
<PAGE>   1
                                  EXHIBIT 4.1

                      DIRECTORS' STOCK OPTION PLAN (1987)
                                       OF
                               ADAC LABORATORIES



                 1.       PURPOSE.

                 The purpose of this Directors' Stock Option Plan (1987) (the
"Plan") is to assist the Company in attracting, motivating and retaining
qualified non-employee directors by providing a means whereby such persons will
be given an opportunity to acquire a proprietary interest in the Company's
future growth by purchasing shares of Company Common Stock.

                 2.       DEFINITIONS.

                 When used in this Plan, unless the context otherwise requires:

                          (a)     "Board of Directors" shall mean the Board of
Directors of the Company as constituted at any time.

                          (b)     "Committee" shall mean the Committee as
hereinafter described in Section 3 hereof.

                          (c)     "Company" shall mean ADAC Laboratories, a
California corporation.

                          (d)     "Directors' Options" shall mean options to
purchase 20,000 shares (subject to adjustment pursuant to Section 12 hereof) of
Company Common Stock which may be granted each fiscal year by the Company to
each person serving as a director of the Company who is not also an employee of
the Company or any of its Subsidiary corporations.

                          (e)     "Fair Market Value" shall mean the closing
price of the Company's Common Stock, as traded on the NASDAQ National Market
System (or, if such shares are then listed on any national securities exchange,
the closing price on such exchange) on the date as of which such value is being
determined.  If the Common Stock is not traded on the NASDAQ National Market
System or any national securities exchange, Fair Market Value shall be
determined by the Board on the basis of the best available market value
information.

                          (f)     "Options" shall mean the Directors' Options
issued pursuant to the Plan.

                          (g)     "Plan" shall mean the Directors' Stock Option
Plan (1987) of the Company authorized and adopted by the Board of Directors at
its meeting held on July 28, 1987 and as amended from time to time.
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Directors' Stock Option Plan (1987)
of ADAC Laboratories



                          (h)     "Share" shall mean a share of Common Stock of
the Company.

                          (i)     "Subsidiary" shall mean any corporation in
which the Company owns, directly or indirectly, stock possessing fifty percent
(50%) or more of the total combined voting power of all classes of stock.

                 3.       ADMINISTRATION.

                 The Plan shall be administered by the Board of Directors or by
a Committee which shall consist of such members of the Board of Directors of
the Company or such other persons as may be appointed by the Board of
Directors.  The Board and, if any, the Committee, shall have full power and
authority to construe, interpret and administer the Plan and to make
determinations which shall be final, conclusive and binding upon all persons,
including but not limited to the Company, the shareholders and any person
having an interest in any Options.  If a member of the Committee, for any
reason, shall cease to serve, the vacancy may be filled by the Board of
Directors.  Any member of the Committee may be removed at any time, with or
without cause, by the Board of Directors.

                 4.       ELIGIBILITY.

                 Options may be granted only to non-employee directors of the
Company; employees of the Company or any of its Subsidiary corporations are not
eligible to receive Options under the Plan.

                 5.       SHARES SUBJECT TO THE PLAN.

                 Subject to the provisions of Section 12 (relating to
adjustments upon changes in shares), the Shares which may be sold pursuant to
Directors' Options granted under the Plan shall not exceed in the aggregate
300,000 shares of the Company's authorized Common Stock, without par value.  If
any Option under the Plan shall for any reason terminate or expire without
having been exercised in full, the Shares not purchased under such Option shall
again be available under the Plan.

                 6.       ANNUAL OPTION GRANTS.

                 The number of Shares to be optioned to each non-employee
director shall be fixed at 20,000 Option Shares during each fiscal year of the
Company.  The initial annual grant shall be made on the date of approval of the
Plan by the shareholders of the Company.  Except for the limitations upon the
duration, vesting, exercise price and method of exercise of Directors' Options
as hereinafter set forth, the form of Option, including the terms and
provisions thereof, shall be as determined from time to time by the Board of
Directors or the Committee and each Option issued may contain terms





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Directors' Stock Option Plan (1987)
of ADAC Laboratories



and provisions different from other Options granted to the same or other Option
recipients.  An Option Agreement, signed by an officer of the Company, shall be
issued to each person to whom an Option is granted.

