Exhibit 4.3


                        THIRD AMENDED AND RESTATED BYLAWS
                                       OF
                             VEECO INSTRUMENTS INC.
                               (THE "CORPORATION")

                           EFFECTIVE OCTOBER 26, 2000



1.       MEETINGS OF STOCKHOLDERS.

         1.1 ANNUAL MEETING. The annual meeting of stockholders shall be held at
a place and time determined by the board of directors (the "Board").

         1.2 SPECIAL MEETINGS. Special meetings of the stockholders may be
called by resolution of the Board or by the president or chief executive officer
and shall be called by the president, chief executive officer or secretary upon
the written request (stating the purpose or purposes of the meeting) of a
majority of the directors then in office or of the holders of 50% of the
outstanding shares entitled to vote. Only business related to the purposes set
forth in the notice of the meeting may be transacted at a special meeting.

         1.3 PLACE AND TIME OF MEETINGS. Meetings of the stockholders may be
held in or outside Delaware at the place and time specified by the Board, the
chief executive officer of the Corporation or the directors or stockholders
requesting the meeting (as applicable).

         1.4 NOTICE OF MEETINGS; WAIVER OF NOTICE. Written notice of each
meeting of stockholders shall be given to each stockholder entitled to vote at
the meeting, except that (a) it shall not be necessary to give notice to any
stockholder who submits a signed waiver of notice before or after the meeting,
and (b) no notice of an adjourned meeting need be given except when required
under Section 1.6 of these bylaws or by law. Each notice of a meeting shall be
given, personally or by mail, not less than 10 nor more than 60 days before the
meeting and shall state the time and place of the meeting, and unless it is the
annual meeting, shall state at whose direction or request the meeting is called
and the purposes for which it is called. If mailed, notice shall be considered
given when mailed to a stockholder at his address on the Corporation's records.
The attendance of any stockholder at a meeting, without protesting at the
beginning of the meeting that the meeting is not lawfully called or convened,
shall constitute a waiver of notice by him.

         1.5 NATURE OF BUSINESS AT MEETINGS OF STOCKHOLDERS. No business may be
transacted at an annual or special meeting of stockholders, other than business
that is either (a) specified in the notice of meeting (or any supplement
thereto) given by or at the direction of the Board (or any duly authorized
committee thereof), (b) otherwise properly brought before the meeting by or at
the direction of the Board (or any duly authorized committee thereof) or (c)
otherwise properly brought before the meeting by any stockholder of the
Corporation (i) who is a stockholder of record on the date of the giving of the
notice provided for in this Section 1.5 and on the record date for the
determination of stockholders entitled to vote at such meeting and (ii) who
complies with the notice procedures set forth in this Section 1.5.







         In addition to any other applicable requirements, for business to be
properly brought before an annual or special meeting by a stockholder, such
stockholder must have given timely notice thereof in proper written form to the
secretary of the Corporation.

         To be timely, a stockholder's notice to the secretary must be delivered
to or mailed and received at the principal executive offices of the Corporation
(a) in the case of an annual meeting, not less than ninety (90) days nor more
than one hundred and twenty (120) days prior to the anniversary date of the
immediately preceding annual meeting of stockholders; PROVIDED, HOWEVER, that in
the event that the annual meeting is called for a date that is not within thirty
(30) days before or after such anniversary date, notice by the stockholder in
order to be timely must be so received not later than the close of business on
the tenth (10th) day following the day on which such notice of the date of the
annual meeting was mailed or such public disclosure of the date of the annual
meeting was made, whichever first occurs; and (b) in the case of a special
meeting, not less than ninety (90) days nor more than one hundred and twenty
(120) days prior to such special meeting.

         To be in proper written form, a stockholder's notice to the secretary
must set forth as to each matter such stockholder proposes to bring before the
meeting (i) a brief description of the business desired to be brought before the
meeting and the reasons for conducting such business at the meeting, (ii) the
name and record address of such stockholder, (iii) the class or series and
number of shares of capital stock of the Corporation which are owned
beneficially or of record by such stockholder, (iv) a description of all
arrangements or understandings between such stockholder and any other person or
persons (including their names) in connection with the proposal of such business
by such stockholder and any material interest of such stockholder in such
business and (v) a representation that such stockholder intends to appear in
person or by proxy at the meeting to bring such business before the meeting.

