SECURITIES AND EXCHANGE COMMISSION

                              Washington, DC 20549

                   -------------------------------------------

                                    FORM 10-Q

    (mark one)

    [ X ] Quarterly Report Pursuant to Section 13 or 15(d) of the Securities
          Exchange Act of 1934 for the Quarter Ended April 4, 1998.

    [   ] Transition Report Pursuant to Section 13 or 15(d) of the Securities
          Exchange Act of 1934.

                         Commission File Number 1-11757

                            THERMO OPTEK CORPORATION
             (Exact name of Registrant as specified in its charter)

    Delaware                                                       04-3283973
    (State or other jurisdiction of                          (I.R.S. Employer
    incorporation or organization)                        Identification No.)

    8 East Forge Parkway
    Franklin, Massachusetts                                             02038
    (Address of principal executive offices)                       (Zip Code)

       Registrant's telephone number, including area code: (781) 622-1000

           Indicate by check mark whether the Registrant (1) has
           filed all reports required to be filed by Section 13
           or 15(d) of the Securities Exchange Act of 1934
           during the preceding 12 months (or for such shorter
           period that the Registrant was required to file such
           reports), and (2) has been subject to such filing
           requirements for the past 90 days. Yes [ X ] No [   ]

           Indicate the number of shares outstanding of each of
           the issuer's classes of Common Stock, as of the
           latest practicable date.

                    Class                     Outstanding at May 1, 1998
         ----------------------------         --------------------------
         Common Stock, $.01 par value                 49,580,581
PAGE
<PAGE>
    PART I - FINANCIAL INFORMATION

    Item 1 - Financial Statements
    -----------------------------

                            THERMO OPTEK CORPORATION

                           Consolidated Balance Sheet
                                   (Unaudited)

                                     Assets


                                                      April 4,   January 3,
    (In thousands)                                        1998         1998
    -----------------------------------------------------------------------
    Current Assets:
      Cash and cash equivalents                       $ 93,065     $ 71,109
      Accounts receivable, less allowances of
        $4,975 and $5,191                               86,424       89,368
      Inventories:
        Raw materials and supplies                      31,995       32,129
        Work in process                                 12,873       11,538
        Finished goods                                  17,984       20,678
      Prepaid expenses                                   8,133        7,276
      Prepaid income taxes                               9,622        9,634
      Due from parent company and affiliated
        companies                                        1,510        6,844
                                                      --------     --------
                                                       261,606      248,576
                                                      --------     --------

    Property, Plant, and Equipment, at Cost             83,291       82,786
      Less: Accumulated depreciation and amortization   29,487       27,573
                                                      --------     --------
                                                        53,804       55,213
                                                      --------     --------
    Patents and Other Assets                             7,318        7,707
                                                      --------     --------
    Due from Thermo Vision Corporation                   3,947        3,947
                                                      --------     --------
    Cost in Excess of Net Assets of Acquired 
      Companies                                        229,579      231,028
                                                      --------     --------
                                                      $556,254     $546,471
                                                      ========     ========


                                        2PAGE
<PAGE>
                            THERMO OPTEK CORPORATION

                     Consolidated Balance Sheet (continued)
                                   (Unaudited)

                    Liabilities and Shareholders' Investment


                                                     April 4,     January 3,
    (In thousands except share amounts)                  1998           1998
    ------------------------------------------------------------------------
    Current Liabilities:
      Notes payable and current maturities of
        long-term obligations (includes $40,000
        due to Thermo Electron)                      $ 54,956       $ 56,875
      Accounts payable                                 21,546         22,095
      Accrued payroll and employee benefits            10,873         11,492
      Accrued income taxes                             22,027         18,811
      Accrued installation and warranty expenses       17,655         18,643
      Deferred revenue                                 21,116         19,229
      Other accrued expenses                           32,351         32,052
                                                     --------       --------
                                                      180,524        179,197
                                                     --------       --------
    Deferred Income Taxes                              12,398         12,456
                                                     --------       --------
    Other Deferred Items                                2,441          2,678
                                                     --------       --------
    Long-term Obligations:
      5% Subordinated convertible debentures           79,916         79,956
      Other                                             1,370          1,444
                                                     --------       --------
                                                       81,286         81,400
                                                     --------       --------

    Shareholders' Investment:
      Common stock, $.01 par value, 100,000,000
        shares authorized; 49,576,317 and
        49,569,819 shares issued                          496            496
      Capital in excess of par value                  240,076        239,507
      Retained earnings                                46,321         37,100
      Treasury stock at cost, 619 and 594 shares          (11)           (10)
      Accumulated other comprehensive items 
        (Note 3)                                       (7,277)        (6,353)
                                                     --------       --------
                                                      279,605        270,740
                                                     --------       --------
                                                     $556,254       $546,471
                                                     ========       ========


    The accompanying notes are an integral part of these consolidated
    financial statements.

