<PAGE>   1


                                 LOAN AGREEMENT

     THIS LOAN AGREEMENT dated as of March  , 2001, is entered into by and
between Spectra-Physics Lasers, Inc., a Delaware corporation with offices
located at 1335 Terra Bella Ave., Mountain View, CA 94030 ("BORROWER"), and
Thermo Electron Corporation, a Delaware corporation with offices located at 81
Wyman Street, Waltham, MA 02454 ("LENDER").

     WHEREAS, Borrower desires to borrow from Lender up to $20 million pursuant
to a revolving line of credit for the purposes described and on the terms and
conditions set forth herein; and

     WHEREAS, Lender desires to lend Borrower up to $20 million for the
purposes described and on the terms and conditions set forth herein.

     NOW THEREFORE, Borrower and Lender hereby agree as follows:

     1.   Definitions. Reference is made to Section 12 of this Loan Agreement
for the definition of certain terms used herein.

     2.   Credit Facility. Subject to the terms and conditions set forth in
this Loan Agreement and the other agreements, instruments and documents
evidencing, governing, and/or pertaining to the Loans, as hereinafter defined
(collectively, together with this Loan Agreement, referred to hereinafter as
the "LOAN DOCUMENTS"). Lender hereby agrees to provide to Borrower the credit
facility described in this Loan Agreement:

     (a) Revolving Line of Credit. Subject to the terms and conditions set
forth herein, Lender agrees to lend to Borrower up to $20 million, on a
revolving basis from time to time during the period commencing on the date
hereof and continuing through the Termination Date (the "REVOLVING LOAN
COMMITMENT"); provided, however, that the commitment of Lender to make
revolving credit loans (the "REVOLVING LINE OF CREDIT") shall not at any time
exceed $20 million, and subject to the terms and conditions hereof, Borrower
may borrow, repay and reborrow under the Revolving Line of Credit. The sums
advanced under the Revolving Line of Credit shall be used for general corporate
purposes relating to the business and operations of Borrower, including the
expansion of Borrower's manufacturing facility, for acquisitions, and for
working capital.

     (b) Notice of Borrowing Under Revolving Line of Credit. Lender reserves
the right to require Borrower to give Lender not less than five (5) business
days prior written notice of each requested advance under the Revolving Line of
Credit, specifying (i) the aggregate amount of such requested advance which
advances shall be in amounts of not less than $1 million and in increments of
$1 million, (ii) the requested date of such advance, and (iii) the purpose for
such advance, with such advances to be requested in a form satisfactory to
Lender, and stating that after giving effect to the requested advance, the
total outstanding principal amount under the Revolving Line of Credit will not
exceed the Revolving Loan Commitment.

     (c) Reduction of Revolving Loan Commitment. The Revolving Loan Commitment
may be reduced upon the written request of Borrower, to any amount requested by
Borrower which is not less than the then outstanding principal amount of all
Loans under the Revolving Line of Credit, provided that any such reduction
shall be made in integral multiples of $100,000. The maximum amount of the
Revolving Loan Commitment shall be fixed at the outstanding balance of the
Revolving Line of Credit


<PAGE>   2
on the first anniversary of the date hereof and repaid as set forth in the form
of Revolving Promissory Note attached hereto as Exhibit A.

      3.    Promissory Note; Reimbursement Obligations.

      (a)   The Note. The Loan shall be evidenced by (i) a Revolving Promissory
Note, dated the date hereof, in the original principal amount of $20 million
made by Borrower and payable to the order of Lender in the form attached hereto
as Exhibit A (the "Note").

      (b)   Interest. Interest on the Note shall accrue at the rate set forth
therein. The principal of and interest on the Note shall be due and payable in
accordance with the terms and conditions set forth in the Note and in this Loan
Agreement.

      4.    Representations and Warranties. Borrower hereby represents and
warrants, and upon each request for an advance under the Revolving Line of
Credit shall be deemed to have further represented and warranted to Lender, as
follows:

      (a)   Existence and Authority. Borrower is a corporation duly organized,
validly existing and in good standing under the laws of the State of Delaware,
and all other states where Borrower is doing business (except where failure to
qualify to do business would not have a material adverse effect on Borrower),
and has all requisite power and authority to execute and deliver the Loan
Documents.

