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                                                                     EXHIBIT 4.2


                          REGISTRATION RIGHTS AGREEMENT

     This REGISTRATION RIGHTS AGREEMENT (the "Agreement") is dated as of the
30th day of August, 2000 by and among IPG Photonics Corporation., a Delaware
corporation (the "Company"), and the persons designated as Investors on the
signature pages hereto and any assignees or transferees thereof (each, an
"Investor" and collectively, the "Investors").

     WHEREAS, the parties to this Agreement have entered into a certain Stock
Purchase Agreement, dated as of August 30, 2000 (the "Purchase Agreement"),
pursuant to which the Investors have agreed to purchase, from the Company shares
of Series B Convertible Participating Preferred Stock, par value $.0001 per
share, of the Company ("Series B Convertible Preferred Stock"), which shares are
convertible into shares of Common Stock, $.0001 par value per share, of the
Company ("Common Stock") and warrants to purchase Common Stock as described in
the Purchase Agreement ("Warrants"); and

     WHEREAS, the execution of this Agreement is an inducement and a condition
to the purchase by the Investors of the Series B Convertible Preferred Stock and
the Warrants under the Purchase Agreement.

     NOW, THEREFORE, in consideration of the foregoing and the mutual promises
of the parties herein contained, and for other good and valuable consideration,
the receipt and sufficiency of which is hereby acknowledged, the Company and the
Investors hereby covenant and agree with each other as follows:

     1.   Certain Definitions.  As used in this Agreement, the following
terms shall have the following respective meanings:

          "Board of Directors" means the Board of Directors of the Company.

          "Commission" shall mean the United States Securities and Exchange
Commission, or any other federal agency at the time administering the Securities
Act and the Exchange Act.

          "Common Stock" shall mean the Common Stock and any other common equity
securities issued by the Company, and any other shares of stock issued or
issuable with respect thereto (whether by way of a stock dividend or stock split
or in exchange for or upon conversion of such shares, recapitalization, merger,
consideration or other corporate reorganization).

          "Company" shall refer to the Company and any successor or successors
thereto.

          "Exchange Act" shall mean the Securities Exchange Act of 1934, as
amended, or any similar successor federal statute, and the rules and regulations
of the Commission thereunder, all as the same shall be in effect at the time.
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          "Majority Interest" means the Investors holding not less than a
majority in interest of the Registrable Securities held by all Investors
(provided, however, that prior to any IPO (as defined hereinafter), a Majority
Interest shall mean Investors holding not less than a Majority of the
Registrable Securities referred to in clause (i)(X) of the definition thereof.

          "Person" shall mean an individual, a corporation, an association, a
joint venture, a partnership, a limited liability company, an estate, a trust,
an unincorporated organization, and any other entity or organization,
governmental or otherwise.

          "Registrable Securities" shall mean (i) any shares of Common Stock
held by the Investors or their transferees, or subject to acquisition by any
Investor or their transferees upon (X) conversion of the Series B Convertible
Preferred Stock or (Y) exercise of the Warrants, (it being understood that for
purposes of this Agreement, a Person will be deemed to be a holder of
Registrable Securities whenever such Person has the right to then acquire or
obtain from the Company any Registrable Securities, whether or not such
acquisition has actually been effected) and (ii) any other securities issued or
issuable with respect to any such shares described in clause (i) by way of a
stock dividend or stock split or in connection with a combination of shares,
recapitalization, merger, consolidation or other reorganization; provided,
however, that notwithstanding anything to the contrary contained herein.

          "Registrable Securities" shall not at any time include any securities
(i) registered and sold pursuant to the Securities Act, (ii) sold to the public
pursuant to Rule 144 promulgated under the Securities Act or (iii) which could
then be sold in their entirety pursuant to Rule 144(k) promulgated under the
Securities Act without limitation or restriction.

          "Registration Expenses" shall mean the expenses so described in
Section 6 hereof.

          "Securities Act" shall mean the Securities Act of 1933, as amended, or
any similar successor federal statute, and the rules and regulations of the
Commission thereunder, all as the same shall be in effect at the time.

