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                                                                    EXHIBIT 10.1



                              EMPLOYMENT AGREEMENT


THIS EMPLOYMENT AGREEMENT (herein "Agreement") is entered into as of April 20,
2000, by and between JMAR Technologies, Inc. ("JMAR") of 3956 Sorrento Valley
Blvd., San Diego, CA 92121 and John H. Carosella ("Carosella"), 876 Spartan
Drive, Rochester Hills, MI 48309.

                                    Recitals

WHEREAS, JMAR is a leading developer and producer of microtechnology equipment
and integrated circuits for the semiconductor, biomedical and telecommunications
industries with strong emphasis on advanced X-ray source and system technology;

WHEREAS, JMAR desires to retain the services of Carosella; and

WHEREAS, Carosella desires to be employed by JMAR.

NOW, THEREFORE, JMAR and Carosella agree as follows:

1.      Employment/Title/Responsibilities. Carosella shall be employed as Senior
        Vice President, Corporate Development and Director of the Advanced Light
        Business Area, reporting directly to the CEO of JMAR. Carosella's
        primary responsibilities shall be to assist JMAR's CEO in establishing
        and implementing a program to create a viable commercial business based
        on JMAR's "light technology". It is expected that Carosella's efforts
        will lead to the formation of a new subsidiary division of JMAR that
        could provide the basis for a separately capitalized, profitable,
        publicly-owned corporation. Carosella will be a leading candidate to
        manage such an organization, subject to future events and Carosella's
        desire to accept such an assignment. During the period of Carosella's
        indoctrination into JMAR he may also be assigned additional corporate
        level business development responsibilities commensurate with those
        assigned to JMAR's most senior executives. Such assignments could
        include: Preparation of business plans for new ventures; identification
        and negotiation of new joint ventures, alliances, acquisitions, etc.;
        advising or managing elements of JMAR's existing advanced light business
        activities; and such other services and duties as may be assigned to him
        from time-to-time. Although his position may require a reasonable amount
        of travel, Carosella will be provided with an office in JMAR's corporate
        headquarters currently located in the San Diego, CA area.

2.      Compensation/Benefits/Review. As compensation for the services provided
        by Carosella under this Agreement, JMAR will pay him an annual salary of
        $140,000 (base pay), payable in accordance with JMAR's usual payroll
        procedures. Carosella will receive all standard JMAR benefits as
        described in the enclosed summary of benefits, except that his vacation
        accrual plan will be modified such


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        that his benefits will be equivalent to those attained by JMAR employees
        upon completion of five years of employment at JMAR.

3.      Initial Stock Options/Future Stock Options. Upon the commencement of
        Carosella's employment, JMAR shall grant him Incentive Stock Options
        (ISO's) to purchase 25,000 shares of JMAR common stock pursuant to the
        terms of JMAR's 1999 Employee Stock Option Plan, a copy of which is
        delivered herewith. The ISO's will vest in equal amounts at the end of
        each of the first three years after the start date of Carosella's
        employment and the exercise price of the ISO's will be equal to the
        average closing prices of JMAR Common Stock for the five trading days
        prior to the date of the grant. The other terms of the options shall be
        contained in JMAR's standard stock option agreement, which shall also
        contain a provision that immediately vests all options granted to
        Carosella in the event that a third party should acquire a controlling
        interest in JMAR.

4.      Signing Bonus. JMAR shall pay Carosella a $30,000 signing bonus (the
        "Signing Bonus") in consideration for Carosella starting employment no
        later than June 5, 2000. The Signing Bonus is payable in cash or JMAR
        shares of common stock, at Carosella's election. In the event this
        Agreement is terminated prior to June 5, 2001 by JMAR pursuant to
        paragraph 7.2 or by Carosella for any reason other than pursuant to
        paragraph 7.3, then Carosella shall refund to JMAR that portion of the
        Signing Bonus which is equal to the product of $2500.00 multiplied by
        the number of calendar months remaining after said termination until
        June 5, 2001.

        As set forth in paragraph 1, above, Carosella's primary goal will be to
        create a viable advanced light commercial business with the intent of
        establishing a profitable, publicly-owned corporation. To help motivate
        employees who will be key to the success of that venture, JMAR plans to
        establish an additional incentive plan based on equity in that new
        entity. It is expected that Carosella in his capacity as Director of the
        Advanced Light Business Area, will have an opportunity to acquire a
        significant equity interest in the new venture, consistent with his
        contributions to its creation.