      (b)   Binding Obligations. The execution, delivery, and performance of
this Loan Agreement and all of the other Loan Documents by Borrower have been
duly authorized by all necessary action by Borrower, and constitute legal,
valid and binding obligations of Borrower, enforceable in accordance with their
respective terms, except as limited by bankruptcy, insolvency or similar laws
of general application relating to the enforcement of creditors' rights and
except to the extent specific remedies may generally be limited by equitable
principles.

      (c)   No Consent. The execution, delivery and performance of this Loan
Agreement and the other Loan Documents, and the consummation of the
transactions contemplated hereby and thereby, do not (i) conflict with, result
in a violation of, or constitute a default under (A) any provision of its
certificate of incorporation or bylaws, or any agreement or other instrument
binding upon Borrower or its Subsidiaries, or (B) any law, governmental
regulation, court decree or order applicable to Borrower, or (ii) require the
consent, approval or authorization of any third party.

      (d)   Financial Condition. Each financial statement of Borrower supplied
to the Lender fairly presents Borrower's financial condition as of the date of
each such statement. There has been no material adverse change in such
financial condition or results of operations of Borrower and its Subsidiaries
subsequent to the date of the most recent financial statements supplied to
Lender.

      (e)   Litigation. Except as previously disclosed in writing to Lender,
there are no actions, suits or proceedings, pending or, to the knowledge of
Borrower, threatened against or affecting Borrower or its Subsidiaries or the
properties of Borrower or its Subsidiaries, before any court or governmental
department, commission or board, which, if determined adversely to Borrower or
its Subsidiaries, would have a material adverse effect on the financial
condition, properties, or operations of Borrower.



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     (f) Taxes; Governmental Charges. Borrower and its Subsidiaries have filed
all federal, state and local tax reports and returns required by any law or
regulation to be filed by them and have either duly paid all taxes, duties and
charges indicated due on the basis of such returns and reports (or is
contesting its obligation to pay such taxes and has established adequate
reserves in accordance with GAAP with respect thereto), and the assessment of
any material amount of additional taxes in excess of those paid and reported is
not reasonably expected.

     5. Conditions Precedent to Advances. Lender's obligation to make any
advance under this Loan Agreement and the other Loan Documents shall be subject
to the conditions precedent that, as of the date of such advance and after
giving effect thereto:

     (a) all representations and warranties made to Lender in this Loan
Agreement and the other Loan Documents shall be true and correct, as of and as
if made on such date;

     (b) no material adverse change in the financial condition of Borrower
since the date hereof shall have occurred and be continuing; and

     (c) no event has occurred and is continuing, or would result from the
requested advance, which with notice or lapse of time, or both, would
constitute a Potential Default or an Event of Default.

     6. Affirmative Covenants. Until (i) the Note and all other obligations
and liabilities of Borrower under this Loan Agreement and the other Loan
Documents are fully paid and satisfied, and (ii) the Lender has no further
commitment to lend hereunder, Borrower agrees and covenants that it will,
unless Lender shall otherwise consent in writing:

     (a) Accounts and Records. maintain the books and records of Borrower and
its Subsidiaries in accordance with GAAP;

     (b) Right of Inspection. permit Lender to visit the properties and
installations of Borrower and its Subsidiaries and to examine, audit and make
and take away copies or reproductions of the books and records of Borrower and
its Subsidiaries, at all reasonable times upon reasonable notice;

     (c) Right to Additional Information. promptly furnish Lender with such
additional information and statements, lists of assets and liabilities, tax
returns, and other reports with respect to the financial condition and business
operations of the Borrower and its Subsidiaries as Lender may reasonably
request from time to time;

     (d) Compliance with Laws. Conduct, and cause its Subsidiaries to conduct,
its business in an orderly and efficient manner consistent with good business
practices, and perform and comply with all statutes, rules, regulations and/or
ordinances imposed by any governmental unit upon Borrower and its Subsidiaries
and their businesses, operations and properties (including without limitation,
all applicable environmental statutes, rules, regulations and ordinances)
except where failure to do so would not have a material adverse effect on
Borrower;