     2.   Demand Registrations.

          (a) At any time after the earlier of (i) the 3rd anniversary of the
date hereof or (ii) the date of the Company's initial public offering of its
Common Stock pursuant to an effective registration under the Securities Act (the
"IPO"), a Majority Interest of the Investors may notify the Company that they
intend to offer or cause to be offered for public sale, and request that the
Company register under the Securities Act for public sale, all or any portion of
the Registrable Securities held by the Investors in the manner specified in such
notice; provided, however, that in the case of such a request pursuant to
clause(ii) above, such registration may not become effective prior to the date
which is the earlier of six (6) months after the date of the Company's IPO and
the date that any applicable Holdback Period (as defined hereinafter) or other
lockup period applicable to such IPO expires. Upon receipt of such request, the
Company shall promptly deliver notice of such request to all Persons holding
Registrable Securities who shall then have thirty (30) days to notify the
Company in writing of their desire to have Registrable Securities held by them
included in such


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registration (which response shall specify the number of Registrable Securities
proposed to be included in such registration). If the request for registration
contemplates an underwritten public offering, the Company shall state such in
the written notice and in such event the right of any Person to include
Registrable Securities in such registration shall be conditioned upon such
Person's participation in such underwritten public offering and the inclusion of
such Person's Registrable Securities in the underwritten public offering to the
extent provided herein.

        The Company will use its commercially reasonable best efforts to
expeditiously effect the registration under the Securities Act of all
Registrable Securities of each holder who requested inclusion of such holders
Registrable Securities in such registration and to qualify such Registrable
Securities for sale under any state blue sky law; provided, however, that the
Company shall not be required to effect more than two (2) registrations pursuant
to requests under this Section 2(a). Notwithstanding anything to the contrary
contained herein, no request may be made under this Section 2 within sixty (60)
days after the effective date of a registration statement filed by the Company
covering a firm commitment underwritten public offering. The Company may
postpone the filing or the effectiveness of any registration statement required
to be filed pursuant to this Section 2 for a reasonable time period, provided
that such postponements shall not exceed sixty (60) days in the aggregate during
any twelve (12) month period, if (i) the Company has been advised by legal
counsel that such filing or effectiveness would require disclosure of a material
financing, acquisition or other corporate transaction, and the Board of
Directors determines in good faith that such disclosure is not in the best
interests of the Company and its stockholders or (ii) the Company is then in
possession of material non-public information the disclosure of which the Board
of Directors has determined would have a material adverse effect upon the
Company or its then current business plans. A registration will not count as a
requested registration under this Section 2(a) unless and until the registration
statement relating to such registration has been declared effective by the
Commission at the request of the initiating holders; provided, however, that a
majority in interest of the participating holders of Registrable Securities may
request, in writing, that the Company withdraw a registration statement which
has been filed under this Section 2(a) but not yet been declared effective, and
a majority in interest of such holders may thereafter request the Company to
reinstate such Registration Statement, if permitted under the Securities Act, or
to file another registration statement, in accordance with the procedures set
forth herein and without reduction in the number of demand registrations
permitted under this Section 2(a);

          (b) If a requested registration involves an underwritten public
offering and the managing underwriter of such offering determines in good faith
that the number of securities sought to be offered should be limited due to
market conditions, then the number of securities to be included in such
underwritten public offering shall be reduced to a number, reasonably deemed
satisfactory by such managing underwriter, provided that the securities to be
excluded shall be determined in the following sequence: (i) first, securities
held by any other Persons (other than Persons holding Registrable Securities)
having contractual, incidental or "piggy-back" registration rights, (ii) second,
securities sought to be registered by the Company and (iii) third, Registrable
Securities held by the Investors, it being understood that no shares shall be
registered for the account of the Company or any shareholder other than the
Investors unless all Registrable Securities for which Investors have requested
registration have been


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registered. If there is a reduction in the number of shares of Common Stock or
Registrable Securities to be registered pursuant to clauses (i), (ii) or (iii)
above, such reduction shall be made within each tranche on a pro rata basis
(based upon the aggregate number of shares of Common Stock or Registrable
Securities held by the holders in each such tranche and subject to the
priorities set forth in the preceding sentence).