5.      Performance Bonus Plan. JMAR shall provide to Carosella an annual
        executive bonus plan that, based upon JMAR's consolidated performance,
        has the potential of paying him up to an additional 50% of his annual
        salary. Carosella's incentive goals for the remainder of year 2000 will
        be agreed upon during his first month of employment. Two-thirds of
        Carosella's signing bonus ($20,000) shall be credited toward any bonus
        payment for his year 2000 performance.

6.      Relocation Benefits/House-hunting/Temporary Living Expenses. JMAR will
        reimburse Carosella for reasonable, actual expenses involved in moving
        his residence from the present location in Michigan to the San Diego
        area pursuant to JMAR's standard Relocation Policy, including the cost
        of such house-hunting trips for Carosella and his family, as are
        necessary; provided, however, that the


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        total costs reimbursable under this Section 6 shall not exceed a total
        of $35K. JMAR will also reimburse Carosella for up to three months
        temporary living expense during the relocation process. These expenses
        may include but are not limited to airfare, car rental and hotel/motel.

7.      Employment at Will; Salary Continuation Payments.

        7.1    Carosella's employment will be "at-will" and may be terminated at
               any time, for any reason, by either Carosella or JMAR. If JMAR
               terminates Carosella for any reason other than pursuant to
               Paragraph 7.2 below within Carosella's first six months of
               employment, Carosella shall be entitled to receive an amount
               ("Salary Continuation Payments") equal to twelve (12) months
               salary (subject to earlier termination upon the occurrence of an
               event specified in Paragraph 7.2), payable commencing on the date
               of such termination at the rate and times as such compensation
               would have been payable to Carosella had this Agreement not been
               terminated pursuant to this Paragraph 7.1. If such termination
               occurs any time after six months, Carosella will be entitled to
               receive an amount equal to six (6) months salary, payable in the
               same manner as described above. In addition to the payment of
               such Salary Continuation Payments, JMAR shall, at its expense,
               continue coverage under those insurance policies in which
               Carosella participates for which COBRA coverage is available for
               the period during which the Salary Continuation Payments are made
               (the "Continued Insurance Coverage").

        7.2    Notwithstanding the provisions of Paragraph 7.1 above, this
               Agreement shall terminate (without any right to Salary
               Continuation Payments or Continued Insurance Coverage) upon the
               occurrence of any of the following events: (a) the death of
               Carosella; (b) the incapacity or disability of Carosella, which
               renders him unable to perform substantially all of the services
               contemplated by this Agreement for a continuous period of sixty
               (60) days; (c) the commission of an act of fraud, dishonesty in a
               matter which is material to his employment, or embezzlement by
               Carosella; (d) the willful neglect by Carosella in the
               performance of the services contemplated by this Agreement in
               such manner as to provide reasonable cause for terminating his
               services; or (e) the substantial breach by Carosella of any of
               the covenants or obligations under this Agreement and such breach
               provides reasonable cause for JMAR to terminate this Agreement;
               provided that, in order to terminate this Agreement pursuant to
               clauses (d) and (e) of this Paragraph 7.2, JMAR shall have given
               thirty (30) days written notice of termination to Carosella and
               Carosella shall have failed to fully cure or correct such willful
               neglect or breach within the thirty days immediately following
               such notice.

        7.3    This Agreement may be terminated by Carosella on thirty (30) days
               written notice of termination to JMAR if JMAR breaches any of its
               covenants or


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               obligations under the Agreement and such breach provides
               reasonable cause for Carosella to terminate this Agreement. In
               such event, Carosella shall also be entitled to the Salary
               Continuation Payments and Continued Insurance Coverage in the
               manner provided in Paragraph 7.1 above; provided that, in order
               to terminate this Agreement pursuant to this provision, JMAR
               shall have failed to fully cure or correct such breach within the
               thirty days immediately following such notice.

8.      Reimbursement for Expenses/Use of Employer Property. JMAR will reimburse
        Carosella for all reasonable expenses incurred by him on the business of
        JMAR in accordance with JMAR policies in effect from time-to-time. JMAR
        will provide to Carosella the necessary equipment and materials to
        accomplish his employment responsibilities, and will also provide him
        with a monthly auto allowance of $400.00 to reimburse him for use of his
        personal auto for business travel.

9.      Travel/Requirements. Carosella will be required to travel from time to
        time not averaging more than 50% of his time for JMAR in the normal
        course of business. On domestic USA trips Carosella will travel coach
        class. On all international trips Carosella may travel business class.
        For all auto rentals Carosella will rent appropriate size vehicles.

10.     Retirement Plan. Carosella shall be able to participate in JMAR's 401(k)
        retirement plan in accordance with the plan's terms and the requirement
        of law.

11.     Confidential Information. Concurrently herewith, Carosella shall enter
        into an Employee Confidentiality and Inventions Agreement with JMAR in
        the form provided to Carosella.

