<PAGE>
                                                                    Exhibit 4.18


THIS WARRANT AND THE COMMON SHARES ISSUABLE UPON EXERCISE OF THIS WARRANT HAVE
NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED. THIS WARRANT
AND THE COMMON SHARES ISSUABLE UPON EXERCISE OF THIS WARRANT MAY NOT BE SOLD,
OFFERED FOR SALE, PLEDGED OR HYPOTHECATED IN THE ABSENCE OF AN EFFECTIVE
REGISTRATION STATEMENT AS TO THIS WARRANT UNDER SAID ACT OR AN OPINION OF
COUNSEL REASONABLY SATISFACTORY TO JMAR TECHNOLOGIES, INC. THAT SUCH
REGISTRATION IS NOT REQUIRED.

                              Right to Purchase 50,000 Shares of Common Stock of
                              JMAR Technologies, Inc. (subject to adjustment as
                              provided herein)

                          COMMON STOCK PURCHASE WARRANT



No. 2004-4                                          Issue Date: February 5, 2004

      JMAR TECHNOLOGIES, INC., a corporation organized under the laws of the
State of Delaware (the "COMPANY"), hereby certifies that, for value received,
LAURUS MASTER FUND, LTD., or assigns (the "HOLDER"), is entitled, subject to the
terms set forth below, to purchase from the Company from and after the Issue
Date of this Warrant and at any time or from time to time before 5:00 p.m., New
York time, through seven (7) years after such date (the "EXPIRATION DATE"), up
to 50,000 fully paid and nonassessable shares of Common Stock (as hereinafter
defined), $.01 par value per share, of the Company, at the Exercise Price (as
defined below). The number and character of such shares of Common Stock and the
Exercise Price are subject to adjustment as provided herein.

      As used herein the following terms, unless the context otherwise requires,
have the following respective meanings:

      (a) The term "Company" shall include JMAR Technologies, Inc. and any
corporation which shall succeed or assume the obligations of JMAR Technologies,
Inc. hereunder.

      (b) The term "Common Stock" includes (a) the Company's Common Stock, $.01
par value per share, and (b) any other securities into which or for which any of
the securities described in (a) may be converted or exchanged pursuant to a plan
of recapitalization, reorganization, merger, sale of assets or otherwise.

      (c) The term "Other Securities" refers to any stock (other than Common
Stock) and other securities of the Company or any other person (corporate or
otherwise) which the holder of the Warrant at any time shall be entitled to
receive, or shall have received, on the exercise of the Warrant, in lieu of or
in addition to Common Stock, or which at any time shall be issuable or shall
have been issued in exchange for or in replacement of Common Stock or Other
Securities pursuant to Section 4 or otherwise.
<PAGE>
      (d) The term "EXERCISE PRICE" shall be $3.61 per share;


      1.    EXERCISE OF WARRANT.

            1.1 Number of Shares Issuable upon Exercise. From and after the date
hereof through and including the Expiration Date, the Holder shall be entitled
to receive, upon exercise of this Warrant in whole or in part, by delivery of an
original or fax copy of the exercise notice attached hereto as Exhibit A (the
"EXERCISE NOTICE"), shares of Common Stock of the Company, subject to adjustment
pursuant to Section 4.

            1.2 Fair Market Value. Fair Market Value of a share of Common Stock
as of a particular date (the "DETERMINATION DATE") shall mean:

                  (a) If the Company's Common Stock is traded on an exchange or
is quoted on the National Association of Securities Dealers, Inc. Automated
Quotation ("NASDAQ") National Market or the NASDAQ SmallCap Market, then the
closing or last sale price, respectively, reported for the last business day
immediately preceding the Determination Date.

                  (b) If the Company's Common Stock is not traded on an exchange
or on the NASDAQ National Market or the NASDAQ SmallCap Market but is traded on
the NASD OTC Bulletin Board or BBX Exchange, then the mean of the average of the
closing bid and asked prices reported for the last business day immediately
preceding the Determination Date.

                  (c) Except as provided in clause (d) below, if the Company's
Common Stock is not publicly traded, then as the Holder and the Company agree or
in the absence of agreement by arbitration in accordance with the rules then in
effect of the American Arbitration Association, before a single arbitrator to be
chosen from a panel of persons qualified by education and training to pass on
the matter to be decided.

                  (d) If the Determination Date is the date of a liquidation,
dissolution or winding up, or any event deemed to be a liquidation, dissolution
or winding up pursuant to the Company's charter, then all amounts to be payable
per share to holders of the Common Stock pursuant to the charter in the event of
such liquidation, dissolution or winding up, plus all other amounts to be
payable per share in respect of the Common Stock in liquidation under the
charter, assuming for the purposes of this clause (d) that all of the shares of
Common Stock then issuable upon exercise of the Warrant are outstanding at the
Determination Date.

