Exhibit 4.6


THIS WARRANT AND THE SHARES OF COMMON STOCK ISSUABLE UPON EXERCISE OF THIS
WARRANT HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED,
AND MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED
OR EXERCISED UNLESS AND UNTIL SAID SECURITY IS REGISTERED UNDER SUCH ACT OR AN
OPINION OF COUNSEL SATISFACTORY TO THE COMPANY IS OBTAINED TO THE EFFECT THAT
SUCH REGISTRATION IS NOT REQUIRED. THIS WARRANT AND THE SHARES OF COMMON STOCK
ISSUABLE UPON EXERCISE OF THIS WARRANT ARE SUBJECT TO THE RESTRICTIONS ON
TRANSFER SET FORTH IN SECTIONS 4 AND 10 OF THIS WARRANT.

Ladenburg Thalmann Warrant No. 1                       Number of Shares:  84,083
                                                         (subject to adjustment)
Date of Issuance:  June 21, 2000


                                APA OPTICS, INC.

                          Common Stock Purchase Warrant

                           (Void after June 20, 2003)

         APA Optics, Inc., a Minnesota corporation (the "Company"), for value
received, hereby certifies that Ladenburg Thalmann & Co. Inc., or its registered
assigns (the "Registered Holder"), is entitled, subject to the terms and
conditions set forth below, to purchase from the Company, at any time or from
time to time on or after the date of issuance and on or before 5:00 p.m.
(Eastern time) on June 20, 2003, 84,083 shares of Common Stock, $.01 par value
per share, of the Company, at a purchase price of $17.8395 per share. The shares
purchasable upon exercise of this Warrant, and the purchase price per share,
each as adjusted from time to time pursuant to the provisions of this Warrant,
are hereinafter referred to as the "Warrant Shares" and the "Purchase Price,"
respectively.

         1. Exercise.

                  (a) This Warrant may be exercised by the Registered Holder, in
whole or in part, by surrendering this Warrant, with the purchase form appended
hereto as Exhibit I duly executed by the Registered Holder or by the Registered
Holder's duly authorized attorney, at the principal office of the Company, or at
such other office or agency as the Company may designate, accompanied by payment
in full, in lawful money of the United States, of the Purchase Price payable in
respect of the number of Warrant Shares purchased upon such exercise.

                  (b) The Registered Holder may, at its option, elect to pay
some or all of the Purchase Price payable upon an exercise of this Warrant by
cancelling a portion of this Warrant. If the Registered Holder wishes to
exercise this Warrant by this method, the number of Warrant Shares purchasable
(which shall in no event exceed the total number of Warrant Shares purchasable
under this Warrant as set forth above, subject to adjustment under Section 2 of
this Warrant) shall be determined as follows:



<PAGE>

                  X = Y [(A-B) / A]

                  X = the number of Warrant Shares to be issued to the Holder.

                  Y = the number of Warrant Shares with respect to which this
                      Warrant is being exercised.

                  A = the Fair Market Value of one share of Common Stock.

                  B = the Purchase Price of one share of Common Stock.

The Fair Market Value per share of Common Stock shall be determined as follows:

                  (i) If the Common Stock is listed on a national securities
         exchange, the Nasdaq National Market or another nationally recognized
         trading system (including, without limitation, the OTC Bulletin Board
         and, if the average daily trading volume for the preceding 10 days has
         been at least 100,000 shares, the Pink Sheets) as of the Exercise Date,
         the Fair Market Value per share of Common Stock shall be deemed to be
         the average of the high and low reported sale prices per share of
         Common Stock thereon on the trading day immediately preceding the
         Exercise Date (provided that if no such price is reported on such day,
         the Fair Market Value per share of Common Stock shall be determined
         pursuant to clause (ii)).

