Document:

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                                                                   EXHIBIT 10.17

                                 LOAN AGREEMENT

         This Loan Agreement (this "Agreement") is made as of August 2, 2001, by
and between Cell Robotics International, Inc., a Colorado corporation (the
"Borrower"), and Dipl. Ing. Oton Tisch (the "Lender").

                              PRELIMINARY STATEMENT

         The Borrower wishes to borrow from the Lender, and the Lender is
willing to lend to the Borrower, an aggregate of up to U.S.$500,000, on the
terms and subject to the conditions provided in this Agreement.

                                    AGREEMENT

         The parties, intending to be legally bound, agree as follows:

1.       DEFINITIONS.

         "Agreement" shall have the meaning provided in the introductory
paragraph of this Agreement.

         "Applicable Law" shall mean all laws, rules and regulations applicable
to the Person, conduct, action, covenant or Loan Documents in question,
including, but not limited to, all applicable common law and equitable
principles, all provisions of all applicable state and federal constitutions,
statutes, rules, regulations and orders of governmental body, and all orders,
judgments and decrees of all courts and arbitrators.

         "Bankruptcy Code" shall mean the United States Bankruptcy Code of 1978,
as amended.

         "Borrower" shall have the meaning provided in the introductory
paragraph of this Agreement.

         "Common Stock" shall mean the common stock of the Borrower, par value
$.004 per share.

         "Default Rate" shall mean the rate per annum equal to the lesser of (a)
12% and (b) the Maximum Legal Rate.

         "Event of Default" shall mean the occurrence of any event or the
existence of any condition specified in Section 6.1.

         "Indebtedness" shall mean all indebtedness, liabilities and obligations
owing, arising, due or payable from the Borrower to the Lender under the Note.

         "Initial Loan" shall have the meaning ascribed to such term in Section
2.1.

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         "Lender" shall have the meaning provided in the introductory paragraph
of this Agreement.

         "Loan" shall mean the Initial Loan and the other loans provided by the
Lender to Borrower under Section 2.1.

         "Loan Documents" shall mean this Agreement, the Note, the Security
Agreement and all other documents and instruments heretofore, now or hereafter
evidencing, describing, guaranteeing or securing the Loan contemplated hereby or
delivered in connection with this Agreement.

         "Maximum Legal Rate" shall have the meaning ascribed to such term in
Section 7.1.

         "Note" shall have the meaning ascribed to such term in Section 2.2.

         "Person" shall mean any natural person, corporation, unincorporated
organization, trust, joint-stock company, joint venture, association, company,
limited or general partnership, any government or any agency or political
subdivision of any government.

         "Registrable Securities" shall mean Shares issued or issuable upon the
exercise of the Warrant and conversion of the Note and any warrants or options
and any Shares issued as a dividend, stock split or other distribution with
respect to or in exchange for or in replacement of such Shares; provided,
however, that Registrable Securities shall not include any Shares which have
previously been registered or which have been sold to the public either pursuant
to a registration statement or Rule 144, or which have been sold in a private
transaction in which the transferor's rights under this Agreement are not
assigned or are not assignable.

         "Registration Statement" shall have the meaning ascribed to such term
in Section 5.1.

         "Rule 144" shall mean Rule 144 as promulgated by the SEC under the
Securities Act, as such rule may be amended from time to time, or any similar
successor rule that may be promulgated by the SEC.

         "SEC" shall mean the Securities and Exchange Commission.

         "Securities Act" shall mean the Securities Act of 1933, as amended, and
the rules and regulations promulgated thereunder.

         "Security Agreement" shall mean that certain Security Agreement dated
the date hereof between the Borrower and the Lender, as the same may be amended,
modified or supplemented from time to time.

         "Shares" shall mean shares of the Borrower's Common Stock.

         "Warrant" shall mean that certain Warrant dated the date hereof issued
by the Borrower to the Lender for the purchase of up to 37,500 Shares.

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         "UCC" means the Uniform Commercial Code as in effect from time to time
in the State of New Mexico or other applicable jurisdiction, as amended at the
time in question.

2.       LOAN; NOTE.

         2.1. Loan. On or before August 3, 2001, Lender agrees to loan the
Borrower in immediately available funds an amount equal to $200,000 (the
"Initial Loan"). Additionally, Lender agrees to loan to Borrower in immediately
available funds an amount equal to $300,000, upon Borrower's request, at any
time after August 31, 2001; provided that between the date of the Initial Loan
and the date of such request, Borrower has not consummated the sale or issuance
by the Borrower of any class or series of Common Stock or other securities of
the Borrower (other than to Lender) pursuant to a private or public round of
financing for capital raising purposes providing gross proceeds to the Borrower
of at least $300,000.

         2.2. Note. The Loan shall be evidenced by a promissory note mutually
acceptable to the Lender and the Borrower (as the same may be amended, modified,
supplemented or renewed from time to time, the "Note"), which shall be executed
by the Borrower and delivered to the Lender contemporaneously with the making of
the Initial Loan.

3.       REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE LENDER.

         Lender makes the following representations, warranties and covenants as
of the date hereof:

         3.1. Valid Existence; Power and Authority. The Lender has the power and
legal capacity to make and perform the Loan Documents executed by him or it, and
all such Loan Documents will constitute the legal, valid and binding obligation
of the Lender, enforceable in accordance with their respective terms, subject
only to bankruptcy, insolvency, reorganization, moratorium or similar laws
affecting creditors' rights generally, and by general principles of equity.