                 7.       PRICE.

                 The purchase price per Share for the Shares to be purchased
pursuant to the exercise of any Option shall be fixed by the Board of Directors
or the Committee at the time of grant of the Option, but shall always equal
100% of the Fair Market Value of the Shares on the date such Option is granted.

                 8.       DURATION OF OPTIONS.

                 All Directors' Options issued under the Plan shall have a
duration of five (5) years from the date of grant, regardless of any
termination of the Plan prior to the exercise of such Options.

                 9.       NON-TRANSFERABILITY OF OPTIONS.

                 Options shall not be transferable by the holder thereof
otherwise than by will or the laws of descent and distribution to the extent
provided herein, and Options may be exercised or surrendered during the
holder's lifetime only by the holder thereof.

                 10.      EXERCISE OF OPTIONS.

                          (a)     Except in the event of death, in which case
they may be exercised in full immediately, and except as provided in Section 12
below, Directors' Options may be exercised only in installments as follows:
50% of the Shares subject to the Option may be exercised after 12 months from
the date of grant; and all of the Shares subject to the Option may be exercised
after 24 months from the date of grant; provided, however, that Options may be
exercised only during the periods beginning on the third business day following
the date on which the Company issues a news release containing the operating
results of a fiscal quarter or fiscal year and ending on the twelfth business
day following such date.

                          (b)     An Option shall be exercised by the delivery
of a duly signed notice in writing to such effect, together with the full
purchase price.  Payment of the purchase price shall be made in cash or
outstanding Common Stock of the Company already owned by the optionee (valued
at Fair Market Value).  Option Agreements under the Plan may contain a
provision to the effect that all Federal and state taxes required to be
withheld or collected from an Optionee upon exercise of an Option may be
satisfied by the withholding of a sufficient number of exercised Option shares





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Directors' Stock Option Plan (1987)
of ADAC Laboratories



which, valued at Fair Market Value on the date of exercise, would be equal to
the total withholding obligation of Optionee.

                          (c)     The Company will, as soon as practicable
after the exercise of an Option, deliver to the person entitled thereto a
certificate or certificates for the Shares purchased pursuant to the exercise
of the Option.

                 11.      TERMINATION.

                 If a holder of a Directors' Option shall resign or be removed
as a director, the Option of such holder shall terminate, except that, subject
to the limitation stated in the last sentence of this Section 11, (i) if his
director's status with the Company is terminated for any reason other than his
death, he may at any time within three months after such termination exercise
his Option but only to the extent that it was exercisable by him on the date of
termination and only if his status was not terminated because of a violation of
his normal duties; and (ii) if he dies while serving as a director of the
Company, or within three months after termination of such status, his Option
may be exercised by the person or persons to whom his rights under the Option
shall pass by will or by the laws of descent and distribution, without regard
to the vesting provisions included in the Option.  In no event may an Option be
exercised to any extent by anyone after the expiration of its term.

                 12.      CHANGES IN CAPITALIZATION:  SPLITS, LIQUIDATIONS,
MERGERS AND REORGANIZATIONS.

                          (a)     The aggregate number of shares of Common
Stock for which Options may be granted to eligible persons under the Plan, the
number of shares of Common Stock covered by each outstanding Option and the
price per share thereof in each such Option may be proportionately adjusted by
the Board of Directors or the Committee for any increase or decrease in the
number of issued shares of Common Stock of the Company resulting from a stock
split, a reverse stock split, a subdivision or consolidation of shares or other
similar capital adjustment, the payment of a stock dividend or any other
increase or decrease in such shares effected without receipt of consideration
by the Company.  Any such determination by the Board of Directors of the
Company shall be conclusive.