     (e) Taxes. pay and discharge when due all of its indebtedness and
obligations, including without limitation, all assessments, taxes, governmental
charges, levies and liens, of every kind and nature, imposed upon Borrower and
its Subsidiaries or their properties, income, or profits, prior to the date on
which penalties would attach, and all lawful claims that, if unpaid, might
become a lien or charge upon any of such properties, income, or profits;
provided, however, Borrower and its Subsidiaries will not be required to pay
and discharge any such assessment, tax, charge, levy, lien or


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claim so long as (i) the legality of the same shall be contested in good faith
by appropriate judicial, administrative or other legal proceedings, and (ii)
Borrower and its Subsidiaries, as appropriate, shall have established on their
books adequate reserves with respect to such contested assessment, tax,
charge, levy, lien or claim in accordance with GAAP;

     (f) Insurance. maintain insurance, including but not limited to, fire
insurance, comprehensive property damage, public liability, worker's
compensation, business interruption and other insurance deemed necessary or
otherwise required by Lender;

     (g) Notice of Indebtedness. promptly inform Lender of the creation,
incurrence or assumption by Borrower or its Subsidiaries of any actual or
contingent liabilities not permitted under this Loan Agreement;

     (h) Notice of Litigation. promptly after the commencement thereof, notify
Lender of all potentially material actions, suits and proceedings before any
court or any governmental department, commission or board affecting Borrower or
its Subsidiaries or any of their properties;

     (i) Notice of Material Adverse Change. promptly inform Lender of (i) any
and all material adverse changes in Borrower's financial condition, and (ii)
all claims made against Borrower or its Subsidiaries which could materially
affect the financial condition of Borrower; and

     (j) Additional Documentation. execute and deliver, or cause to be executed
and delivered, any and all other agreements, instruments or documents which
Lender may reasonably request in order to give effect to the transactions
contemplated under this Loan Agreement and the other Loan Documents.

     7. Negative Covenants. Until (i) the Note and all other obligations and
liabilities of Borrower under this Loan Agreement and the other Loan Documents
are fully paid and satisfied, and (ii) the Lender has no further commitment to
lend hereunder, Borrower will not, without the prior written consent of Lender:

     (a) Nature of Business. make any material change in the nature of the
business of Borrower and its Subsidiaries as carried on as of the date hereof;

     (b) Liquidations, Mergers, Consolidations. liquidate, merge or consolidate
Borrower or its Subsidiaries with or into any other entity, provided however
that Borrower and its Subsidiaries may merge or consolidate with entities
within Borrower's consolidated group following prior written notice to Lender;

     (c) Sale of Assets. sell, transfer or otherwise dispose of any material
portion of the assets or properties or Borrower or its Subsidiaries;

     (d) Liens. create or incur any lien or encumbrance on any of the assets of
Borrower or its Subsidiaries, other than Permitted Liens;

     (e) Indebtedness. create, incur or assume, or allow any of its
Subsidiaries to create, incur or assume, any indebtedness for borrowed money or
issue or assume any note, debenture, bond or other evidences of indebtedness,
or guarantee any such indebtedness or such evidences of indebtedness of others,
other than indebtedness outstanding on the date hereof or as described on
Exhibit B attached hereto, and other than borrowings from Lender:


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<PAGE>   5
     (f)  Loans. Make, or permit its Subsidiaries to make, any loans to any
Person, provided, however, that Borrower and its Subsidiaries shall be
permitted to make: (i) an existing loan in the amount of approximately $1
million secured by a mortgage on certain real estate, (ii) loans to Japanese
customers of the Borrower and its Subsidiaries in amounts equal to not more
than the amounts of the invoices for sales by Borrower or its Subsidiaries of
products or services to such customers, (iii) inter-company loans among the
entities within Borrower's consolidated group, and (iv) loans to employees that
do not exceed $400,000 in the aggregate; or

     (g)  Dividends. declare or pay, or permit any of its Subsidiaries to
declare or pay, any dividends on any shares of its capital stock, make, or
permit any of its Subsidiaries to make, any other distributions with respect to
any payment on account of the purchase, redemption, or other acquisition or
retirement of any shares of its capital stock, or make, or permit any of its
Subsidiaries to make, any other distribution, sale, transfer or lease of any of
assets, in each case other than to Borrower and other than in the ordinary
course of business, unless any such amounts are directly utilized for the
payment of principal or interest on indebtedness and obligations owing from
time to time by Borrower to Lender.

