<PAGE>   1
                              EMPLOYMENT AGREEMENT
                              --------------------



This Agreement is made as of September 26, 1996 by and between American Science
and Engineering, Inc. (the "Company"), a Massachusetts corporation having its
principal place of business in Billerica, Massachusetts, and Ralph S. Sheridan
(the "Executive").

The Company desires to retain the services of the Executive, and the Executive
is willing to render such services in accordance with the terms hereinafter set
forth.

The Board of Directors of the Company (the "Board") has by appropriate
resolutions authorized the employment of the Executive as provided for in this
Agreement.

Accordingly, the Company and the Executive agree:

                                    ARTICLE I

1.1 TERM.
    ----
The term of this Agreement shall begin as of September 25, 1996 (the    
"Effective Date") and shall extend until September 25, 1999, unless earlier
terminated pursuant to Article V (the "Term"). The Executive's employment under
this Agreement may be extended or renewed solely by means of a written
agreement signed by the Executive and a representative of the Company expressly
authorized by the Board.

                                   ARTICLE II

2.1 PRESIDENT AND CHIEF EXECUTIVE OFFICER.
    -------------------------------------
The Executive shall be the President and the Chief Executive Officer of the
Company, shall report solely and directly to the Board on all matters relating
to the Executive's performance of his duties, and shall perform such duties and
responsibilities on behalf of the Company and its subsidiaries as may be
designated from time to time by the Board.

The Executive shall devote his full business time and his best efforts, business
judgment, skill and knowledge exclusively to the advancement of the business and
interests of the Company and its subsidiaries and to the discharge of his duties
and responsibilities hereunder. The Executive will use his best judgment not to
accept any outside responsibilities that will jeopardize his ability to fulfill
his responsibilities as President and Chief Executive Officer of the Company.

One or more members of the Compensation Committee of the Board shall meet with
the Executive at least annually during the Term, shall review with him the
Company's performance to date, shall discuss his management accomplishments as
well as any areas requiring improvement, and shall review his base compensation
as provided in Section 3.1.

2.2 DIRECTOR.
    --------
Subject to the vote of the stockholders at subsequent annual meetings, the
Executive shall continue to serve as a Director of the Company during the term
of this Agreement.

                                      -10-

<PAGE>   2


                                   ARTICLE III


3.1 BASE SALARY.
    -----------
For services rendered by the Executive under this Agreement during the Term,
the Company shall pay or cause to be paid to the Executive, in accordance       
with the Company's normal payroll practices for senior executives of the        
Company, base salary ("Base Salary") for the initial year of employment at the
annual rate of $240,000. The Base Salary will be formally reviewed on an annual
basis by the Compensation Committee and increased in the ensuing years if the
Committee determines that an increase is warranted.

3.2 BONUSES.
    -------
In addition to Base Salary, the Executive shall be paid an annual bonus not to
exceed $230,000 annually, which bonus will be established by the Compensation 
Committee (the "Bonus"). Promptly following the execution of this Employment 
Agreement, the Company and the Executive will meet to establish the 
performance goals upon which the award of the Bonus for the first year of
employment pursuant to this Employment Agreement (the "First Bonus Period")
will be determined. Seventy-five percent of the Bonus will be based upon an
agreed-upon pre-tax income goal plus the amount expended by the Company in such 
year for research and development ("Target Income"). Target Income will be
adjusted each year by the mutual consent of the Compensation Committee and the
Executive. Twenty-five percent of the Bonus will be based on personal
performance goals which will be established annually by the Compensation
Committee and the Executive promptly after the execution of this Employment
Agreement and revised on an annual basis in each subsequent year of this
Employment Agreement. During each subsequent year of employment pursuant to the
terms of this Employment Agreement ("Subsequent Bonus Periods"), the Chairman
of the Board and the Executive shall meet periodically to discuss the
Executive's progress concerning these goals. Promptly after the end of each
such Subsequent Bonus Period, the Compensation Committee shall meet to discuss
the Executive's performance with regard to such goals and shall, in its
discretion, determine the amount, if any, of the Bonus to be paid to the
Executive for such Subsequent Bonus Period. For the purpose of this
determination, the goals shall be laddered so that attainment of some, but not
all, goals will give rise to the payment of a partial Bonus.