                                        3PAGE
<PAGE>
                            THERMO OPTEK CORPORATION

                        Consolidated Statement of Income
                                   (Unaudited)


                                                       Three Months Ended
                                                     ---------------------
                                                     April 4,    March 29,
    (In thousands except per share amounts)              1998         1997
    ----------------------------------------------------------------------
    Revenues                                         $103,554     $106,175
                                                     --------     --------

    Costs and Operating Expenses:
      Cost of revenues                                 55,472       56,784
      Selling, general, and administrative expenses    26,004       26,779
      Research and development expenses                 5,599        6,407
                                                     --------     --------
                                                       87,075       89,970
                                                     --------     --------

    Operating Income                                   16,479       16,205

    Interest Income (includes $187 from related
      party in 1998)                                    1,090          893
    Interest Expense (includes $578 to related
      party in 1998)                                   (1,792)      (1,793)
                                                     --------     --------
    Income Before Provision for Income Taxes           15,777       15,305
    Provision for Income Taxes                          6,556        6,407
                                                     --------     --------
    Net Income                                       $  9,221     $  8,898
                                                     ========     ========
    Earnings per Share (Note 2):
      Basic                                          $    .19     $    .18
                                                     ========     ========
      Diluted                                        $    .18     $    .17
                                                     ========     ========
    Weighted Average Shares (Note 2):
      Basic                                            49,573       48,450
                                                     ========     ========
      Diluted                                          55,720       55,017
                                                     ========     ========


    The accompanying notes are an integral part of these consolidated
    financial statements.


                                        4PAGE
<PAGE>
                            THERMO OPTEK CORPORATION

                      Consolidated Statement of Cash Flows
                                   (Unaudited)

                                                        Three Months Ended
                                                      ----------------------
                                                      April 4,     March 29,
    (In thousands)                                        1998          1997
    ------------------------------------------------------------------------
    Operating Activities:
      Net income                                      $  9,221      $  8,898
      Adjustments to reconcile net income to net
        cash provided by operating activities:
          Depreciation and amortization                  3,440         3,855
          Provision for losses on accounts receivable      102            33
          Other noncash items                              389           415
          Changes in current accounts, excluding
            the effects of acquisitions:
              Accounts receivable                        2,387        (8,442)
              Inventories                                1,289        (5,515)
              Other current assets                        (891)       (1,840)
              Accounts payable                            (537)         (673)
              Amounts due to affiliated companies       (1,305)       12,643
              Other current liabilities                  3,917         2,209
          Other                                            269           237
                                                      --------      --------
    Net cash provided by operating activities           18,281        11,820
                                                      --------      --------

    Investing Activities:
      Acquisitions, net of cash acquired                     -        (2,571)
      Refund from parent company for acquisitions        6,737             -
      Purchases of property, plant, and equipment       (1,061)       (1,929)
      Other                                               (201)           94
                                                      --------      --------
    Net cash provided by (used in) investing 
      activities                                         5,475        (4,406)
                                                      --------      --------
    Financing Activities:
      Net proceeds from issuance of Company common
        stock                                               36             -
      Repayment of short-term obligations, net          (1,823)       (7,452)
      Repayment of long-term obligations                   (85)         (115)
                                                      --------      --------
    Net cash used in financing activities               (1,872)       (7,567)
                                                      --------      --------
    Exchange Rate Effect on Cash                            72          (452)
                                                      --------      --------
    Increase (Decrease) in Cash and Cash Equivalents    21,956          (605)
    Cash and Cash Equivalents at Beginning of Period    71,109        66,293
                                                      --------      --------
    Cash and Cash Equivalents at End of Period        $ 93,065      $ 65,688
                                                      ========      ========