         3.2. Authority; Non-Contravention. The execution, delivery and
performance of the Loan Documents by the Lender (a) have been duly authorized by
all necessary action of the Lender, as applicable, and (b) do not violate (i)
any provision of Applicable Law, or (ii) any provision of any agreement to which
such Lender is bound, except where the violation thereof could not reasonably be
expected to have a material adverse effect on such Lender.

         3.3. Further Assurances. Until payment in full of the Loan, the Lender
shall take such further actions and provide to the Borrower such further
assurances as may be reasonably requested by the Borrower to ensure compliance
with the intent of the Loan Documents.

         3.4 Accredited Investor. The Lender qualifies as an "accredited
investor" as defined in Rule 501(a) of Regulation D under the Securities Act.
The Lender is purchasing the Note, the Warrant and the Shares issued upon
conversion of the Note and exercise of the Warrant for Lender's own account for
investment purposes only and not with a view to, or for the resale in connection
with, any "distribution" thereof for purposes of the Securities Act. By
executing this

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Agreement, the Lender further represents that it does not have any contract,
undertaking, agreement or arrangement with any person to sell, transfer or grant
participation to such person or to any third person, with respect to the Note,
the Warrant or any of the Shares issuable upon conversion or exercise thereof.
The Lender understands that the Note, the Warrant and the Shares issued upon
conversion of the Note and exercise of the Warrant have not been registered
under the Securities Act or any applicable state securities laws by reason of a
specific exemption therefrom that depends upon, among other things, the bona
fide nature of the investment intent as expressed herein.

         3.5 Access to Information. The Lender has received or been made
available all such information as the Lender deems necessary and appropriate to
enable the Lender to evaluate the financial risk inherent in making an
investment in the Note, the Warrant and the Shares issued upon conversion of the
Note and exercise of the Warrant, including, but not limited to, the Borrower's
Form 10-KSB's, Form 10-QSB's and various press releases. The Lender has received
satisfactory and complete information concerning the business and financial
condition of the Borrower in response to the Lender's inquiries. The Lender
recognizes that the investment in the Borrower involves substantial risks. The
Lender is able, without impairing the Lender's financial condition, to hold the
Note, the Warrant and the Shares issued upon conversion of the Note and exercise
of the Warrant for an indefinite period of time and to suffer a complete loss of
the Lender's investment. The Lender understands all of the risks related to the
purchase of the Note, the Warrant and the Shares issued upon conversion of the
Note and exercise of the Warrant. By virtue of the Lender's experience in
evaluating and investing in private placement transactions of securities in
companies similar to the Borrower, the Lender is capable of evaluating the
merits and risks of the Lender's investment in the Borrower and has the capacity
to protect the Lender's own interests.

         3.6 Limitation on Transfer; Legends. The Lender understands that the
Note, the Warrant and the Shares issued upon conversion of the Note and exercise
of the Warrant must be held indefinitely unless and until subsequently
registered under the Securities Act or unless an exemption from registration is
otherwise available. The Lender is aware of Rule 144 that permits limited resale
of securities purchased in a private placement subject to the satisfaction of
certain conditions. The Lender understands that the Note and the Shares issued
upon conversion of the Note will be imprinted with a legend which prohibits the
transfer of the Note and such Shares unless they are registered or such
registration is not required in the opinion of counsel for the Borrower. The
legend relating to the Securities Act endorsed pursuant to this Section 3.6 and
the stop transfer instructions with respect to the Shares represented thereby
shall be removed and the Borrower shall issue a certificate or instrument
without such legend to the Lender if the Note and the Shares issued upon
conversion of the Note are registered under the Securities Act and a prospectus
meeting the requirements of Section 10 of the Securities Act is available, or if
the Lender provides to the Borrower an opinion of counsel for Lender reasonably
satisfactory to the Borrower or a no-action letter or interpretive opinion of
the staff of the SEC to the effect that a public sale, transfer or assignment of
the Note and the Shares issued upon conversion of the Note may be made without
registration and without compliance with any restriction such as Rule 144. Any
legend imposed by state securities laws will be removed if the state agency
imposing such legend has consented to its removal.

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4.       REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE BORROWER.

         The Borrower makes the following representations, warranties and
covenants as of the date hereof:

         4.1. Valid Existence; Power and Authority. The Borrower is a
corporation duly organized, validly existing and in good standing under the laws
of the jurisdiction of its incorporation and is duly qualified to transact
business in all places where the failure to be so qualified would have a
material adverse effect on it. The Borrower has the power to make and perform
the Loan Documents executed by it, and all such Loan Documents will constitute
the legal, valid and binding obligations of the Borrower, enforceable in
accordance with their respective terms, subject only to bankruptcy, insolvency,
reorganization, moratorium or similar laws affecting creditors' rights
generally, and by general principles of equity.

         4.2. Authority; Non-Contravention. The execution, delivery and
performance of the Loan Documents by the Borrower (a) have been duly authorized
by all necessary corporate action of the Borrower, and (b) do not violate (i)
any provision of Applicable Law, (ii) any provision of the articles of
incorporation or bylaws of the Borrower or (iii) any governing instrument or
agreement to which the Borrower is bound, except where the violation thereof
could not reasonably be expected to have a material adverse effect on the
Borrower.