      2.    PROCEDURE FOR EXERCISE.

            2.1 Delivery of Stock Certificates, etc. on Exercise. The Company
agrees that the shares of Common Stock purchased upon exercise of this Warrant
shall be deemed to be issued to the Holder as the record owner of such shares as
of the close of business on the date on which this Warrant shall have been
surrendered and payment made for such shares as aforesaid. As soon as
practicable after the exercise of this Warrant in full or in part, and in any
event within 3 business days thereafter, the Company at its expense (including
the payment by it of any


                                       2
<PAGE>
applicable issue taxes) will cause to be issued in the name of and delivered to
the Holder, or as such Holder (upon payment by such holder of any applicable
transfer taxes) may direct in compliance with applicable securities laws, a
certificate or certificates for the number of duly and validly issued, fully
paid and nonassessable shares of Common Stock (or Other Securities) to which
such Holder shall be entitled on such exercise, plus, in lieu of any fractional
share to which such holder would otherwise be entitled, cash equal to such
fraction multiplied by the then Fair Market Value of one full share, together
with any other stock or other securities and property (including cash, where
applicable) to which such Holder is entitled upon such exercise pursuant to
Section 1 or otherwise.

            2.2   Exercise.

                  (a) Payment may be made by delivery of the Warrant, and/or
Common Stock receivable upon exercise of the Warrant in accordance with Section
(b) below, for the number of Common Shares specified in such form (as such
exercise number shall be adjusted to reflect any adjustment in the total number
of shares of Common Stock issuable to the holder per the terms of this Warrant)
and the Holder shall thereupon be entitled to receive the number of duly
authorized, validly issued, fully-paid and non-assessable shares of Common Stock
(or Other Securities) determined as provided herein.

                  (b) Notwithstanding any provisions herein to the contrary, if
the Fair Market Value of one share of Common Stock is greater than the Exercise
Price (at the date of calculation as set forth below), the Holder may elect to
receive shares equal to the value (as determined below) of this Warrant (or the
portion thereof being exercised) by surrender of this Warrant at the principal
office of the Company together with the properly endorsed Exercise Notice in
which event the Company shall issue to the Holder a number of shares of Common
Stock computed using the following formula:



            X=Y (A-B)
                ------
                  A
            ----------


      Where X =   the number of shares of Common Stock to be issued to the
                  Holder

            Y =   the number of shares of Common Stock purchasable under the
                  Warrant or, if only a portion of the Warrant is being
                  exercised, the portion of the Warrant being exercised (at the
                  date of such calculation)

            A =   the Fair Market Value of one share of the Company's
                  Common Stock (at the date of such calculation)

            B =   Exercise Price (as adjusted to the date of such calculation)


                                       3
<PAGE>

      3.    EFFECT OF REORGANIZATION, ETC.; ADJUSTMENT OF EXERCISE PRICE.

            3.1 Reorganization, Consolidation, Merger, etc. In case at any time
or from time to time, the Company shall (a) effect a reorganization, (b)
consolidate with or merge into any other person, or (c) transfer all or
substantially all of its properties or assets to any other person under any plan
or arrangement contemplating the dissolution of the Company, then, in each such
case, as a condition to the consummation of such a transaction, proper and
adequate provision shall be made by the Company whereby the Holder of this
Warrant, on the exercise hereof as provided in Section 1 at any time after the
consummation of such reorganization, consolidation or merger or the effective
date of such dissolution, as the case may be, shall receive, in lieu of the
Common Stock (or Other Securities) issuable on such exercise prior to such
consummation or such effective date, the stock and other securities and property
(including cash) to which such Holder would have been entitled upon such
consummation or in connection with such dissolution, as the case may be, if such
Holder had so exercised this Warrant, immediately prior thereto, all subject to
further adjustment thereafter as provided in Section 4.

            3.2 Dissolution. In the event of any dissolution of the Company
following the transfer of all or substantially all of its properties or assets,
the Company, prior to such dissolution, shall at its expense deliver or cause to
be delivered the stock and other securities and property (including cash, where
applicable) receivable by the Holder of the Warrant after the effective date of
such dissolution pursuant to Section 3.1 to a bank or trust company having its
principal office in New York, NY, as trustee for the Holder of the Warrant.

