Exhibit 4.1

                            NANOMETRICS INCORPORATED

                          EMPLOYEE STOCK PURCHASE PLAN

                         (As amended through March 1998)

         The following  constitute the provisions of the Employee Stock Purchase
Plan of Nanometrics Incorporated.

         1.       Purpose.  The purpose of the Plan is to provide  employees  of
the Company and its  Designated  Subsidiaries  with an  opportunity  to purchase
Common Stock of the Company through accumulated  payroll  deductions.  It is the
intention of the Company to have the Plan qualify as an "Employee Stock Purchase
Plan" under Section 423 of the Internal  Revenue Code of 1954,  as amended.  The
provisions  of the Plan shall,  accordingly,  be  construed  so as to extend and
limit participation in a manner consistent with the requirements of that section
of the Code.

         2.       Definitions.

                  (a) "Board" shall mean the Board of Directors of the Company.

                  (b) "Code"  shall mean the Internal  Revenue Code of 1954,  as
amended.

                  (c) "Common Stock" shall mean the Common stock,  no par value,
of the Company.

                  (d)  "Company"   shall  mean   Nanometrics   Incorporated,   a
California corporation.

                  (e) "Compensation"  shall mean all regular straight time gross
earnings,   exclusive  of  payments  for  overtime,  shift  premium,   incentive
compensation,  incentive payments,  bonuses,  commissions or other compensation.

                  (f)  "Designated  Subsidiaries"  shall  mean the  Subsidiaries
which have been designated by the Board from time to time in its sole discretion
as eligible to participate in the Plan.

                  (g)  "Employee"  shall mean any person,  including an officer,
who is  customarily  employed  for at least  twenty (20) hours per week and more
than five (5) months in a calendar year by the Company or one of its  Designated
Subsidiaries.  For purposes of the Plan,  the employment  relationship  shall be
treated as  continuing  intact  while the  individual  is on sick leave or other
leave of absence  approved by the Company.  Where the period of leave exceeds 90
days and the  individual's  right to  reemployment  is not guaranteed  either by
statute or by  contract,  the  employment  relationship  shall be deemed to have
terminated on the 91st day of such leave.

                  (h)  "Exercise  Date" shall mean the last day of each offering
period of the Plan.
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                  (i) "Offering  Date" shall mean the first day of each offering
period of the Plan.

                  (j) "Plan" shall mean this Employee Stock Purchase Plan.

                  (k)  "Subsidiary"  shall  mean  a  corporation,   domestic  or
foreign, of which not less than 50% of the voting shares are held by the Company
or a  Subsidiary,  whether or not such  corporation  now exists or is  hereafter
organized or acquired by the Company or a Subsidiary.

         3.       Eligibility.

                  (a) Any  Employee  as  defined  in  paragraph  2 who  shall be
employed by the Company on the date his  participation  in the Plan is effective
shall be eligible to participate in the Plan, subject to limitations  imposed by
Section 423(b) of the Code.

                  (b)   Any   provisions   of   the   Plan   to   the   contrary
notwithstanding,  no Employee  shall be granted an option under the Plan (i) if,
immediately  after the grant,  such  Employee  (or any other  person whose stock
would be  attributed to such  Employee  pursuant to Section  424(d) of the Code)
would own stock and/or hold  outstanding  options to purchase  stock  possessing
five  percent  (5%) or more of the total  combined  voting power or value of all
classes of stock of the Company or of any  subsidiary  of the  Company,  or (ii)
which  permits his rights to purchase  stock under all employee  stock  purchase
plans of the  Company  and its  subsidiaries  to accrue at a rate which  exceeds
Twenty-Five  Thousand  Dollars  ($25,000)  of fair  market  value of such  stock
(determined  at the time such option is granted) for each calendar year in which
such option is outstanding at any time.