3.3 STOCK OPTIONS.
    ------------- 
GRANT OF UNCONDITIONAL OPTION. The Company grants to the Executive a
non-statutory stock option (the "Unconditional Option"), in the form of the
stock option agreement attached hereto as Exhibit B, to purchase in the
aggregate 225,000 shares of the Company's Common Stock. The purchase price per
share of the 225,000 shares covered by the Unconditional Option shall be the
fair market value of the stock as of the date of the execution of the stock
option agreement granting the Unconditional Option. The option to acquire the
first seventy five thousand shares will vest on the first anniversary date of
the commencement of this Employment Agreement. The option to acquire an
additional 75,000 shares will vest on the second anniversary and a final option
to acquire 75,000 shares will vest on the third anniversary of this Employment
Agreement. The stock options shall be subject to termination only if employment
is terminated by the Company for Cause or if the Executive voluntarily requests
termination prior to September 25, 1999 for reasons other than for Good Reason.
All stock options will immediately vest if the Executive terminates employment
for Good Reason as defined in Article V 5.1(b) herein or if the Company or all
or substantially all of its assets or stock are acquired by a third party or by
merger, consolidation or otherwise.

                                      -11-

<PAGE>   3



3.4 SECURITIES ACT OF 1933. 
    ----------------------
The Company agrees to register the shares subject to the stock options  
referred to in this Article III pursuant to the Securities Act of 1933, as
promptly as practicable.



                                   ARTICLE IV

4.1 BENEFITS DURING THE TERM.                                   
    ------------------------
During the Term, the Executive will be covered by and receive benefits not
specifically dealt with in this Agreement (such as the payment provisions set
forth in Article V in the event of termination of employment, which are
intended to be exclusive) under the benefit plans and programs maintained by
the Company from time to time for its senior executives. The Executives shall
also be entitled to such other perquisites of office as are generally provided  
from time to time by the Company to its senior executive officers. The
Executive shall be reimbursed for all reasonable out-of-pocket expenses
reasonably incurred by him in the performance of his duties hereunder, upon
submission of appropriate documentation in accordance with the Company's
written policies.

4.2 AUTOMOBILE.
    ----------
The Company shall provide the Executive, at his request, with an automobile for
his use during the Term. The Company will pay for all expenses  associated with
the Executive's business use of the automobile. At the end of the Term, the
Executive shall return the automobile to the Company in substantially the same
condition as on the date he first receive it, reasonable wear and tear
excepted.



                                    ARTICLE V

5.1  TERMINATION BY THE COMPANY WITHOUT CAUSE OR BY THE EXECUTIVE FOR GOOD 
     ---------------------------------------------------------------------
     REASON.
     ------
(a) The Company may, upon written notice to the Executive, immediately terminate
the Executive's employment hereunder without Cause. For purposes of this Article
V, "Cause" shall mean:

     (i)  the Executive's willful and continuing failure to perform his duties
          in the course of his employment under this Agreement, which failure is
          not cured by the Executive within 30 days after notice specifically
          describing such failure is provided in writing by the Company to the
          Executive; or

     (ii) the conviction of the Executive for, or his plea of nolo contendere 
          to, a felony or any other crime which involves fraud, dishonesty or 
          moral turpitude.

(b) The Executive may, upon 15 days' written notice to the Company, terminate
his employment hereunder for Good Reason. For purposes of this Article V, "Good
Reason" shall mean:



                                      -12-

<PAGE>   4

      (i) the assignment of the Executive of any duties, inconsistent in any
          respect with the Executive's position as the President and Chief
          Executive Officer of the Company or any other action by the Company
          which results in a diminution in such position, authority, duties or
          responsibilities, excluding for this purpose an isolated,
          insubstantial and inadvertent action not taken in bad faith and which
          is remedied by the Company within 30 days after receipt of written
          notice thereof given by the Executive, PROVIDED, HOWEVER, that any
          change or diminution of the business of the Company or of any
          subsidiary or subsidiaries of the Company, including without
          limitation the sale or transfer of such subsidiaries, or any or all of
          their assets, shall not constitute "Good Reason";

     (ii) any failure of the Company to comply with any of the provisions of the
          Employment Agreement, other than an insubstantial failure not
          occurring in bad faith and which is remedied by the Company within 30
          days after receipt of written notice thereof given by the Executive;

    (iii) failure of the Company and the Executive, bargaining in good faith,
          to agree upon performance goals pursuant to Section 3.2(b) and an
          annual Base Salary for the second and third year of this contract;

     (iv) any failure of the Company to obtain a satisfactory agreement from any
          successor to all or substantially all of the business or assets of the
          Company to assume and agree to perform this Agreement; or

      (v) any purported termination by the Company of the Executive's employment
          otherwise than as expressly permitted by the Employment Agreement.

