward contracts with maturities of two months or less, to manage our exposure associated with anticipated cash flows and net asset and liability positions denominated in foreign currencies. Gains and losses on the forward contracts are mitigated by gains and losses on the underlying instruments. We do not use derivative financial instruments for speculative or trading purposes. The credit risk amounts represent the Company’s gross exposure to potential accounting loss on derivative instruments that are outstanding or unsettled if all counterparties failed to perform according to the terms of the contract, based on then-current currency or interest rates at each respective date.
	For derivative instruments that are not designated as hedging instruments, gains and losses are recognized in other income (expense).
	Non-Designated Derivatives
	The outstanding notional contract and fair value asset (liability) amounts of non-designated hedge contracts, with maximum maturity of four months, are as follows (in thousands):
		U.S. Notional Contract Value								U.S. Fair Value
		April 4, 2015				September 27, 2014				April 4, 2015				September 27, 2014
	Euro currency hedge contracts
	Purchase	$	34,449			$	31,926			$	(1,663	)		$	(1,153	)
	Japanese YEN currency hedge contracts
	Purchase	$	6,763			$	471			$	124			$	(3	)
	Sell	$	(18,373	)		$	(15,084	)		$	(651	)		$	169
	Korean Won currency hedge contracts
	Purchase	$	886			$	—			$	26			$	—
	Sell	$	(9,711	)		$	(2,991	)		$	(68	)		$	72
	Chinese RMB currency hedge contracts
	Purchase	$	431			$	—			$	—			$	—
	Sell	$	(9,202	)		$	(15,678	)		$	(17	)		$	(56	)
	Other foreign currency hedge contracts
	Purchase	$	3,035			$	1,899			$	50			$	(35	)
	Sell	$	(6,529	)		$	(3,515	)		$	130			$	63
	Designated Derivatives
	Cash flow hedges related to anticipated transactions are designated and documented at the inception of the hedge when we enter into contracts for specific future transactions. Cash flow hedges are evaluated for effectiveness quarterly. The effective portion of the gain or loss on these hedges is reported as a component of Other Comprehensive Income ("OCI") in stockholder's equity and is reclassified into earnings when the underlying transaction affects earnings. The majority of the after-tax net income or loss related to derivative instruments included in OCI at April 4, 2015 is expected to be reclassified into earnings within 12 months. Changes in the fair value of currency forward contracts due to changes in time value are excluded from the assessment of effectiveness and recognized in other income (expense) as incurred. We classify the cash flows from the foreign exchange forward contracts that are accounted for as cash flow hedges in the same section as the underlying item, primarily within cash flows from operating activities since we do not designate our cash flow hedges as investing or financing activities.
	The outstanding notional contract and fair value asset (liability) amounts of designated cash flow hedge contracts, with maximum maturity of thirteen months, are as follows (in thousands):
		U.S. Notional Contract Value								U.S. Fair Value
		4-Apr-15				27-Sep-14				4-Apr-15				27-Sep-14
	Euro currency hedge contracts
	Purchase	$	—			$	11,149			$	—			$	(950	)
	Japanese Yen currency hedge contracts
	Sell	$	(2,875	)		$	(12,091	)		$	(37	)		$	63
	We have entered into certain derivative forward contracts to sell Japanese Yen and buy Euro to hedge revenue exposures related to our photonics-based solutions in Asia. In order to facilitate the hedge, we transact with counterparties in the U.S. directly and then allocate the hedge contracts to our affiliates through a back-to-back relationship with our German subsidiary. The German subsidiary designates these hedge contracts as cash flow hedges under ASC 815.
	The fair value of our derivative instruments is included in prepaid expenses and other assets and in other current liabilities in our Condensed Consolidated Balance Sheets (see Note 3); such amounts were not material as of April 4, 2015 and September 27, 2014.
			Location in financial statements	Three Months Ended								Six Months Ended
				April 4, 2015				March 29, 2014				April 4, 2015				March 29, 2014
	Derivatives designated as hedging instruments
	Gains(losses) in AOCI on derivatives (effective portion), after tax		AOCI	$	175			$	—			$	550			$	—
	Gains(losses) reclassified from AOCI into income (effective portion)		Cost of sales	$	(1,106	)		$	—			$	(1,720	)		$	—
	Gains(losses) reclassified from AOCI into income (effective portion)		Revenue	$	(92	)		$	—			$	208			$	—
	Gains(losses) recognized in income on derivatives (ineffective portion and amount excluded from effectiveness testing)		Other income(expense)	$	(77	)		$	—			$	(112	)		$	—
	Derivatives not designated as hedging instruments
	Gains(losses) recognized in income		Other income(expense)	$	(5,413	)		$	197			$	(6,125	)		$	159
	During the three and six months ended April 4, 2015 we recognized a loss of $0.1 million in other income (expense) as ineffectiveness related to a portion of an anticipated hedged transaction that failed to occur within the original hedge period plus two months. The remainder of the hedged transaction occurred as expected and effective amounts were recognized in revenue as disclosed in the above table.
	The amounts that will be reclassified from AOCI to earnings will generally be offset by the recognition of the hedged transactions (e.g., anticipated cost of sales) in earnings, thereby achieving the realization of prices contemplated by the underlying risk management strategies and will vary from the expected amounts presented above as a result of changes in foreign exchange rates.
	To mitigate credit risk in derivative transactions, we enter into master netting arrangements that allow each counterparty in the arrangements to net settle amounts of multiple and separate derivative transactions under certain conditions. We present the fair value of derivative assets and liabilities within our condensed consolidated balance sheet on a gross basis even when derivative transactions are subject to master netting arrangements and may otherwise qualify for net presentation. Our derivative contracts do not contain any credit risk related contingent features and do not require collateral or other security to be furnished by us or the counterparties.
	Offsetting of Financial Assets/Liabilities under Master Netting Agreements with Derivative Counterparties as of April 4, 2015 and September 27, 2014 (in thousands):
															Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets
			Gross Amounts of Recognized Derivative Assets				Gross Amounts Offset in the Condensed Consolidated Balance Sheets				Net Amounts of Derivative Assets Presented in the Condensed Consolidated Balance Sheets				Financial Instruments (1)			Cash Collateral Received		Net Amounts
	As of April 4, 2015:
	Foreign exchange contracts		$	331			$	—			$	331			$	(316	)	$	—	$	15
	As of September 27, 2014:
	Foreign exchange contracts		$	367			$	—			$	367			$	(367	)	$	—	$	—
	(1) The balances at April 4, 2015 and September 27, 2014 were related to derivative liabilities which are allowed to be net settled against derivative assets in accordance with the master netting agreements.
															Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets
			Gross Amounts of Recognized Derivative Liabilities				Gross Amounts Offset in the Condensed Consolidated Balance Sheets				Net Amounts of Derivative Liabilities Presented in the Condensed Consolidated Balance Sheets				Financial Instruments (1)			Cash Collateral Paid		Net Amounts
	As of April 4, 2015:
	Foreign exchange contracts		$	(2,437	)		$	—			$	(2,437	)		$	316		$	—	$	(2,121	)
	As of September 27, 2014:
	Foreign exchange contracts		$	(2,197	)		$	—			$	(2,197	)		$	367		$	—	$	(1,830	)
	(1) The balances at April 4, 2015 and September 27, 2014 were related to derivative assets which are allowed to be net settled against derivative liabilities in accordance with the master netting agreements.

Derivative_Instruments_and_Hed1

Derivative Instruments and Hedging Activities Offset Liabilities (Notes)	6 Months Ended
	Apr. 04, 2015
Offsetting Liabilities [Line Items]
Offsetting Liabilities [Table Text Block]
										Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets
		Gross Amounts of Recognized Derivative Liabilities			Gross Amounts Offset in the Condensed Consolidated Balance Sheets		Net Amounts of Derivative Liabilities Presented in the Condensed Consolidated Balance Sheets			Financial Instruments (1)		Cash Collateral Paid		Net Amounts
	As of April 4, 2015:
	Foreign exchange contracts	$	(2,437	)	$	—	$	(2,437	)	$	316	$	—	$	(2,121	)
	As of September 27, 2014:
	Foreign exchange contracts	$	(2,197	)	$	—	$	(2,197	)	$	367	$	—	$	(1,830	)
	(1) The balances at April 4, 2015 and September 27, 2014 were related to derivative assets which are allowed to be net settled against derivative liabilities in accordance with the master netting agreements.