         4.       Offering  Periods.  The  Plan  shall  be  implemented  by  one
offering  during  each six  month  period of the  Plan,  commencing  on or about
September 28, 1986, and  continuing  thereafter  until  terminated in accordance
with  paragraph 19 hereof.  The Board of Directors of the Company shall have the
power to  change  the  duration  of  offering  periods  with  respect  to future
offerings  without  shareholder  approval if such change is  announced  at least
fifteen (15) days prior to the scheduled  beginning of the first offering period
to be affected.

        5.        Participation.

                  (a) An eligible  Employee may become a participant in the Plan
by completing a subscription agreement authorizing payroll deduction on the form
provided by the Company and filing it with the Company's payroll office prior to
the applicable  Offering Date,  unless a later time for filing the  subscription
agreement is set by the Board for all eligible Employees with respect to a given
offering.

                  (b) Payroll deductions for a participant shall commence on the
first payroll  following the Offering Date and shall end on the Exercise Date of
the offering to which such authorization is applicable, unless sooner terminated
by the participant as provided in paragraph 10.

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         6.       Payroll Deductions.

                  (a)  At  the  time  a  participant   files  his   subscription
agreement,  he shall elect to have payroll deductions made on each payday during
the  offering  period  in an  amount  not  exceeding  ten  percent  (10%) of the
Compensation which he received on the payday immediately  preceding the Offering
Date, and the aggregate of such payroll  deductions  during the offering  period
shall not exceed ten percent  (10%) of his  aggregate  Compensation  during said
offering period.

                  (b) All  payroll  deductions  made by a  participant  shall be
credited  to his  account  under  the  Plan.  A  participant  may not  make  any
additional payments into such account.

                  (c) A participant  may discontinue  his  participation  in the
Plan as provided in paragraph 10, or may lower but not increase, the rate of his
payroll  deductions  during the offering period by completing or filing with the
Company a new authorization for payroll  deduction.  The change in rate shall be
effective  fifteen  (15)  days  following  the  Company's  receipt  of  the  new
authorization.

                  (d) Notwithstanding the foregoing,  to the extent necessary to
comply  with  Section   423(b)(8)  of  the  Code  and  Section  3(b)  hereof,  a
participant's  payroll  deductions  may be decreased to zero percent (0%) at any
time during an Offering Period.  Payroll deductions shall recommence at the rate
provided in such  participant's  subscription  agreement at the beginning of the
first Offering Period which is scheduled to end in the following  calendar year,
unless terminated by the participant as provided in Section 10 hereof.

                  (e) At the time the option is exercised,  in whole or in part,
or at the time some or all of the  Company's  Common Stock issued under the Plan
is disposed of, the participant  must make adequate  provision for the Company's
federal, state, or other tax withholding  obligations,  if any, which arise upon
the exercise of the option or the  disposition of the Common Stock. At any time,
the Company may, but shall not be obligated to, withhold from the  participant's
compensation the amount necessary for the Company to meet applicable withholding
obligations, including any withholding required to make available to the Company
any tax  deductions or benefits  attributable  to sale or early  disposition  of
Common Stock by the Employee.

         7.       Grant of Option.

                  (a) On the Offering  Date of each six month  offering  period,
each eligible  Employee  participating in the Plan shall be granted an option to
purchase  (at the per  share  option  price)  up to a number  of  shares  of the
Company's Common Stock determined by dividing such Employee's payroll deductions
to be accumulated  during such offering period (not to exceed an amount equal to
ten percent (10%) of his  Compensation as of the date of the commencement of the
applicable  offering  period) by  eighty-five  percent  (85%) of the fair market
value of a share of the Company's Common Stock on the Offering Date,  subject to
the  limitations  set forth in Section 3(b) and 12 hereof;  provided  that in no
event shall an Employee be permitted  to purchase  during each  Offering  Period
more than 5,000 shares  (subject to any adjustment  pursuant to Section 19), and
provided  further that such  purchase  shall be subject to the  limitations  set
forth in  Sections  3(b) and

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12 hereof.  Exercise of the option  shall occur as provided in Section 8 hereof,
unless the participant has withdrawn  pursuant to Section 10 hereof.  The Option
shall  expire on the last day of the  Offering  Period.  Fair market  value of a
share of the  Company's  Common Stock shall be determined as provided in Section
7(b) herein.