            3.3 Continuation of Terms. Upon any reorganization, consolidation,
merger or transfer (and any dissolution following any transfer) referred to in
this Section 3, this Warrant shall continue in full force and effect and the
terms hereof shall be applicable to the shares of stock and other securities and
property receivable on the exercise of this Warrant after the consummation of
such reorganization, consolidation or merger or the effective date of
dissolution following any such transfer, as the case may be, and shall be
binding upon the issuer of any such stock or other securities, including, in the
case of any such transfer, the person acquiring all or substantially all of the
properties or assets of the Company, whether or not such person shall have
expressly assumed the terms of this Warrant as provided in Section 4. In the
event this Warrant does not continue in full force and effect after the
consummation of the transactions described in this Section 3, then only in such
event will the Company's securities and property (including cash, where
applicable) receivable by the holders of the Warrant be delivered to the Trustee
as contemplated by Section 3.2.

            3.4 Adjustment of Warrant Exercise Price and Number of Shares upon
Issuance of Common Stock. Other than (i) pursuant to warrants or options that
are outstanding as of the date hereof and warrants and options that may be
granted in the future under any option plan of the Company, or any employment
agreement, joint venture, credit, leasing or other financing agreement or any
joint venture or other strategic arrangement, in each case now or hereinafter
entered into by the Company, (ii) pursuant to any securities issued by the
Company to the Holder, (iii) pursuant to any agreement entered into by the
Company or any of its subsidiaries for the acquisition of another business
(whether by stock purchase or asset purchase, merger or otherwise; ((i), (ii)
and (iii) above, are hereinafter referred to as the "EXCLUDED ISSUANCES")), if
the Company at any time shall issue any shares of Common Stock prior to the
complete exercise


                                       4
<PAGE>
of this Warrant for a consideration less than the Exercise Price that would be
in effect at the time of such issue, then, and thereafter successively upon each
such issue, the Exercise Price shall be reduced as follows: (i) the number of
shares of Common Stock outstanding immediately prior to such issue shall be
multiplied by the Exercise Price in effect at the time of such issue and the
product shall be added to the aggregate consideration, if any, received by the
Company upon such issue of additional shares of Common Stock; and (ii) the sum
so obtained shall be divided by the number of shares of Common Stock outstanding
immediately after such issue. The resulting quotient shall be the adjusted
Exercise Price. For purposes of this adjustment, the issuance of any security of
the Company carrying the right to convert such security into shares of Common
Stock or of any warrant, right or option to purchase Common Stock shall result
in an adjustment to the Exercise Price upon the issuance of shares of Common
Stock upon exercise of such conversion or purchase rights..

      4. EXTRAORDINARY EVENTS REGARDING COMMON STOCK. In the event that the
Company shall (a) issue additional shares of the Common Stock as a dividend or
other distribution on outstanding Common Stock, (b) subdivide its outstanding
shares of Common Stock, or (c) combine its outstanding shares of the Common
Stock into a smaller number of shares of the Common Stock, then, in each such
event, the Exercise Price shall, simultaneously with the happening of such
event, be adjusted by multiplying the then Exercise Price by a fraction, the
numerator of which shall be the number of shares of Common Stock outstanding
immediately prior to such event and the denominator of which shall be the number
of shares of Common Stock outstanding immediately after such event, and the
product so obtained shall thereafter be the Exercise Price then in effect. The
Exercise Price, as so adjusted, shall be readjusted in the same manner upon the
happening of any successive event or events described herein in this Section 4.
The number of shares of Common Stock that the holder of this Warrant shall
thereafter, on the exercise hereof as provided in Section 1, be entitled to
receive shall be increased to a number determined by multiplying the number of
shares of Common Stock that would otherwise (but for the provisions of this
Section 4) be issuable on such exercise by a fraction of which (a) the numerator
is the Exercise Price that would otherwise (but for the provisions of this
Section 4) be in effect, and (b) the denominator is the Exercise Price in effect
on the date of such exercise.

      5. CERTIFICATE AS TO ADJUSTMENTS. In each case of any adjustment or
readjustment in the shares of Common Stock (or Other Securities) issuable on the
exercise of the Warrant, the Company at its expense will promptly cause its
Chief Financial Officer or other appropriate designee to compute such adjustment
or readjustment in accordance with the terms of the Warrant and prepare a
certificate setting forth such adjustment or readjustment and showing in detail
the facts upon which such adjustment or readjustment is based, including a
statement of (a) the consideration received or receivable by the Company for any
additional shares of Common Stock (or Other Securities) issued or sold or deemed
to have been issued or sold, (b) the number of shares of Common Stock (or Other
Securities) outstanding or deemed to be outstanding, and (c) the Exercise Price
and the number of shares of Common Stock to be received upon exercise of this
Warrant, in effect immediately prior to such adjustment or readjustment and as
adjusted or readjusted as provided in this Warrant. The Company will forthwith
mail a copy of each such certificate to the holder of the Warrant and any
Warrant agent of the Company (appointed pursuant to Section 11 hereof).