     8.   Debt Service Coverage Ratio. Unit (i) all obligations of Borrower to
Lender under the Loans have been fully paid and satisfied, and (ii) the Lender
has no further commitment to lend hereunder, Borrower will maintain, on a
consolidated basis, as of the last day of each fiscal quarter, a ratio of (a)
net income before interest, taxes, depreciation, and amortization (EBITDA)
(determined in accordance with GAAP) for the 12 month period ending with such
fiscal quarter, to (b) short term debt, long-term debt, and long-term capital
lease obligations, of not less than 3.0 to 1.0.

     9.   Reporting Requirements. Until (i) the Note and all other obligations
and liabilities of Borrower under the Loan Documents are fully paid and
satisfied, and (ii) the Lender has no further commitment to lend hereunder,
Borrower will, unless Lender shall otherwise consent in writing, furnish to
Lender:

     (a)  Interim Financial Statements. as soon as available, and in any event
within forty-five (45) days after the end of each quarter of each fiscal year
of Borrower, a balance sheet and income statement of Borrower and its
consolidated Subsidiaries as of the end of such fiscal quarter, all in form and
substance and in reasonable detail satisfactory to Lender and duly certified
(subject to year-end review adjustments) by the President and/or Chief
Financial Officer of Borrower (i) as being true and correct in all material
aspects to the best of his or her knowledge and (ii) as having been prepared in
accordance with GAAP;

     (b)  Annual Financial Statements. as soon as available and in any event
within ninety (90) days after the end of each fiscal year of Borrower,
beginning with the fiscal year ending December 31, 2000, a balance sheet and
income statement of Borrower and its consolidated Subsidiaries as of the end of
such fiscal year, in each case audited by independent public accountants of
recognized standing acceptable to Lender;

     (c)  Compliance Certificate. a certificate signed by Borrower's President
or Vice President, Finance, within forty-five (45) days after the end of each
quarter of each fiscal year, stating that Borrower is in full compliance with
all of its obligations under the Loan Documents and is not in default of any
term or provisions hereof or thereof, and including the calculation
demonstrating compliance with all financial ratios and covenants set forth in
this Loan Agreement, including the debt service coverage ratio set forth in
Section 8 hereof;


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      (d)   Tax Returns. Copies of Borrower's income tax returns (federal and
state, if any) within thirty (30) days after filing; and

      (e)   Other. For so long as Borrower remains a Subsidiary of Lender, such
other information as Lender may require to permit Lender to satisfy any
reporting requirements imposed on Lender.

      10.   Events of Default.

      (a)   Each of the following shall constitute an "EVENT OF DEFAULT" under
this Loan Agreement:

      (i)   the failure, refusal or neglect of Borrower to pay within five (5)
business days of the date when due any part of the principal of, or interest
on, the Note or any other indebtedness owing to Lender by Borrower from time to
time, and the failure of Borrower to timely and properly observe, keep or
perform any of the covenants or agreements in Sections 6(g), (h), (i) and (j),
Section 7, or Section 9 hereof;

      (ii)  the failure of Borrower to timely and properly observe, keep or
perform any covenant, agreement, warranty or condition required in any of the
Loan Documents (other than the covenants and agreements identified in Section
10(a)(i) of this Loan Agreement as to which no notice by Lender is required) if
not cured within ten (10) days after written notice from Lender specifying such
default;

      (iii) the occurrence of an event of default under any material agreement
or any obligation of Borrower to Lender with respect to borrowed funds now
existing or hereafter arising between Lender and Borrower or its Subsidiaries
after the giving of any required notice and expiration of any applicable cure
period;

      (iv)  any representation by Borrower in any of the Loan Documents is
false or misleading in any material respect when made;

      (v)   the occurrence of any event which permits the acceleration of the
maturity of any indebtedness owing by Borrower or any of its Subsidiaries to
any third party under any agreement or understanding;