                  (b) The  option  price per share of the  shares  offered  in a
given offering period shall be the lower of: (i) 85% of the fair market value of
a share of the Common Stock of the Company on the Offering  Date; or (ii) 85% of
the fair  market  value of a share of the  Common  Stock of the  Company  on the
Exercise  Date.  The fair market value of the Company's  Common Stock on a given
date shall be determined by the Board in its discretion; provided, however, that
where there is a public market for the Common  Stock,  the fair market value per
Share shall be the mean of the bid and asked prices of the Common Stock for such
date,  as reported  in the Wall  Street  Journal  (or,  if not so  reported,  as
otherwise  reported by the National  Association of Securities Dealers Automated
Quotation  (NASDAQ)  System)  or, in the event the  Common  Stock is listed on a
stock  exchange,  the fair market value per Share shall be the closing  price on
such exchange on such date, as reported in the Wall Street Journal.

         8.       Exercise of Option.  Unless a participant  withdraws  from the
Plan as provided in paragraph  10, his option for the purchase of shares will be
exercised  automatically  on the Exercise Date of the offering  period,  and the
maximum number of full shares subject to option will be purchased for him at the
applicable option price with the accumulated  payroll deductions in his account.
No fractional shares shall be purchased; any payroll deductions accumulated in a
participant's  account which are not  sufficient to purchase a full share either
may be retained in the participant's account for the subsequent Offering Period,
subject to earlier  withdrawal  by the  participant  as  provided  in Section 10
hereof,  or may be returned to the participant.  Any other monies left over in a
participant's  account  after  the  Exercise  Date  shall  be  returned  to  the
participant.  The shares purchased upon exercise of an option hereunder shall be
deemed to be  transferred to the  participant  on the Exercise Date.  During his
lifetime,  a participant's  option to purchase  shares  hereunder is exercisable
only by him.

         9.       Delivery.  As promptly as practicable  after the Exercise Date
of each offering, the Company shall arrange the delivery to each participant, as
appropriate, of a certificate representing the shares purchased upon exercise of
his option.  Any cash remaining to the credit of a  participant's  account under
the Plan after a purchase by him of shares at the  termination  of each offering
period, or which is insufficient to purchase a full share of Common Stock of the
Company, shall be returned to said participant.

         10.      Withdrawal; Termination of Employment.

                  (a) A  participant  may withdraw all but not less than all the
payroll  deductions  credited to his account under the Plan at any time prior to
the  Exercise  Date of the  offering  period  by  giving  written  notice to the
Company.  All of the participant's  payroll  deductions  credited to his account
will be paid to him promptly  after receipt of his notice of withdrawal  and his
option for the

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current  period  will  be  automatically  terminated,  and  no  further  payroll
deductions for the purchase of shares will be made during the offering period.

                  (b) Upon termination of the participant's  employment prior to
the Exercise Date of the offering period for any reason, including retirement or
death,  the payroll  deductions  credited to his account will be returned to him
or, in the case of his death,  to the person or persons  entitled  thereto under
paragraph 14, and his option will be automatically terminated.

                  (c) In the event an Employee fails to remain in the continuous
employ  of the  Company  for at least  twenty  (20)  hours per week  during  the
offering  period in which the  employee is a  participant,  he will be deemed to
have elected to withdraw  from the Plan and the payroll  deductions  credited to
his account will be returned to him and his option terminated.

                  (d) A participant's  withdrawal from an offering will not have
any effect upon his  eligibility to  participate in a succeeding  offering or in
any similar plan which may hereafter be adopted by the Company.