         4.3. Further Assurances. Until payment in full of the Loan, the
Borrower shall take such further actions and provide to the Lender such further
assurances as may be reasonably requested by the Lender to ensure compliance
with the intent of the Loan Documents.

         4.4. Use of Proceeds. The proceeds of the Loan shall be used by the
Borrower solely for payment of existing indebtedness, capital expenditures,
working capital and other general corporate needs.

5.       REGISTRATION RIGHTS.

         5.1 Registration by the Company. Subject to the terms and conditions of
this Agreement, the Borrower shall file with the SEC within thirty (30) days
following the date the SEC declares effective the Post-Effective Amendment No. 6
to Form SB-2 (333-40895) a registration statement on Form SB-2 under the
Securities Act (the "Registration Statement") for the registration of the resale
by the Lender of the Registrable Securities. The Borrower shall use reasonable
best efforts to cause such filed Registration Statement to become and remain
effective (pursuant to Rule 415 under the Securities Act or otherwise); prepare
and file with the SEC such amendments and supplements to such Registration
Statement and the prospectus used in connection therewith as may be necessary to
keep such Registration Statement effective during the term of this Agreement;
and comply in all material respects with the provisions of the Securities Act
with respect to the disposition of all Registrable Securities covered by such
Registration Statement during such period in accordance with the intended
methods of disposition by the Lender. It is a condition precedent to the
obligations of the Borrower under this Section 5.1 that Lender shall furnish to
the Borrower in writing such information regarding the Lender, the Registrable
Securities and the intended method of disposition thereof as the

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Borrower shall reasonably request and as shall be required in connection with
the action to be taken by the Borrower. So long as the Borrower complies with
this Section 5.1, the Lender shall have no right to take any action to restrain,
enjoin or otherwise delay any registration as the result of any controversy that
might arise with respect to the interpretation or implementation of this Article
5.

         5.2 Market Standoff Rights. Lender agrees that in connection with an
underwritten sale of Shares to the public effected pursuant to a registration
statement filed with, and declared effective by, the SEC under the Securities
Act, if requested by the Borrower and the managing underwriters in such
offering, not to effect any public sale or distribution or other transfer or
disposal (including encumbrances) of any of the Borrower's securities (other
than securities acquired in or after such offering), including a sale pursuant
to Rule 144 (except as part of such underwritten offering), for a period of up
to 180 days after the closing date of such underwritten offering. The Borrower
may impose stop-transfer instructions with respect to the Shares (or other
securities) subject to the foregoing restriction until the end of such 180-day
period; provided, however, that the foregoing obligation shall be conditioned
upon all officers and directors of the Borrower entering into similar agreements
and not being released from such agreements at any time before or during such
180-day period.

         5.3 Termination of Registration Rights. Except as set forth in this
Section 5.3, the right of Lender to request registration or inclusion in any
registration pursuant to this Article 5 and the obligations of the Borrower
under this Article 5 shall terminate if all Shares of Registrable Securities
held or entitled to be held upon exercise or conversion by the Lender may
immediately be sold under Rule 144 during any 90-day period. The provisions of
Section 5.3 shall not apply if the Lender owns more than ten percent of the
outstanding Common Stock until such time as the Lender owns less than ten
percent of the outstanding Common Stock.

         5.4 Indemnification. If any Registrable Securities are included in a
registration statement under this Agreement:

                  (a) To the extent permitted by law, the Borrower will defend,
indemnify and hold harmless the Lender and any underwriter (as defined in the
Securities Act) for the Lender and each person, if any, who controls the Lender
or such underwriter within the meaning of the Securities Act, from and against
any and all loss, damage, liability, cost and expense to which the Lender or any
such underwriter or controlling person may become subject under the Securities
Act or otherwise, insofar as such losses, damages, liabilities, costs or
expenses are caused by any untrue statement or alleged untrue statement of any
material fact contained in such registration statement, any prospectus contained
therein or any amendment or supplement thereto, or arise out of or are based
upon the omission or alleged omission to state therein a material fact required
to be stated therein or necessary to make the statements therein, in light of
the circumstances in which they were made, not misleading (each, a "Violation");
provided, however, that the Borrower will not be liable in any such case to the
extent that any such loss, damage, liability, cost or expenses arises out of or
is based upon an untrue statement or alleged untrue statement or omission or
alleged omission so made in conformity with information furnished by the Lender,
such underwriter or such controlling person in writing specifically for use in
the preparation thereof.

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                  (b) To the extent permitted by law, the Lender will defend,
indemnify and hold harmless the Borrower and any underwriter (as defined in the
Securities Act) and each person, if any, who controls the Borrower or such
underwriter within the meaning of the Securities Act, from and against any and
all loss, damage, liability, cost and expense to which the Borrower or any such
underwriter or controlling person may become subject under the Securities Act or
otherwise, insofar as such losses, damages, liabilities, costs or expenses are
caused by any Violation, in each case to the extent such Violation arises out of
or is based upon an untrue statement or alleged untrue statement of any material
fact or omission or alleged omission to state therein a material fact so made in
conformity with information furnished by the Lender, such underwriter or such
controlling person in writing specifically for use in the preparation of a
registration statement, any prospectus contained therein or any amendment or
supplement thereto.