         At the same time or prior to the submission of any stockholder proposal
of business to be conducted at an annual or special meeting that, if approved,
could not be implemented by the Corporation without notifying or obtaining the
consent or approval of any federal, state, municipal or other regulatory body,
the proponent stockholder or stockholders shall submit to the secretary of the
Corporation an analysis, satisfactory to the Board, demonstrating that the
proposal will have no material detrimental effect on the business and operations
of the Corporation after making the requisite notices or obtaining the requisite
consents or approvals and after giving effect to the potential responses
thereto.

         No business shall be conducted at a meeting of stockholders except
business brought before the meeting in accordance with the procedures set forth
in this Section 1.5; PROVIDED, HOWEVER, that, once business has been properly
brought before the meeting in accordance with such procedures, nothing in this
Section 1.5 shall be deemed to preclude discussion by any stockholder of any
such business. If the chairman of the meeting determines that business was not
properly brought before the meeting in accordance with such procedures, the
chairman shall declare to the meeting that the business was not properly brought
before the meeting and such business shall not be transacted.

         1.6 QUORUM. At any meeting of stockholders, the presence in person or
by proxy of


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the holders of 50% of the shares entitled to vote shall constitute a quorum for
the transaction of any business. In the absence of a quorum, a majority in
voting interest of those present or, if no stockholders are present, any officer
entitled to preside at or to act as secretary of the meeting, may adjourn the
meeting until a quorum is present. At any adjourned meeting at which a quorum is
present any action may be taken which might have been taken at the meeting as
originally called. No notice of an adjourned meeting need be given if the time
and place are announced at the meeting at which the adjournment is taken except
that, if adjournment is for more than thirty days or if, after the adjournment,
a new record date is fixed for the meeting, notice of the adjourned meeting
shall be given pursuant to Section 1.4.

         1.7 VOTING; PROXIES. Each stockholder of record shall be entitled to
one vote for every share registered in his name. Corporate action to be taken by
stockholder vote, other than the election of directors, shall be authorized by a
majority of the votes cast at a meeting of stockholders, except as otherwise
provided by law or by Section 1.9 of these bylaws. Directors shall be elected in
the manner provided in Section 2.1 of these bylaws. Voting need not be by ballot
unless ordered by the chairman of the meeting; however, all elections of
directors shall be by written ballot, unless otherwise provided in the
certificate of incorporation. Each stockholder entitled to vote at any meeting
of stockholders or to express consent to or dissent from corporate action in
writing without a meeting may authorize another person to act for him by proxy.
Every proxy must be signed by the stockholder or his attorney-in-fact. No proxy
shall be valid after three years from its date unless it provides otherwise.

         1.8 LIST OF STOCKHOLDERS. Not less than 10 days prior to the date of
any meeting of stockholders, the secretary of the Corporation shall prepare a
complete list of stockholders entitled to vote at the meeting, arranged in
alphabetical order and showing the address of each stockholder and the number of
shares registered in his name. For a period of not less than 10 days prior to
the meeting, the list shall be available during ordinary business hours for
inspection by any stockholder for any purpose germane to the meeting. During
this period, the list shall be kept either (a) at a place within the city where
the meeting is to be held, if that place shall have been specified in the notice
of the meeting, or (b) if not so specified, at the place where the meeting is to
be held. The list shall also be available for inspection by stockholders at the
time and place of the meeting.

         1.9 ACTION BY CONSENT WITHOUT A MEETING. No action required or
permitted to be taken at any meeting of stockholders may be taken by written
consent without a meeting.