         11.      Interest.  No interest shall accrue on the payroll  deductions
of a participant in the Plan.

         12.      Stock.

                  (a) The maximum number of shares of the Company's Common Stock
which shall be made  available for sale under the Plan shall be 250,000  shares,
subject to adjustment upon changes in  capitalization of the Company as provided
in paragraph 18. If the total number of shares which would  otherwise be subject
to options  granted  pursuant to Section 7(a) hereof on the Offering  Date of an
offering  period  exceeds  the number of shares  then  available  under the Plan
(after deduction of all shares for which options have been exercised or are then
outstanding),  the  Company  shall  make a pro  rata  allocation  of the  shares
remaining  available  for  option  grant  in as  uniform  a  manner  as shall be
practicable  and as it shall  determine  to be  equitable.  In such  event,  the
Company  shall give  written  notice of such  reduction  of the number of shares
subject to the option to each  Employee  affected  thereby  and shall  similarly
reduce the rate of payroll deductions, if necessary.

                  (b) The  participant  will have no interest or voting right in
shares covered by his option until such option has been exercised.

                  (c) Shares to be  delivered  to a  participant  under the Plan
will  be  registered  in the  name  of the  participant  or in the  name  of the
participant and his spouse.

         13.      Administration. The Plan shall be administered by the Board of
the Company or a committee of members of the Board  appointed by the Board.  The
administration,  interpretation  or  application of the Plan by the Board or its
committee shall be final, conclusive and binding upon all participants.

         14.      Designation of Beneficiary.

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                  (a)  A  participant  may  file  a  written  designation  of  a
beneficiary   who  is  to  receive  any  shares  and  cash,  if  any,  from  the
participant's  account under the Plan in the event of such  participant's  death
subsequent  to the end of the  offering  period but prior to  delivery to him of
such shares and cash. In addition,  a participant may file a written designation
of a beneficiary who is to receive any cash from the participant's account under
the Plan in the event of such participant's  death prior to the Exercise Date of
the offering period.

                  (b) Such  designation  of  beneficiary  may be  changed by the
participant  at any time by  written  notice.  In the  event  of the  death of a
participant  and in the absence of a beneficiary  validly  designated  under the
Plan who is living at the time of such  participant's  death,  the Company shall
deliver such shares and/or cash to the executor or  administrator  of the estate
of the participant,  or if no such executor or administrator  has been appointed
(to the knowledge of the Company),  the Company, in its discretion,  may deliver
such  shares  and/or  cash to the  spouse  or to any one or more  dependents  or
relatives of the participant, or if no spouse, dependent or relative is known to
the Company, then to such other person as the Company may designate.

         15.      Transferability.  Neither  payroll  deductions  credited  to a
participant's account nor any rights with regard to the exercise of an option or
to  receive  shares  under the Plan may be  assigned,  transferred,  pledged  or
otherwise  disposed of in any way (other  than by will,  the laws of descent and
distribution or as provided in paragraph 14 hereof) by the participant. Any such
attempt at assignment,  transfer,  pledge or other  disposition shall be without
effect,  except  that the  Company may treat such act as an election to withdraw
funds in accordance with paragraph 10.

         16.      Use of Funds. All payroll  deductions  received or held by the
Company under the Plan may be used by the Company for any corporate purpose, and
the Company  shall not be obligated to segregate  such payroll  deductions.


         17.      Reports.  Individual  accounts  will be  maintained  for  each
participant  in the Plan.  Statements of account will be given to  participating
Employees  semi-annually  promptly following the Exercise Date, which statements
will set forth the amounts of payroll deductions,  the per share purchase price,
the number of shares purchased and the remaining cash balance, if any.