                  (ii) If the Common Stock is not listed on a national
         securities exchange, the Nasdaq National Market or another nationally
         recognized trading system as of the Exercise Date, the Fair Market
         Value per share of Common Stock shall be deemed to be the amount most
         recently determined by the Board of Directors to represent the fair
         market value per share of the Common Stock (including without
         limitation a determination for purposes of granting Common Stock
         options or issuing Common Stock under an employee benefit plan of the
         Company); and, upon request of the Registered Holder, the Board of
         Directors (or a representative thereof) shall promptly notify the
         Registered Holder of the Fair Market Value per share of Common Stock.
         Notwithstanding the foregoing, if the Board of Directors has not made
         such a determination within the three-month period prior to the
         Exercise Date, then (A) the Board of Directors shall make a
         determination of the Fair Market Value per share of the Common Stock
         within 15 days of a request by the Registered Holder that it do so, and
         (B) the exercise of this Warrant pursuant to this subsection 1(b) shall
         be delayed until such determination is made.

                  (c) Each exercise of this Warrant shall be deemed to have been
effected immediately prior to the close of business on the day on which this
Warrant shall have been surrendered to the Company as provided in subsection
1(a) above accompanied by payment in full of the Purchase Price (the "Exercise
Date"). At such time, the person or persons in whose name or names any
certificates for Warrant Shares shall be issuable upon such exercise as provided
in subsection 1(d) below shall be deemed to have become the holder or holders of
record of the Warrant Shares represented by such certificates.



                                       2
<PAGE>

                  (d) As soon as practicable after the exercise of this Warrant
in full or in part, and in any event within 5 business days thereafter, the
Company, at its expense, will cause to be issued in the name of, and delivered
to, the Registered Holder, or as such Holder (upon payment by such Holder of any
applicable transfer taxes) may direct:

                  (i) a certificate or certificates for the number of full
         Warrant Shares to which the Registered Holder shall be entitled upon
         such exercise plus, in lieu of any fractional share to which the
         Registered Holder would otherwise be entitled, cash in an amount
         determined pursuant to Section 3 hereof; and

                  (ii) in case such exercise is in part only, a new warrant or
         warrants (dated the date hereof) of like tenor, calling in the
         aggregate on the face or faces thereof for the number of remaining
         Warrant Shares (without giving effect to any adjustment therein).

         2. Adjustments.

                  (a) Adjustment for Stock Splits and Combinations. If the
Company shall at any time or from time to time after the date on which this
Warrant was first issued (the "Original Issue Date") effect a subdivision of the
outstanding Common Stock, the Purchase Price then in effect immediately before
that subdivision shall be proportionately decreased. If the Company shall at any
time or from time to time after the Original Issue Date combine the outstanding
shares of Common Stock, the Purchase Price then in effect immediately before the
combination shall be proportionately increased. Any adjustment under this
paragraph shall become effective at the close of business on the date the
subdivision or combination becomes effective.

                  (b) Adjustment for Certain Dividends and Distributions. In the
event the Company at any time, or from time to time after the Original Issue
Date shall make or issue, or fix a record date for the determination of holders
of Common Stock entitled to receive, a dividend or other distribution payable in
additional shares of Common Stock, then and in each such event the Purchase
Price then in effect immediately before such event shall be decreased as of the
time of such issuance or, in the event such a record date shall have been fixed,
as of the close of business on such record date, by multiplying the Purchase
Price then in effect by a fraction:

                           (1) the numerator of which shall be the total number
                  of shares of Common Stock issued and outstanding immediately
                  prior to the time of such issuance or the close of business on
                  such record date, and

                           (2) the denominator of which shall be the total
                  number of shares of Common Stock issued and outstanding
                  immediately prior to the time of such issuance or the close of
                  business on such record date plus the number of shares of
                  Common Stock issuable in payment of such dividend or
                  distribution;

provided, however, if such record date shall have been fixed and such dividend
is not fully paid or if such distribution is not fully made on the date fixed
therefor, the Purchase Price shall be recomputed accordingly as of the close of
business on such record date and thereafter the




                                       3
<PAGE>

Purchase Price shall be adjusted pursuant to this paragraph as of the time of
actual payment of such dividends or distributions.

                  (c) Adjustment in Number of Warrant Shares. When any
adjustment is required to be made in the Purchase Price pursuant to subsections
2(a) or 2(b), the number of Warrant Shares purchasable upon the exercise of this
Warrant shall be changed to the number determined by dividing (i) an amount
equal to the number of shares issuable upon the exercise of this Warrant
immediately prior to such adjustment, multiplied by the Purchase Price in effect
immediately prior to such adjustment, by (ii) the Purchase Price in effect
immediately after such adjustment.