                                        5PAGE
<PAGE>
                            THERMO OPTEK CORPORATION

                Consolidated Statement of Cash Flows (continued)
                                   (Unaudited)


                                                        Three Months Ended
                                                      ---------------------
                                                      April 4,    March 29,
    (In thousands)                                        1998         1997
    -----------------------------------------------------------------------
    Noncash Activities:
      Conversion of convertible debentures            $     40     $      -
                                                      ========     ========

      Fair value of assets of acquired companies      $      -     $ 51,032
      Cash paid for acquired companies                       -       (3,016)
      Stock issuable to parent company for acquired
        companies                                            -          (12)
      Due to parent company for acquired companies           -      (38,891)
                                                      --------     --------

        Liabilities assumed of acquired companies     $      -     $  9,113
                                                      ========     ========


    The accompanying notes are an integral part of these consolidated
    financial statements.










                                        6PAGE
<PAGE>
                            THERMO OPTEK CORPORATION

                   Notes to Consolidated Financial Statements

    1.  General

        The interim consolidated financial statements presented have been
    prepared by Thermo Optek Corporation (the Company) without audit and, in
    the opinion of management, reflect all adjustments of a normal recurring
    nature necessary for a fair statement of the financial position at April
    4, 1998, the results of operations for the three-month periods ended
    April 4, 1998, and March 29, 1997, and the cash flows for the three-month
    periods ended April 4, 1998, and March 29, 1997. Interim results are not
    necessarily indicative of results for a full year.

        The consolidated balance sheet presented as of January 3, 1998, has
    been derived from the consolidated financial statements that have been
    audited by the Company's independent public accountants. The consolidated
    financial statements and notes are presented as permitted by Form 10-Q
    and do not contain certain information included in the annual financial
    statements and notes of the Company. The consolidated financial
    statements and notes included herein should be read in conjunction with
    the financial statements and notes included in the Company's Annual
    Report on Form 10-K for the fiscal year ended January 3, 1998, filed with
    the Securities and Exchange Commission.

    2.  Earnings per Share

        Basic and diluted earnings per share were calculated as follows:

                                                         Three Months Ended
                                                        --------------------
                                                        April 4,   March 29,
    (In thousands except per share amounts)                 1998        1997
    ------------------------------------------------------------------------
    Basic
    Net income                                          $  9,221    $  8,898
                                                        --------    --------
    Weighted average shares                               49,573      48,450
                                                        --------    --------
    Basic earnings per share                            $    .19    $    .18
                                                        ========    ========
    Diluted
    Net income                                          $  9,221    $  8,898
    Effect of convertible debentures                         599         722
                                                        --------    --------
    Income available to common shareholders, 
      as adjusted                                       $  9,820    $  9,620
                                                        --------    --------
    Weighted average shares                               49,573      48,450
    Effect of:
      Convertible debentures                               5,731       6,481
      Stock options                                          416          86
                                                        --------    --------
    Weighted average shares, as adjusted                  55,720      55,017
                                                        --------    --------
    Diluted earnings per share                          $    .18    $    .17
                                                        ========    ========

                                        7PAGE
<PAGE>
                            THERMO OPTEK CORPORATION

    3.  Comprehensive Income

        During the first quarter of 1998, the Company adopted Statement of
    Financial Accounting Standards (SFAS) No. 130, "Reporting Comprehensive
    Income." This pronouncement sets forth requirements for disclosure of the
    Company's comprehensive income and accumulated other comprehensive items.
    In general, comprehensive income combines net income and "other
    comprehensive items," which represents foreign currency translation
    adjustments reported as a component of shareholders' investment in the
    accompanying balance sheet. During the first quarter of 1998 and 1997,
    the Company's comprehensive income totaled $8,297,000 and $3,323,000,
    respectively.

    Item 2 - Management's Discussion and Analysis of Financial Condition and
    ------------------------------------------------------------------------
             Results of Operations
             ---------------------

        Forward-looking statements, within the meaning of Section 21E of the
    Securities Exchange Act of 1934, are made throughout this Management's
    Discussion and Analysis of Financial Condition and Results of Operations.
    For this purpose, any statements contained herein that are not statements
    of historical fact may be deemed to be forward-looking statements.
    Without limiting the foregoing, the words "believes," "anticipates,"
    "plans," "expects," "seeks," "estimates," and similar expressions are
    intended to identify forward-looking statements. There are a number of
    important factors that could cause the results of the Company to differ
    materially from those indicated by such forward-looking statements,
    including those detailed under the heading "Forward-looking Statements"
    in Exhibit 13 to the Company's Annual Report on Form 10-K for the fiscal
    year ended January 3, 1998, filed with the Securities and Exchange
    Commission.

