------------------------------
                                                         OMB APPROVAL

                                                  OMB Number     3235-0145
                                                  Expires:  October 31, 2002
                                                  Estimated average burden
                                                  hours per response . . . 14.90
                                                  ------------------------------




                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549




                                  SCHEDULE 13G



                    Under the Securities Exchange Act of 1934
                                (Amendment No. 1)

                                   Vicor Corp.
--------------------------------------------------------------------------------
                                (Name of Issuer)

                                  Common Stock
--------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                    925815102
--------------------------------------------------------------------------------
                                 (CUSIP Number)

                               September 30, 2001
--------------------------------------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule
is filed:

         [ X ]    Rule 13d-1(b)

         [   ]    Rule 13d-1(c)

         [   ]    Rule 13d-1(d)


*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter the
disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).



                               PAGE 1 OF 11 PAGES



----------------------------------------- -------------------------------------- CUSIP No. 925815102 13G Page 2 of 11 Pages ----------------------------------------- -------------------------------------- ---------- ------------------------------------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (entities only). John Hancock Financial Services, Inc. I.R.S. No. 04-3483032 ---------- ------------------------------------------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) |_| (b) |_| N/A ---------- ------------------------------------------------------------------------------------------------------------- 3 SEC USE ONLY ---------- ------------------------------------------------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware ---------- ------------------------------------------------------------------------------------------------------------- 5 SOLE VOTING POWER Number of Shares -0- -------- ------------------------------------------------------------------------------------------- Beneficially 6 SHARED VOTING POWER Owned by Each -0- -------- ------------------------------------------------------------------------------------------- Reporting 7 SOLE DISPOSITIVE POWER Person With -0- -------- ------------------------------------------------------------------------------------------- 8 SHARED DISPOSITIVE POWER -0- ---------- ------------------------------------------------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON None, except through its indirect, wholly-owned subsidiary, John Hancock Advisers, Inc. ---------- ------------------------------------------------------------------------------------------------------------- 10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* N/A ---------- ------------------------------------------------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 See line 9, above. ---------- ------------------------------------------------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON* HC ---------- ------------------------------------------------------------------------------------------------------------- *SEE INSTRUCTIONS BEFORE FILLING OUT! PAGE 2 OF 11 PAGES ----------------------------------------- -------------------------------------- CUSIP No. 925815102 13G Page 3 of 11 Pages ----------------------------------------- -------------------------------------- ---------- ------------------------------------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (entities only). John Hancock Life Insurance Company I.R.S. No. 04-1414660 ---------- ------------------------------------------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) |_| (b) |_| N/A ---------- ------------------------------------------------------------------------------------------------------------- 3 SEC USE ONLY ---------- ------------------------------------------------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION Commonwealth of Massachusetts ---------- ------------------------------------------------------------------------------------------------------------- 5 SOLE VOTING POWER Number of Shares -0- -------- ------------------------------------------------------------------------------------------- Beneficially 6 SHARED VOTING POWER Owned by Each -0- -------- ------------------------------------------------------------------------------------------- Reporting 7 SOLE DISPOSITIVE POWER Person With -0- -------- ------------------------------------------------------------------------------------------- 8 SHARED DISPOSITIVE POWER -0- ---------- ------------------------------------------------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON None, except through its indirect, wholly-owned subsidiary, John Hancock Advisers, Inc. ---------- ------------------------------------------------------------------------------------------------------------- 10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* N/A ---------- ------------------------------------------------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 See line 9, above. ---------- ------------------------------------------------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON* IC, IA, HC ---------- ------------------------------------------------------------------------------------------------------------- *SEE INSTRUCTIONS BEFORE FILLING OUT! PAGE 3 OF 11 PAGES ----------------------------------------- -------------------------------------- CUSIP No. 925815102 13G Page 4 of 11 Pages ----------------------------------------- -------------------------------------- ---------- ------------------------------------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (entities only). John Hancock Subsidiaries, Inc. I.R.S. No. 04-2687223 ---------- ------------------------------------------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) |_| (b) |_| N/A ---------- ------------------------------------------------------------------------------------------------------------- 3 SEC USE ONLY ---------- ------------------------------------------------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware ---------- ------------------------------------------------------------------------------------------------------------- 5 SOLE VOTING POWER Number of Shares -0- -------- ------------------------------------------------------------------------------------------- Beneficially 6 SHARED VOTING POWER Owned by Each -0- -------- ------------------------------------------------------------------------------------------- Reporting 7 SOLE DISPOSITIVE POWER Person With -0- -------- ------------------------------------------------------------------------------------------- 8 SHARED DISPOSITIVE POWER -0- ---------- ------------------------------------------------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON None, except through its indirect, wholly-owned subsidiary, John Hancock Advisers, Inc. ---------- ------------------------------------------------------------------------------------------------------------- 10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* N/A ---------- ------------------------------------------------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 See line 9, above. ---------- ------------------------------------------------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON* HC ---------- ------------------------------------------------------------------------------------------------------------- *SEE INSTRUCTIONS BEFORE FILLING OUT! PAGE 4 OF 11 PAGES ----------------------------------------- -------------------------------------- CUSIP No. 925815102 13G Page 5 of 11 Pages ----------------------------------------- -------------------------------------- ---------- ------------------------------------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (entities only). The Berkeley Financial Group, Inc. I.R.S. No. 04-3145626 ---------- ------------------------------------------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) |_| (b) |_| N/A ---------- ------------------------------------------------------------------------------------------------------------- 3 SEC USE ONLY ---------- ------------------------------------------------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware ---------- ------------------------------------------------------------------------------------------------------------- 5 SOLE VOTING POWER Number of Shares -0- -------- ------------------------------------------------------------------------------------------- Beneficially 6 SHARED VOTING POWER Owned by Each -0- -------- ------------------------------------------------------------------------------------------- Reporting 7 SOLE DISPOSITIVE POWER Person With -0- -------- ------------------------------------------------------------------------------------------- 8 SHARED DISPOSITIVE POWER -0- ---------- ------------------------------------------------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON None, except through its indirect, wholly-owned subsidiary, John Hancock Advisers, Inc. ---------- ------------------------------------------------------------------------------------------------------------- 10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* N/A ---------- ------------------------------------------------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 See line 9, above. ---------- ------------------------------------------------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON* HC ---------- ------------------------------------------------------------------------------------------------------------- *SEE INSTRUCTIONS BEFORE FILLING OUT! PAGE 5 OF 11 PAGES ----------------------------------------- -------------------------------------- CUSIP No. 925815102 13G Page 6 of 11 Pages ----------------------------------------- -------------------------------------- ---------- ------------------------------------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (entities only). John Hancock Advisers, Inc. I.R.S. No. 04-2441573 ---------- ------------------------------------------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) |_| (b) |_| N/A ---------- ------------------------------------------------------------------------------------------------------------- 3 SEC USE ONLY ---------- ------------------------------------------------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware ---------- ------------------------------------------------------------------------------------------------------------- 5 SOLE VOTING POWER Number of Shares 3,374,741 -------- ------------------------------------------------------------------------------------------- Beneficially 6 SHARED VOTING POWER Owned by Each -0- -------- ------------------------------------------------------------------------------------------- Reporting 7 SOLE DISPOSITIVE POWER Person With 3,374,741 -------- ------------------------------------------------------------------------------------------- 8 SHARED DISPOSITIVE POWER -0- ---------- ------------------------------------------------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 3,374,741 ---------- ------------------------------------------------------------------------------------------------------------- 10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* N/A ---------- ------------------------------------------------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 11.1% ---------- ------------------------------------------------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON* IA ---------- ------------------------------------------------------------------------------------------------------------- *SEE INSTRUCTIONS BEFORE FILLING OUT! PAGE 6 OF 11 PAGES The original statement shall be signed by each person on whose behalf the statement is filed or his authorized representative. If the statement is signed on behalf of a person by his authorized representative other than an executive officer or general partner of the filing person, evidence of the representative's authority to sign on behalf of such person shall be filed with the statement, provided, however, that a power of attorney for this purpose which is already on file with the Commission may be incorporated by reference. The name and any title of each person who signs the statement shall be typed or printed beneath his signature. Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Sec. 240.13d-7 for other parties for whom copies are to be sent. Attention: Intentional misstatements or omissions of fact constitute Federal criminal violations (See 18 U.S.C. 1001) Item 1(a) Name of Issuer: -------------- Vicor Corp Item 1(b) Address of Issuer's Principal Executive Offices: ----------------------------------------------- 25 Frontage Road Andover, MA 01810 Item 2(a) Name of Person Filing: --------------------- This filing is made on behalf of John Hancock Financial Services, Inc. ("JHF"), JHF's direct, wholly-owned subsidiary, John Hancock Life Insurance Company ("JHLICO"), JHLICO's direct, wholly-owned subsidiary, John Hancock Subsidiaries, Inc. ("JHSI"), JHSI's direct, wholly-owned subsidiary, The Berkeley Financial Group, Inc. ("TBFG") and TBFG's wholly-owned subsidiary, John Hancock Advisers, Inc. ("JHA"). Item 2(b) Address of the Principal Offices: -------------------------------- The principal business offices of JHF, JHLICO and JHSI are located at John Hancock Place, P.O. Box 111, Boston, MA 02117. The principal business offices of TBFG and JHA are located at 101 Huntington Avenue, Boston, Massachusetts 02199. Item 2(c) Citizenship: ----------- JHLICO was organized and exists under the laws of the Commonwealth of Massachusetts. JHF, JHSI, TBFG and JHA were organized and exist under the laws of the State of Delaware. Item 2(d) Title of Class of Securities: ---------------------------- Common Stock Item 2(e) CUSIP Number: ------------ 925815102 Item 3 If the Statement is being filed pursuant to Rule ------------------------------------------------ 13d-1(b), or 13d-2(b), check whether the person filing is a: ------------------------------------------------------------ JHF: (g) (X) Parent Holding Company, in accordance with ss.240.13d-1(b)(ii)(G). JHLICO: (c) (X) Insurance Company as defined inss.3(a)(19) of the Act. (e) (X) Investment Adviser registered under ss.203 of the Investment Advisers Act of 1940. (g) (X) Parent Holding Company, in accordance with ss.240.13d-1(b)(ii)(G). PAGE 7 