                          (b)     Upon the dissolution or liquidation of the
Company or upon any reorganization, merger, consolidation pursuant to which the
Company does not survive (except for a reincorporation of the Company in
another state), or sale of all or substantially all of the assets of the
Company or upon a change in the composition of the Board of Directors (not
approved by a majority of the directors in office at the time of such change)
which results in a change in "control" of the Company (for purposes of this
subsection





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Directors' Stock Option Plan (1987)
of ADAC Laboratories



"control" is defined in Rule 405 promulgated by the Securities Exchange
Commission under the Securities Act of 1933, as amended) the Plan and each
outstanding Option shall terminate; provided that in such event each
outstanding unexercised Option shall become fully vested under the Plan and
shall be immediately exercisable thirty (30) days prior to the effective date
of such dissolution, liquidation, reorganization, merger, consolidation, sale
of assets or change in control, and each Optionee may exercise, in whole or in
part, any unexpired Option or Options previously issued to him, without regard
to the installment or vesting provisions of his Option or Options.  The grant
of an Option under the Plan shall not affect in any way the ability of the
Company to change or adjust its capital structure or to merge, consolidate,
dissolve, liquidate or to sell or transfer all or any part of its business or
assets.

                 13.      ISSUANCE OF SHARES AND COMPLIANCE WITH SECURITIES
ACT.

                 The Company may postpone the issuance and delivery of Shares
upon any exercise of an Option until (a) the admission of such Shares to
listing on any stock exchange on which Shares of the Company of the same class
are then listed and (b) the completion of such registration or other
qualification of such Shares under any state or Federal law, rule or regulation
as the Company shall determine to be necessary or advisable.  Any person
exercising an Option shall make such representations and furnish such
information as may, in the opinion of counsel for the Company, be appropriate
to permit the Company to issue the Shares in compliance with the provisions of
the Securities Act of 1933, as amended.

                 14.      AMENDMENT AND TERMINATION OF THE PLAN.

                          (a)     Except as hereinafter provided, the Board of
Directors or the Committee may at any time withdraw or from time to time amend
the Plan and the terms and conditions of any Options not theretofore issued,
and the Board of Directors or the Committee, with the consent of the affected
holder of an Option, may at any time amend the terms and conditions of such
Options as have been theretofore granted.  Notwithstanding the foregoing, any
amendment to the Plan by the Board of Directors or Committee which would (i)
increase the number of Shares issuable under Options, (ii) change the class of
persons to whom Options may be granted or (iii) change in any material respect
the limitations or provisions pertaining to Options, shall be subject to the
approval of the holders of a majority of the shares of the Company present at
any meeting of shareholders and entitled to vote thereat either prior to or
within one year after such amendment.

                          (b)     The determination of the Board of Directors
or the Committee as to any questions which may arise with respect to





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Directors' Stock Option Plan (1987)
of ADAC Laboratories



the interpretation of the provisions of the Plan and Options granted hereunder
shall be final and conclusive.

                          (c)     The Board of Directors or the Committee may
authorize and establish such rules, regulations and revisions thereof, not
inconsistent with the provisions of the Plan, as it may deem advisable to make
the Plan and Options effective or provide for their administration, and may
take such other action with regard to the Plan and Options as it shall deem
desirable to effectuate their purpose.

                          (d)     The Plan shall remain in effect until such
time as it is terminated by the Board of Directors of the Company.  No such
termination shall affect Options granted prior thereto.

                 15.      EFFECTIVE DATE OF THE PLAN.

                 The Plan was adopted on July 28, 1987, and is subject to
approval of the holders of a majority of the shares of the Company present at
any meeting of shareholders and entitled to vote thereat.  Options may not be
granted under the Plan prior to such shareholder approval.

                                                   Adopted by the Board of
                                                   Directors on July 28, 1987





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