    Overview

        The Company is a worldwide leader in instrumentation based upon
    energy and light measurements (molecular and elemental analysis), and
    systems for materials analysis, characterization, and preparation
    (materials science). The Company provides industry, government, and
    academia with complete solutions to specific analytical problems, moving
    sophisticated analytical technology outside the laboratory. The Company's
    instruments are used in virtually every industry for research and
    development, manufacturing, and quality control.

        For molecular and elemental analysis, the Company has three principal
    operating units: Madison, Wisconsin-based Nicolet Instrument Corporation,
    a manufacturer and distributor of Fourier transform infrared (FT-IR) and
    FT-Raman spectrometry products; Franklin, Massachusetts-based Thermo
    Jarrell Ash Corporation, a manufacturer and distributor of atomic
    absorption (AA) and atomic emission (AE) spectrometry products; and
    Ecublens, Switzerland-based A.R.L. Applied Research Laboratories S.A., a
    manufacturer and distributor of wavelength-dispersive X-ray fluorescence
    and AE instruments.

                                        8PAGE
<PAGE>
                            THERMO OPTEK CORPORATION

    Overview (continued)

        For materials science, the Company has one principal operating unit,
    VG Systems Limited, located in the United Kingdom. VG Systems primarily
    includes VG Semicon, a manufacturer and distributor of equipment for the
    production of molecular-beam epitaxy products, and VG Scientific, a
    manufacturer and distributor of instrumentation for surface and chemical
    analysis. 

        Effective March 12, 1997, the Company acquired Spectronic Instruments
    Inc., a supplier of ultraviolet/visible (UV/Vis) spectrophotometers and
    accessories, fluorescence instruments, and diffraction gratings based in
    Rochester, New York, from Thermo Instrument Systems Inc.

        In December 1997, the Company distributed 100 percent of its Thermo
    Vision Corporation subsidiary's capital stock in the form of a dividend
    to the Company's shareholders. Thermo Vision designs, manufactures, and
    markets a diverse array of photonic products, including optical
    components, imaging sensors and systems, lasers, optically based
    instruments, optoelectronics, and fiber optics. As a result of the
    distribution, Thermo Vision is a publicly traded, majority-owned
    subsidiary of Thermo Instrument. The consolidated financial statements of
    the Company include the results for Thermo Vision through December 15,
    1997.

        The Company sells its products worldwide. Although the Company seeks
    to charge its customers in the same currency as its operating costs, the
    Company's financial performance and competitive position can be affected
    by currency exchange rate fluctuations. Where appropriate, the Company
    uses forward contracts to reduce its exposure to currency fluctuations.

        During 1997, the Company's U.S. and foreign operations had revenues
    to customers in Asia of approximately 22% of total revenues. Certain
    countries in Asia are experiencing a severe economic crisis, which has
    been characterized by sharply reduced economic activity and liquidity,
    highly volatile foreign-currency-exchange and interest rates, and
    unstable stock markets. Revenues to customers in South Korea, Taiwan,
    Singapore, Malaysia, and Indonesia represented approximately 5% of the
    Company's total 1997 revenues. The Company's sales to Asia could be
    adversely affected by the unstable economic conditions there. 

    Results of Operations

    First Quarter 1998 Compared With First Quarter 1997
    ---------------------------------------------------

        Revenues decreased to $103.6 million in the first quarter of 1998
    from $106.2 million in the first quarter of 1997. An increase in revenues
    of $6.6 million in the first quarter of 1998, due to acquisitions, was
    more than offset by the distribution of Thermo Vision in late 1997, which
    had revenues of $7.7 million in the first quarter of 1997. In addition,
    the Company's revenues decreased by $2.0 million due to the unfavorable
    effects of currency translation as a result of the strengthening in value
    of the U.S. dollar relative to currencies in foreign countries in which
    the Company operates.

