REVOLVING LINE OF CREDIT NOTE


$2,000,000.00                                          San Francisco, California
                                                                October 30, 2000

         FOR  VALUE  RECEIVED,  the  undersigned  OPTICNET,   INC.  ("Borrower")
promises to pay to the order of BEI TECHNOLOGIES,  Inc. ("Lender") at its office
at One Post Street,  Suite 2500,  San  Francisco,  California,  or at such other
place as the holder hereof may  designate,  in lawful money of the United States
of America and in immediately  available funds, the principal sum of Two Million
Dollars  ($2,000,000.00),  or  so  much  thereof  as  may  be  advanced  and  be
outstanding, with interest thereon, to be computed on each advance from the date
of its disbursement as set forth herein.

                                  DEFINITIONS:

         As used herein,  the following  terms shall have the meanings set forth
below,  and any other term defined in this Note shall have the meaning set forth
at the place defined:

         "Business Day" means any day except a Saturday, Sunday or any other day
on which  commercial  banks in California  are  authorized or required by law to
close.

INTEREST

         (a) Interest. The outstanding principal balance of this Note shall bear
interest  (computed on the basis of a 360-day year,  actual days elapsed) at the
rate of prime plus 1.5% per annum.

         (b) Payment of Interest. Interest accrued on this Note shall be payable
on the first day of each quarter,  commencing the first of the quarter after any
borrowing hereunder.

         (c) Late Charge.  From and after  September  28, 2002,  or such earlier
date as all principal owing hereunder becomes due and payable by acceleration or
otherwise,  the outstanding  principal  balance of this Note shall bear interest
until paid in full at an  increased  rate per annum  (computed on the basis of a
360-day year,  actual days elapsed)  equal to two percent (2%) above the rate of
interest set forth above and otherwise applicable to this Note.

BORROWING AND REPAYMENT:

         (a) Borrowing and Repayment.  Borrower may from time to time during the
term of this  instrument  borrow,  partially  or wholly  repay  its  outstanding
borrowings,  and  reborrow,  subject  to  all  of  the  limitations,  terms  and
conditions  of this Note and of any  document  executed  in  connection  with or
governing this Note;  provided,  however,  that the total outstanding  principal
amount  of  the  borrowings  under  this  Note  shall  not at  any  time  exceed
$2,000,000. The unpaid principal balance of this obligation at any time shall be
the total  amounts  advanced  hereunder by

                                       1.
<PAGE>

the holder  hereof less the amount of principal  payments  made hereon by or for
the  Borrower,  which  balance may be  endorsed  hereon from time to time by the
holder. The outstanding  principal balance of this Note shall be due and payable
in full on September 28, 2002.

         (b) Advances.  Advances hereunder, to the total amount of the principal
sum stated above,  may be made by the holder upon five (5) Business  Days' prior
written request by the Chief Financial Officer, Corporate Secretary or Treasurer
of the Borrower,  any one acting alone who is authorized to request advances and
direct the disposition of any advances until written notice of the revocation of
such authority is received by the holder at the office designated above.

         (c)  Application  of Payments.  Each payment made on this Note shall be
credited first, to any accrued interest and second, to the outstanding principal
balance hereof.

PREPAYMENT:

         Borrower may prepay  principal on any portion of this Note at any time,
in any amount and without penalty.

COMPLIANCE WITH OTHER AGREEMENTS:

         The obligation of the Lender to advance sums under this Note is subject
to (1) the Lender's own ability to borrow under the terms and conditions of that
certain Credit  Agreement  between BEI  Technologies,  Inc. and its wholly-owned
subsidiary,  BEI Sensors & Systems Company, Inc., and Wells Fargo Bank, National
Association  dated as of December  15,  1998,  as amended from time to time (the
"Credit  Agreement"),  (2) no event of default having occurred as defined within
the Credit  Agreement and being continuing and (3) the advance of sums hereunder
not  causing  an event of default  to occur for the  Lender  under that  certain
Credit  Agreement.  In the event that as of the date of any requested  borrowing
hereunder,  Lender  shall be unable to advance sums to the Borrower as set forth
above,   Lender  shall  (i)  immediately  provide  notice  to  Borrower  of  the
non-availability  of sums  hereunder  as of such date and (ii)  arrange  for the
advance to Borrower of such sums  requested  hereunder as soon as feasible after
such date.

MISCELLANEOUS:

         (a) Remedies.  Upon the occurrence of any Event of Default or Change in
Control  (each as  defined  below),  the holder of this  Note,  at the  holder's
option, may declare all sums of principal and interest outstanding  hereunder to
be  immediately  due  and  payable  without  presentment,   demand,   notice  of
nonperformance,  notice of protest,  protest or notice of dishonor, all of which
are expressly waived by Borrower,  and the obligation,  if any, of the holder to
extend any further  credit  hereunder  shall  immediately  cease and  terminate.
Borrower shall pay to the holder  immediately upon demand the full amount of all
payments,  advances, charges, costs and expenses,  including attorneys' fees (to
include outside  counsel fees and all allocated  costs of the holder's  in-house
counsel),  expended or incurred by the holder in connection with the enforcement
of the holder's  rights  including,  without  limitation,  the collection of any
amounts  which become due to the holder under this Note,  and the defense of any
action in any way related to this,  whether  incurred at the trial or  appellate
level,  in an  proceeding  or  otherwise,  and

                                       2.
<PAGE>

including any of the expenses and costs  incurred by the holder of this Note, in
connection with any adversary proceeding,  contested matter or motion brought by
Lender or any other  person  relating  to the  Borrower  or any other  person or
entity.

         Each of the following events shall be an "Event of Default" hereunder:

         (i) Borrower fails to pay timely any of the principal  amount due under
this Note on the date the same  becomes due and payable or any accrued  interest
or other  amounts due under this Note within five  calendar  days after the date
the same becomes due and payable;

         (ii)  Borrower  files any  petition  or  action  for  relief  under any
bankruptcy,  reorganization,  insolvency or moratorium law, or any other law for
the relief of, or relating to, debtors, now or hereafter in effect, or makes any
assignment  for the  benefit  of  creditors,  or takes any  corporate  action in
furtherance of any of the foregoing; or

         (iii) An involuntary  petition is filed against  Borrower  (unless such
petition  is  dismissed  or  discharged  within  sixty  (60)  days),  under  any
bankruptcy  statute  now or  hereafter  in  effect,  or a  custodian,  receiver,
trustee,  assignee for the benefit of creditors (or other  similar  official) is
appointed to take possession, custody or control of any property of Borrower.

         A "Change in Control"  shall mean: (i) any  consolidation  or merger of
the Borrower with or into any other  corporation  or other entity or person,  or
any other corporate  reorganization,  in which the  stockholders of the Borrower
immediately   prior   to   such   consolidation,   merger,   reorganization   or
recapitalization,  own less than 65% of the surviving entity's voting securities
immediately    after   such    consolidation,    merger,    reorganization    or
recapitalization,  (ii)  any  transaction  or  series  of  related  transactions
resulting  in the  transfer  of  control  of in excess of 65% of the  Borrower's
voting securities, or (iii) the sale or an agreement by the Borrower to sell all
or substantially all of its assets.

          (b)  Governing  Law.  This Note shall be governed by and  construed in
accordance  with the laws of the State of California as such laws are applied to
agreements between California  residents entered into and to be performed within
the state of California.

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

OPTICNET, INC.



By:    __________________________________________

Name:  __________________________________________

Title: __________________________________________


                                       3.