ShortTerm_Investments

Short-Term Investments	6 Months Ended
	Mar. 29, 2014
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Short-Term Investments	SHORT-TERM INVESTMENTS
	We consider all highly liquid investments with maturities of three months or less at the time of purchase to be cash equivalents. Investments classified as available-for-sale are reported at fair value with unrealized gains and losses, net of related income taxes, recorded as a separate component of other comprehensive income (“OCI”) in stockholders’ equity until realized. Interest and amortization of premiums and discounts for debt securities are included in interest income. Gains and losses on securities sold are determined based on the specific identification method and are included in other income (expense).
	Cash, cash equivalents and short-term investments consist of the following (in thousands):
		April 4, 2015
		Cost Basis		Unrealized		Unrealized			Fair Value
				Gains		Losses
	Cash and cash equivalents	$	115,081	$	—	$	—		$	115,081
	Short-term investments:
	Available-for-sale securities:
	Commercial paper	$	16,985	$	—	$	—		$	16,985
	U.S. Treasury and agency obligations	154,648		908		(17		)	155,539
	Corporate notes and obligations	41,122		177		(38		)	41,261
	Equity Securities	15,299		269		—			15,568
	Total short-term investments	$	228,054	$	1,354	$	(55	)	$	229,353
		September 27, 2014
		Cost Basis		Unrealized		Unrealized			Fair Value
				Gains		Losses
	Cash and cash equivalents	$	91,217	$	—	$	—		$	91,217
	Short-term investments:
	Available-for-sale securities:
	Commercial paper	$	23,983	$	—	$	—		$	23,983
	U.S. Treasury and agency obligations	149,260		831		(3		)	150,088
	Corporate notes and obligations	52,834		195		(42		)	52,987
	Total short-term investments	$	226,077	$	1,026	$	(45	)	$	227,058
	None of the unrealized losses as of April 4, 2015 or September 27, 2014 were considered to be other-than-temporary impairments.
	The amortized cost and estimated fair value of available-for-sale investments in debt securities as of April 4, 2015 and September 27, 2014 classified as short-term investments on our condensed consolidated balance sheet were as follows (in thousands):
		April 4, 2015				September 27, 2014
		Amortized Cost		Estimated Fair Value		Amortized Cost			Estimated Fair Value
	Investments in available-for-sale debt securities due in less than one year	$	168,338	$	169,230	$	178,329		$	179,223
	Investments in available-for-sale debt securities due in one to five years (1)	$	44,417	$	44,555	$	47,748		$	47,835
	(1) Classified as short-term investments because these securities are highly liquid and can be sold at any time.
	During the three and six months ended April 4, 2015, we received proceeds totaling $48.3 million and $77.8 million, respectively, from the sale of available-for-sale securities and realized gross gains of less than $0.1 million and $0.1 million, respectively. During the three and six months ended March 29, 2014, we received proceeds totaling $7.0 million and $14.1 million, respectively, from the sale of available-for-sale securities and realized gross gains of less than $0.1 million and $0.1 million, respectively.

Goodwill_and_Intangible_Assets

Goodwill and Intangible Assets	6 Months Ended
	Apr. 04, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	GOODWILL AND INTANGIBLE ASSETS
	During the six months ended April 4, 2015, we noted no indications of impairment or triggering events to cause us to review goodwill for potential impairment. We will conduct our annual goodwill testing during the fourth fiscal quarter.
	The changes in the carrying amount of goodwill by segment for the period from September 27, 2014 to April 4, 2015 are as follows (in thousands):
		Specialty			Commercial			Total
		Lasers and			Lasers and
		Systems			Components
	Balance as of September 27, 2014	$	103,150		$	6,363		$	109,513
	Translation adjustments and other	(10,125		)	—			(10,125		)
	Balance as of April 4, 2015	$	93,025		$	6,363		$	99,388
	Components of our amortizable intangible assets are as follows (in thousands):
		April 4, 2015									September 27, 2014
		Gross			Accumulated			Net			Gross		Accumulated			Net
		Carrying			Amortization						Carrying		Amortization
		Amount									Amount
	Existing technology	$	76,104		$	(58,320	)	$	17,784		$	81,551	$	(57,827	)	$	23,724
	Customer lists	15,154			(9,463		)	5,691			16,632		(9,199		)	7,433
	Trade name	392			(337		)	55			431		(346		)	85
	In-process research & development	366			—			366			424		—			424
	Total	$	92,016		$	(68,120	)	$	23,896		$	99,038	$	(67,372	)	$	31,666
	For accounting purposes, when an intangible asset is fully amortized, it is removed from the disclosure schedule.
	Amortization expense for intangible assets for the six months ended April 4, 2015 and March 29, 2014 was $4.2 million and $4.9 million, respectively, which includes $3.3 million and $3.8 million, respectively, for amortization of existing technology. The change in the accumulated amortization also includes $3.5 million of foreign exchange impact for the six months ended April 4, 2015.
	At April 4, 2015, estimated amortization expense for the remainder of fiscal 2015, the next five succeeding fiscal years and all fiscal years thereafter are as follows (in thousands):
		Estimated
		Amortization
		Expense
	2015 (remainder)	$	3,931
	2016	7,484
	2017	6,359
	2018	3,745
	2019	2,036
	2020	131
	Thereafter	210
	Total	$	23,896

Balance_Sheet_Details

Balance Sheet Details	6 Months Ended
	Apr. 04, 2015
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Details	BALANCE SHEET DETAILS
	Inventories consist of the following (in thousands):
		April 4,			September 27,
		2015			2014
	Purchased parts and assemblies	$	48,440		$	51,091
	Work-in-process	59,567			70,486
	Finished goods	45,652			48,906
	Total inventories	$	153,659		$	170,483
	Prepaid expenses and other assets consist of the following (in thousands):
		April 4,			September 27,
		2015			2014
	Prepaid and refundable income taxes	$	8,965		$	11,001
	Other taxes receivable	15,892			5,184
	Prepaid expenses and other	13,681			11,654
	Total prepaid expenses and other assets	$	38,538		$	27,839
	Other assets consist of the following (in thousands):
		April 4,			September 27,
		2015			2014
	Assets related to deferred compensation arrangements	$	26,039		$	26,484
	Deferred tax assets	34,526			37,616
	Other assets	5,551			5,617
	Total other assets	$	66,116		$	69,717
	Other current liabilities consist of the following (in thousands):
		April 4,			September 27,
		2015			2014
	Accrued payroll and benefits	$	35,269		$	29,228
	Deferred income	16,256			15,536
	Warranty reserve	15,941			16,961
	Accrued expenses and other	12,100			13,410
	Other taxes payable	16,334			5,036
	Customer deposits	3,259			2,335
	Total other current liabilities	$	99,159		$	82,506
	Components of the reserve for warranty costs during the first six months of fiscal 2015 and 2014 were as follows (in thousands):
		Six Months Ended
		April 4,			March 29,
		2015			2014
	Beginning balance	$	16,961		$	18,508
	Additions related to current period sales	11,618			12,434
	Warranty costs incurred in the current period	(10,822		)	(12,713		)
	Adjustments to accruals related to foreign exchange and other	(1,816		)	(248		)
	Ending balance	$	15,941		$	17,981
	Other long-term liabilities consist of the following (in thousands):
		April 4,			September 27,
		2015			2014
	Long-term taxes payable	$	7,725		$	15,776
	Deferred compensation	27,578			27,858
	Deferred tax liabilities	5,277			6,511
	Deferred income	3,010			3,448
	Asset retirement obligations liability	2,124			2,222
	Other long-term liabilities	6,650			6,592
	Total other long-term liabilities	$	52,364		$	62,407

ShortTerm_Borrowings

Short-Term Borrowings	6 Months Ended
	Mar. 29, 2014
Short-term Debt [Abstract]
Short-Term Borrowings	SHORT-TERM BORROWINGS
	We have several lines of credit which allow us to borrow in the applicable local currency. We have a total of $7.8 million of unsecured foreign lines of credit as of April 4, 2015.  At April 4, 2015, we had used $2.8 million of these available foreign lines of credit as guarantees. These credit facilities were used in Europe, Japan and China during the second fiscal quarter of 2015.  In addition, our domestic line of credit consists of a $50.0 million unsecured revolving credit account with Union Bank of California. The agreement will expire on May 31, 2017. The line of credit is subject to covenants related to financial ratios and tangible net worth with which we are currently in compliance.  No amounts have been drawn upon our domestic line of credit as of April 4, 2015.

StockBased_Compensation

Stock-Based Compensation	6 Months Ended
	Apr. 04, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION
	Fair Value of Stock Compensation
	We recognize compensation expense for all share based payment awards based on the fair value of such awards. The expense is recognized on a straight-line basis over the respective requisite service period of the awards.
	Determining Fair Value
	The fair values of shares purchased under the Employee Stock Purchase Plan (“ESPP”) for the three and six months ended April 4, 2015 and March 29, 2014, respectively, were estimated using the following weighted-average assumptions:
			Employee Stock Purchase Plan
			Three Months Ended								Six Months Ended
			April 4,				March 29,				April 4,				March 29,
			2015				2014				2015				2014
	Expected life in years		0.5				0.5				0.5				0.5
	Expected volatility		24.8		%		22.8		%		24.8		%		23.7		%
	Risk-free interest rate		0.1		%		0.1		%		0.1		%		0.1		%
	Expected dividend yield		—		%		—		%		—		%		—		%
	Weighted average fair value per share		$	14.26			$	13.89			$	14.11			$	13.69
	There were no stock options granted during the three and six months ended April 4, 2015 and March 29, 2014.
	We grant market-based performance restricted stock unit award grants to officers and certain employees. The performance stock unit agreements provide for the award of performance stock units with each unit representing the right to receive one share of our common stock to be issued after the applicable award vesting period. The final number of units awarded, if any, for these performance grants will be determined as of the vesting dates, based upon our total shareholder return over the performance period compared to the Russell 2000 Index and could range from no units to a maximum of twice the initial award units. The weighted average fair value for these performance units was determined using a Monte Carlo simulation model incorporating the following weighted average assumptions:
			Six Months Ended
			April 4, 2015				March 29, 2014
	Risk-free interest rate		0.96		%		0.62		%
	Volatility		28.7		%		36.9		%
	Weighted average fair value		$	70.57			$	77.1
	We recognize the estimated cost of these awards, as determined under the simulation model, over the related service period, with no adjustment in future periods based upon the actual shareholder return over the performance period.
	Stock-Based Compensation Expense
	The following table shows total stock-based compensation expense and related tax benefits included in the condensed consolidated statements of operations for the three and six months ended April 4, 2015 and March 29, 2014 (in thousands):
		Three Months Ended								Six Months Ended
		April 4, 2015				March 29, 2014				April 4, 2015				March 29, 2014
	Cost of sales	$	676			$	648			$	1,273			$	1,186
	Research and development	556				500				886				1,022
	Selling, general and administrative	3,550				3,524				7,013				7,332
	Income tax benefit	(1,303		)		(1,326		)		(1,733		)		(2,665		)
		$	3,479			$	3,346			$	7,439			$	6,875
	During the three and six months ended April 4, 2015, $0.7 million and $1.4 million was capitalized into inventory for all stock plans, $0.7 million and $1.3 million was amortized to cost of sales and $0.8 million remained in inventory at April 4, 2015. During the three and six months ended March 29, 2014, $0.6 million and $1.3 million was capitalized into inventory for all stock plans, $0.6 million and $1.2 million was amortized to cost of sales and $0.7 million remained in inventory at March 29, 2014.
	At April 4, 2015, the total compensation cost related to unvested stock-based awards granted to employees under the Company’s stock plans but not yet recognized was approximately $27.0 million, net of estimated forfeitures of $0.8 million. This cost will be amortized on a straight-line basis over a weighted-average period of approximately 1.6 years and will be adjusted for subsequent changes in estimated forfeitures.
	At April 4, 2015, total compensation cost related to options to purchase common shares under the ESPP but not yet vested was approximately $0.1 million, which will be recognized over the six month offering period.
	Stock Awards Activity
	The following table summarizes the activity of our time based and market- performance based restricted stock units for the first six months of fiscal 2015 (in thousands, except per share amounts):
		Time Based Restricted Stock Units							Market-Based Performance Restricted Stock Units
		Number of			Weighted				Number of			Weighted
		Shares			Average				Shares			Average
					Grant Date							Grant Date
					Fair Value							Fair Value
	Nonvested stock units at September 27, 2014	390			$	58.66			230			$	61.46
	Granted	235			64.88				51			70.57
	Vested(1)	(216	)		53.59				(39	)		53.46
	Forfeited	(5	)		59.38				(43	)		53.46
	Nonvested stock at April 4, 2015	404			$	65			199			$	67.09
	__________________________________________
	(1)Service-based restricted stock vested during each fiscal year. Performance-based awards and units included at 100% of target goal; under the terms of the awards, the recipient may earn between 0% and 200% of the award.