                  (c) Promptly after receipt by an indemnified party under this
Section 5.4 of notice of the commencement of any action (including any
governmental action), such indemnified party shall, if a claim in respect
thereof is to be made against any indemnifying party under this Section 5.4,
deliver to the indemnifying party a written notice of the commencement thereof
and the indemnifying party shall have the right to participate in, and, to the
extent the indemnifying party so desires, jointly with any other indemnifying
party similarly noticed, to assume the defense thereof with counsel mutually
satisfactory to the parties; provided, however, that an indemnified party
(together with all other indemnified parties which may be represented without
conflict by one counsel) will have the right to retain one separate counsel,
with the reasonable fees and expenses to be paid by the indemnifying party, if
representation of such indemnified party by the counsel retained by the
indemnifying party is inappropriate due to actual or potential differing
interests between such indemnified party and any other party represented by such
counsel in such proceeding. The failure to deliver written notice to the
indemnifying party within a reasonable time of the commencement of any such
action, if materially prejudicial to its ability to defend such action, shall
relieve such indemnifying party of any liability to the indemnified party under
this Section 5.4, but the omission so to deliver written notice to the
indemnifying party shall not relieve it of any liability that it may have to any
indemnified party otherwise than under this Section 5.4.

6.       DEFAULTS AND REMEDIES.

         6.1. Events of Default. The following shall constitute an Event of
Default with respect to the Indebtedness:

                  (a) Any representation or warranty made by the Borrower under
or in connection with the Loan Documents which shall prove to have been
incorrect in any material respect when made, or any failure by the Borrower to
perform or observe any term, covenant or agreement contained in the Loan
Documents on its part to be performed or observed, and if capable of being
remedied such failure shall remain unremedied for 30 days after written notice
thereof shall have been given to the Borrower by the Lender;

                  (b) The Borrower shall fail to pay any of the Indebtedness on
the due date thereon (whether due at stated maturity, on demand, upon
acceleration or otherwise) and such failure shall not be remedied within five
days after the occurrence thereof; or

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                  (c) The Borrower shall (i) become insolvent within the meaning
of the Bankruptcy Code, (ii) admit in writing its inability to pay or otherwise
fail to pay its debts generally as they become due, (iii) voluntarily seek,
consent to or acquiesce in the benefit or benefits of any Debtor Relief Law
(meaning the Bankruptcy Code and all other applicable liquidation,
conservatorship, bankruptcy, moratorium, rearrangement, receivership,
insolvency, reorganization or similar debtor relief laws from time to time in
effect affecting the rights of creditors generally) or (iv) be made the subject
of an involuntary case for bankruptcy (or a petition for a receiving order)
which is not dismissed within 60 days after commencement of the case.

         6.2. Acceleration of the Indebtedness. Upon or at any time after the
occurrence of an Event of Default, the principal amount of the Indebtedness then
outstanding together with all interest accrued thereon shall, at the option of
the Lender and without notice or demand by the Lender, become at once due and
payable and the Borrower shall forthwith pay to the Lender, in addition to any
and all sums and charges due, the entire principal of and accrued and unpaid
interest on the Indebtedness plus reasonable attorneys' fees and expenses, if
the same is collected by or through an attorney at law. From and after the
occurrence and during the continuance of an Event of Default, the Indebtedness
shall bear interest at the Default Rate.

         6.3. Remedies. Upon or at any time after the occurrence of any Event of
Default, the Lender shall have and may exercise, at its election, from time to
time any and all rights and remedies available to a secured party under the UCC,
in addition to any and all other rights and remedies afforded by this Agreement,
at law, in equity or otherwise, including, without limitation, (a) declaring the
entire unpaid balance of the Indebtedness, or any part thereof, immediately due
and payable, whereupon it shall be due and payable; (b) reducing any claim to
judgment; and (c) bringing suit or other proceedings before any appropriate
court either for specific performance of any covenant or condition contained in
this Agreement or in aid of the exercise of any right granted to the Lender in
this Agreement.

7.       MISCELLANEOUS.

         7.1. Maximum Rate of Interest. Notwithstanding anything to the contrary
contained herein, no provisions of the Loan Documents shall require the payment
or permit the collection of interest in excess of the maximum rate permitted by
law (the "Maximum Legal Rate"). If any excess of interest in such respect is
herein provided for, or shall be adjudicated to be so provided, in the Loan
Documents or otherwise in connection with this loan transaction, the provisions
of this paragraph shall govern and prevail, and neither the Borrower nor the
sureties, guarantors, successors or assigns of the Borrower shall be obligated
to pay the excess amount of such interest, or any other excess sum paid for the
use, forbearance or detention of sums evidenced hereby. If for any reason
interest in excess of the Maximum Legal Rate shall be deemed charged, required
or permitted by any court of competent jurisdiction, any such excess shall be
applied as a payment and reduction of the principal amount hereof until it has
been paid in full, and any remaining excess shall forthwith be paid to the
Borrower. In determining whether or not the interest paid or payable exceeds the
Maximum Legal Rate, the Borrower and the Lender shall, to the extent permitted
by Applicable Law, (a) characterize any non-principal payment as

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an expense, fee or premium rather than as interest, (b) exclude voluntary
prepayments and the effects thereof and (c) amortize, prorate, allocate and
spread in equal or unequal parts the total amount of interest throughout the
entire contemplated term of the Note so that the interest for the entire term
does not exceed the Maximum Legal Rate.