(c) In case of any termination of the Executive's employment hereunder without
Cause or for Good Reason (as defined above), the Company shall pay to the
Executive (or in the event of his death, his designated beneficiary or his
estate, as the case may be): (1) a sum equal to the Executive's then annual Base
Salary in cash payable at the times such sum would have been paid to the
Executive if he had remained in the employ of the Company and was entitled to
receive such sum in the form of Base Salary during the 12-month period following
his termination of employment, and (2) the amount the Executive earned in Bonus
payments and, if such termination occurs prior to September 25, 1997, the value
of any stock received in the year previous to such termination, payable at such
time such Bonus would have been paid had the Executive remained in the employ of
the Company. In addition, any unvested stock options outstanding on the date of
the Executive's termination of employment shall become vested and exercisable in
accordance with their terms. The failure of the Company to extend the term of
this Employment Agreement or any extension of this Employment Agreement for an
additional term of not less than one year on terms no less favorable to the
Company than those contained herein and if requested by the Executive shall be
deemed a termination for Good Reason requiring the Company to make the severance
and benefits to the Executive as described in this Section 5.1(c).

5.2 TERMINATION BY THE COMPANY FOR CAUSE OR BY THE EXECUTIVE OTHER THAN FOR GOOD
    ----------------------------------------------------------------------------
    REASON.
    ------
During the Term, the Company, by action of the board, may terminate the
Executive's employment hereunder for Cause by written notice to the Executive   
stating in detail the reasons for such termination.

                                      -13-

<PAGE>   5



During the Term, the Executive may, by written notice to the Board, terminate
his employment hereunder other than for Good Reason. In the event of any such
termination for Cause or other than for Good Reason (and other than by reason of
his death or disability), the Executive shall not be entitled to any unpaid
bonus that may have been earned through such date, nor shall he be entitled to
exercise the Unconditional Option which have not been vested.



5.3  TERMINATION FOR DISABILITY.
     --------------------------
(a) The Company may terminate the Executive's employment hereunder, upon notice
to him, in the event that he becomes disabled through any illness, injury,
accident or condition of either a physical or psychological nature and, as a
result, is unable to perform substantially all of his duties and
responsibilities hereunder for any consecutive 60 day period.

(b) If any question shall arise as to whether during any period the Executive is
disabled through any illness, injury, accident or condition of either a physical
or psychological nature so as to be unable to perform substantially all of his
duties hereunder, the Executive may, and at the request of the Company shall,
submit to a medical examination by a physician mutually acceptable to the
Company and the Executive or his guardian to determine whether the Executive is
so disabled, and such determination shall for the purposes of this Agreement be
conclusive of the issue. In the event that a physician cannot be selected by
mutual agreement, a physician shall be appointed by the Massachusetts Medical
Society.

(c) If the Executive's employment hereunder is terminated as the result of his
disability, the Executive will receive his Base Salary through the date of
termination, together with any unpaid Bonus that may have been earned through
such date, but shall otherwise look solely to the Company's disability insurance
policy or policies for compensation (except that any waiting period for
eligibility purposes shall be waived by the Company).

5.4 TERMINATION IN THE EVENT OF DEATH.
    ---------------------------------
In the event of the Executive's death during the Term, his employment hereunder
shall be deemed to have terminated for  all purposes of this Agreement on his
date of death and neither his designated beneficiary nor his estate shall be
entitled to any of the compensation or benefits provided for herein, other than
the Executive's Base Salary, and any unpaid Bonus earned by the Executive,
through his date of death (it being understood that his designated beneficiary
or estate, as the case may be, shall be entitled to receive the life insurance
benefits available under the Company's executive life insurance policies), and
to exercise the Unconditional Option to the extent exercisable on his date of
death, within one year of his date of death, but not later than the expiration
date of such Option.