      (vi)  if Borrower or any of its Subsidiaries: (A) becomes insolvent, or
makes a transfer in fraud of creditors, or makes an assignment for the benefit
of creditors, or admits in writing its inability to pay its debts as they
become due; (B) generally is not paying its debts as such debts become due; (C)
has a receiver, trustee or custodian appointed for, or take possession of, all
or substantially all of the assets of such party, either in proceeding brought
by such party or in a proceeding brought against such party and (in a
proceeding brought against such party) such appointment is not discharged or
such possession is not terminated within sixty (60) days after the effective
date thereof or such party consents to or acquiesces in such appointment or
possession; (D) files a petition for relief under the United States Bankruptcy
Code or any other present or future federal or state insolvency, bankruptcy or
similar laws (all of the foregoing hereinafter collectively called "APPLICABLE
BANKRUPTCY LAW") or an involuntary petition for relief is filed against such
party under any Applicable Bankruptcy Law and such involuntary petition is not
dismissed within sixty (60) days after the filing thereof, or an order for
relief naming such party is entered under any Applicable Bankruptcy Law, or any
composition, rearrangement, extension, reorganization or other relief of
debtors now or hereafter existing is proposed, requested or consented to by
such party; (E) fails to have discharged within a period of thirty (30) days
any attachment, sequestration or similar writ levied upon any property of such
party; or (F) fails to pay within thirty (30) days any final money judgment
against such party;



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<PAGE>   7

     (vii) the liquidation, dissolution, merger or consolidation of Borrower or
any of its Subsidiaries; and

     (viii) the entry of any judgment against Borrower or any of its
Subsidiaries or the issuance or entry of any attachment or other lien against
any of the property of Borrower or any of its Subsidiaries for an amount in
excess of $1 million, if undischarged, unbounded or undismissed within thirty
(30) days after such entry.

     (b) Nothing contained in this Loan Agreement shall be construed to limit
the Events of Default enumerated in any of the other Loan Documents and all
such Events of Default shall be cumulative.

     11. Remedies. Upon the occurrence of any one or more of the foregoing
Events of Default, (a) the entire unpaid balance of principal of the Note,
together with all accrued but unpaid interest thereon, and all other
indebtedness owing to Lender by Borrower at such time shall, at the option of
Lender, become immediately due and payable without further notice, demand,
presentation, notice of dishonor, notice of intent to accelerate, notice of
acceleration, protest or notice of protest of any kind, all of which are
expressly waived by Borrower, and (b) Lender may, at its option, cease further
advances under any of the Note. All rights and remedies of Lender set forth in
this Loan Agreement and in any of the other Loan Documents may also be
exercised by Lender, at its option to be exercised in its sole discretion, upon
the occurrence of an Event of Default.

     12. Certain Definitions. As used in this Loan Agreement, all exhibits and
schedules hereto, and all other Loan Documents entered into or delivered under
this Loan Agreement, the following terms shall have the meaning assigned to
them in this Section 12, or in the Section or recital of this Loan Agreement
referred to below, or in the other Loan Documents referred to below:

     "AFFILIATE" means any individual or entity directly or indirectly
Controlling, Controlled by, or under common Control with, another individual or
entity.

     "APPLICABLE BANKRUPTCY LAW" has the meaning set forth in Section 10(a)(vi)
hereof.

     "BORROWER" has the meaning set forth in the introductory recital on the
first page hereof.

     "BUSINESS DAY" has the meaning set forth in the Note.

     "CONTROL" shall mean the possession, directly or indirectly, of the power
to direct or cause the direction of the management or policies of a Person,
whether through the ownership of stock or other equity interests, by contract,
or otherwise, and "CONTROLLING" and "CONTROLLED" shall have meanings
correlative thereto.

     "EVENT OF DEFAULT" has the meaning set forth in Section 10(a) hereof.

     "GAAP" means those generally accepted accounting principles and practices,
applied on a consistent basis, which are recognized as such by the American
Institute of Certified Public Accountants acting through its Accounting
Principles Board and the Financial Accounting Standards Board and/or their
respective successors and which are applicable in the circumstances as of the
date in question.


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<PAGE>   8
     "LIABILITIES" means (without duplication), with respect to any Person, all
indebtedness, obligations, and liabilities of such Person, including without
limitation (a) all "liabilities" which would be reflected on a balance sheet of
such Person, (b) all obligations of such Person in respect of any guaranty,
letter of credit, or bankers' acceptance, (c) all obligations of such Person in
respect of any capital lease, (d) all obligations, indebtedness, and
liabilities secured by any lien or any security interest on any property or
assets of such Person, and (e) any obligation to redeem or repurchase any of
such Person's stock.