                  (d) Adjustment for Mergers or Reorganizations, etc. If there
shall occur any reorganization, recapitalization, consolidation or merger
involving the Company in which the Common Stock is converted into or exchanged
for securities, cash or other property (other than a transaction covered by
subsections 2(a) or 2(b)), then, following any such reorganization,
recapitalization, consolidation or merger, the Registered Holder shall receive
upon exercise hereof the kind and amount of securities, cash or other property
which the Registered Holder would have been entitled to receive if, immediately
prior to such reorganization, recapitalization, consolidation or merger, the
Registered Holder had held the number of shares of Common Stock subject to this
Warrant ("Substituted Property"). In the event that the Company is not the
acquiring or surviving entity in such transaction, then the acquiror or
survivor, at its option, may repurchase this Warrant, effective not later than
the effective date of the acquisition, merger, or other transaction, by issuing
to the Holder the Substituted Property which would have been issuable if the
Holder had chosen to exercise this Warrant in full using the exercise method
described in Section 1(b), above, at the time of the repurchase.

                  (e) Certificate as to Adjustments. Upon the occurrence of each
adjustment or readjustment of the Purchase Price pursuant to this Section 2, the
Company at its expense shall promptly compute such adjustment or readjustment in
accordance with the terms hereof and furnish to the Registered Holder a
certificate setting forth such adjustment or readjustment (including the kind
and amount of securities, cash or other property for which this Warrant shall be
exercisable and the Purchase Price) and showing in detail the facts upon which
such adjustment or readjustment is based. The Company shall, upon the written
request at any time of the Registered Holder, furnish or cause to be furnished
to the Registered Holder a certificate setting forth (i) the Purchase Price then
in effect and (ii) the number of shares of Common Stock and the amount, if any,
of other securities, cash or property which then would be received upon the
exercise of this Warrant.

         3. Fractional Shares. The Company shall not be required upon the
exercise of this Warrant to issue any fractional shares, but shall make an
adjustment therefor in cash on the basis of the Fair Market Value per share of
Common Stock, as determined pursuant to subsection 1(b) above.

         4. Requirements for Transfer.

                  (a) This Warrant and the Warrant Shares shall not be sold or
transferred unless either (i) they first shall have been registered under the
Securities Act of 1933, as



                                       4
<PAGE>

amended (the "Act"), or (ii) the Company first shall have been furnished with an
opinion of legal counsel, reasonably satisfactory to the Company, to the effect
that such sale or transfer is exempt from the registration requirements of the
Act.

                  (b) Notwithstanding the foregoing, no registration or opinion
of counsel shall be required for (i) a transfer by a Registered Holder which is
a corporation to a wholly owned subsidiary of such corporation, a transfer by a
Registered Holder which is a partnership to a partner of such partnership or a
retired partner of such partnership or to the estate of any such partner or
retired partner, a transfer by a Registered Holder which is a limited liability
company to a member of such limited liability company or a retired member or to
the estate of any such member or retired member, or a transfer by a Registered
Holder which is a member of the National Association of Securities Dealers (the
"NASD") to an officer of the Registered Holder as permitted by NASD rules,
provided that the transferee in each case agrees in writing to be subject to the
terms of this Section 4, or (ii) a transfer made in accordance with Rule 144
under the Act.

                  (c) Each certificate representing Warrant Shares shall bear a
legend substantially in the following form:

                  "The securities represented by this certificate have not been
                  registered under the Securities Act of 1933, as amended, and
                  may not be offered, sold or otherwise transferred, pledged or
                  hypothecated unless and until such securities are registered
                  under such Act or an opinion of counsel satisfactory to the
                  Company is obtained to the effect that such registration is
                  not required."

The foregoing legend shall be removed from the certificates representing any
Warrant Shares, at the request of the holder thereof, at such time as they
become eligible for resale pursuant to Rule 144(k) under the Act.

         5. No Impairment. The Company will not, by amendment of its charter or
through any reorganization, transfer of assets, consolidation, merger,
dissolution, issue or sale of securities or any other voluntary action, avoid or
seek to avoid the observance or performance of any of the terms of this Warrant,
but will at all times in good faith assist in the carrying out of all such terms
and in the taking of all such action as may be necessary or appropriate in order
to protect the rights of the holder of this Warrant against impairment.