                                   ARTICLE VI

6.1 DESIGNATION OF A BENEFICIARY OR BENEFICIARIES.
    ---------------------------------------------
The Executive may designate in a writing filed with the Company one or more
persons (including his estate)  as the beneficiary or beneficiaries of the
benefits provided for under the Agreement after the Executive's death. The
Executive may change his designation of beneficiary or beneficiaries from time
to time, and the last designation in writing filed with the Company prior to
his death will control. If the Executive has failed to file a designation of
beneficiary at the time of the Executive's  death, or if all designated
beneficiaries have predeceased him, the amounts  payable under this Agreement
shall be paid to the Executive's estate.

                                      -14-

<PAGE>   6





                                   ARTICLE VII

7.1 NOTICES.
    -------
All notices required by this Agreement shall be in writing and delivered by
hand, by overnight courier against receipt, by registered or certified mail,
postage prepaid, or by telephonic facsimile transmission duly acknowledged,
and, in the case of the Executive, addressed to the Executive at 79 Byron Road,
Weston, MA 02193, or, in the case of the Company, to its principal office,
addressed to the attention of the Clerk. Either party may from time to time
designate a new address by notice given in accordance with this Paragraph 7.1.

7.2 ASSIGNMENT. 
    ---------- 
The Company may not assign all or any part of its obligation under this
Agreement. The Company will require any successor (whether direct or indirect, 
by purchase, merger, consolidation or otherwise) to all or substantially all    
of the business or assets of the Company expressly to assume and agree to
perform this Agreement to the same extent that the Company would be required to
perform it if no succession had taken place. As used in this Agreement, unless 
the context requires otherwise, the "Company" shall mean the Company as defined 
above or any successor to its business or assets as aforesaid which assumes and
agrees to perform this Agreement, by operation of law, or otherwise. This
Agreement shall inure to the benefit of and be enforceable by and binding upon
(I) any such successor and (ii) the Executive's personal or legal
representatives, executors, administrators and designated beneficiaries.

7.3 ENTIRE AGREEMENT.
    ----------------
This Agreement contains the entire agreement between the parties and supersedes
all prior oral and written agreements, understandings and commitments between 
the parties relating to this Agreement. No amendment to this Agreement shall 
be made except by a written instrument signed by both parties.


7.4 PROPRIETARY INFORMATION AND NON COMPETITION.
    -------------------------------------------
The Executive acknowledges and stipulates that, in the performance of his
duties hereunder, the Executive is entrusted by the Company and its
subsidiaries with confidential and secret information of a proprietary nature,
including, but not limited to scientific data, financial and statistical        
information regarding affairs of the Company and its subsidiaries, supplier and
subcontractor lists, price and cost information, business plans and programs,
expansion plans, data, methods, techniques, marketing data, designs and
know-how, developed or obtained by the Company or its subsidiaries
(collectively, "Proprietary Information"). The Executive may not at any time
use, or cause or permit others to use, the Proprietary Information except in
the performance of his duties for the Company and shall not directly or
indirectly disclose at any time either during the Term or for a period of two
years thereafter any such Proprietary Information to any third party other than
in the course of the performance of his duties for the Company. "Proprietary
Information" shall not include any (I) information which is part of the public
domain (other than by act of the Executive), or (ii) any information required
to be disclosed by law.

                                      -15-

<PAGE>   7




     Executive agrees that, subsequent to the termination of this Employment
Agreement, unless terminated by the Company without Cause or by the Executive
for Good Reason, Executive shall not:

      (i) request, cause or encourage any person or entity to cancel, terminate
          or refuse to enter into any business relationship with the Company;

     (ii) during the one-year period following such termination solicit or
          encourage, directly or indirectly, any employee of the Company to
          leave the employment of the Company; or

    (iii) during the one-year period following such termination either engage
          in any business or undertake employment or consulting services in the
          area of x-ray detection devices which would directly compete with
          devices then manufactured and/or marketed by the Company.

The provisions of this Section 7.4 shall continue in effect after the Term.

7.5 PARTIAL INVALIDITY.
    ------------------
If for any reason any provision of this Agreement shall be held invalid in
whole or in part, such invalidity shall not affect such provision to the extent
not so held invalid, nor any other provisions of this Agreement not held so
invalid, and such provisions and all other such provisions shall to the full
extent be consistent with law continue in full force and effect.