     "LIEN" means any lien, mortgage, security interest, tax lien, pledge,
encumbrance, conditional sale or title retention arrangement, or any other
interest in property designed to secure the repayment of Liabilities, whether
arising by agreement or under any statute or law, or otherwise.

     "LOAN AGREEMENT" has the meaning set forth in the introductory recital on
the first page hereof.

     "LOAN DOCUMENTS" has the meaning set forth in Section 2 hereof.

     "LOANS," collectively, shall mean all advances under the Revolving Line of
Credit.

     "NOTE" has the meaning set forth in Section 3(a).

     "OBLIGATIONS" means all present and future indebtedness, obligations, and
Liabilities and all renewals and extensions thereof, or any part thereof, now
or hereafter owed to Lender by Borrower, whether arising pursuant to any of the
Loan Documents, or otherwise, and all renewals and extensions thereof, together
with all interest accruing thereon and costs, expenses, and attorneys' fees
incurred in the enforcement or collection thereof.

     "PERMITTED LIENS" means (a) Liens in favor of Lender to secure the
Obligations, (b) pledges or deposits made to secure payment of worker's
compensation (or to participate in any fund in connection with worker's
compensation), unemployment insurance, pensions, or social security programs,
(c) Liens imposed by mandatory provisions of law such as for materialmen's,
mechanic's, warehousemen's, and other like Liens arising in the ordinary course
of a Company's business, securing indebtedness whose payment is not yet due,
(d) Liens for taxes imposed upon a Person or upon such Person's income,
profits, or property, if the same are not yet due and payable or if the same
are being contested in good faith and as to which adequate reserves are
maintained in accordance with GAAP, (e) good faith deposits in connection with
leases, real estate bids or contracts (other than contracts involving the
borrowing of money), pledges or deposits to secure (or in lieu of) surety,
stay, appeal, or customs bonds and deposits to secure the payment of taxes,
assessments, customs, duties, or other similar charges, (f) encumbrances
consisting of zoning restrictions, easements, or other restrictions on the use
of real property, provided that such encumbrances do not impair the use of such
property for the uses intended, and none of which is violated by existing or
proposed structures or land use, and (g) liens described on Exhibit B attached
hereto.

     "PERSON" shall include an individual, corporation, joint venture, general
or limited partnership, trust, unincorporated organization, or government, or
any agency or political subdivision thereof.

     "POTENTIAL DEFAULT" means the occurrence of any event or existence of any
circumstance which, with the giving of notice or lapse of time, or both, would
become an Event of Default.

     "REVOLVING LINE OF CREDIT" has the meaning set forth in Section 2(a)
hereof.


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<PAGE>   9

     "REVOLVING LOAN COMMITMENT" shall mean the lesser of (i) $20 million, or
(ii) the Revolving Loan Commitment, as the same is reduced under Section 2(c)
hereof.

     "SUBSIDIARY" or "SUBSIDIARIES" means, with respect to any Person (herein
referred to as the "PARENT"), any corporation, partnership, limited liability
company, association, or other business entity (a) of which stock or other
equity interests representing more than fifty percent (50%) of the equity or
more than fifty percent (50%) of the ordinary voting power or more than fifty
percent (50%) of the general partnership interests are, at the time any
determination is being made, owned, Controlled, or held, or (b) which is, at
the time any determination is made, otherwise Controlled, by the parent or one
or more subsidiaries of the parent or by the parent and one or more
subsidiaries of the parent.

     "TERMINATION DATE" means the earlier of: (a) the date on which all of the
Borrower's obligations under the Loans have been paid or satisfied, or (b) the
effective date of any other termination or cancellation of Lender's commitments
to lend under, and in accordance with, this Loan Agreement.

     13. Rights Cumulative. All rights of Lender under the terms of this Loan
Agreement shall be cumulative of, and in addition to, the rights of Lender
under any and all other agreements between Borrower and Lender (including, but
not limited to, the other Loan Documents), and not in substitution or
diminution of any rights now or hereafter held by Lender under the terms of any
other agreement.