Commitments_and_Contingencies

Commitments and Contingencies	6 Months Ended
	Apr. 04, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES
	We are subject to legal claims and litigation arising in the ordinary course of business, such as product liability, employment or intellectual property claims, including, but not limited to, the matters described below. On May 14, 2013, IMRA America (“Imra”) filed a complaint for patent infringement against two of our subsidiaries in the Regional Court of Düsseldorf, Germany, captioned In re IMRA America Inc. versus Coherent Kaiserslautern GmbH et. al. 4b O 38/13. The complaint alleges that the use of certain of the Company’s lasers infringes upon EP Patent No. 754,103, entitled “Method For Controlling Configuration of Laser Induced Breakdown and Ablation,” issued November 5, 1997. The patent is owned by the University of Michigan and licensed to Imra. The complaint seeks unspecified compensatory damages, the cost of court proceedings and seeks to permanently enjoin the Company from infringing the patent in the future. The referenced patent has since expired. Management has made an accrual of the amount which is reasonably estimable and probable with respect to this matter and has determined, based on its current knowledge, that the amount or range of reasonably possible losses in excess of the amounts already accrued is not reasonably estimable. Although we do not expect that such legal claims and litigation will ultimately have a material adverse effect on our condensed consolidated financial position, results of operations or cash flows, an adverse result in one or more matters could negatively affect our results in the period in which they occur.
	The United States and many foreign governments impose tariffs and duties on the import and export of certain products we sell.  From time to time our duty calculations and payments are audited by government agencies.  We are currently under audit in South Korea for customs duties and value added tax for the period March 2009 to March 2014.  At this time, management has not made an accrual of an amount related to this matter. Although we do not expect that the audit will ultimately have a material adverse effect on our condensed consolidated financial position, results of operations or cash flows, an adverse result in this matter could negatively affect our results in the period in which they occur.

Stock_Repurchases

Stock Repurchases	6 Months Ended
	Apr. 04, 2015
Stockholders' Equity Note [Abstract]
Stock Repurchase [Text Block]	STOCK REPURCHASE
	On July 25, 2014, the Board of Directors authorized a buyback program whereby we were authorized to repurchase up to $25.0 million of our common stock from time to time through July 31, 2015. During the first quarter of fiscal 2015, we repurchased and retired 300,441shares of outstanding common stock at an average price of $57.55 per share for a total of $17.3 million, excluding expenses. During the second quarter of fiscal 2015, we repurchased and retired 133,673 shares of outstanding common stock under this plan at an average price of $57.66 per share for a total of $7.7 million, completing the repurchase program.
	On January 21, 2015, our Board of Directors authorized an additional stock repurchase program to repurchase up to $25.0 million of our outstanding common stock from time to time through January 31, 2016. No repurchases have been made under this program as of April 4, 2015.

Earnings_Per_Share

Earnings Per Share	6 Months Ended
	Apr. 04, 2015
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE
	Basic earnings per share is computed based on the weighted average number of shares outstanding during the period, excluding unvested restricted stock. Diluted earnings per share is computed based on the weighted average number of shares outstanding during the period increased by the effect of dilutive employee stock awards, including stock options, restricted stock awards and stock purchase plan contracts, using the treasury stock method.
	The following table presents information necessary to calculate basic and diluted earnings per share (in thousands, except per share data):
		Three Months Ended				Six Months Ended
		April 4,		March 29,		April 4,		March 29,
		2015		2014		2015		2014
	Weighted average shares outstanding —basic	24,709		24,782		24,823		24,662
	Dilutive effect of employee stock awards	182		262		219		318
	Weighted average shares outstanding—diluted	24,891		25,044		25,042		24,980
	Net income	$	18,413	$	15,307	$	35,843	$	27,010
	Net income per basic share	$	0.75	$	0.62	$	1.44	$	1.1
	Net income per diluted share	$	0.74	$	0.61	$	1.43	$	1.08
	A total of 1,333 and 41,559 potentially dilutive securities have been excluded from the diluted share calculation for the three and six months ended April 4, 2015 as their effect was anti-dilutive. A total of zero and 40,738 potentially dilutive securities have been excluded from the diluted share calculation for the three and six months ended March 29, 2014 as their effect was anti-dilutive.

Other_Income_Expense

Other Income (Expense)	6 Months Ended
	Apr. 04, 2015
Other Income and Expenses [Abstract]
Other Income (Expense)	13.  OTHER INCOME (EXPENSE)
	Other income (expense) is as follows (in thousands):
		Three Months Ended					Six Months Ended
		April 4,		March 29,			April 4,			March 29,
		2015		2014			2015			2014
	Foreign exchange gain (loss)	$	1,080	$	(388	)	$	(81	)	$	(2,512	)
	Gain on deferred compensation investments, net	671		1,291			1,055			3,167
	Other	92		87			99			79
	Other - net	$	1,843	$	990		$	1,073		$	734

Income_Taxes

Income Taxes	6 Months Ended
	Apr. 04, 2015
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES
	Income tax expense includes a provision for federal, state and foreign taxes based on the annual estimated effective tax rate applicable to us and our subsidiaries, adjusted for items which are considered discrete to the period. Our effective tax rates for the three and six months ended April 4, 2015 were 23.7% and 24.9%, respectively. Our effective tax rates for the three and six months ended April 4, 2015 were lower than the statutory rate of 35% primarily due to differences related to the benefit of income subject to foreign tax rates that are lower than U.S. statutory tax rates including South Korea and Singapore tax exemptions, the benefit of foreign tax credits and the benefit of the federal research and development tax credits including renewal of the federal research and development tax credits for fiscal 2014. These amounts are partially offset by deemed dividend inclusions under the Subpart F tax rules, stock-based compensation not deductible for tax purposes and limitations on the deductibility of compensation under IRC Section 162(m).
	Determining the consolidated provision for income taxes, income tax liabilities and deferred tax assets and liabilities involves judgment. We calculate and provide for income taxes in each of the tax jurisdictions in which we operate, which involves estimating current tax exposures as well as making judgments regarding the recoverability of deferred tax assets in each jurisdiction. The estimates used could differ from actual results, which may have a significant impact on operating results in future periods.
	We are subject to taxation and file income tax returns in the U.S. federal jurisdiction and in many state and foreign jurisdictions. For U.S. federal income tax purposes, all years prior to 2011 are closed. In our major foreign jurisdictions and our major state jurisdictions, the years prior to 2006 and 2010, respectively, are closed to examination. Earlier years in our various jurisdictions may remain open for adjustment to the extent that we have tax attribute carryforwards from those years. In December 2011 and January 2012, three of our German subsidiaries received notices of tax audits for the fiscal years 2006 through 2010. In fiscal year 2013, we received a preliminary assessment for two of the German subsidiaries and the amount is immaterial; the audit for the other German subsidiary is currently in process.
	Management believes that it has adequately provided for any adjustments that may result from tax examinations. We regularly engage in discussions and negotiations with tax authorities regarding tax matters in various jurisdictions. It is reasonably possible that certain foreign tax matters may be concluded in the next 12 months.
	The Tax Increase Prevention Act of 2014 (“the Act”), was enacted on December 19, 2014. Under the Act, the federal research and development tax credit was retroactively extended for amounts paid or incurred after December 31, 2013
	through December 31, 2014. The effects of the change in the tax law are recognized in our first quarter of fiscal 2015, which is the quarter that the law was enacted. Accordingly, prior year research and development tax credits of approximately $1.3 million less appropriate reserves were recognized in the first quarter of fiscal 2015.