          18.      Adjustments Upon Changes in Capitalization.

                  (a) Changes in Capitalization.  Subject to any required action
by the shareholders of the Company, the number of shares of Common Stock covered
by each option under the Plan which has not yet been exercised and the number of
shares of Common Stock which have been  authorized  for issuance  under the Plan
but have not yet been placed under option  (collectively,  the  "Reserves"),  as
well as the price per share of Common  Stock  covered by each  option  under the
Plan which has not yet been exercised, shall be proportionately adjusted for any
increase or decrease in the number of issued  shares of Common  Stock  resulting
from a  stock  split,  reverse  stock  split,  stock  dividend,  combination  or
reclassification  of the Common Stock,  or any other increase or decrease in the
number of shares of Common Stock effected  without receipt of  consideration  by
the Company; provided, however, that conversion of any convertible securities of
the  Company  shall  not be deemed to have been  "effected  without  receipt  of
consideration".  Such adjustment shall be made by

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<PAGE>

the Board,  whose  determination  in that  respect  shall be final,  binding and
conclusive.  Except as  expressly  provided  herein,  no issue by the Company of
shares of stock of any class, or securities  convertible into shares of stock of
any class,  shall affect, and no adjustment by reason thereof shall be made with
respect to, the number or price of shares of Common Stock  subject to an option.

                  (b) Dissolution or  Liquidation.  In the event of the proposed
dissolution or liquidation of the Company,  the Offering Period then in progress
shall be shortened by setting a new Exercise Date (the "New Exercise Date"), and
shall  terminate   immediately  prior  to  the  consummation  of  such  proposed
dissolution or  liquidation,  unless  provided  otherwise by the Board.  The New
Exercise Date shall be before the date of the Company's proposed  dissolution or
liquidation.  The Board shall notify each  participant in writing,  at least ten
(10)  business days prior to the New Exercise  Date,  that the Exercise Date for
the participant's  option has been changed to the New Exercise Date and that the
participant's option shall be exercised  automatically on the New Exercise Date,
unless prior to such date the participant has withdrawn from the Offering Period
as  provided in Section 10 hereof.

                  (c) Merger or Asset Sale.  In the event of a proposed  sale of
all or  substantially  all of the  assets of the  Company,  or the merger of the
Company  with or into  another  corporation,  each  outstanding  option shall be
assumed or an equivalent  option  substituted by the successor  corporation or a
Parent  or  Subsidiary  of the  successor  corporation.  In the  event  that the
successor  corporation  refuses  to assume or  substitute  for the  option,  the
Offering  Period then in progress  shall be  shortened by setting a new Exercise
Date (the "New Exercise  Date").  The New Exercise Date shall be before the date
of  the  Company's  proposed  sale  or  merger.  The  Board  shall  notify  each
participant  in  writing,  at least  ten  (10)  business  days  prior to the New
Exercise  Date,  that the Exercise  Date for the  participant's  option has been
changed to the New  Exercise  Date and that the  participant's  option  shall be
exercised  automatically on the New Exercise Date, unless prior to such date the
participant  has  withdrawn  from the Offering  Period as provided in Section 10
hereof.

         The  Board  may,  if it so  determines  in the  exercise  of  its  sole
discretion, also make provision for adjusting the Reserves, as well as the price
per share of Common Stock covered by each outstanding  option, in the event that
the  Company  effects  one or more  reorganizations,  recapitalizations,  rights
offerings or other increases or reductions of shares of its  outstanding  Common
Stock,  and in the event of the Company being  consolidated  with or merged into
any other corporation.

          19.      Amendment or Termination.

                  (a) The Board of  Directors of the Company may at any time and
for any reason  terminate  or amend the Plan.  Except as  provided in Section 19
hereof, no such termination can affect options previously granted, provided that
an Offering  Period may be  terminated by the Board of Directors on any Exercise
Date if the Board  determines  that the  termination  of the Plan is in the best
interests of the Company and its stockholders.  Except as provided in Section 19
hereof, no amendment may make any change in any option theretofore granted which
adversely  affects the rights of any  participant.  To the extent  necessary  to
comply with Section 423 of the Code (or any

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<PAGE>

other  applicable  law,  regulation or stock exchange  rule),  the Company shall
obtain shareholder approval in such a manner and to such a degree as required.