12.     No Violation of Other Contracts. Carosella represents and warrants that
        the execution, delivery and performance of this Agreement by Carosella
        does not and will not result in a breach of or violation of, or
        constitute a default under, any agreement to which Carosella is a party
        or by which Carosella is bound.

13.     No Conflicts of Interest. Except as set forth on Schedule 1, hereto,
        Carosella does not have any financial interest, whether by stock
        ownership or otherwise, in any entity which is a supplier, customer or
        competitor of JMAR.

14.     Compliance with JMAR's Rules. Carosella agrees to comply with all of the
        rules, regulations and standard practices of JMAR as in effect from time
        to time. JMAR will provide Carosella with all such current rules,
        regulations and standard practices and all future updates.

15.     General Provisions.


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        15.1 Assignment. Neither the rights nor obligations under this Agreement
        may be assigned, transferred, pledged or hypothecated by any party
        hereto, except that this Agreement shall be binding upon and inure to
        the benefit of any successor of JMAR.

        15.2 Notices. Any notice required or permitted to be given under this
        Agreement shall be deemed to have been duly given if in writing and if
        personally delivered or sent by registered or certified mail, return
        receipt requested, with postage prepaid:

                      if to JMAR:

                      JMAR Technologies, Inc.
                      3956 Sorrento Valley Blvd.
                      San Diego, CA 92121
                      Attn: Joseph G. Martinez, Esq., General Counsel
                      If to the Employee:

                      John H. Carosella
                      876 Spartan Drive
                      Rochester Hills, MI 48309

        Any party may change the address to which notices are to be sent to it
        or him by giving ten days' written notice of such change of address to
        the other party in the manner above provided for giving notice. Notices
        will be considered delivered on the date of personal delivery or on the
        date of deposit in the United States mail in the manner above provided
        for giving notice by mail.

        15.3 Arbitration. Any controversy or claim arising out of or relating to
        this Agreement, or the breach thereof, shall be settled by arbitration
        at San Diego, California, in accordance with the Commercial Arbitration
        Rules of the American Arbitration Association, and judgment upon the
        award of the arbitrator(s) shall be entered in any court with
        appropriate jurisdiction as the final binding judgment. The provisions
        of California Code of Civil Procedure Section 1283.05 (related to the
        availability of certain discovery procedures) are hereby incorporated
        into and made applicable to this Agreement. In addition to any other
        relief as may be granted, the prevailing party shall be entitled to
        reasonable attorneys' fees in such arbitration, with the amount thereof
        to be determined by the arbitrator or the court.

        15.4 Counterparts. This Agreement may be executed in several
        counterparts, and all counterparts so executed shall constitute one
        agreement binding on all of the parties hereto notwithstanding that all
        parties are not signatory to the original or same counterpart.


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        15.5 Entire Agreement. This Agreement constitutes the entire agreement
        and understanding between Carosella and JMAR with respect to the
        employment of Carosella, and supersedes all other agreements, written or
        oral, regarding such employment. This Agreement may be altered or
        amended only by a written instrument executed by each of the parties
        hereto.

        15.6 Severability. If any provision of this Agreement or the application
        thereof to any person or circumstance shall be invalid or unenforceable
        to any extent, the remainder of this Agreement and the application of
        such provisions to other persons or circumstances shall not be affected
        thereby and shall be enforced to the greatest extent permitted by law.

        15.7 Interpretation of Agreement. In the event of any arbitration or
        other dispute, neither this Agreement nor any provision hereof shall be
        interpreted for or against any party on the basis said party or its
        attorney drafted the Agreement or provision in question.

        15.8 Waiver. The waiver by any party hereto of a breach of any of the
        provisions of this Agreement by the other party shall not operate or be
        construed as a waiver of any subsequent breach hereof by such party.

        15.9 California Law. This Agreement shall be governed by and considered
        in accordance with the laws of the State of California.

        15.10 Headings. The subject headings of the Sections of this Agreement
        are included for the purposes of convenience only and shall not affect
        the construction or interpretation of any term or provision hereof.

        15.11 Disclosure. Subject to JMAR's disclosure obligations under
        applicable laws, JMAR and Carosella agree not to publicly disclose the
        terms of this Agreement without each other's prior consent which will
        not be unreasonably withheld.

AGREED TO AND ACCEPTED BY:

Employer:                               Employee:

JMAR TECHNOLOGIES, INC.

By: /s/ JOHN S. MARTINEZ                /s/ JOHN H. CAROSELLA
    --------------------------          ----------------------------
    John S. Martinez, CEO               John H. Carosella




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