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                                                                     Exhibit 3.3

                          CERTIFICATE OF INCORPORATION
                                       OF
                   TYLAN GENERAL ACQUISITION SUBSIDIARY, INC.

         The undersigned, a natural person (the "Sole Incorporator"), for the
purpose of organizing a corporation to conduct the business and promote the
purposes hereinafter stated, under the provisions and subject to the
requirements of the laws of the State of Delaware hereby certifies that:

                                       I.

   The name of this corporation is TYLAN GENERAL ACQUISITION SUBSIDIARY, INC.

                                       II.

         The address of the registered office of the corporation in the State of
Delaware is 9 East Loockerman Street, City of Dover, County of Kent, and the
name of the registered agent of the corporation in the State of Delaware at such
address is National Registered Agents, Inc.

                                      III.

         The purpose of this corporation is to engage in any lawful act or
activity for which a corporation may be organized under the General Corporation
Law of the State of Delaware.

                                       IV.

         The corporation is authorized to issue only one class of stock, to be
designated "Common Stock." The total number of shares of Common Stock presently
authorized is ten thousand (10,000), each having a par value of one-tenth of one
cent ($.001).

                                       V.

         The management of the business and the conduct of the affairs of the
corporation shall be vested in its Board of Directors. The number of directors
which shall constitute the whole Board of Directors shall be fixed exclusively
by one or more resolutions adopted by the Board of Directors.

                                       VI.

         In furtherance and not in limitation of the powers conferred by
statute, the Board of Directors shall have the power, both before and after
receipt of any payment for any of the corporation's capital stock, to adopt,
amend, repeal or otherwise alter the By-laws of the corporation without any
action on the part of the stockholders; provided, however, that the grant
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of such power to the Board of Directors shall not divest the stockholders of nor
limit their power to adopt, amend, repeal or otherwise alter the By-laws.

                                      VII.

         Elections of directors need not be by written ballot unless the By-laws
of the corporation shall so provide.

                                      VIII.

         A director of the corporation shall, to the full extent permitted by
the Delaware General Corporation Law, as it now exists or as it may hereafter be
amended, not be liable to the corporation or its stockholders for monetary
damages for breach of fiduciary duty as a director. Neither any amendment nor
repeal of this Article VIII, nor the adoption of any provision of this
Certificate of Incorporation inconsistent with this Article VIII, shall
eliminate or reduce the effect of this Article VIII in respect of any matter
occurring, or any cause of action, suit or claim that, but for this Article
VIII, would accrue or arise, prior to such amendment, repeal or adoption of an
inconsistent provision.

                                       IX.

         The corporation reserves the right to adopt, repeal, rescind or amend
in any respect any provision contained in this Certificate of Incorporation, in
the manner now or hereafter prescribed by statute, and all rights conferred upon
the stockholders herein are granted subject to this reservation.

                                       X.

         The name and the mailing address of the Sole Incorporator is as
follows:

                  NAME                        MAILING ADDRESS

                  Jane K. Adams               Cooley Godward Castro
                                                Huddleson & Tatum
                                              4365 Executive Drive, Suite 1100
                                              San Diego, California  92121


         IN WITNESS WHEREOF, this Certificate has been subscribed this 19th day
of February, 1996 by the undersigned who affirms that the statements made herein
are true and correct.


                                         /s/  Jane K. Adams
                                         ------------------------------
                                         Jane K. Adams
                                         Sole Incorporator