         7.2. No Third Party Beneficiaries. This Agreement shall not confer any
rights or remedies upon any Person other than the parties and their respective
successors and permitted assigns.

         7.3. Entire Agreement. This Agreement (including the documents referred
to in this Agreement) and the other Loan Documents constitute the entire
agreement among the parties and supersede any prior understandings, agreements
or representations by or among the parties, written or oral, to the extent they
relate in any way to the subject matter hereof.

         7.4. Succession and Assignment. This Agreement shall be binding upon
and inure to the benefit of the parties named in this Agreement and their
respective successors and permitted assigns. No party may assign either this
Agreement or any of its rights, interests or obligations hereunder without the
prior written approval of the other party.

         7.5. Counterparts. This Agreement may be executed in one or more
counterparts, each of which shall be deemed an original but all of which
together shall constitute one and the same instrument.

         7.6. Headings. The article and section headings contained in this
Agreement are inserted for convenience only and shall not affect in any way the
meaning or interpretation of this Agreement.

         7.7. Notices. All notices, requests, demands, claims and other
communications under this Agreement and the other Loan Documents shall be in
writing. Any notice, request, demand, claim or other communication hereunder
shall be deemed duly given if (and then two business days after) it is sent by
(a) confirmed facsimile; (b) overnight delivery; or (c) registered or certified
mail, return receipt requested, postage prepaid, and addressed to the intended
recipient as set forth below:

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        If to the Borrower:                    Cell Robotics International, Inc.
                                               2715 Broadbent Parkway N.E.
                                               Albuquerque, New Mexico 87107
                                               Attn: Ronald K. Lohrding, Ph.D.
                                               Telephone: (505) 343-1131
                                               Facsimile: (505) 344-8112

        With a copy to, which copy shall not   Baker & McKenzie
        constitute notice:                     2001 Ross Avenue, Suite 2300
                                               Dallas, Texas 75201
                                               Attn: W. Crews Lott
                                               Telephone: (214) 978-3000
                                               Facsimile: (214) 978-3099

        If to the Lender:                      Dipl. Ing. Oton Tisch
                                               Apartado 76949
                                               Caracas 1070 Venezuela

Either party may send any notice, request, demand, claim or other communication
hereunder to the intended recipient at the address set forth above using any
other means (including personal delivery, expedited courier, messenger service,
telecopy, telex, ordinary mail or electronic mail), but no such notice, request,
demand, claim or other communication shall be deemed to have been duly given
unless and until it actually is received by the intended recipient. Either party
may change the address to which notices, requests, demands, claims and other
communications hereunder are to be delivered by giving the other party notice in
the manner provided in this Agreement.

         7.8. GOVERNING LAW. THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED
IN ACCORDANCE WITH THE DOMESTIC LAWS OF THE STATE OF NEW MEXICO WITHOUT GIVING
EFFECT TO ANY CHOICE OR CONFLICT OF LAW PROVISION OR RULE (WHETHER OF THE STATE
OF NEW MEXICO OR ANY OTHER JURISDICTION) THAT WOULD CAUSE THE APPLICATION OF THE
LAWS OF ANY JURISDICTION OTHER THAN THE STATE OF NEW MEXICO. Any legal action or
proceeding with respect to any Loan Document shall be brought in any New Mexico
state or federal court sitting in Bernalillo County, New Mexico, and, by
execution and delivery of this Agreement, each party hereby accepts for itself
and in respect of its property, generally and unconditionally, the jurisdiction
of the aforesaid courts. Each party hereby irrevocably waives any objection,
including, without limitation, any objection to the laying of venue or based on
the grounds of forum non conveniens, which it may now or hereafter have to the
bringing of any such action or proceeding in such respective jurisdictions.

         7.9. Amendments; Waivers; Remedies Cumulative. No amendment of any
provision of this Agreement shall be valid unless the same shall be in writing
and signed by the Borrower, and the Lender. No failure on the part of the Lender
to exercise, and no delay by the Lender in exercising, any right or remedy
hereunder or under any other Loan Document shall operate as a waiver thereof,
nor shall any single or partial exercise of any right or remedy hereunder
preclude any other or further exercise thereof or the exercise of any other
right or remedy. The rights and

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remedies herein provided are cumulative and are in addition to any other rights
and remedies provided by Applicable Law, any Loan Document or otherwise.

         7.10. Severability. Any term or provision of this Agreement that is
invalid or unenforceable in any situation in any jurisdiction shall not affect
the validity or enforceability of the remaining terms and provisions hereof or
the validity or enforceability of the offending term or provision in any other
situation or in any other jurisdiction.

         7.11. Construction. The parties have participated jointly in the
negotiation and drafting of this Agreement. In the event an ambiguity or
question of intent or interpretation arises, this Agreement shall be construed
as if drafted jointly by the parties and no presumption or burden of proof shall
arise favoring or disfavoring any party by virtue of the authorship of any of
the provisions of this Agreement. Any reference to any federal, state, local or
foreign statute or law shall be deemed also to refer to all rules and
regulations promulgated thereunder, unless the context requires otherwise. The
word "including" shall mean "including, without limitation." The terms "herein,"
"hereof" and "hereunder" and other words of similar import refer to this
Agreement as a whole and not to any particular section, paragraph or
subdivision. Any pronoun used shall be deemed to cover all genders. Terms
defined in the singular have the same meaning when used in the plural and vice
versa. All references to any instruments or agreements, including, without
limitation, references to this Agreement and any of the other Loan Documents,
shall include any and all modifications or amendments thereto and any and all
extensions or renewals thereof.