                                        9PAGE
<PAGE>
                            THERMO OPTEK CORPORATION

    First Quarter 1998 Compared With First Quarter 1997 (continued)
    ---------------------------------------------------

        The gross profit margin remained relatively unchanged at 46.4% in the
    first quarter of 1998 and 46.5% in the first quarter of 1997.

        Selling, general, and administrative expenses as a percentage of
    revenues were 25% in the first quarter of 1998 and 1997.

        Research and development expenses as a percentage of revenues
    decreased to 5.4% in the first quarter of 1998 from 6.0% in the first
    quarter of 1997, primarily due to the distribution of Thermo Vision.
    During the first quarter of 1997, Thermo Vision invested approximately
    11% of sales in research and development.

        Interest income increased slightly to $1.1 million in the first
    quarter of 1998 from $0.9 million in the first quarter of 1997. Interest
    expense remained unchanged at $1.8 million in 1998 and 1997. 

        The effective tax rate was 42% in the first quarter of 1998 and 1997.
    The effective tax rates exceeded the statutory federal income tax rate
    primarily due to the impact of state income taxes, the nondeductible
    amortization of cost in excess of net assets of acquired companies, and
    the inability to provide a tax benefit on foreign losses, offset in part
    by the tax benefit associated with a foreign sales corporation.

    Liquidity and Capital Resources

        Consolidated working capital was $81.1 million at April 4, 1998,
    compared with $69.4 million at January 3, 1998. Included in working
    capital are cash and cash equivalents of $93.1 million at April 4, 1998,
    compared with $71.1 million at January 3, 1998. Cash provided by
    operating activities was $18.3 million in the first quarter of 1998. Cash
    provided by the Company's operating results benefited from a $3.9 million
    increase in other current liabilities due to an increase in accrued
    income taxes related to the timing of tax payments. In addition, cash was
    provided by a $2.4 million decrease in accounts receivable and a $1.3
    million decrease in inventory. The decreases in accounts receivable and
    inventory are the result of management efforts to reduce the Company's
    investment in these assets.

        The Company's investing activities provided $5.5 million of cash in
    the first quarter of 1998. The Company received a refund of $6.7 million
    from Thermo Instrument relating to the purchase of the former Fisons
    businesses. The Company expended $1.1 million for the purchase of
    property, plant, and equipment and plans to expend an additional $7.0
    million for such purchases in the remainder of 1998. 

        The Company's financing activities used $1.9 million of cash in the
    first quarter of 1998. The Company used $1.8 million for the repayment of
    short-term borrowings.

        Although the Company expects to have positive cash flow from its
    existing operations, the Company may require significant amounts of cash
    for any acquisition of complementary businesses. The Company expects that
    it will finance any such acquisitions through a combination of internal
    funds, additional debt or equity financing from capital markets, or 

                                       10PAGE
<PAGE>
                            THERMO OPTEK CORPORATION

    Liquidity and Capital Resources (continued)

    short-term borrowings from Thermo Instrument or Thermo Electron
    Corporation, although it has no agreement with these companies to ensure
    that funds will be available on acceptable terms or at all. The Company
    believes its existing resources are sufficient to meet the capital
    requirements of its existing operations for the foreseeable future.

    PART II - OTHER INFORMATION

    Item 6 - Exhibits
    -----------------

        See Exhibit Index on the page immediately preceding exhibits.
















                                       11PAGE
<PAGE>
                            THERMO OPTEK CORPORATION

                                   SIGNATURES


        Pursuant to the requirements of the Securities Exchange Act of 1934,
    the Registrant has duly caused this report to be signed on its behalf by
    the undersigned thereunto duly authorized as of the 12th day of May 1998.

                                           THERMO OPTEK CORPORATION



                                           Paul F. Kelleher
                                           ---------------------------
                                           Paul F. Kelleher
                                           Chief Accounting Officer



                                           John N. Hatsopoulos
                                           ---------------------------
                                           John N. Hatsopoulos
                                           Chief Financial Officer and
                                             Senior Vice President

















                                       12PAGE
<PAGE>
                            THERMO OPTEK CORPORATION

                                  EXHIBIT INDEX


    Exhibit
    Number       Description of Exhibit
    ------------------------------------------------------------------------

      27         Financial Data Schedule.