OF 11 PAGES JHSI: (g) (X) Parent Holding Company, in accordance with ss.240.13d-1(b)(ii)(G). TBFG: (g) (X) Parent Holding Company, in accordance with ss.240.13d-1(b)(ii)(G). JHA: (e) (X) Investment Adviser registered under ss.203 of the Investment Advisers Act of 1940. Item 4 Ownership: --------- (a) Amount Beneficially Owned: JHA has direct beneficial ownership of 3,374,741 shares of Common Stock. Through their parent-subsidiary relationship to JHA, JHF, JHLICO, JHSI and TBFG have indirect, beneficial ownership of these same shares. (b) Percent of Class: 11.1% ---------------- (c) (i) sole power to vote or to direct the vote: JHA has sole power to vote or to direct the vote of 3,374,741 shares of Common Stock under the Advisory Agreements as follows: Number Date of Fund Name of Shares Advisory Agreement --------- --------- ------------------ JHA Private Accounts 75,851 V.A. Relative Value Fund 93,900 January 02, 1998 Small Cap Equity Fund 57,650 Large Cap Value 1,342,550 December 22, 1994 John Hancock Small Cap Value Fund 1,567,950 October 31, 1998 Raytheon 176,400 January 20, 2000 John Hancock Insurance Company of VT Protected Cell No. V01 Hallmark (TOHI) 14,000 November 30, 2000 Fundamental Value 2L 1,440 December 30, 1994 John Hancock Focused Relative Value Fund 45,000 November 01, 2000 (ii) shared power to vote or to direct the vote: -0- (iii) sole power to dispose or to direct the disposition of: JHA has sole power to dispose or to direct the disposition of 3,374,741 shares of Common Stock under the Advisory Agreement noted in Item 4(c)(i) above. (iv) shared power to dispose or to direct the disposition of: -0- Item 5 Ownership of Five Percent or Less of a Class: -------------------------------------------- If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following { }. Item 6 Ownership of More than Five Percent on Behalf of Another Person: --------------------------------------------------------------- See Item 4. PAGE 8 OF 11 PAGES Item 7 Identification and Classification of the Subsidiary which --------------------------------------------------------- Acquired the Security Being Reported on by the Parent Holding Company: --------------------------------------------------------------------- See Items 3 and 4 above. Item 8 Identification and Classification of Members of the Group: --------------------------------------------------------- Not applicable. Item 9 Notice of Dissolution of a Group: -------------------------------- Not applicable. Item 10 Certification: ------------- By signing below the undersigned certifies that, to the best of its knowledge and belief, the securities referred to above were acquired in the ordinary course of business and were not acquired for the purpose of and do not have the effect of changing or influencing the control of the issuer of such securities and were not acquired in connection with or as a participant in any transaction having such purpose or effect. PAGE 9 OF 11 PAGES SIGNATURE After reasonable inquiry and to the best of its knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct. John Hancock Financial Services, Inc. By: /s/Barry J. Rubenstein ---------------------- Name: Barry J. Rubenstein Dated: October 09, 2001 Title: Vice President, Counsel and Secretary John Hancock Life Insurance Company By: /s/Gregory P. Winn ------------------ Name: Gregory P. Winn Dated: October 09, 2001 Title: Vice President & Treasurer John Hancock Subsidiaries, Inc. By: /s/Gregory P. Winn ------------------ Name: Gregory P. Winn Dated: October 09, 2001 Title: Treasurer The Berkeley Financial Group, Inc. By: /s/Susan S. Newton ------------------ Name: Susan S. Newton Dated: October 09, 2001 Title: Senior Vice President John Hancock Advisers, Inc. By: /s/Susan S. Newton ------------------ Name: Susan S. Newton Dated: October 09, 2001 Title: Senior Vice President PAGE 10 OF 11 PAGES EXHIBIT A JOINT FILING AGREEMENT John Hancock Financial Services, Inc., John Hancock Life Insurance Company, John Hancock Subsidiaries, Inc., The Berkeley Financial Group and John Hancock Advisers, Inc. agree that the Schedule 13G (Amendment No. 1) to which this Agreement is attached, relating to the Common Stock of Vicor Corp. is filed on behalf of each of them. John Hancock Financial Services, Inc. By: /s/Barry J. Rubenstein ---------------------- Name: Barry J. Rubenstein Dated: October 09, 2001 Title: Vice President, Counsel and Secretary John Hancock Life Insurance Company By: /s/Gregory P. Winn ------------------ Name: Gregory P. Winn Dated: October 09, 2001 Title: Vice President & Treasurer John Hancock Subsidiaries, Inc. By: /s/Gregory P. Winn ------------------ Name: Gregory P. Winn Dated: October 09, 2001 Title: Treasurer The Berkeley Financial Group, Inc. By: /s/Susan S. Newton ------------------ Name: Susan S. Newton Dated: October 09, 2001 Title: Senior Vice President John Hancock Advisers, Inc. By: /s/Susan S. Newton ------------------ Name: Susan S. Newton Dated: October 09, 2001 Title: Senior Vice President PAGE 11 OF 11 PAGES