         7.12 Expenses. The Borrower shall pay all costs and other expenses
incurred in connection with the preparation and negotiation of the Loan
Documents, provided that the Borrower shall not be responsible for the attorney
fees of Lender's counsel to the extent they exceed $2,000.

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         The parties have executed and delivered this Agreement as of the date
of the first sentence of this Agreement.

THE BORROWER:

CELL ROBOTICS INTERNATIONAL, INC.

By: /s/ Ronald K. Lohrding, Ph.D.
   ------------------------------
   Ronald K. Lohrding, Ph.D.
   President and CEO

THE LENDER:

/s/ Dipl. Ing. Oton Tisch
---------------------------------
Dipl. Ing. Oton Tisch

                                       12<PAGE>   1
                                                                   EXHIBIT 10.18

THIS NOTE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED
(THE "SECURITIES ACT"), OR ANY STATE SECURITIES LAWS AND MAY NOT BE OFFERED,
SOLD, PLEDGED OR OTHERWISE TRANSFERRED OR DISPOSED OF UNLESS AND UNTIL THIS NOTE
IS REGISTERED UNDER THE SECURITIES ACT AND APPLICABLE STATE SECURITIES LAWS OR
AN EXEMPTION FROM SUCH REGISTRATION IS AVAILABLE.

                                 PROMISSORY NOTE

$500,000.00                                                       August 2, 2001

         FOR VALUE RECEIVED, the undersigned, CELL ROBOTICS INTERNATIONAL, INC.,
a Colorado corporation ("Maker"), promises to pay to the order of DIPL. ING.
OTON TISCH ("Payee"), at Apartado 76949, Caracas 1070 Venezuela (or such other
place as Payee may from time to time designate), the sum of Five Hundred
Thousand and No/100 Dollars ($500,000.00), or so much as may have been advanced
hereunder, together with interest on the unpaid principal balance from time to
time outstanding at a rate per annum equal to ten percent (calculated on the
basis of the actual number of days elapsed, but computed as if each calendar
year consisted of 365 days). This Note is the "Note" referred to in that certain
Loan Agreement, dated August 2, 2001 (the "Loan Agreement"), by and between
Payee and Maker. Capitalized terms used but not defined herein shall have the
meanings ascribed to those terms in the Loan Agreement. Notwithstanding anything
to the contrary contained herein, no provision of this Note shall require the
payment or permit the collection of interest in excess of the Maximum Legal
Rate.

         Interest on this Note shall accrue from the date hereof. All principal
of and interest on this Note shall be paid on August 2, 2002.

         All past due principal of and accrued interest on this Note shall bear
interest from maturity (stated, by acceleration, or otherwise) until
indefeasibly paid in full at the lesser of 12% and the Maximum Legal Rate.

         1. Optional Prepayments. Maker, at any time and from time to time, may
prepay the unpaid principal amount of this Note in whole or in part without
premium; provided, however, that any such optional prepayment shall be applied
to accrued but unpaid interest and then to the unpaid principal amount of this
Note.

         2. Events of Default and Remedies. Upon or at any time after the
occurrence of an Event of Default, the principal amount of this Note together
with all interest accrued thereon shall, at the option of Payee and without
notice or demand by Payee, become at once due and payable and Maker shall
forthwith pay to Payee, in addition to any and all sums and charges due, the
entire principal of and accrued and unpaid interest on this Note plus reasonable
attorneys' fees and expenses, if the same are collected by or through an
attorney at law. Upon or at any time after the occurrence of any Event of
Default, Payee shall have and may exercise, at its election, from time to time
any and all rights and remedies available to a secured party under the UCC (as
defined in the Loan Agreement), in addition to any and all other rights and
remedies

<PAGE>   2

afforded by this Note, at law, in equity or otherwise, including, without
limitation, (a) declaring the entire unpaid balance of this Note, or any part
thereof, immediately due and payable, whereupon it shall be due and payable; (b)
reducing any claim to judgment; and (c) bringing suit or other proceedings
before any appropriate court either for specific performance of any covenant or
condition contained in this Note or in aid of the exercise of any right granted
to Payee in this Note.

         3. Optional Conversion. This Note shall be convertible at the option of
the Maker, in whole or in part, at any time or from time to time into the number
of fully paid and nonassessable shares of common stock ("Common Stock") of Maker
equal to the unpaid principal amount of this Note plus the accrued but unpaid
interest hereon divided by the Conversion Price (as defined below) in effect
from time to time. In the event of any such conversion, the amount due under
this Note shall be reduced by an amount equal to the number of shares of Common
Stock issued upon such conversion multiplied by the applicable Conversion Price,
with the amount of such reduction being first applied to accrued and unpaid
interest and then to principal.