Segment_Information

Segment Information	6 Months Ended
	Apr. 04, 2015
Segment Reporting [Abstract]
Segment Information	SEGMENT INFORMATION
	The following table provides net sales and income from operations for our operating segments and a reconciliation of our total income from operations to net income (in thousands):
		Three Months Ended						Six Months Ended
		April 4,			March 29,			April 4,			March 29,
		2015			2014			2015			2014
	Net sales:
	Specialty Laser Systems	$	140,016		$	143,795		$	285,107		$	280,618
	Commercial Lasers and Components	63,705			55,427			119,229			112,160
	Total net sales	$	203,721		$	199,222		$	404,336		$	392,778
	Income(expense) from operations:
	Specialty Laser Systems	$	32,078		$	31,117		$	66,632		$	59,749
	Commercial Lasers and Components	2,279			(129		)	2,982			177
	Corporate and other	(12,225		)	(10,948		)	(23,173		)	(24,102		)
	Total income from operations	$	22,132		$	20,040		$	46,441		$	35,824
	Total other income, net	1,990			1,040			1,305			820
	Income before income taxes	24,122			21,080			47,746			36,644
	Provision for income taxes	5,709			5,773			11,903			9,634
	Net Income	$	18,413		$	15,307		$	35,843		$	27,010
	Major Customers
	We had one major customer during the three and six months ended April 4, 2015 who accounted for 17.4% and 18.0%, respectively, of consolidated revenue. This same customer accounted for 11.5% and 12.6%, respectively, of consolidated revenue for the three and six months ended March 29, 2014. The customer purchased primarily from our SLS segment.
	We had one major customer who accounted for 15.7% and 15.2% of accounts receivable at April 4, 2015 and September 27, 2014, respectively. There was one additional major customer who accounted for 11.6% of accounts receivable at September 27, 2014. Both customers purchased primarily from our SLS segment.

Fair_Values_Tables

Fair Values (Tables)	6 Months Ended
	Apr. 04, 2015
Fair Value Disclosures [Abstract]
Schedule of financial assets and liabilities measured at fair value	Financial assets and liabilities measured at fair value as of April 4, 2015 and September 27, 2014 are summarized below (in thousands):
			Aggregate Fair Value			Quoted Prices		Significant			Aggregate Fair Value			Quoted Prices		Significant
						in		Other						in		Other
						Active Markets		Observable						Active Markets		Observable
						for Identical		Inputs						for Identical		Inputs
						Assets								Assets
			4-Apr-15								27-Sep-14
						(Level 1)		(Level 2)						(Level 1)		(Level 2)
	Assets:
	Cash equivalents:
	Money market fund deposits		$	8,315		$	8,315	$	—		$	5,975		$	5,975	$	—
	Certificates of deposit		17,600			—		17,600			12,084			—		12,084
	Commercial paper (1)		9,297			—		9,297			1,400			—		1,400
	Short-term investments:
	U.S. Treasury and agency obligations (1)		155,539			—		155,539			150,088			—		150,088
	Corporate notes and obligations (1)		41,261			—		41,261			52,987			—		52,987
	Commercial paper (1)		16,985			—		16,985			23,983			—		23,983
	Equity securities (1)		15,568			—		15,568			—			—		—
	Prepaid and other assets:
	Foreign currency contracts (2)		331			—		331			366			—		366
	Mutual funds — Deferred comp and supplemental plan (3)		14,040			14,040		—			15,000			15,000		—
	Total		$	278,936		$	22,355	$	256,581		$	261,883		$	20,975	$	240,908
	Liabilities:
	Other current liabilities:
	Foreign currency contracts (2)		$	(2,437	)	$	—	$	(2,437	)	$	(2,196	)	$	—	$	(2,196	)
	Total		$	276,499		$	22,355	$	254,144		$	259,687		$	20,975	$	238,712
	___________________________________________________
	-1	Valuations are based upon quoted market prices in active markets involving similar assets. The market inputs used to value these instruments generally consist of market yields, reported trades, broker/dealer quotes or alternative pricing sources with reasonable levels of price transparency. Pricing sources include industry standard data providers, security master files from large financial institutions, and other third party sources which are input into a distribution-curve-based algorithm to determine a daily market value. This creates a “consensus price” or a weighted average price for each security.
	-2	The principal market in which we execute our foreign currency contracts is the institutional market in an over-the-counter environment with a relatively high level of price transparency. The market participants usually are large commercial banks. Our foreign currency contracts’ valuation inputs are based on quoted prices and quoted pricing intervals from public data sources and do not involve management judgment. At September 27, 2014, prepaid expenses and other assets include $303 non-designated forward contracts and $63 foreign currency contracts designated for cash flow hedges, respectively; other current liabilities include $1,246 non-designated forward contracts and $950 cash flow contracts, respectively. At April 4, 2015, prepaid expenses and other assets include $331 non-designated forward contracts and zero cash flow contracts, respectively; other current liabilities include $2,400 non-designated forward contracts and $37 cash flow contracts, respectively. See Note 5, "Derivative Instruments and Hedging Activities".
	-3	The fair value of mutual funds is determined based on quoted market prices. Securities traded on a national exchange are stated at the last reported sales price on the day of valuation; other securities traded in over-the-counter markets and listed securities for which no sale was reported on that date are stated as the last quoted bid price.

Derivative_Instruments_and_Hed2

Derivative Instruments and Hedging Activities (Tables)	6 Months Ended
	Apr. 04, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of outstanding notional contract and fair value amount of hedge contracts	The outstanding notional contract and fair value asset (liability) amounts of non-designated hedge contracts, with maximum maturity of four months, are as follows (in thousands):
		U.S. Notional Contract Value						U.S. Fair Value
		April 4, 2015			September 27, 2014			April 4, 2015			September 27, 2014
	Euro currency hedge contracts
	Purchase	$	34,449		$	31,926		$	(1,663	)	$	(1,153	)
	Japanese YEN currency hedge contracts
	Purchase	$	6,763		$	471		$	124		$	(3	)
	Sell	$	(18,373	)	$	(15,084	)	$	(651	)	$	169
	Korean Won currency hedge contracts
	Purchase	$	886		$	—		$	26		$	—
	Sell	$	(9,711	)	$	(2,991	)	$	(68	)	$	72
	Chinese RMB currency hedge contracts
	Purchase	$	431		$	—		$	—		$	—
	Sell	$	(9,202	)	$	(15,678	)	$	(17	)	$	(56	)
	Other foreign currency hedge contracts
	Purchase	$	3,035		$	1,899		$	50		$	(35	)
	Sell	$	(6,529	)	$	(3,515	)	$	130		$	63
	Designated Derivatives
	Cash flow hedges related to anticipated transactions are designated and documented at the inception of the hedge when we enter into contracts for specific future transactions. Cash flow hedges are evaluated for effectiveness quarterly. The effective portion of the gain or loss on these hedges is reported as a component of Other Comprehensive Income ("OCI") in stockholder's equity and is reclassified into earnings when the underlying transaction affects earnings. The majority of the after-tax net income or loss related to derivative instruments included in OCI at April 4, 2015 is expected to be reclassified into earnings within 12 months. Changes in the fair value of currency forward contracts due to changes in time value are excluded from the assessment of effectiveness and recognized in other income (expense) as incurred. We classify the cash flows from the foreign exchange forward contracts that are accounted for as cash flow hedges in the same section as the underlying item, primarily within cash flows from operating activities since we do not designate our cash flow hedges as investing or financing activities.
	The outstanding notional contract and fair value asset (liability) amounts of designated cash flow hedge contracts, with maximum maturity of thirteen months, are as follows (in thousands):
		U.S. Notional Contract Value						U.S. Fair Value
		4-Apr-15			27-Sep-14			4-Apr-15			27-Sep-14
	Euro currency hedge contracts
	Purchase	$	—		$	11,149		$	—		$	(950	)
	Japanese Yen currency hedge contracts
	Sell	$	(2,875	)	$	(12,091	)	$	(37	)	$	63

ShortTerm_Investments_Tables

Short-Term Investments (Tables)	6 Months Ended
	Mar. 29, 2014
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Schedule of cash, cash equivalents and short-term investments	Cash, cash equivalents and short-term investments consist of the following (in thousands):
		April 4, 2015
		Cost Basis		Unrealized		Unrealized			Fair Value
				Gains		Losses
	Cash and cash equivalents	$	115,081	$	—	$	—		$	115,081
	Short-term investments:
	Available-for-sale securities:
	Commercial paper	$	16,985	$	—	$	—		$	16,985
	U.S. Treasury and agency obligations	154,648		908		(17		)	155,539
	Corporate notes and obligations	41,122		177		(38		)	41,261
	Equity Securities	15,299		269		—			15,568
	Total short-term investments	$	228,054	$	1,354	$	(55	)	$	229,353
		September 27, 2014
		Cost Basis		Unrealized		Unrealized			Fair Value
				Gains		Losses
	Cash and cash equivalents	$	91,217	$	—	$	—		$	91,217
	Short-term investments:
	Available-for-sale securities:
	Commercial paper	$	23,983	$	—	$	—		$	23,983
	U.S. Treasury and agency obligations	149,260		831		(3		)	150,088
	Corporate notes and obligations	52,834		195		(42		)	52,987
	Total short-term investments	$	226,077	$	1,026	$	(45	)	$	227,058
Schedule of amortized cost and estimated fair value of available-for-sale investments in debt securities	The amortized cost and estimated fair value of available-for-sale investments in debt securities as of April 4, 2015 and September 27, 2014 classified as short-term investments on our condensed consolidated balance sheet were as follows (in thousands):
		April 4, 2015				September 27, 2014
		Amortized Cost		Estimated Fair Value		Amortized Cost			Estimated Fair Value
	Investments in available-for-sale debt securities due in less than one year	$	168,338	$	169,230	$	178,329		$	179,223
	Investments in available-for-sale debt securities due in one to five years (1)	$	44,417	$	44,555	$	47,748		$	47,835