2.       BOARD OF DIRECTORS.

         2.1 NUMBER, QUALIFICATION, ELECTION AND TERM OF DIRECTORS. The business
of the Corporation shall be managed by the Board. The Board shall consist of not
less than three nor more then fifteen members, the exact number of which shall
be determined from time to time by resolution adopted by a majority vote of the
directors then serving, but no decrease in the number of directors that
constitutes the Board may shorten the term of any incumbent director. Subject to
the rights of the holders of any series of preferred stock to elect additional
directors under specified circumstances, the directors shall be divided into
three (3) classes designated as Class I, Class II and Class III, respectively,
as nearly equal in size as possible. Unless otherwise provided in the
certificate of incorporation, directors shall be elected at each annual meeting
of


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stockholders and shall hold office for a full term of three (3) years to succeed
the directors of the class whose terms expire at such annual meeting. Each
director shall also serve until the election and qualification of their
respective successors, subject to the provisions of Section 2.10. As used in
these bylaws, the term "entire Board" means the total number of directors which
the Corporation would have if there were no vacancies on the Board.

         2.2 NOMINATION OF DIRECTORS. Only persons who are nominated in
accordance with the following procedures shall be eligible for election as
directors of the Corporation, except as may be otherwise provided in the
Certificate of Incorporation with respect to the right of holders of preferred
stock of the Corporation, if any, to nominate and elect a specified number of
directors in certain circumstances. Nominations of persons for election to the
Board may be made at any annual meeting of stockholders, or at any special
meeting of stockholders called for the purpose of electing directors, (a) by or
at the direction of the Board (or any duly authorized committee thereof) or (b)
by any stockholder of the Corporation (i) who is a stockholder of record on the
date of the giving of the notice provided for in this Section 2.2 and on the
record date for the determination of stockholders entitled to vote at such
meeting and (ii) who complies with the notice procedures set forth in this
Section 2.2.

             In addition to any other applicable requirements, for a
nomination to be made by a stockholder, such stockholder must have given timely
notice thereof in proper written form to the secretary of the Corporation.

             To be timely, a stockholder's notice to the secretary must be
delivered to or mailed and received at the principal executive offices of the
Corporation (a) in the case of an annual meeting, not less than ninety (90) days
nor more than one hundred and twenty (120) days prior to the anniversary date of
the immediately preceding annual meeting of stockholders; PROVIDED, HOWEVER,
that in the event that the annual meeting is called for a date that is not
within thirty (30) days before or after such anniversary date, notice by the
stockholder in order to be timely must be so received not later than the close
of business on the tenth (10th) day following the day on which such notice of
the date of the annual meeting was mailed or such public disclosure of the date
of the annual meeting was made, whichever first occurs; and (b) in the case of a
special meeting of stockholders called for the purpose of electing directors,
not less than ninety (90) days nor more than one hundred and twenty (120) days
prior to such special meeting.

             To be in proper written form, a stockholder's notice to the
secretary must set forth (a) as to each person whom the stockholder proposes to
nominate for election as a director (i) the name, age, business address and
residence address of the person, (ii) the principal occupation or employment of
the person, (iii) the class or series and number of shares of capital stock of
the Corporation which are owned beneficially or of record by the person and (iv)
any other information relating to the person that would be required to be
disclosed in a proxy statement or other filings required to be made in
connection with solicitations of proxies for election of directors pursuant to
Section 14 of the Securities Exchange Act of 1934, as amended (the "Exchange
Act"), and the rules and regulations promulgated thereunder; and (b) as to the
stockholder giving the notice (i) the name and record address of such
stockholder, (ii) the class or series and number of shares of capital stock of
the Corporation which are owned beneficially or of record by such stockholder,
(iii) a description of all arrangements or understandings between such
stockholder and each proposed nominee and any other person or persons (including
their


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names) pursuant to which the nomination(s) are to be made by such
stockholder, (iv) a representation that such stockholder intends to appear in
person or by proxy at the meeting to nominate the persons named in its notice
and (v) any other information relating to such stockholder that would be
required to be disclosed in a proxy statement or other filings required to be
made in connection with solicitations of proxies for election of directors
pursuant to Section 14 of the Exchange Act and the rules and regulations
promulgated thereunder. Such notice must be accompanied by a written consent of
each proposed nominee to being named as a nominee and to serve as a director if
elected.

             No person shall be eligible for election as a director of the
Corporation unless nominated in accordance with the procedures set forth in this
Section 2.2. If the chairman of the meeting determines that a nomination was not
made in accordance with the foregoing procedures, the chairman shall declare to
the meeting that the nomination was defective and such defective nomination
shall be disregarded.