                  (a) Conversion Procedures. If Maker desires to convert this
Note into Common Stock, Payee shall surrender this Note to Maker at its
principal executive offices, accompanied by proper instruments of transfer to
Maker or in blank, accompanied by irrevocable written notice to Maker of the
name or names (with address) in which a certificate or certificates for Common
Stock are to be issued. Maker shall, as soon as practicable after such written
notice and compliance with any other conditions herein contained, deliver at
such office to Payee, certificates for the number of full shares of Common Stock
or other securities to which it shall be entitled, adjusted by any fraction of a
share as hereinafter provided. Subject to the following provisions of this
paragraph, such conversion shall be deemed to have been made as of the date of
such surrender of this Note, and the person or persons entitled to receive the
Common Stock or other securities deliverable upon conversion shall be treated
for all purposes as the record holder or holders thereof on such date. Upon
partial conversion of this Note, a new Note containing the same date and
provisions of this Note shall be issued by the Payee to the Maker for the
principal balance of this Note and interest which shall not have been converted
or paid.

                  (b) Conversion Price; Certain Adjustments. The conversion
price for determining the number of shares of Common Stock deliverable upon
conversion (the "Conversion Price") shall be the lesser of (i) $0.5994 per share
of Common Stock (the "Initial Conversion Price") or (ii) ninety percent (90%) of
the average closing price per share of the Common Stock for the fifteen (15)
trading days ending on the trading day immediately prior to the date of
conversion. Notwithstanding the foregoing, in no event shall the Conversion
Price be less than $.30 per share of Common Stock (the "Conversion Price
Floor"). The Initial Conversion Price and the Conversion Price Floor and the
number of securities issuable upon conversion of this Note shall be subject to
adjustment from time to time as follows:

                           (i) In the event of any change in the Common Stock by
         reason of any combination, subdivision, split, reclassification, stock
         dividend or any similar change affecting the Common Stock, then in any
         such event the Initial Conversion Price and the Floor Conversion Price
         shall be adjusted, in such manner as the Board of Directors deems

                                       2
<PAGE>   3

         equitable to prevent substantial dilution or enlargement of the rights
         granted to the Payee. The adjustment shall become effective immediately
         after the record date in the case of a dividend or distribution and
         immediately after the effective date in the case of a subdivision,
         combination or reclassification. Such adjustment shall be made
         successively whenever any event listed above shall occur.

                           (ii) In the event that at any time, as a result of
         any adjustment made pursuant to these provisions, Payee shall become
         entitled to receive any shares of Maker other than shares of Common
         Stock or to receive any other securities, the number of such other
         shares or securities so receivable upon conversion of this Note shall
         be subject to adjustment from time to time in a manner and on terms as
         nearly equivalent as practicable to the provisions contained in these
         provisions with respect to the Common Stock.

                  (c) Reclassification, Consolidation, Merger or Sale of Assets.
If at any time while this Note is outstanding and unexpired there shall be (i) a
reorganization of the Maker, (ii) a merger or consolidation of the Maker with or
into another entity in which the Maker is not the surviving entity, or a reverse
triangular merger in which the Maker is the surviving entity but the shares of
the Maker's capital stock outstanding immediately prior to the merger are
converted by virtue of the merger into other property, whether in the form of
securities, cash or otherwise, or (iii) a sale or transfer of the Maker's
properties and assets as, or substantially as, an entirety to any other Person,
then lawful and adequate provision will be made whereby the Payee will
thereafter have the right to purchase and receive upon the basis and upon the
terms and conditions specified in this Note and in lieu of the shares of Common
Stock of the Maker immediately theretofore purchasable and receivable upon the
conversion of this Note, the kind and amount of stock and other securities and
assets (including, without limitation, cash) receivable upon such merger,
consolidation or sale by a holder of the number of shares of Common Stock
deliverable upon the conversion of this Note immediately prior to such merger,
consolidation or sale. In any such case, appropriate provisions will be made
with respect to the rights and interests of the Payee to the end that the
provisions hereof (including, without limitation, provisions for adjustments of
the Conversion Price and of the number of shares of Common Stock purchasable
upon the conversion of this Note) will thereafter be applicable, as nearly as
may be, in relation to any shares of stock, securities or assets thereafter
deliverable upon the conversion hereof. The foregoing provisions of this Section
shall similarly apply to successive reorganizations, mergers, consolidations and
sales and to the stock or securities of any other corporation that are at the
time receivable upon the conversion of this Note. If this Section applies to a
transaction, Section 3(b)(i) and (ii) shall not apply to such transaction.

                  (d) Notice of Adjustment. Whenever the Conversion Price is
adjusted, the Maker shall promptly mail to the Payee a notice setting forth the
Conversion Price after such adjustment and setting forth a brief statement of
the facts requiring such adjustment. Such certificate prepared in good faith
shall be conclusive evidence of the correctness of such adjustment absent
manifest error.

                  (e) Maker Determination Final. Any determination that the
Maker or the Board of Directors must make pursuant to this Note is conclusive
absent manifest error.

                                       3
<PAGE>   4

                  (f) When No Adjustment Required. No adjustment need be made
for any transaction referred to in Section 3(b)(i) and Section 3(c) if the Payee
is entitled to participate in the transaction on a basis and with notice that
the Board of Directors determines to be fair and appropriate in light of the
basis and notice on which holders of Common Stock participate in the
transaction. No adjustment need be made for a change in the par value or no par
value of the Common Stock.