Goodwill_and_Intangible_Assets1

Goodwill and Intangible Assets (Tables)	6 Months Ended
	Apr. 04, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of changes in carrying amount of goodwill by segment	The changes in the carrying amount of goodwill by segment for the period from September 27, 2014 to April 4, 2015 are as follows (in thousands):
		Specialty			Commercial			Total
		Lasers and			Lasers and
		Systems			Components
	Balance as of September 27, 2014	$	103,150		$	6,363		$	109,513
	Translation adjustments and other	(10,125		)	—			(10,125		)
	Balance as of April 4, 2015	$	93,025		$	6,363		$	99,388
Schedule of components of amortizable intangible assets	Components of our amortizable intangible assets are as follows (in thousands):
		April 4, 2015									September 27, 2014
		Gross			Accumulated			Net			Gross		Accumulated			Net
		Carrying			Amortization						Carrying		Amortization
		Amount									Amount
	Existing technology	$	76,104		$	(58,320	)	$	17,784		$	81,551	$	(57,827	)	$	23,724
	Customer lists	15,154			(9,463		)	5,691			16,632		(9,199		)	7,433
	Trade name	392			(337		)	55			431		(346		)	85
	In-process research & development	366			—			366			424		—			424
	Total	$	92,016		$	(68,120	)	$	23,896		$	99,038	$	(67,372	)	$	31,666
	For accounting purposes, when an intangible asset is fully amortized, it is removed from the disclosure schedule.
	Amortization expense for intangible assets for the six months ended April 4, 2015 and March 29, 2014 was $4.2 million and $4.9 million, respectively, which includes $3.3 million and $3.8 million, respectively, for amortization of existing technology.
Schedule of estimated amortization expense	At April 4, 2015, estimated amortization expense for the remainder of fiscal 2015, the next five succeeding fiscal years and all fiscal years thereafter are as follows (in thousands):
		Estimated
		Amortization
		Expense
	2015 (remainder)	$	3,931
	2016	7,484
	2017	6,359
	2018	3,745
	2019	2,036
	2020	131
	Thereafter	210
	Total	$	23,896

Balance_Sheet_Details_Tables

Balance Sheet Details (Tables)	6 Months Ended
	Apr. 04, 2015
Balance Sheet Related Disclosures [Abstract]
Schedule of inventories	Inventories consist of the following (in thousands):
		April 4,			September 27,
		2015			2014
	Purchased parts and assemblies	$	48,440		$	51,091
	Work-in-process	59,567			70,486
	Finished goods	45,652			48,906
	Total inventories	$	153,659		$	170,483
Schedule of prepaid expenses and other assets	Prepaid expenses and other assets consist of the following (in thousands):
		April 4,			September 27,
		2015			2014
	Prepaid and refundable income taxes	$	8,965		$	11,001
	Other taxes receivable	15,892			5,184
	Prepaid expenses and other	13,681			11,654
	Total prepaid expenses and other assets	$	38,538		$	27,839
Schedule of other assets	Other assets consist of the following (in thousands):
		April 4,			September 27,
		2015			2014
	Assets related to deferred compensation arrangements	$	26,039		$	26,484
	Deferred tax assets	34,526			37,616
	Other assets	5,551			5,617
	Total other assets	$	66,116		$	69,717
Schedule of Other Current Liabilities	Other current liabilities consist of the following (in thousands):
		April 4,			September 27,
		2015			2014
	Accrued payroll and benefits	$	35,269		$	29,228
	Deferred income	16,256			15,536
	Warranty reserve	15,941			16,961
	Accrued expenses and other	12,100			13,410
	Other taxes payable	16,334			5,036
	Customer deposits	3,259			2,335
	Total other current liabilities	$	99,159		$	82,506
Schedule of components of reserve for warranty costs	Components of the reserve for warranty costs during the first six months of fiscal 2015 and 2014 were as follows (in thousands):
		Six Months Ended
		April 4,			March 29,
		2015			2014
	Beginning balance	$	16,961		$	18,508
	Additions related to current period sales	11,618			12,434
	Warranty costs incurred in the current period	(10,822		)	(12,713		)
	Adjustments to accruals related to foreign exchange and other	(1,816		)	(248		)
	Ending balance	$	15,941		$	17,981
Schedule of Other Long-term liabilities	Other long-term liabilities consist of the following (in thousands):
		April 4,			September 27,
		2015			2014
	Long-term taxes payable	$	7,725		$	15,776
	Deferred compensation	27,578			27,858
	Deferred tax liabilities	5,277			6,511
	Deferred income	3,010			3,448
	Asset retirement obligations liability	2,124			2,222
	Other long-term liabilities	6,650			6,592
	Total other long-term liabilities	$	52,364		$	62,407

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	6 Months Ended
	Apr. 04, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of weighted-average assumptions used to estimate fair value of stock options granted and shares purchased	The fair values of shares purchased under the Employee Stock Purchase Plan (“ESPP”) for the three and six months ended April 4, 2015 and March 29, 2014, respectively, were estimated using the following weighted-average assumptions:
			Employee Stock Purchase Plan
			Three Months Ended								Six Months Ended
			April 4,				March 29,				April 4,				March 29,
			2015				2014				2015				2014
	Expected life in years		0.5				0.5				0.5				0.5
	Expected volatility		24.8		%		22.8		%		24.8		%		23.7		%
	Risk-free interest rate		0.1		%		0.1		%		0.1		%		0.1		%
	Expected dividend yield		—		%		—		%		—		%		—		%
	Weighted average fair value per share		$	14.26			$	13.89			$	14.11			$	13.69
Schedule of weighted average assumptions of performance units	The weighted average fair value for these performance units was determined using a Monte Carlo simulation model incorporating the following weighted average assumptions:
			Six Months Ended
			April 4, 2015				March 29, 2014
	Risk-free interest rate		0.96		%		0.62		%
	Volatility		28.7		%		36.9		%
	Weighted average fair value		$	70.57			$	77.1
Schedule of stock-based compensation expense	The following table shows total stock-based compensation expense and related tax benefits included in the condensed consolidated statements of operations for the three and six months ended April 4, 2015 and March 29, 2014 (in thousands):
		Three Months Ended								Six Months Ended
		April 4, 2015				March 29, 2014				April 4, 2015				March 29, 2014
	Cost of sales	$	676			$	648			$	1,273			$	1,186
	Research and development	556				500				886				1,022
	Selling, general and administrative	3,550				3,524				7,013				7,332
	Income tax benefit	(1,303		)		(1,326		)		(1,733		)		(2,665		)
		$	3,479			$	3,346			$	7,439			$	6,875
Schedule of restricted stock award and restricted stock unit activity	The following table summarizes the activity of our time based and market- performance based restricted stock units for the first six months of fiscal 2015 (in thousands, except per share amounts):
		Time Based Restricted Stock Units							Market-Based Performance Restricted Stock Units
		Number of			Weighted				Number of			Weighted
		Shares			Average				Shares			Average
					Grant Date							Grant Date
					Fair Value							Fair Value
	Nonvested stock units at September 27, 2014	390			$	58.66			230			$	61.46
	Granted	235			64.88				51			70.57
	Vested(1)	(216	)		53.59				(39	)		53.46
	Forfeited	(5	)		59.38				(43	)		53.46
	Nonvested stock at April 4, 2015	404			$	65			199			$	67.09
	__________________________________________
	(1)Service-based restricted stock vested during each fiscal year. Performance-based awards and units included at 100% of target goal; under the terms of the awards, the recipient may earn between 0% and 200% of the award.

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	6 Months Ended
	Apr. 04, 2015
Earnings Per Share [Abstract]
Schedule of information necessary to calculate basic and diluted earnings (loss) per share	The following table presents information necessary to calculate basic and diluted earnings per share (in thousands, except per share data):
		Three Months Ended				Six Months Ended
		April 4,		March 29,		April 4,		March 29,
		2015		2014		2015		2014
	Weighted average shares outstanding —basic	24,709		24,782		24,823		24,662
	Dilutive effect of employee stock awards	182		262		219		318
	Weighted average shares outstanding—diluted	24,891		25,044		25,042		24,980
	Net income	$	18,413	$	15,307	$	35,843	$	27,010
	Net income per basic share	$	0.75	$	0.62	$	1.44	$	1.1
	Net income per diluted share	$	0.74	$	0.61	$	1.43	$	1.08

Other_Income_Expense_Tables

Other Income (Expense) (Tables)	6 Months Ended
	Apr. 04, 2015
Other Income and Expenses [Abstract]
Schedule of other nonoperating income (expense)	Other income (expense) is as follows (in thousands):
		Three Months Ended					Six Months Ended
		April 4,		March 29,			April 4,			March 29,
		2015		2014			2015			2014
	Foreign exchange gain (loss)	$	1,080	$	(388	)	$	(81	)	$	(2,512	)
	Gain on deferred compensation investments, net	671		1,291			1,055			3,167
	Other	92		87			99			79
	Other - net	$	1,843	$	990		$	1,073		$	734

Segment_Information_Tables

Segment Information (Tables)	6 Months Ended
	Apr. 04, 2015
Segment Reporting [Abstract]
Schedule of sales and income (loss) from operations	The following table provides net sales and income from operations for our operating segments and a reconciliation of our total income from operations to net income (in thousands):
		Three Months Ended						Six Months Ended
		April 4,			March 29,			April 4,			March 29,
		2015			2014			2015			2014
	Net sales:
	Specialty Laser Systems	$	140,016		$	143,795		$	285,107		$	280,618
	Commercial Lasers and Components	63,705			55,427			119,229			112,160
	Total net sales	$	203,721		$	199,222		$	404,336		$	392,778
	Income(expense) from operations:
	Specialty Laser Systems	$	32,078		$	31,117		$	66,632		$	59,749
	Commercial Lasers and Components	2,279			(129		)	2,982			177
	Corporate and other	(12,225		)	(10,948		)	(23,173		)	(24,102		)
	Total income from operations	$	22,132		$	20,040		$	46,441		$	35,824
	Total other income, net	1,990			1,040			1,305			820
	Income before income taxes	24,122			21,080			47,746			36,644
	Provision for income taxes	5,709			5,773			11,903			9,634
	Net Income	$	18,413		$	15,307		$	35,843		$	27,010