                                       5
<PAGE>
      6. RESERVATION OF STOCK, ETC. ISSUABLE ON EXERCISE OF WARRANT. The Company
will at all times reserve and keep available, solely for issuance and delivery
on the exercise of the Warrant, shares of Common Stock (or Other Securities)
from time to time issuable on the exercise of the Warrant.

      7. ASSIGNMENT; EXCHANGE OF WARRANT. Subject to compliance with applicable
securities laws, this Warrant, and the rights evidenced hereby, may be
transferred by any registered holder hereof (a "TRANSFEROR") with respect to any
or all of the Shares. On the surrender for exchange of this Warrant, with the
Transferor's endorsement in the form of Exhibit B attached hereto (the
"TRANSFEROR ENDORSEMENT FORM") and together with evidence reasonably
satisfactory to the Company demonstrating compliance with applicable securities
laws, which shall include, without limitation, a legal opinion from the
Transferor's counsel that such transfer is exempt from the registration
requirements of applicable securities laws, the Company at its expense (but with
payment by the Transferor of any applicable transfer taxes) will issue and
deliver to or on the order of the Transferor thereof a new Warrant of like
tenor, in the name of the Transferor and/or the transferee(s) specified in such
Transferor Endorsement Form (each a "Transferee"), calling in the aggregate on
the face or faces thereof for the number of shares of Common Stock called for on
the face or faces of the Warrant so surrendered by the Transferor.

      8. REPLACEMENT OF WARRANT. On receipt of evidence reasonably satisfactory
to the Company of the loss, theft, destruction or mutilation of this Warrant
and, in the case of any such loss, theft or destruction of this Warrant, on
delivery of an indemnity agreement or security reasonably satisfactory in form
and amount to the Company or, in the case of any such mutilation, on surrender
and cancellation of this Warrant, the Company at its expense will execute and
deliver, in lieu thereof, a new Warrant of like tenor.

      9.    REGISTRATION RIGHTS.  The Holder of this Warrant has been
granted certain registration rights by the Company.  These registration
rights are set forth in a Registration Rights  Agreement entered into by
the Company and Purchaser at or prior to the issue date of this Warrant.

      10. MAXIMUM EXERCISE. The Holder shall not be entitled to exercise this
Warrant on an exercise date, in connection with that number of shares of Common
Stock which would result in beneficial ownership by the Holder and its
affiliates of more than 4.99% of the shares of Common Stock of the Company on
such date. For the purposes of the proviso to the immediately preceding
sentence, beneficial ownership shall be determined in accordance with Section
13(d) of the Securities Exchange Act of 1934, as amended, and Regulation 13d-3
thereunder. Subject to the foregoing, the Holder shall not be limited to
aggregate exercises which would result in the issuance of more than 4.99%. The
restriction described in this paragraph may be revoked upon 75 days prior notice
from the Holder to the Company and is automatically null and void upon an Event
of Default under the Preferred Stock.

      11. WARRANT AGENT. The Company may, by written notice to the each holder
of the Warrant, appoint an agent for the purpose of issuing Common Stock (or
Other Securities) on the exercise of this Warrant pursuant to Section 1,
exchanging this Warrant pursuant to Section 7, and replacing this Warrant
pursuant to Section 8, or any of the foregoing, and thereafter any such


                                       6
<PAGE>
issuance, exchange or replacement, as the case may be, shall be made at such
office by such agent.

      12. TRANSFER ON THE COMPANY'S BOOKS. Until this Warrant is transferred on
the books of the Company, the Company may treat the registered holder hereof as
the absolute owner hereof for all purposes, notwithstanding any notice to the
contrary.

      13. NOTICES, ETC. All notices and other communications from the Company to
the Holder of this Warrant shall be mailed by first class registered or
certified mail, postage prepaid, at such address as may have been furnished to
the Company in writing by such holder or, until any such Holder furnishes to the
Company an address, then to, and at the address of, the last Holder of this
Warrant who has so furnished an address to the Company.