          (c) With respect to a request for registration pursuant to Section
2(a) which is for an underwritten public offering, the managing underwriter
shall be chosen by the Company, subject to the Investors' consent, which consent
shall not be unreasonably withheld. The Company may not cause any other
registration of securities for sale for its own account (other than a
registration effected solely to implement an employee benefit plan or a
transaction to which Rule 145 of the Securities Act is applicable) to become
effective within one hundred eighty (180) days following the effective date of
any registration required pursuant to this Section 2.

     3. Form S-3. After the first public offering of its securities registered
under the Securities Act, the Company shall use its best efforts to qualify and
remain qualified to register securities on Form S-3 (or any successor form)
under the Securities Act. An Investor or Investors holding Registrable
Securities anticipated to have an aggregate sale price (net of underwriting
discounts and commissions, if any) in excess of $500,000 shall have the right,
on one or more occasions, to request registration on Form S-3 (or any successor
form) for the Registrable Securities held by such requesting Investor or
Investors. Such requests shall be in writing and shall state the number of
shares of Registrable Securities to be disposed of and the intended method of
disposition of such securities by such holder or holders. The Company shall give
notice to all other holders of Registrable Securities of the receipt of a
request for registration pursuant to this Section 3, and such other holders of
Registrable Securities shall then have thirty (30) days to notify the Company in
writing of their desire to participate in the registration, subject to the
limitations set forth in Section 4. The Company may postpone the filing or the
effectiveness of any registration statement pursuant to this Section 3 for a
reasonable period of time, provided that such postponements shall not exceed
forty-five (45) days in the aggregate during any twelve (12) month period, if
(a) the Company has been advised by legal counsel that such filing or
effectiveness would require disclosure of a material financing, acquisition or
other corporate transaction, and the Board of Directors of the Company
determines in good faith that such disclosure is not in the best interests of
the Company and its stockholders, (b) the Company is then in possession of
material non-public information the disclosure of which the Board of Directors
has determined would have a material adverse effect upon the Company or its then
current business plans, (c) the managing underwriter determines in good faith
that an audit (other than the Company's regular year-end audit) would be
required to successfully market such offering, and (d) the Company's President
certifies in writing that the Company is then currently engaged in discussions
with its managing underwriter concerning a registration statement that would be
subject to Section 4 hereof.

     4. Piggy-Back Registration. If the Company at any time proposes to register
any of its Common Stock under the Securities Act for sale to the public either
for its own account or for the account of another Person other than the
Investors (except pursuant to a demand by the Investors under Section 2 hereof,
which demand registration shall be governed by the terms of said Section 2, and
except with respect to registration statements on Forms


                                       4
<PAGE>
S-4, S-8 or any other form not available for registering the Registrable
Securities for sale to the public), each such time it will promptly give written
notice to each holder of Registrable Securities of its intention to effect such
registration. Upon the written request of any such holder of Registrable
Securities given within thirty (30) days after receipt by such holder of such
notice, the Company will, subject to the limits contained in this Section 4, use
its commercially reasonable best efforts to cause all Registrable Securities of
such holder that such holder so requests to be registered under the Securities
Act and qualified for sale under any state blue sky law, all to the extent
required to permit such sale or other disposition of said Registrable
Securities; provided, however, that if the Company is advised in writing in good
faith by the managing underwriter of the Company's securities being offered in
an underwritten public offering pursuant to such registration statement that the
amount to be sold by Persons other than the Company (collectively, "Selling
Stockholders") is greater than the amount which can be offered without adversely
affecting the marketability of the offering, the Company may reduce the amount
offered for the accounts of Selling Stockholders (including any holders of
Registrable Securities) to a number reasonably deemed satisfactory by such
managing underwriter; and provided, further, that the securities to be excluded
shall be determined in the following sequence: (i) first, securities held by any
Persons not having any contractual, incidental or "Piggy-Back" registration
rights, (ii) second, securities held by any Persons having contractual,
incidental or "Piggy-Back" registration rights pursuant to an agreement which is
not this Agreement and Registrable Securities held by the Investors and (iii)
securities sought to be registered by the Company. If there is a reduction in
the number of shares of Common Stock or Registrable Securities to be registered
pursuant to clauses (i) or (ii) above, such reduction shall be made within each
tranche on a pro rata basis (based upon the aggregate number of shares of Common
Stock or Registrable Securities held by the holders in each such tranche and
subject to the priorities set forth in the preceding sentence).