Recent_Accounting_Standards_Re

Recent Accounting Standards Result of new accounting rule adoption (Details) (USD $)	6 Months Ended		3 Months Ended
	Apr. 04, 2015	Mar. 29, 2014	Dec. 27, 2014
Item Effected [Line Items]
Decrease in long term taxes payable	$9,871,000	$4,474,000
Adjustments for New Accounting Pronouncement [Member]
Item Effected [Line Items]
Decrease in long term taxes payable			7,900,000
Decrease in noncurrent deferred tax assets			$7,900,000

Fair_Values_Details

Fair Values (Details) (Fair Value, Measurements, Recurring, USD $)	Apr. 04, 2015		Sep. 27, 2014
In Thousands, unless otherwise specified
Quoted Prices in Active Markets for Identical Assets (Level 1) | Supplemental Employee Retirement Plans, Defined Benefit | Other assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Mutual funds - Deferred comp and supplemental plan	$14,040	[1]	$15,000	[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market fund deposits | Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	8,315		5,975
Quoted Prices in Active Markets for Identical Assets (Level 1) | Certificates of deposit | Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0		0
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. and international government obligations | Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments, Fair Value Disclosure	0	[2]	0	[2]
Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate notes and obligations | Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments, Fair Value Disclosure	0	[2]	0	[2]
Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial Paper [Member] | Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	[2]
Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial Paper [Member] | Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments, Fair Value Disclosure	0	[2]	0	[2]
Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity Securities [Member] | Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments, Fair Value Disclosure	0	[2]	0	[2]
Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign Exchange Contract [Member] | Other Current Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Foreign currency contracts	0	[3]	0	[3]
Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign Exchange Contract [Member] | Other assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Foreign currency contracts	0	[3]	0	[3]
Quoted Prices in Active Markets for Identical Assets (Level 1) | Financial Assets, Balance Sheet Location [Member] | Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial assets and liabilities, fair value disclosure	22,355		20,975
Quoted Prices in Active Markets for Identical Assets (Level 1) | Financial Assets, Balance Sheet Location [Member] | Other current liabilities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial assets and liabilities, fair value disclosure	22,355		20,975
Significant Other Observable Inputs (Level 2) | Supplemental Employee Retirement Plans, Defined Benefit | Other assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Mutual funds - Deferred comp and supplemental plan	0	[1]	0	[1]
Significant Other Observable Inputs (Level 2) | Foreign Exchange Forward [Member] | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	331		303
Significant Other Observable Inputs (Level 2) | Foreign Exchange Forward [Member] | Other Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	2,400		1,246
Significant Other Observable Inputs (Level 2) | Cash Flow Hedging [Member] | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	0		63
Significant Other Observable Inputs (Level 2) | Cash Flow Hedging [Member] | Other Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	37		950
Significant Other Observable Inputs (Level 2) | Money market fund deposits | Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0		0
Significant Other Observable Inputs (Level 2) | Certificates of deposit | Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	17,600		12,084
Significant Other Observable Inputs (Level 2) | U.S. and international government obligations | Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments, Fair Value Disclosure	155,539	[2]	150,088	[2]
Significant Other Observable Inputs (Level 2) | Corporate notes and obligations | Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments, Fair Value Disclosure	41,261	[2]	52,987	[2]
Significant Other Observable Inputs (Level 2) | Commercial Paper [Member] | Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	9,297	[2]	1,400	[2]
Significant Other Observable Inputs (Level 2) | Commercial Paper [Member] | Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments, Fair Value Disclosure	16,985	[2]	23,983	[2]
Significant Other Observable Inputs (Level 2) | Equity Securities [Member] | Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments, Fair Value Disclosure	15,568	[2]	0	[2]
Significant Other Observable Inputs (Level 2) | Foreign Exchange Contract [Member] | Other Current Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Foreign currency contracts	-2,437	[3]	-2,196	[3]
Significant Other Observable Inputs (Level 2) | Foreign Exchange Contract [Member] | Other assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Foreign currency contracts	331	[3]	366	[3]
Significant Other Observable Inputs (Level 2) | Financial Assets, Balance Sheet Location [Member] | Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial assets and liabilities, fair value disclosure	256,581		240,908
Significant Other Observable Inputs (Level 2) | Financial Assets, Balance Sheet Location [Member] | Other current liabilities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial assets and liabilities, fair value disclosure	254,144		238,712
Total Fair Value | Supplemental Employee Retirement Plans, Defined Benefit | Other assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Mutual funds - Deferred comp and supplemental plan	14,040	[1]	15,000	[1]
Total Fair Value | Money market fund deposits | Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	8,315		5,975
Total Fair Value | Certificates of deposit | Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	17,600		12,084
Total Fair Value | U.S. and international government obligations | Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments, Fair Value Disclosure	155,539	[2]	150,088	[2]
Total Fair Value | Corporate notes and obligations | Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments, Fair Value Disclosure	41,261	[2]	52,987	[2]
Total Fair Value | Commercial Paper [Member] | Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	9,297	[2]	1,400	[2]
Total Fair Value | Commercial Paper [Member] | Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments, Fair Value Disclosure	16,985	[2]	23,983	[2]
Total Fair Value | Equity Securities [Member] | Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments, Fair Value Disclosure	15,568	[2]	0	[2]
Total Fair Value | Foreign Exchange Contract [Member] | Other Current Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Foreign currency contracts	-2,437	[3]	-2,196	[3]
Total Fair Value | Foreign Exchange Contract [Member] | Other assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Foreign currency contracts	331	[3]	366	[3]
Total Fair Value | Financial Assets, Balance Sheet Location [Member] | Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial assets and liabilities, fair value disclosure	278,936		261,883
Total Fair Value | Financial Assets, Balance Sheet Location [Member] | Other current liabilities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial assets and liabilities, fair value disclosure	$276,499		$259,687
[1]	The fair value of mutual funds is determined based on quoted market prices. Securities traded on a national exchange are stated at the last reported sales price on the day of valuation; other securities traded in over-the-counter markets and listed securities for which no sale was reported on that date are stated as the last quoted bid price.
[2]	Valuations are based upon quoted market prices in active markets involving similar assets. The market inputs used to value these instruments generally consist of market yields, reported trades, broker/dealer quotes or alternative pricing sources with reasonable levels of price transparency. Pricing sources include industry standard data providers, security master files from large financial institutions, and other third party sources which are input into a distribution-curve-based algorithm to determine a daily market value. This creates a “consensus price” or a weighted average price for each security.
[3]	The principal market in which we execute our foreign currency contracts is the institutional market in an over-the-counter environment with a relatively high level of price transparency. The market participants usually are large commercial banks. Our foreign currency contracts’ valuation inputs are based on quoted prices and quoted pricing intervals from public data sources and do not involve management judgment. At September 27, 2014, prepaid expenses and other assets include $303 non-designated forward contracts and $63 foreign currency contracts designated for cash flow hedges, respectively; other current liabilities include $1,246 non-designated forward contracts and $950 cash flow contracts, respectively. At April 4, 2015, prepaid expenses and other assets include $331 non-designated forward contracts and zero cash flow contracts, respectively; other current liabilities include $2,400 non-designated forward contracts and $37 cash flow contracts, respectively. See Note 5, "Derivative Instruments and Hedging Activities".

Derivative_Instruments_and_Hed3

Derivative Instruments and Hedging Activities (Notional and Fair Value) (Details) (USD $)	Apr. 04, 2015	Sep. 27, 2014
In Thousands, unless otherwise specified
Purchase [Member] | Other Foreign Countries [Member]
Derivatives, Fair Value [Line Items]
Notional Contract Amount Of Foreign Currency Derivative Purchase Contracts	$3,035	$1,899
U.S. Notional Fair Value, Purchase	50	-35
sell [Member] | Other Foreign Countries [Member]
Derivatives, Fair Value [Line Items]
Notional Contract Amount Of Foreign Currency Derivative Sales Contracts	-6,529	-3,515
U.S. Notional Fair Value, Sell	130	63
Euro Member Countries, Euro | Purchase [Member]
Derivatives, Fair Value [Line Items]
Notional Contract Amount Of Foreign Currency Derivative Purchase Contracts	34,449	31,926
U.S. Notional Fair Value, Purchase	-1,663	-1,153
Euro Member Countries, Euro | Purchase [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	0	11,149
Derivative, Fair Value, Net	0	-950
Japan, Yen | Purchase [Member]
Derivatives, Fair Value [Line Items]
Notional Contract Amount Of Foreign Currency Derivative Purchase Contracts	6,763	471
U.S. Notional Fair Value, Purchase	124	-3
Japan, Yen | sell [Member]
Derivatives, Fair Value [Line Items]
Notional Contract Amount Of Foreign Currency Derivative Sales Contracts	-18,373	-15,084
U.S. Notional Fair Value, Sell	-651	169
Japan, Yen | sell [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	-2,875	-12,091
Derivative, Fair Value, Net	-37	63
Korea (South), Won | Purchase [Member]
Derivatives, Fair Value [Line Items]
Notional Contract Amount Of Foreign Currency Derivative Purchase Contracts	886	0
U.S. Notional Fair Value, Purchase	26	0
Korea (South), Won | sell [Member]
Derivatives, Fair Value [Line Items]
Notional Contract Amount Of Foreign Currency Derivative Sales Contracts	-9,711	-2,991
U.S. Notional Fair Value, Sell	-68	72
China, Yuan Renminbi | Purchase [Member]
Derivatives, Fair Value [Line Items]
Notional Contract Amount Of Foreign Currency Derivative Purchase Contracts	431	0
U.S. Notional Fair Value, Purchase	0	0
China, Yuan Renminbi | sell [Member]
Derivatives, Fair Value [Line Items]
Notional Contract Amount Of Foreign Currency Derivative Sales Contracts	-9,202	-15,678
U.S. Notional Fair Value, Sell	($17)	($56)

Derivative_Instruments_and_Hed4

Derivative Instruments and Hedging Activities (Gain/Loss) (Details) (USD $)	3 Months Ended				6 Months Ended
	Apr. 04, 2015		Mar. 29, 2014		Apr. 04, 2015		Mar. 29, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Loss on Fair Value Hedge Ineffectiveness					$100,000
Foreign exchange contracts	175,000	[1]	0	[1]	550,000	[1]	0	[1]
Revenue, Net [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Foreign exchange contracts	-92,000		0		208,000		0
Cost of Sales [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Foreign exchange contracts	-1,106,000		0		-1,720,000		0
Other Income (Expense) [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Foreign exchange contracts	-77,000		0		-112,000		0
Other Income (Expense) [Member] | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Foreign exchange contracts	-5,413,000		197,000		-6,125,000		159,000
Other Comprehensive Income (Loss) [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Foreign exchange contracts	$175,000		$0		$550,000		$0
[1]	Tax expense of $102 and $319 was provided on net gains (losses) on derivative instruments during the three and six months ended April 4, 2015.