     14. Waiver and Agreement. Neither the failure nor any delay on the part of
Lender to exercise any right, power or privilege herein or under any of the
Loan Documents shall operate as a waiver thereof, nor shall any single or
partial exercise of such right, power or privilege preclude any other or
further exercise thereof or the exercise of any other right, power or
privilege. No waiver of any provision in this Loan Agreement or in any of the
other Loan Documents and no departure by Borrower therefrom shall be effective
unless the same shall be in writing and signed by Lender, and then shall be
effective only in the specific instance and for the purpose for which given and
to the extent specified in such writing. No modification or amendment to any of
the Loan Documents shall be valid or effective unless the same is signed by the
party against whom it is sought to be enforced.

     15. Benefits. This Loan Agreement shall be binding upon and inure to the
benefit of Lender and Borrower, and their respective successors and assigns,
provided, however, that Borrower may not, without the prior written consent of
Lender, assign any rights, powers, duties or obligations under any of the Loan
Documents.

     16. Notices. All notices, requests, demands or other communications
required or permitted to be given pursuant to the Loan Documents shall be in
writing and given to the Treasurer of the other party by (i) personal delivery,
(ii) expedited delivery service with proof of delivery, or (iii) United States
mail, postage prepaid, registered or certified mail, return receipt requested,
sent to the intended addressee at the address set forth on the first page
hereof and shall be deemed to have been received either, in the case of
personal delivery, as of the time of personal delivery, or in the case of other
delivery service, as of the date of first attempted delivery at the address and
in the manner provided herein. Either party shall have the right to change its
address for notice hereunder to any other location within the continental
United States by notice to the other party of such new address at least thirty
(30) days prior to the effective date of such new address.

     17. Construction. The Loan Documents have been executed and delivered in
the Commonwealth of Massachusetts, shall be governed by and construed in
accordance with the laws of


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<PAGE>   10
the Commonwealth of Massachusetts,and shall be performable by the parties
hereto in the county in the Commonwealth of Massachusetts where the Lender's
address set forth on the first page hereof is located.

      18.   Invalid Provisions. If any provision of the Loan Document is held
to be illegal, invalid or unenforceable under present or future laws, such
provision shall be fully severable and the remaining provisions of the Loan
Documents shall remain in full force and effect and shall not be affected by
the illegal, invalid or unenforceable provision or by its severance.

      19.   Expenses. Borrower shall pay all costs and expenses (including,
without limitation, reasonable attorneys' fees) in connection with any action
in the enforcement of Lender's rights upon the occurrence of Event of Default.

      20.   Conflicts. In the event any term or provision hereof is
inconsistent with or conflicts with any provision of the other Loan Documents,
the terms and provisions contained in this Loan Agreement shall be controlling.

      21.   Counterparts. This Loan Agreement may be separately executed in any
number of counterparts, each of which shall be an original, but all of which,
taken together, shall be deemed to constitute one and the same instrument.

      22.   Facsimile Documents and Signatures. For purposes of negotiating and
finalizing this Loan Agreement, if this document or any document executed in
connection with it is transmitted by facsimile machine, it shall be treated for
all purposes as an original document. Additionally, the signature of any party
on this document transmitted by way of facsimile machine shall be considered
for all purposes as an original signature. Any such document transmitted by
facsimile machine shall be considered to have the same binding legal effect as
an original document. At the request of any party, any document sent by
facsimile machine shall be re-executed by each signatory party in an original
form.

      THIS WRITTEN AGREEMENT REPRESENTS THE FINAL AGREEMENT BETWEEN THE PARTIES
AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR
SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL
AGREEMENTS BETWEEN THE PARTIES.

      IN WITNESS WHEREOF, the parties hereto have executed this Agreement as a
document under seal as of the date first written above.

SPECTRA-PHYSICS LASERS, INC.              THERMO ELECTRON CORPORATION


By:   /s/ SETH HALIO                      By:   /s/ THEO MELAS-KYRIAZI
   -----------------------------------       ----------------------------------
   Name:  Seth Halio                         Name:  Theo Melas-Kyriazi
   Title: Vice President-Finance             Title: Vice President and Chief
          Spectra-Physics Lasers, Inc.              Financial Officer
                                                    Thermo Electron Corporation



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<PAGE>   11
                                   EXHIBIT A