7.6 WITHHOLDING.
    -----------
All payments made by the Company under this Agreement shall be reduced by any
tax or other amounts required to be withheld by the Company under applicable 
law.

7.7 GOVERNING LAW.
    -------------
This Agreement shall be construed and enforced under and be governed in all
respects by the law of the Commonwealth of Massachusetts, without regard to 
the conflict of law principles thereof.

IN WITNESS WHEREOF, the Company has caused this instrument to be executed on its
behalf by a duly authorized officer and the Executive has executed this
instrument, all as of the date set forth above.



                                    AMERICAN SCIENCE AND ENGINEERING, INC.


                                    By: /s/ Herman Feshbach
                                        -------------------------------------- 
                                        Herman Feshbach, Chairman of the Board


                                        /s/ Ralph S. Sheridan
                                        -------------------------------------- 
                                        Ralph S. Sheridan


                                      -16-

<PAGE>   8



                                    EXHIBIT B
                                    ---------

                     AMERICAN SCIENCE AND ENGINEERING, INC.

                      NON-STATUTORY STOCK OPTION AGREEMENT
                             Covering 225,000 Shares
                                 of Common Stock


AGREEMENT made as of this 24th day of October, 1996, by and between AMERICAN
SCIENCE AND ENGINEERING, INC., a corporation duly organized under the laws of
The Commonwealth of Massachusetts (the "Company"), and Ralph S. Sheridan, the
President and Chief Executive Officer of the Company (the "Optionee").

                                WITNESSETH THAT:

WHEREAS, the Company and the Optionee have entered into an Employment Agreement
dated as of September 25, 1996 (the "Employment Agreement"), providing among
other things for the employment of the Optionee as President and Chief Executive
Officer of the Company and the grant of non-statutory stock options to the
Optionee; and

WHEREAS, the Board of Directors of the Company has appointed the Compensation
Committee to administer this Agreement (the Board of Directors, such committee
or any successor to such committee being hereinafter referred to as the
"Board");

NOW, THEREFORE, for and in consideration of the mutual covenants hereinafter set
forth and for other good and valuable consideration, it is agreed as follows:

1. GRANT OF OPTION.
   ---------------
The Company hereby grants to the Optionee a non-statutory stock option (the
"Option") to purchase 225,000 shares of its common stock at $____ per share,
being 100% of the fair market value of such stock on the date hereof. The
Optionee's right to purchase said stock shall be exercised in the manner and
subject to the terms and conditions hereinafter provided. The Company shall, at
all times while the Option is in force, reserve such number of shares of common
stock as will be sufficient to satisfy the requirements of this Agreement.

2. TIME OF EXERCISE OF THE OPTION.
   -------------------------------
(a) Subject always to the provisions of Sections 2(b) and 3 and the terms and
conditions of the Employment Agreement: (i) the Option may not be exercised
prior to September 25, 1997; and (ii) on and after September 25, 1997, the
Option may be exercised as to seventy-five thousand shares covered thereby. On
and after September 25, 1998, the Option may be exercised as to an additional
seventy five thousand shares covered thereby. On and after September 25, 1999,
the Option may be exercised as to the remaining seventy five thousand shares
covered thereby.


                                       B-1
<PAGE>   9


(b) Notwithstanding Section 2(a), the Option may be exercised as to all of the
shares covered thereby upon the occurrence of a Change in Control of the
Company. For the purposes of this subsection 2(b), a "Change in Control" of the
Company shall be deemed to have occurred if:

      (i) any person (as defined in Section 13(d) or 14(d)(2) of the 1934 Act)
          shall have become the beneficial owner of 50 percent or more of the
          combined voting power of the Company's voting securities;

     (ii) the Continuing Directors and the Optionee shall have ceased for any
          reason to constitute a majority of the Board of Directors of the
          Company. For this purpose, a "Continuing Director" shall include
          member of the Board of Directors of the Company as of September 26,
          1996 and any person nominated for election to the Board of Directors
          of the Company by a vote of a majority of the then Continuing
          Directors;

    (iii) the stockholders approve the complete liquidation or dissolution of
          the Company, or