      14. MISCELLANEOUS. This Warrant and any term hereof may be changed,
waived, discharged or terminated only by an instrument in writing signed by the
party against which enforcement of such change, waiver, discharge or termination
is sought. This Warrant shall be governed by and construed in accordance with
the laws of State of New York without regard to principles of conflicts of laws.
Any action brought concerning the transactions contemplated by this Warrant
shall be brought only in the state courts of New York or in the federal courts
located in the state of New York; provided, however, that the Holder may choose
to waive this provision and bring an action outside the state of New York. The
individuals executing this Warrant on behalf of the Company agree to submit to
the jurisdiction of such courts and waive trial by jury. The prevailing party
shall be entitled to recover from the other party its reasonable attorney's fees
and costs. In the event that any provision of this Warrant is invalid or
unenforceable under any applicable statute or rule of law, then such provision
shall be deemed inoperative to the extent that it may conflict therewith and
shall be deemed modified to conform with such statute or rule of law. Any such
provision which may prove invalid or unenforceable under any law shall not
affect the validity or enforceability of any other provision of this Warrant.
The headings in this Warrant are for purposes of reference only, and shall not
limit or otherwise affect any of the terms hereof. The invalidity or
unenforceability of any provision hereof shall in no way affect the validity or
enforceability of any other provision. The Company acknowledges that legal
counsel participated in the preparation of this Warrant and, therefore,
stipulates that the rule of construction that ambiguities are to be resolved
against the drafting party shall not be applied in the interpretation of this
Warrant to favor any party against the other party.

                      [THIS SPACE INTENTIONALLY LEFT BLANK]


                                       7
<PAGE>
      IN WITNESS WHEREOF, the Company has executed this Warrant under seal as of
the date first written above.

                                          JMAR TECHNOLOGIES, INC.



                                          By: /s/ JOSEPH G. MARTINEZ



Witness:



/s/ DENNIS E. VALENTINE


                                       8
<PAGE>
                                                                       EXHIBIT A

                            FORM OF SUBSCRIPTION
                 (To be signed only on exercise of Warrant)

TO:   JMAR Technologies, Inc.

The undersigned, pursuant to the provisions set forth in the attached Warrant
(No.____), hereby irrevocably elects to purchase (check applicable box):

___   ________ shares of the Common Stock covered by such Warrant; or

___ the maximum number of shares of Common Stock covered by such Warrant
pursuant to the cashless exercise procedure set forth in Section 2.

The undersigned herewith makes payment of the full Exercise Price for such
shares at the price per share provided for in such Warrant, which is
$___________. Such payment takes the form of (check applicable box or boxes):

___ the cancellation of such portion of the attached Warrant as is exercisable
for a total of _______ shares of Common Stock (using a Fair Market Value of
$_______ per share for purposes of this calculation); and/or

___ the cancellation of such number of shares of Common Stock as is necessary,
in accordance with the formula set forth in Section 2, to exercise this Warrant
with respect to the maximum number of shares of Common Stock purchaseable
pursuant to the cashless exercise procedure set forth in Section 2.

The undersigned requests that the certificates for such shares be issued in the
name of, and delivered to ____________________ whose address is _______________

_____________________________________.

The undersigned represents and warrants that all offers and sales by the
undersigned of the securities issuable upon exercise of the within Warrant shall
be made pursuant to registration of the Common Stock under the Securities Act of
1933, as amended (the "Securities Act") or pursuant to an exemption from
registration under the Securities Act.

Dated:___________________           _______________________________________
                                    (Signature must conform to name of
                                    holder as specified on the face of the
                                    Warrant)

                                    _______________________________________
                                    (Address)
<PAGE>
                                                                       EXHIBIT B

                         FORM OF TRANSFEROR ENDORSEMENT
                   (To be signed only on transfer of Warrant)

            For value received, the undersigned hereby sells, assigns, and
transfers unto the person(s) named below under the heading "Transferees" the
right represented by the within Warrant to purchase the percentage and number of
shares of Common Stock of JMAR Technologies, Inc. to which the within Warrant
relates specified under the headings "Percentage Transferred" and "Number
Transferred," respectively, opposite the name(s) of such person(s) and appoints
each such person Attorney to transfer its respective right on the books of JMAR
Technologies, Inc. with full power of substitution in the premises.



<TABLE>
<CAPTION>
        Transferees                 Percentage                  Number
                                   Transferred               Transferrred
________________________________________________________________________________
<S>                                <C>                       <C>

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________
</TABLE>


Dated:___________________           _______________________________________
                                    (Signature must conform to name of
                                    holder as specified on the face of the
                                    Warrant)

Signed in the presence of:

________________________________    ________________________________________
             (Name)                                (address)

ACCEPTED AND AGREED:                ________________________________________
[TRANSFEREE]                                       (address)

________________________________
            (Name)