                             FORM OF REVOLVING NOTE

                           REVOLVING PROMISSORY NOTE

                                                                  March __, 2001

     FOR VALUE RECEIVED, the undersigned Spectra-Physics Lasers, Inc., a
Delaware corporation having its principal place of business at 1335 Terra
Bella Ave., Mountain View, CA 94030 (the "Borrower"), promises to pay to the
order of Thermo Electron Corporation, a Delaware corporation having its
principal place of business at 81 Wyman Street, Waltham, MA 02454-9046 (the
"Lender"), as described herein, the principal sum of Twenty Million Dollars
($20,000,000) or so much thereof as shall have been advanced to the Borrower
pursuant to the Revolving Line of Credit under the Loan Agreement dated as of
the date hereof by and between Borrower and Lender (the "Loan Agreement"), or
such part thereof as then remains unpaid, and to pay interest from the date
hereof on the whole amount of said principal sum remaining from time to time
unpaid at a rate per annum equal to the rate of the London interbank borrowing
rate (LIBOR) for 90-day maturities as reported in The Wall Street Journal (or
if not reported in The Wall Street Journal, as reported by Telerate) on the
first business day of each fiscal quarter of the Lender plus two hundred
seventy-five (275) basis points (the "Applicable Rate"), which rate shall be
adjusted as of the first business day of each fiscal quarter of the Lender
during the term of the Loan Agreement and shall be in effect for the entirety
of such fiscal quarter.

     Interest only on the unpaid principal from time to time outstanding
hereunder shall be paid quarterly in arrears on the last business day of each
fiscal quarter of the Lender during the one-year period following the date
hereof. The outstanding principal amount of this Note together with all accrued
and unpaid interest shall be due and payable on the first anniversary of the
date hereof.

     Interest shall be computed on an actual 360-day basis. Principal and
interest shall be payable in lawful money of the United States of America, in
immediately available funds, at the principal office of the Lender or at such
other place as the holder may designate from time to time in writing to the
Borrower.

     This Note may be prepaid at any time in whole or in part at any time
without premium, penalty or prior notice. Overdue principal and interest shall
bear interest at a rate per annum equal to the Applicable Rate plus two percent
(2%).

     The Borrower hereby waives presentment, demand, notice of nonpayment and
protest.

     The then unpaid principal amount of, and interest outstanding on, this
Note shall be and become immediately due and payable without notice or demand,
at the option of the holder hereof, upon the occurrence of any Event of Default
as that term is defined in the Loan Agreement. No failure by the Lender to take
action with respect to any Event of Default shall affect its subsequent rights
to take action with respect to the same or any other Event of Default. In the
event of an Event of Default the Borrower agrees to pay all reasonable costs of
collection, including reasonable attorney's fees, to the extent allowed by law.
No delay or omission on the part of the Lender in exercising any right
hereunder shall operate as a waiver of such right or any other right. A waiver
of any right on any one or more occasion shall not operate as a bar or waiver
of any right on any future occasion.

     This Note shall be governed by and construed in accordance with the laws
(other than the conflict of laws rules) of the Commonwealth of Massachusetts.
In the event of any conflict between the terms of this Note and the terms of
the Loan Agreement, the terms of the Loan Agreement shall prevail.


                                       11


<PAGE>   12
     IN WITNESS WHEREOF, the undersigned has caused this Note to be executed
under seal by its duly authorized officer.

SPECTRA-PHYSICS LASERS, INC.

By: /s/ SETH HALIO
   ---------------------------
   Name:  Seth Halio
   Title: VP - Finance



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<PAGE>   13
                                   EXHIBIT B

                        PERMITTED INDEBTEDNESS AND LIENS
                        --------------------------------

1.   Indebtedness under loan agreements between Spectra-Physics Lasers, Inc.
     and third party creditors which agreements exist on the date hereof and
     copies of which have been provided to Lender, and any extensions or
     renewals of such agreements or substitutions of alternate arrangements
     with other lenders, provided that such extensions, renewals, or
     substitutions provide for indebtedness in amounts no greater than the
     amounts covered by the agreements they replace and are on terms and
     conditions no less favorable to Borrower and its Subsidiaries than those
     they replace.

2.   Indebtedness and liens relating to operating leases.

3.   Liens for purchase money security interests.

4.   Inter-company indebtedness in non-material amounts among the Borrower and
     its Subsidiaries.



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