     (iv) the stockholders approve by the requisite vote any of the following
          transactions: (x) a merger or consolidation of the Company (except for
          a merger in respect of which no vote of the stockholders of the
          Company is required); (y) a sale, lease, exchange, mortgage, pledge,
          transfer or other disposition (in one transaction or a series of
          transactions), whether as part of a dissolution or otherwise, of
          assets of the Company or of any direct or indirect majority-owned
          subsidiary or the Company (other than to any direct or indirect
          wholly-owned subsidiary or to the Company) having an aggregate market
          value equal to 50% or more of either that aggregate market value of
          all of the assets of the Company determined on a consolidated basis or
          the aggregate market value of all the outstanding stock of the
          Company; or (z) a proposed tender or exchange offer for 50% or more of
          the outstanding voting stock of the Company.

(c) Notwithstanding Section 2(a) and subject to Section 4 hereof, the Option may
be exercised as to all of the shares covered thereby in the event that the
Optionee's employment shall have been terminated without Cause or for Good
Reason as provided by Section 5.1 of the Employment Agreement.

(d) Notwithstanding any of the foregoing, the Option shall not be exercisable
after the expiration of 10 years from the date hereof.


3.   METHOD OF EXERCISE.
     -------------------
(a) Stock purchased under the Option shall at the time of exercise be paid in
full. The Option may be exercised from time to time by written notice to the
Company stating the number of shares with respect to which the Option is being
exercised, and the time of the delivery thereof, which time shall be at least
five business days after the giving of such notice unless an earlier date shall
have been mutually agree upon. At the time specified in such notice, the Company
shall, without transfer or issue tax to the Optionee (or other person entitled
to exercise the Option), deliver to the Optionee (or other person entitled to
exercise the

                                       B-2



<PAGE>   10


Option) at the main office of the Company, or such other place as shall be
mutually acceptable, a certificate or certificates for such shares (as the
number of such shares may be reduced subject to subsection (c) below) out of
theretofore authorized but unissued shares or reacquired shares of its common
stock, as the Company may elect, against payment of the Option price in full for
the number of shares to be delivered by certified or bank cashier's check or the
equivalent thereof acceptable to the Company (including, but not limited to,
shares of capital stock of the Company); provided, however, that the time of
such delivery may be postponed by the Company for such period as may be required
for it with reasonable diligence to comply with any applicable listing
requirements of any national securities exchange. If the Optionee (or other
person entitled to exercise the Option) fails to accept delivery of and pay for
all or any part of the number of shares specified in such notice upon tender of
delivery thereof, his right to exercise the Option with respect to such
undelivered shares may be terminated by the Board.

(b) Promptly upon receipt of the written notice provided for in subsection (a)
above, the Board shall, with the assistance of appropriate employees of the
Company, determine if any portion of such intended exercise (the "Disallowance
Portion") may reasonably be expected to result in receipt of compensation by the
Optionee as to which the Company will not be allowed to claim a deduction in
respect of the Company's taxable year during which such exercise occurs, when
the amount of remuneration attributable to such exercise is taken together with
the Optionee's base salary and the reasonably likely cash and stock bonuses
payable to him in respect of such taxable year, pursuant to Section 162(m) of
the Internal Revenue Code of 1986, as amended, and the regulations thereunder.

(c) The Board shall promptly notify the Optionee of its determination as to the
Disallowance Portion, and, subject to subsection (d) below, the exercise
contemplated by the written notice in subsection (a) shall be deemed to be
reduced by the number of shares in the Disallowance Portion.

(d) Notwithstanding the foregoing, in the event of a Change in Control (as
defined in Section 2(b), the Disallowance Portion shall be deemed to be zero (0)
shares.



4. TERMINATION OF EMPLOYMENT.
   -------------------------
The Optionee may, at any time within three months after the date of termination
of his employment with the Company or any of its subsidiaries for any reason 
except death, but not later than the date of expiration of the Option,  
exercise the Option to the extent he was entitled to do so on the date of
termination; provided that the Optionee shall not be deemed to be so    
entitled on the date of termination of his employment if he shall have been
terminated for Cause or other than for Good Reason as provided by Section 5.2
of the Employment Agreement. If the Option or any portion of the Option is not
so exercised, or if the Optionee shall be deemed not to be entitled to exercise
it or any portion thereof, the Option or portion thereof shall terminate.
However, the Option shall not be affected by any change in the duties or
position of the Optionee (including transfer to or from a subsidiary) so long
as the Optionee continues in the employ of the Company or one of its
subsidiaries.