                  (g) No Fractional Shares. The Maker shall not be required to
issue fractions of shares of Common Stock upon conversion of this Note or to
distribute certificates which evidence fractional shares of Common Stock. If the
conversion of this Note would result in a fractional share of Common Stock or
the right to acquire a fractional share of Common Stock, such fractional share
shall be disregarded and the number of shares of Common Stock issuable upon the
conversion of this Note shall be rounded up or down to the nearest whole share.
The Payee expressly waives his right to receive any fractional shares upon
conversion of this Note.

                  (h) Reservation of Shares; Etc. Subject to the terms and
conditions of the immediately following sentence, Maker shall at all times
reserve and keep available, out of its authorized and unissued stock, solely for
the purpose of effecting the conversion of this Note, such number of shares of
its Common Stock and other securities free of preemptive rights as shall from
time to time be sufficient to effect the conversion of this Note. Maker shall
from time to time, in accordance with the laws of the state of its
incorporation, use its reasonable best efforts to increase the authorized number
of shares of Common Stock if at any time the number of shares of Common Stock
not outstanding shall not be sufficient to permit the conversion of this Note.
If any shares of Common Stock required to be reserved for purposes of conversion
of this Note require registration with or approval of any governmental authority
under any Federal or State law before such shares may be issued upon conversion,
Maker will in good faith endeavor to cause such shares to be duly registered or
approved, as the case may be. If the Common Stock is listed on the New York
Stock Exchange, the Nasdaq National Market, or any other national securities
exchange, Maker will, if permitted by the rules of such exchange, list and keep
listed on such exchange, upon official notice of issuance, all shares of Common
Stock issuable upon conversion of this Note.

                  (i) Payment of Taxes. The issuance of a certificate or
certificates for shares of Common Stock upon conversion of this Note shall be
made without charge for any stamp or other similar tax in respect of such
issuance. However, if any such certificate is to be issued in a name other than
that of the Payee, the Person or Persons requesting the issuance thereof shall
pay to the Maker the amount of any tax which may be payable in respect of any
transfer involved in such issuance or shall establish to the satisfaction of the
Maker that such tax has been paid.

         4. Cumulative Rights. No failure on the part of Payee to exercise, and
no delay by Payee in exercising, any right or remedy hereunder shall operate as
a waiver thereof, nor shall any single or partial exercise of any right or
remedy hereunder preclude any other or further exercise thereof or the exercise
of any other right or remedy. The rights and remedies herein provided are
cumulative and are in addition to any other rights and remedies provided by
Applicable Law or otherwise.

                                       4
<PAGE>   5

         5. Waiver. Maker, and each surety, endorser, guarantor and other party
ever liable for the payment of any sum of money payable on this Note, jointly
and severally waive demand, presentment, protest, notice of nonpayment, notice
of intention to accelerate, notice of acceleration, notice of protest and any
and all lack of diligence or delay in the collection or filing of suit hereon
which may occur; agree that their liability on this Note shall not be affected
by any renewal or extension in the time of payment hereof, by any indulgences,
or by any release or change in any security for the payment of this Note; and
hereby consent to any and all renewals, extensions, indulgences, releases or
changes hereof or hereto, regardless of the number of such renewals, extensions,
indulgences, releases or changes.

         6. NO ORAL AGREEMENTS. THIS NOTE (ALONG WITH THE OTHER LOAN DOCUMENTS)
REPRESENTS THE FINAL AGREEMENT BETWEEN MAKER AND PAYEE AND MAY NOT BE
CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS
OF MAKER AND PAYEE. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN MAKER AND
PAYEE.

         7. GOVERNING LAW. THIS NOTE SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE DOMESTIC LAWS OF THE STATE OF NEW MEXICO WITHOUT GIVING
EFFECT TO ANY CHOICE OR CONFLICT OF LAW PROVISION OR RULE (WHETHER OF THE STATE
OF NEW MEXICO OR ANY OTHER JURISDICTION) THAT WOULD CAUSE THE APPLICATION OF THE
LAWS OF ANY JURISDICTION OTHER THAN THE STATE OF NEW MEXICO. Any legal action or
proceeding with respect to this Note shall be brought in any New Mexico state or
federal court sitting in Bernalillo County, New Mexico, and, by execution and
delivery of this Note, Maker hereby accepts for itself and in respect of its
property, generally and unconditionally, the jurisdiction of the aforesaid
courts. Maker hereby irrevocably waives any objection, including, without
limitation, any objection to the laying of venue or based on the grounds of
forum non conveniens, which it may now or hereafter have to the bringing of any
such action or proceeding in such respective jurisdictions.

         8. Severability. Any term or provision of this Note that is invalid or
unenforceable in any situation in any jurisdiction shall not affect the validity
or enforceability of the remaining terms and provisions hereof or the validity
or enforceability of the offending term or provision in any other situation or
in any other jurisdiction.

         9. Succession and Assignment. This Note shall be binding upon and inure
to the benefit of Maker and Payee and their respective successors and permitted
assigns. Payee may not assign either this Note or any of its rights, interests
or obligations hereunder without the prior written approval of the Maker.

                                       5
<PAGE>   6

         IN WITNESS WHEREOF, the undersigned has executed this Note as of the
day and year first above written.

                                       CELL ROBOTICS INTERNATIONAL, INC.

                                       By: /s/ Ronald K. Lohrding, Ph.D.
                                          --------------------------------------
                                          Ronald K. Lohrding, Ph.D.
                                          President and CEO

                                       6

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