         6. Notices of Record Date, etc. In the event:

                  (a) the Company shall take a record of the holders of its
Common Stock (or other stock or securities at the time deliverable upon the
exercise of this Warrant) for the purpose of entitling or enabling them to
receive any dividend or other distribution, or to receive any right to subscribe
for or purchase any shares of stock of any class or any other securities, or to
receive any other right; or

                  (b) of any capital reorganization of the Company, any
reclassification of the Common Stock of the Company, any consolidation or merger
of the Company with or into another corporation (other than a consolidation or
merger in which the Company is the surviving



                                       5
<PAGE>

entity and its Common Stock is not converted into or exchanged for any other
securities or property), or any transfer of all or substantially all of the
assets of the Company; or

                  (c) of the voluntary or involuntary dissolution, liquidation
or winding-up of the Company,

then, and in each such case, the Company will mail or cause to be mailed to the
Registered Holder a notice specifying, as the case may be, (i) the record date
for such dividend, distribution or right, and the amount and character of such
dividend, distribution or right, or (ii) the effective date on which such
reorganization, reclassification, consolidation, merger, transfer, dissolution,
liquidation or winding-up is to take place, and the time, if any is to be fixed,
as of which the holders of record of Common Stock (or such other stock or
securities at the time deliverable upon the exercise of this Warrant) shall be
entitled to exchange their shares of Common Stock (or such other stock or
securities) for securities or other property deliverable upon such
reorganization, reclassification, consolidation, merger, transfer, dissolution,
liquidation or winding-up. Such notice shall be mailed at least ten days prior
to the record date or effective date for the event specified in such notice.
Failure by the Company to give timely notice, as specified above, shall not
invalidate any action taken by the Board of Directors or the stockholders in
connection with the matter to which the record date relates.

         7. Reservation of Stock. The Company will at all times reserve and keep
available, solely for issuance and delivery upon the exercise of this Warrant,
such number of Warrant Shares and other securities, cash and/or property, as
from time to time shall be issuable upon the exercise of this Warrant.

         8. Exchange of Warrants. Upon the surrender of this Warrant by the
Registered Holder, properly endorsed, to the Company at the principal office of
the Company, the Company will, subject to the provisions of Section 4 hereof,
issue and deliver to or upon the order of such Holder, at the Company's expense,
a new Warrant or Warrants of like tenor, in the name of the Registered Holder or
as the Registered Holder (upon payment by the Registered Holder of any
applicable transfer taxes) may direct, calling in the aggregate on the face or
faces thereof for the number of shares of Common Stock (or other securities,
cash and/or property) then issuable upon exercise of this Warrant.

         9. Replacement of Warrants. Upon receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Warrant and (in the case of loss, theft or destruction) upon delivery of an
indemnity agreement (with surety if reasonably required) in an amount reasonably
satisfactory to the Company, or (in the case of mutilation) upon surrender and
cancellation of this Warrant, the Company will issue, in lieu thereof, a new
Warrant of like tenor.



                                       6
<PAGE>

         10. Transfers, etc.

                  (a) The Company will maintain a register containing the name
and address of the Registered Holder of this Warrant. The Registered Holder may
change its or his address as shown on the warrant register by written notice to
the Company requesting such change.

                  (b) Subject to the provisions of Section 4 hereof, this
Warrant and all rights hereunder are transferable, in whole or in part, upon
surrender of this Warrant with a properly executed assignment (in the form of
Exhibit II hereto) at the principal office of the Company.

                  (c) Until any transfer of this Warrant is made in the warrant
register, the Company may treat the Registered Holder as the absolute owner
hereof for all purposes; provided, however, that if and when this Warrant is
properly assigned in blank, the Company may (but shall not be obligated to)
treat the bearer hereof as the absolute owner hereof for all purposes,
notwithstanding any notice to the contrary.

         11. Representations of the Registered Holder. The Registered Holder of
this Warrant represents and warrants to the Company as follows:

                  (a) Investment. The Registered Holder is acquiring this
Warrant and the Warrant Shares issuable upon the exercise of this Warrant, for
its own account for investment and not with a view to, or for sale in connection
with, any distribution thereof, nor with any present intention of distributing
or selling the same, except as otherwise may be permitted under applicable
securities laws.