Derivative_Instruments_and_Hed5

Derivative Instruments and Hedging Activities Offsetting of financial assets (Details) (Foreign Exchange Contract [Member], USD $)	Apr. 04, 2015	Sep. 27, 2014
In Thousands, unless otherwise specified
Foreign Exchange Contract [Member]
Offsetting Assets [Line Items]
Derivative Asset, Fair Value, Gross Asset	$331	$367
Derivative Liability, Fair Value, Gross Liability	0	0
Net amounts of assets presented in balance sheets	331	367
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	-316	-367
Derivative, Collateral, Right to Reclaim Cash	0	0
Derivative asset, net amount	$15	$0

Derivative_Instruments_and_Hed6

Derivative Instruments and Hedging Activities Offsetting of financial liabilities (Details) (Foreign Exchange Contract [Member], USD $)	Apr. 04, 2015	Sep. 27, 2014
In Thousands, unless otherwise specified
Foreign Exchange Contract [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability	($2,437)	($2,197)
Derivative Asset, Fair Value, Gross Asset	0	0
Net amounts of liabilities presented in balance sheets	-2,437	-2,197
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	316	367
Derivative, Collateral, Obligation to Return Cash	0	0
Derivative liabilities, net amount	($2,121)	($1,830)

ShortTerm_Investments_Details

Short-Term Investments (Details) (USD $)	3 Months Ended			6 Months Ended
	Apr. 04, 2015		Mar. 29, 2014	Apr. 04, 2015		Mar. 29, 2014	Sep. 27, 2014
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Cash and cash equivalent, Cost Basis	$115,081,000			$115,081,000			$91,217,000
Cash and cash equivalent, Unrealized Gains	0			0			0
Cash and cash equivalent, Unrealized Losses	0			0			0
Cash and cash equivalent, Fair Value	115,081,000			115,081,000			91,217,000
Available-for-sale securities: Cost Basis	228,054,000			228,054,000			226,077,000
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments	1,354,000			1,354,000			1,026,000
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments	-55,000			-55,000			-45,000
Available-for-sale securities: Fair Value	229,353,000			229,353,000			227,058,000
Available-for-sale Securities, Debt Maturities [Abstract]
Investments in available-for-sale debt securities due in less than one year, Amortized Cost	168,338,000			168,338,000			178,329,000
Investments in available-for-sale debt securities due in one to five years, Amortized Cost	44,417,000	[1]		44,417,000	[1]		47,748,000	[1]
Investments in available-for-sale debt securities due in less than one year, Estimated Fair Value	169,230,000			169,230,000			179,223,000
Investments in available-for-sale debt securities due in one to five years, Estimated Fair Value	44,555,000	[1]		44,555,000	[1]		47,835,000	[1]
Proceeds from sale of available-for-sale securities	48,300,000		7,000,000	77,800,000		14,100,000
Maximum [Member]
Available-for-sale Securities, Debt Maturities [Abstract]
Realized gross gains from sale of available-for-sale securities	100,000		100,000	100,000		100,000
Commercial Paper [Member]
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Available-for-sale securities: Cost Basis	16,985,000			16,985,000			23,983,000
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments	0			0			0
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments	0			0			0
Available-for-sale securities: Fair Value	16,985,000			16,985,000			23,983,000
US Treasury and Government [Member]
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Available-for-sale securities: Cost Basis	154,648,000			154,648,000			149,260,000
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments	908,000			908,000			831,000
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments	-17,000			-17,000			-3,000
Available-for-sale securities: Fair Value	155,539,000			155,539,000			150,088,000
Equity Securities [Member]
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Available-for-sale securities: Cost Basis	15,299,000			15,299,000
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments	269,000			269,000
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments	0			0
Available-for-sale securities: Fair Value	15,568,000			15,568,000
Corporate Note Securities [Member]
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Available-for-sale securities: Cost Basis	41,122,000			41,122,000			52,834,000
Available For Sale Securities Gross Unrealized Gain Accumulated In Investments	177,000			177,000			195,000
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments	-38,000			-38,000			-42,000
Available-for-sale securities: Fair Value	$41,261,000			$41,261,000			$52,987,000
[1]	(1) Classified as short-term investments because these securities are highly liquid and can be sold at any time.

Goodwill_and_Intangible_Assets2

Goodwill and Intangible Assets (Goodwill) (Details) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Apr. 04, 2015
Goodwill [Roll Forward]
Goodwill, beginning of period	$109,513
Translation adjustments and other	-10,125
Goodwill, end of period	99,388
Commercial Lasers and Components
Goodwill [Roll Forward]
Goodwill, beginning of period	6,363
Translation adjustments and other	0
Goodwill, end of period	6,363
Specialty Laser Systems
Goodwill [Roll Forward]
Goodwill, beginning of period	103,150
Translation adjustments and other	-10,125
Goodwill, end of period	$93,025

Goodwill_and_Intangible_Assets3

Goodwill and Intangible Assets (Intangible Assets) (Details) (USD $)	6 Months Ended
	Apr. 04, 2015		Mar. 29, 2014	Sep. 27, 2014
Finite-Lived Intangible Assets, Net [Abstract]
Intangible Assets, Gross Carrying Amount	$92,016,000	[1]		$99,038,000	[1]
Intangible Assets, Accumulated Amortization	-68,120,000	[1]		-67,372,000	[1]
Intangible Assets, Net	23,896,000	[1]		31,666,000	[1]
Amortization expense for intangible assets	4,216,000		4,879,000
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
2015 (remainder)	3,931,000
2016	7,484,000
2017	6,359,000
2018	3,745,000
2019	2,036,000
2020	131,000
Thereafter	210,000
Intangible Assets, Net	23,896,000	[1]		31,666,000	[1]
foreign exchange impact on accumulated amortization of intangible assets	3,500,000
Existing Technology and Production Know-how [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Amortization expense for intangible assets	3,300,000		3,800,000
Existing technology
Finite-Lived Intangible Assets, Net [Abstract]
Intangible Assets, Gross Carrying Amount	76,104,000			81,551,000
Intangible Assets, Accumulated Amortization	-58,320,000			-57,827,000
Intangible Assets, Net	17,784,000			23,724,000
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
Intangible Assets, Net	17,784,000			23,724,000
Customer lists
Finite-Lived Intangible Assets, Net [Abstract]
Intangible Assets, Gross Carrying Amount	15,154,000			16,632,000
Intangible Assets, Accumulated Amortization	-9,463,000			-9,199,000
Intangible Assets, Net	5,691,000			7,433,000
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
Intangible Assets, Net	5,691,000			7,433,000
Trade name
Finite-Lived Intangible Assets, Net [Abstract]
Intangible Assets, Gross Carrying Amount	392,000			431,000
Intangible Assets, Accumulated Amortization	-337,000			-346,000
Intangible Assets, Net	55,000			85,000
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
Intangible Assets, Net	55,000			85,000
In-process research and development
Finite-Lived Intangible Assets, Net [Abstract]
Intangible Assets, Gross Carrying Amount	366,000			424,000
Intangible Assets, Accumulated Amortization	0			0
Intangible Assets, Net	366,000			424,000
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
Intangible Assets, Net	$366,000			$424,000
[1]	For accounting purposes, when an intangible asset is fully amortized, it is removed from the disclosure schedule.

Balance_Sheet_Details_Details

Balance Sheet Details (Details) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Apr. 04, 2015	Mar. 29, 2014	Sep. 27, 2014
Inventory, Net [Abstract]
Purchased parts and assemblies	$48,440		$51,091
Work-in-process	59,567		70,486
Finished goods	45,652		48,906
Total inventories	153,659		170,483
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid and refundable income taxes	8,965		11,001
Other Taxes Receivable	15,892		5,184
Prepaid expenses and other	13,681		11,654
Total prepaid expenses and other assets	38,538		27,839
Other Assets, Noncurrent Disclosure [Abstract]
Assets related to deferred compensation arrangements	26,039		26,484
Deferred tax assets	34,526		37,616
Other assets	5,551		5,617
Total other assets	66,116		69,717
Other Liabilities, Current [Abstract]
Accrued payroll and benefits	35,269		29,228
Deferred income	16,256		15,536
Warranty reserve	15,941		16,961
Accrued expenses and other	12,100		13,410
Other taxes payable	16,334		5,036
Customer deposits	3,259		2,335
Total other current liabilities	99,159		82,506
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Beginning balance	16,961	18,508
Additions related to current period sales	11,618	12,434
Warranty costs incurred in the current period	-10,822	-12,713
Adjustments to accruals related to foreign exchange and other	-1,816	-248
Ending balance	15,941	17,981
Other Liabilities, Noncurrent [Abstract]
Long-term taxes payable	7,725		15,776
Deferred compensation	27,578		27,858
Deferred tax liabilities	5,277		6,511
Deferred income	3,010		3,448
Asset retirement obligations	2,124		2,222
Other long-term liabilities	6,650		6,592
Total other long-term liabilities	$52,364		$62,407