         2.3 QUORUM AND MANNER OF ACTING. A majority of the entire Board shall
constitute a quorum for the transaction of business at any meeting. Action of
the Board shall be authorized by the vote of a majority of the directors present
at the time of the vote if there is a quorum, unless otherwise provided by law
or these bylaws. In the absence of a quorum, a majority of the directors present
may adjourn any meeting from time to time until a quorum is present.

         2.4 PLACE OF MEETINGS.  Meetings of the Board may be held in or
outside Delaware.

         2.5 ANNUAL AND REGULAR MEETINGS. Annual meetings of the Board, for the
election of officers and consideration of other matters, shall be held either
(a) without notice immediately after the annual meeting of stockholders and at
the same place, or (b) at such time and place as the chairman of the board shall
determine, on notice as provided in Section 2.7 of these Bylaws. Regular
meetings of the Board may be held without notice at such times and places as the
Board determines. If the day fixed for a regular is a legal holiday, the meeting
shall be held on the next business day.

         2.6 SPECIAL MEETINGS.  Special meetings of the Board may be called by
the chief executive officer of the Corporation or by a majority of the entire
Board.

         2.7 NOTICE OF MEETINGS; WAIVER OF NOTICE. Notice of the time and place
of each special meeting of the Board, and of each annual meeting not held
immediately after the annual meeting of stockholders and at the same place,
shall be given to each director by mailing it to him at his residence or usual
place of business at least three days before the meeting, or by delivering or
telephoning or telecopying it to him at least two days before the meeting.
Notice of a special meeting shall also state the purpose or purposes for which
the meeting is called. Notice need not be given to any director who submits a
signed waiver of notice before or after the meeting or who attends the meeting
without protesting at the beginning of the meeting the transaction of any
business because the meeting was not lawfully called or convened. Notice of any
adjourned meeting need not be given, other than by announcement at the meeting
at which the adjournment is taken.

         2.8 BOARD OR COMMITTEE ACTION WITHOUT A MEETING. Any action required or
permitted



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to be taken by the Board or by any committee of the Board may be taken without a
meeting if all of the members of the Board or of the committee consent in
writing to the adoption of a resolution authorizing the action. The resolution
and the written consents by the members of the Board or the committee shall be
filed with the minutes of the proceeding of the Board or of the committee.

         2.9 PARTICIPATION IN BOARD OR COMMITTEE MEETINGS BY CONFERENCE
TELEPHONE. Any or all members of the Board or of any committee of the Board may
participate in a meeting of the Board or of the committee by means of a
conference telephone or similar communications equipment allowing all persons
participating in the meeting to hear each other at the same time. Participation
by such means shall constitute presence in person at the meeting.

        2.10 RESIGNATION AND REMOVAL OF DIRECTORS. Any director may resign at
any time by delivering his resignation in writing to the chief executive officer
of the Corporation or secretary of the Corporation, to take effect at the time
specified in the resignation; the acceptance of a resignation, unless required
by its terms, shall not be necessary to make it effective. Any or all of the
directors may be removed, but only for cause, by vote of the stockholders at a
meeting duly called for such purpose.

        2.11 VACANCIES. Any vacancy in the Board, including one created by an
increase in the number of directors, may be filled for the unexpired term by a
majority vote of the remaining directors, though less than a quorum.

        2.12 COMPENSATION. Directors who are not executive officers of the
Corporation shall receive such compensation as the Board determines, together
with reimbursement of their reasonable expenses in connection with the
performance of their duties. Directors who are also executive officers of the
Corporation shall receive no additional compensation for service as directors. A
director may also be paid for serving the Corporation, its affiliates or
subsidiaries in other capacities.

3.       COMMITTEES.

         3.1 EXECUTIVE COMMITTEE. The Board, by resolution adopted by a majority
of the entire Board, may designate an Executive Committee of one or more
directors which shall have such powers and duties as the Board shall determine,
except as limited by section 141(c) of the Delaware General Corporation Law or
any other applicable law. The members of the Executive Committee shall serve at
the pleasure of the Board. All action of the Executive Committee shall be
reported to the Board at its next meeting.