                  (b) Authority. The Registered Holder has full power and
authority to enter into and to perform this Warrant in accordance with its
terms. The Registered Holder has not been organized, reorganized or
recapitalized specifically for the purpose of investing in the Company.

                  (c) Accredited Investor. The Registered Holder is an
Accredited Investor within the definition set forth in Rule 501(a) promulgated
under the Securities Act.

         12. Mailing of Notices, etc. All notices and other communications from
the Company to the Registered Holder shall be mailed by first-class certified or
registered mail, postage prepaid, to the address last furnished to the Company
in writing by the Registered Holder. All notices and other communications from
the Registered Holder or in connection herewith to the Company shall be mailed
by first-class certified or registered mail, postage prepaid, to the Company at
its principal office set forth below. If the Company should at any time change
the location of its principal office to a place other than as set forth below,
it shall give prompt written notice to the Registered Holder and thereafter all
references in this Warrant to the location of its principal office at the
particular time shall be as so specified in such notice.

         13. No Rights as Stockholder. Until the exercise of this Warrant, the
Registered Holder shall not have or exercise any rights by virtue hereof as a
stockholder of the Company. Notwithstanding the foregoing, in the event (i) the
Company effects a split of the Common Stock by means of a stock dividend and the
Purchase Price of and the number of Warrant Shares are adjusted as of the date
of the distribution of the dividend (rather than as of the record date for



                                       7
<PAGE>

such dividend), and (ii) the Registered Holder exercises this Warrant between
the record date and the distribution date for such stock dividend, the
Registered Holder shall be entitled to receive, on the distribution date, the
stock dividend with respect to the shares of Common Stock acquired upon such
exercise, notwithstanding the fact that such shares were not outstanding as of
the close of business on the record date for such stock dividend.

         14. Change or Waiver. Any term of this Warrant may be changed or waived
only by an instrument in writing signed by the party against which enforcement
of the change or waiver is sought.

         15. Section Headings. The section headings in this Warrant are for the
convenience of the parties and in no way alter, modify, amend, limit or restrict
the contractual obligations of the parties.

         16. Governing Law. This Warrant will be governed by and construed in
accordance with the internal laws of the State of Minnesota (without reference
to the conflicts of law provisions thereof).

         EXECUTED as of the Date of Issuance indicated above.

                                    APA OPTICS, INC.



                                    By:________________________________
                                    Title:_______________________________

ATTEST:



_________________________




                                       8
<PAGE>


                                                                       EXHIBIT I

                                  PURCHASE FORM

To:_________________                                          Dated:____________


         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 1(b).

         The undersigned herewith makes payment of the full purchase 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):

         [ ]      $______ in lawful money of the United States; and/or

         [ ]      the cancellation of such portion of the attached Warrant as is
                  exercisable for a total of _____ Warrant Shares (using a Fair
                  Market Value of $_____ per share for purposes of this
                  calculation); and/or

         [ ]      the cancellation of such number of Warrant Shares as is
                  necessary, in accordance with the formula set forth in Section
                  1(b), to exercise this Warrant with respect to the maximum
                  number of Warrant Shares purchasable pursuant to the cashless
                  exercise procedure set forth in Section 1(b).

                                    Signature: ______________________

                                      Address: ______________________

                                               ______________________


<PAGE>


                                                                      EXHIBIT II

                                 ASSIGNMENT FORM



FOR VALUE RECEIVED, ________________________________________ hereby sells,
assigns and transfers all of the rights of the undersigned under the attached
Warrant (No. ____) with respect to the number of shares of Common Stock covered
thereby set forth below, unto:

Name of Assignee                    Address                        No. of Shares
----------------                    -------                        -------------





Dated:_____________________           Signature:________________________________
                                                     Signature Guaranteed:

By: ________________________________
The signature should be guaranteed by
an eligible guarantor institution (banks,
stockbrokers, savings and loan associations
and credit unions with membership in
an approved signature guarantee medallion
program) pursuant to Rule 17Ad-15
under the Securities Exchange Act of 1934.