                                       B-3



<PAGE>   11


Nothing in this Agreement shall confer on the Optionee any right to continue in
the employ of the Company or its subsidiaries; affect the right of the Company
or its subsidiaries to terminate the Optionee's employment at any time; or be
deemed a waiver or modification of any provision contained in the Employment
Agreement of any other agreement between the Optionee and the Company of any
such subsidiary.


5. EXERCISE BY REPRESENTATIVE, ETC.
   -------------------------------
If the Optionee dies while in the employ of the Company or its subsidiaries or
within three months after termination of employment (except termination for 
Cause or other than for Good Reason, as provided by Section 5.2 of the
Employment Agreement), the person or persons to whom the Option is transferred
by will or the laws of decent and distribution may, at any time within one year
after the date of death but not later than the date of expiration of the 
Option, exercise the Option to the extent the Optionee was entitled to do so on
the date of his death. If the Option or any portion of the Option of the
deceased Optionee is not so exercised, it shall terminate.

6. NON-TRANSFERABILITY OF OPTION.
   -----------------------------
The Option may not be transferred except by will or by the laws of the descent
and distribution nor may it be  otherwise assigned, transferred, pledged,
hypothecated or disposed of in any way (by operation of law or otherwise) and
it shall not be subject to execution, attachment or similar process. During the
lifetime of the Optionee, the Option may be exercised only by the Optionee or
the Optionee's duly appointed guardian or personal representative.


7. CHANGES IN COMMON STOCK.
   -----------------------
In the event of any reorganization, recapitalization, stock split, stock
dividend, merger, consolidation, combination of shares or other change
affecting the Company's common stock, the Board shall make adjustments in the
number and kind of securities to be subject to the Option, such adjustments to
be consistent with adjustments made with respect to options held by other
employees and directors of the Company. Any such adjustment made by the Board
shall be conclusive. This Agreement shall not affect the right of the Company
or any of its subsidiaries to reclassify, recapitalize or otherwise change its
capital or debt structure or to merge, consolidate, convey any or all of its
assets, dissolve, or liquidate, wind up or otherwise reorganize.


8. RESTRICTION ON ISSUANCE OF SHARES.
   ---------------------------------
The Company shall not be obligated to sell or issue any shares pursuant to
the Option unless the shares with respect to which the Option is being
exercised are at that time effectively registered or exempt from registration
under the Securities Act of 1933, as amended


9. RIGHTS AS A STOCKHOLDER.
   -----------------------
The Optionee shall have no rights as a stockholder with respect to any shares
covered by the Option until the date of issuance of a stock certificate to the 
Optionee for such shares. No adjustment shall be made for dividends or other 
rights for which the record date is prior to the date such stock certificate is
issued.


                                       B-4



<PAGE>   12


10. WITHHOLDING.
    -----------
The Company or any subsidiary that employs the Optionee shall have the right to
deduct any sums that federal, state or local tax law requires to be withheld
with respect to the exercise of the Option. In the alternative, the Optionee or
other person exercising the Option may elect to pay such sums to the employer
corporation either by check or with capital stock of the Company by delivering
written notice of that election to the Clerk of the Company no less than 30
days nor more than 60 days prior to exercise. there is no obligation hereunder
that the Optionee be advised of the amount which the employer corporation or
the Company will be required to withhold.

11. INTERPRETATION OF PLAN AND OPTION.
    ---------------------------------
As used herein the term "subsidiary of the Company" shall mean a subsidiary
corporation as defined in  Section 425 of the Internal Revenue Code of 1986. In
all other respects, questions of interpretation and application of this 
Agreement shall be determined by a majority of the Board, and the determinations
of such majority shall be final and binding upon all persons.

EXECUTED as a sealed instrument at Cambridge, Massachusetts, as of the date
appearing in the first paragraph of this Agreement.


                                         AMERICAN SCIENCE AND
                                         ENGINEERING, INC.


                                         By: /s/ Jeffrey Bernfeld
                                             -----------------------------------
                                             Jeffrey Bernfeld
                                             Vice President & General Counsel

                                             /s/ Ralph S. Sheridan
                                             -----------------------------------
                                             Ralph S. Sheridan


                                       B-5