                  (b) Without  stockholder consent and without regard to whether
any participant rights may be considered to have been "adversely  affected," the
Board (or its committee) shall be entitled to change the Offering Periods, limit
the frequency and/or number of changes in the amount withheld during an Offering
Period,  establish  the  exchange  ratio  applicable  to amounts  withheld  in a
currency other than U.S.  dollars,  permit payroll  withholding in excess of the
amount  designated by a participant in order to adjust for delays or mistakes in
the Company's processing of properly completed withholding elections,  establish
reasonable  waiting and  adjustment  periods  and/or  accounting  and  crediting
procedures  to ensure that amounts  applied  toward the purchase of Common Stock
for  each  participant  properly  correspond  with  amounts  withheld  from  the
participant's  Compensation,  and establish such other limitations or procedures
as the Board (or its  committee)  determines  in its sole  discretion  advisable
which are consistent with the Plan.

         20.      Notices.  All notices or other communications by a participant
to the Company under or in connection with the Plan shall be deemed to have been
duly given when  received in the form  specified by the Company at the location,
or by the person, designated by the Company for the receipt thereof.

         21.      Shareholder Approval. Continuance of the Plan shall be subject
to approval by the  shareholders  of the Company  within twelve months before or
after the date the Plan is adopted. If such shareholder  approval is obtained at
a duly held shareholders' meeting, it may be obtained by the affirmative vote of
the holders of a majority of the  outstanding  shares of the Company  present or
represented  and  entitled to vote  thereon,  which  approval  shall be:

                  (a) (1) solicited  substantially  in  accordance  with Section
14(a) of the  Securities  Act of 1934,  as amended (the "Act") and the rules and
regulations  promulgated  thereunder,  or (2)  solicited  after the  Company has
furnished  in writing to the  holders  entitled to vote  substantially  the same
information concerning the Plan as that which would be required by the rules and
regulations  in  effect  under  Section  14(a)  of  the  Act at  the  time  such
information is furnished; and

                  (b)  obtained  at or  prior to the  first  annual  meeting  of
shareholders  held  subsequent to the first  registration  of Common Stock under
Section 12 of the Act.

         In the case of approval by written consent,  it must be obtained by the
unanimous  written  consent of all  shareholders  of the Company,  or by written
consent  of  a  smaller  percentage  of  shareholders  but  only  if  the  Board
determines,  on the basis of an opinion rendered by the Company's legal counsel,
that the  written  consent of such a smaller  percentage  of  shareholders  will
comply with all applicable laws and will not adversely affect the qualifications
of the Plan under Section 423 of the Code.

         22.      Conditions Upon Issuance of Shares. Shares shall not be issued
with  respect to an option  unless the  exercise of such option and the issuance
and delivery of such shares  pursuant  thereto shall comply with all  applicable
provisions  of law,  domestic or foreign,  including,  without

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limitation,  the Securities Act of 1933, as amended, the Securities Exchange Act
of 1934, as amended, the rules and regulations promulgated  thereunder,  and the
requirements of any stock exchange upon which the shares may then be listed, and
shall be further subject to the approval of counsel for the Company with respect
to such compliance.

         As a condition  to the  exercise of an option,  the Company may require
the person  exercising  such option to represent  and warrant at the time of any
such  exercise  that the  shares are being  purchased  only for  investment  and
without  any  present  intention  to sell or  distribute  such shares if, in the
opinion of counsel for the Company,  such a representation is required by any of
the  aforementioned  applicable  provisions  of law.

         23.      Term of Plan. The Plan shall become effective upon the earlier
to occur of its  adoption  by the  Board of  Directors  or its  approval  by the
shareholders  of the Company as described in paragraph 21. It shall  continue in
effect for a term of twenty (20) years unless sooner  terminated under paragraph
19.

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