         3.2 OTHER COMMITTEES. The Board, by resolution adopted by a majority of
the entire Board, may designate other committees of one or more directors, which
shall serve at the Board's pleasure and have such powers and duties as the Board
determines, except as limited by section 141(c) of the Delaware General
Corporation Law or any other applicable law.

         3.3 COMMITTEES. The following committees are hereby created, with the
powers and duties hereinafter set forth.


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                           (A)      COMPENSATION COMMITTEE.  The Compensation
Committee shall be comprised of three (3) or more directors (as set from time to
time by resolution of a majority of the entire Board). The Compensation
Committee shall fix the compensation of the chief executive officer and such
other executive officers as it shall determine and administer any stock option,
stock appreciation or other incentive compensation programs of the Corporation.

                           (B)      AUDIT COMMITTEE.  The Audit Committee
shall be comprised of three (3) or more directors (as set from time to time by
resolution of the majority of the entire Board) who are not employees of the
Corporation. The Audit Committee shall have full corporate power and authority
to act in respect of any matter which may develop or arise in connection with
any audit or the maintenance of internal accounting controls or any other matter
relating to the Corporation's financial affairs. The Audit Committee shall
review, at least once each fiscal year, the services performed and to be
performed by the Corporation's independent public accountants and the fees
charged therefor, and, in connection therewith, consider the effect of any
nonaudit services on the independence of such accountants. The Audit Committee
shall also review with the Corporation's independent public accountants and its
internal audit department the general scope of their respective audit coverages,
the procedure and internal accounting controls adopted by the Corporation and
any significant matters encountered by any of them.

                           (C)      NOMINATING COMMITTEE.  The Nominating
Committee shall be comprised of three (3) or more directors (as set from time to
time by resolution of a majority of the entire Board). The Nominating Committee
shall provide to the Board its recommendations regarding individuals to be
considered for election as directors of the Corporation at meetings of the
stockholders of the Corporation and shall have such other powers and duties as
may be determined by the Board from time to time.

         3.4 RULES APPLICABLE TO COMMITTEES. The Board, by vote of a majority of
the entire Board, may designate one or more directors as alternate members of
any committee, who may replace any absent or disqualified member at any meeting
of the committee. In the absence or disqualification of any member of a
committee, the member or members present at a meeting of the committee and not
disqualified, whether or not a quorum, may unanimously appoint another director
to act at the meeting in place of the absent or disqualified member. All action
of a committee shall be reported to the Board at its next meeting.

4.       OFFICERS.

         4.1 NUMBER. The executive officers of the Corporation shall be the
chairman of the board and chief executive officer, the president, one or more
vice presidents, a secretary and a treasurer. Any two or more offices may be
held by the same person.

         4.2 ELECTION; TERM OF OFFICE. The executive officers of the Corporation
shall be elected annually by the Board, and each such officer shall hold office
until the next annual meeting of the Board, and until the election of his
successor, subject to the provisions of Section 4.4.

         4.3 SUBORDINATE OFFICERS. The Board and the chief executive officer may
appoint


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subordinate officers (including assistant secretaries and assistant treasurers),
agents or employees, each of whom shall hold office for such period and have
such powers and duties as the Board or the chief executive officer determines.
The chief executive officer may delegate to any executive officer the power to
appoint and define the powers and duties of any subordinate officers, agents or
employees.

         4.4 RESIGNATION AND REMOVAL OF OFFICERS. Any officer may resign at any
time by delivering his resignation in writing to the chief executive officer or
secretary of the Corporation, to take effect at the time specified in the
resignation; the acceptance of a resignation, unless required by its terms,
shall not be necessary to make it effective. Any officer appointed by the Board
or appointed by an executive officer or by a committee may be removed by the
Board either with or without cause, and in the case of an officer appointed by
an executive officer or by a committee, by the officer or committee who
appointed him or by the chief executive officer of the Corporation.

         4.5 VACANCIES. A vacancy in any office may be filled for the unexpired
term in the manner prescribed in Sections 4.2 and 4.3 of these bylaws for
election or appointment to the office.