ShortTerm_Borrowings_Details

Short-Term Borrowings (Details) (USD $)	Apr. 04, 2015
Line of Credit, Foreign
Line of Credit Facility [Line Items]
Lines of credit	$7,800,000
Amounts drawn upon line of credit	2,800,000
Line of Credit, Domestic
Line of Credit Facility [Line Items]
Amounts drawn upon line of credit	0
Line of Credit, Domestic | Union Bank of California, Unsecured Revolving Credit Account
Line of Credit Facility [Line Items]
Lines of credit	$50,000,000

StockBased_Compensation_Fair_V

Stock-Based Compensation (Fair Value of Stock Compensation) (Details) (USD $)	3 Months Ended		6 Months Ended
	Apr. 04, 2015	Mar. 29, 2014	Apr. 04, 2015	Mar. 29, 2014
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Award vesting period			3 years
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Award vesting period			3 years
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected life in years	0 years 6 months	0 years 6 months	0 years 6 months	0 years 6 months
Expected volatility	24.80%	22.80%	24.80%	23.70%
Risk-free interest rate	0.10%	0.10%	0.10%	0.10%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Weighted average fair value per share	$14.26	$13.89	$14.11	$13.69
Performance Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected volatility			28.70%	36.90%
Risk-free interest rate			0.96%	0.62%
Weighted average fair value per share			$70.57	$77.10
Performance Restricted Stock Units [Member] | Annual vesting
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Award vesting period			2 years
Performance Restricted Stock Units [Member] | Single vest measurement
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Award vesting period			3 years

StockBased_Compensation_Stock_

Stock-Based Compensation (Stock Compensation Expense) (Details) (USD $)	3 Months Ended		6 Months Ended
	Apr. 04, 2015	Mar. 29, 2014	Apr. 04, 2015	Mar. 29, 2014
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures			0
Allocated stock-based compensation expense	$3,479,000	$3,346,000	$7,439,000	$6,875,000
Total stock-based compensation cost capitalized as part of inventory	700,000	600,000	1,400,000	1,300,000
Total stock-based compensation cost amortized into income	700,000	600,000	1,300,000	1,200,000
Total compensation cost, unvested stock-based awards granted but not yet recognized	27,000,000		27,000,000
Total compensation cost, unvested stock-based awards granted, but not yet recognized, forfeitures	800,000		800,000
Total compensation cost, weighted-average period of amortization (in years)			1 year 7 months 6 days
Cost of Sales [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated stock-based compensation expense	676,000	648,000	1,273,000	1,186,000
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated stock-based compensation expense	556,000	500,000	886,000	1,022,000
Selling, general and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated stock-based compensation expense	3,550,000	3,524,000	7,013,000	7,332,000
Income tax benefit
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated stock-based compensation expense	-1,303,000	-1,326,000	-1,733,000	-2,665,000
Employee Stock [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total compensation cost, unvested stock-based awards granted but not yet recognized	100,000		100,000
Total compensation cost, weighted-average period of amortization (in years)			6 months
PeriodEnd [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation cost capitalized as part of inventory			$800,000	$700,000

StockBased_Compensation_Stock_1

Stock-Based Compensation (Stock Options and Awards Activity) (Details) (USD $)	6 Months Ended
	Apr. 04, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Granted, Number of Shares	0
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Nonvested stock, Number of Shares, beginning of period	390,000	[1]
Nonvested stock, Weighted Average Grant Date Fair Value, beginning of period	58.66
Granted, Number of Shares	235,000	[1]
Granted, Weighted Average Grant Date Fair Value	64.88
Vested, Number of Shares	-216,000	[1]
Vested, Weighted Average Grant Date Fair Value	53.59
Forfeited, Number of Shares	-5,000	[1]
Forfeited, Weighted Average Grant Date Fair Value	59.38
Nonvested stock, Number of Shares, end of period	404,000	[1]
Nonvested stock, Weighted Average Grant Date Fair Value, end of period	65
Performance Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Nonvested stock, Number of Shares, beginning of period	230,000	[2]
Nonvested stock, Weighted Average Grant Date Fair Value, beginning of period	61.46
Granted, Number of Shares	51,000	[2]
Granted, Weighted Average Grant Date Fair Value	70.57
Vested, Number of Shares	-39,000	[2]
Vested, Weighted Average Grant Date Fair Value	53.46
Forfeited, Number of Shares	-43,000	[2]
Forfeited, Weighted Average Grant Date Fair Value	53.46
Nonvested stock, Number of Shares, end of period	199,000	[2]
Nonvested stock, Weighted Average Grant Date Fair Value, end of period	67.09
Restricted Stock Units and Awards [Abstract]
Targeted goal of performance based awards and units	100.00%
Performance Restricted Stock Units [Member] | Minimum
Restricted Stock Units and Awards [Abstract]
Percentage of performance-based awards earned by recipient	0.00%
Performance Restricted Stock Units [Member] | Maximum [Member]
Restricted Stock Units and Awards [Abstract]
Percentage of performance-based awards earned by recipient	200.00%
[1]	Service-based restricted stock vested during each fiscal year.
[2]	Performance-based awards and units included at 100% of target goal; under the terms of the awards, the recipient may earn between 0% and 200% of the award.

Stock_Repurchases_Details

Stock Repurchases (Details) (USD $)	0 Months Ended	1 Months Ended	3 Months Ended
	Jul. 25, 2014	Jan. 31, 2015	Apr. 04, 2015	Dec. 27, 2014	Jan. 21, 2015	Jul. 25, 2014
Stock Repurchase [Line Items]
Stock Repurchase Program, Authorized Amount					$25,000,000	$25,000,000
Stock Repurchased During Period, Shares			133,673	300,441
Stock repurchase, price paid per share	$57.55	$57.66
Total cost of stock repurchased, net	$17,300,000	$7,700,000

Earnings_Per_Share_Details

Earnings Per Share (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Share data, unless otherwise specified	Apr. 04, 2015	Mar. 29, 2014	Apr. 04, 2015	Mar. 29, 2014
Earnings Per Share, Basic and Diluted [Abstract]
Weighted average shares outstanding—basic	24,709,000	24,782,000	24,823,000	24,662,000
Dilutive effect of employee awards	182,000	262,000	219,000	318,000
Weighted average shares outstanding—diluted	24,891,000	25,044,000	25,042,000	24,980,000
Net income	$18,413	$15,307	$35,843	$27,010
Net income per basic share	$0.75	$0.62	$1.44	$1.10
Net income per diluted share	$0.74	$0.61	$1.43	$1.08
Earnings Per Share, Diluted, Other Disclosures [Abstract]
Dilutive securities excluded from calculation of dilutive shares	1,333	0	41,559	40,738

Other_Income_Expense_Details

Other Income (Expense) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Apr. 04, 2015	Mar. 29, 2014	Apr. 04, 2015	Mar. 29, 2014
Component of Other Income (Expense), Nonoperating [Line Items]
Other - net	$1,843	$990	$1,073	$734
Foreign Exchange Contract [Member]
Component of Other Income (Expense), Nonoperating [Line Items]
Foreign exchange gain (loss)	1,080	-388	-81	-2,512
Gain (Loss) On Deferred Compensation Investments, Net [Member]
Component of Other Income (Expense), Nonoperating [Line Items]
Gain on deferred compensation investments, net	671	1,291	1,055	3,167
Other Income [Member]
Component of Other Income (Expense), Nonoperating [Line Items]
Other Income	$92	$87	$99	$79

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended	6 Months Ended
In Millions, unless otherwise specified	Apr. 04, 2015	Apr. 04, 2015	Dec. 27, 2014
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Estimated effective income tax rate	23.70%	24.90%
U.S. Federal statutory rate		35.00%
Tax Credit Carryforward, Amount			$1.30

Segment_Information_Details

Segment Information (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Apr. 04, 2015	Mar. 29, 2014	Apr. 04, 2015	Mar. 29, 2014
Segment Reporting Information [Line Items]
Net sales	$203,721	$199,222	$404,336	$392,778
Income (Loss) from Continuing Operations Attributable to Parent	22,132	20,040	46,441	35,824
Nonoperating Income (Expense)	1,990	1,040	1,305	820
Income before income taxes	24,122	21,080	47,746	36,644
Provision for income taxes	5,709	5,773	11,903	9,634
Net income	18,413	15,307	35,843	27,010
Other Operating Income (Expense), Net	1,990	1,040	1,305	820
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	24,122	21,080	47,746	36,644
Commercial Lasers and Components
Segment Reporting Information [Line Items]
Net sales	63,705	55,427	119,229	112,160
Operating Income (Loss)	2,279	-129	2,982	177
Specialty Laser Systems
Segment Reporting Information [Line Items]
Net sales	140,016	143,795	285,107	280,618
Operating Income (Loss)	32,078	31,117	66,632	59,749
Corporate and other
Segment Reporting Information [Line Items]
Operating Income (Loss)	($12,225)	($10,948)	($23,173)	($24,102)

Segment_Information_Major_Cust

Segment Information Major Customers (Details) (Customer Concentration Risk [Member])	6 Months Ended	3 Months Ended		6 Months Ended
	Apr. 04, 2015	Apr. 04, 2015	Mar. 29, 2014	Mar. 29, 2014	Sep. 27, 2014
	customers	customers	customers	customers	customers
Concentration Risk [Line Items]
Concentration Risk, Customer	1
Number of Customers, Concentration Risk, Accounts Receivable	1	1			1
Sales [Member]
Concentration Risk [Line Items]
Number of Customers for Concentration of Risk	1	1	1	1
Customer 1 [Member] | Sales [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	18.00%	17.40%	11.50%	12.60%
Customer 1 [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Number of Customers, Concentration Risk, Percentage	15.70%	15.70%			15.20%
Customer 2 [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Number of Customers, Concentration Risk, Percentage					11.60%