         4.6 THE CHAIRMAN OF THE BOARD AND CHIEF EXECUTIVE OFFICER. The chairman
of the board and chief executive officer of the Corporation shall be the chief
executive officer of the Corporation, and shall preside at all meetings of the
Board and of the stockholders. The chief executive officer of the Corporation
shall be in charge of the business and affairs of the Corporation and be its
chief policy making officer, subject to the powers of the Board. During the
absence or disability of the president of the Corporation, the chief executive
officer of the Corporation shall exercise all of the powers and discharge all of
the duties of the president of the Corporation. The chief executive officer of
the Corporation shall also perform such other duties and may exercise such other
powers as may from time to time be assigned to him by the Board.

         4.7 THE PRESIDENT. The president of the Corporation shall, subject to
the control of the Board and the chief executive officer of the Corporation,
have general supervision over the business of the Corporation and shall see that
all orders and resolutions of the Board are carried into effect. The president
of the Corporation shall also perform such other duties and may exercise such
other powers as may from time to time be assigned to him by the chief executive
officer of the Corporation.

         4.8 VICE PRESIDENT. Each vice president of the Corporation shall have
such powers and duties as the chief executive officer of the Corporation assigns
to him.

         4.9 THE TREASURER. The treasurer of the Corporation shall be the chief
financial officer or the Corporation and shall be in charge of the Corporation's
books and accounts. The treasurer shall also perform such other duties and may
exercise such other powers as may from time to time be assigned to him by the
chief executive officer of the Corporation.

        4.10 THE SECRETARY. The secretary of the Corporation shall be the
secretary of, and keep the minutes of, all meetings of the Board and of the
stockholders, shall be responsible for giving notice of all meetings of
stockholders and of the Board, and shall keep the seal and, when


                                       8


authorized by the Board, apply it to any instrument requiring it. Subject to the
control of the Board, he shall have such powers and duties as the Board or the
chief executive officer of the Corporation assigns to him. In the absence of the
secretary of the Corporation from any meeting, the minutes shall be kept by the
person appointed for that purpose by the presiding officer.

        4.11 SALARIES. Subject to the provisions of Section 3.3(A) hereof, the
chief executive officer may fix the officers' salaries.

5.       SHARES.

         5.1 CERTIFICATES. The Corporation's shares shall be represented by
certificates in the form approved by the Board. Each certificate shall be signed
by the chief executive officer, the president or a vice president and by the
secretary or an assistant secretary, or the treasurer or an assistant treasurer,
and shall be sealed with the Corporation's seal or a facsimile of the seal. Any
or all of the signatures on the certificate may be a facsimile.

         5.2 TRANSFERS. Shares shall transferable only on the Corporation's
books, upon surrender of the certificate for the shares, properly endorsed. The
Board may require satisfactory surety before issuing a new certificate to
replace a certificate claimed to have been lost or destroyed.

         5.3 DETERMINATION OF STOCKHOLDERS OF RECORD. The Board may fix, in
advance, a date as the record date for the determination of stockholders
entitled to notice of or to vote at any meeting of the stockholders, or to
express consent to or dissent from any proposal without a meeting, or to receive
payment of any dividend or the allotment of any rights, or for the purpose of
any other action. The record date may not be more than 60 or less than 10 days
before the date of the meeting or more than 60 days before any other action.

6.       MISCELLANEOUS.

         6.1 SEAL. The Board shall adopt a corporate seal, which shall be in the
form of a circle and shall bear the Corporation's name and the year and state in
which it was incorporated.

         6.2 FISCAL YEAR. The Board may determine the Corporation's fiscal year.
Until changed by the Board, the Corporation's fiscal year shall be the calendar
year.

         6.3 VOTING OF SHARES IN OTHER CORPORATIONS. Shares in other
corporations which are held by the Corporation may be represented and voted by
the chief executive officer, the president or a vice president of this
Corporation or by proxy or proxies appointed by one of them. The Board may,
however, appoint some other person to vote the shares.

         6.4 AMENDMENTS. The affirmative vote of a majority of the entire Board
shall be required to adopt, amend, alter or repeal the Corporation's Bylaws. The
Corporation's Bylaws also may be adopted, amended, altered or repealed by the
affirmative vote of the holders of at least two-thirds of the voting power of
the shares entitled to vote at an election of directors, at a meeting duly
called for such purpose.

                                    * * * * *


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