     5.   Registration Procedures.  If and whenever the Company is required
by the provisions of this Agreement to effect the registration of any of its
securities under the Securities Act, the Company will, as expeditiously as
possible:

          (a) use its commercially reasonable best efforts diligently to prepare
and file with the Commission a registration statement on the appropriate form
under the Securities Act with respect to such securities, which form shall
comply as to form in all material respects with the requirements of the
applicable form and include all financial statements required by the Commission
to be filed therewith, and use its reasonable best efforts to cause such
registration statement to become and remain effective until completion of the
proposed offering (but not for more than one hundred eighty (180) days);

          (b) use its commercially reasonable best efforts to prepare and file
with the Commission such amendments and supplements to such registration
statement and the prospectus used in connection therewith as may be necessary to
keep such registration statement effective until the completion of the offering
(but not for more than one hundred eighty (180) days) and to comply with the
provisions of the Securities Act with respect to the sale or other disposition
of all securities covered by such registration statement whenever the seller or
sellers of such securities shall desire to sell or otherwise dispose of the
same, but only to the extent provided in this Agreement;


                                       5
<PAGE>
          (c) furnish to each selling holder and the underwriters, if any, such
number of copies of such registration statement, any amendments thereto, any
documents incorporated by reference therein, the prospectus, including a
preliminary prospectus, in conformity with the requirements of the Securities
Act, and such other documents as such selling holder may reasonably request in
order to facilitate the public sale or other disposition of the securities owned
by such selling holder;

          (d) use its commercially reasonable best efforts to register or
qualify the securities covered by such registration statement under and to the
extent required by such other securities or state blue sky laws of such
jurisdictions as each selling holder shall reasonably request, and do any and
all other acts and things which may be necessary under such securities or blue
sky laws to enable such selling holder to consummate the public sale or other
disposition in such jurisdictions of the securities owned by such selling
holder, except that the Company shall not for any such purpose be required to
qualify to do business as a foreign corporation in any jurisdiction wherein it
is not so qualified;

          (e) within a reasonable time before each filing of the registration
statement or prospectus or amendments or supplements thereto with the
Commission, furnish to counsel selected by the holders of Registrable Securities
copies of such documents proposed to be filed, which documents shall be subject
to the reasonable approval of such counsel;

          (f) promptly notify each selling holder of Registrable Securities,
such selling holders' counsel and any underwriter and (if requested by any such
Person) confirm such notice in writing, of the happening of any event which
makes any statement made in the registration statement or related prospectus
untrue or which requires the making of any changes in such registration
statement or prospectus so that they will not contain any untrue statement of a
material fact or omit to state any material fact required to be stated therein
or necessary to make the statements therein in the light of the circumstances
under which they were made not misleading; and, as promptly as practicable
thereafter, prepare and file with the Commission and furnish a supplement or
amendment to such prospectus so that, as thereafter deliverable to the
purchasers of such Registrable Securities, such prospectus will not contain any
untrue statement of a material fact or omit to state a material fact necessary
to make the statements therein, in the light of the circumstances under which
they were made, not misleading;

          (g) use its commercially reasonable best efforts to prevent the
issuance of any order suspending the effectiveness of a registration statement,
and if one is issued use its commercially reasonable best efforts to obtain the
withdrawal of any order suspending the effectiveness of a registration statement
at the earliest possible moment;

          (h) if requested by the managing underwriter or underwriters (if any),
any selling holder, or such selling holder's counsel, promptly incorporate in a
prospectus supplement or post-effective amendment such information as such
Person requests to be included therein with respect to the selling holder or the
securities being sold, including, without limitation, with respect to the
securities being sold by such selling holder to such underwriter or
underwriters, the purchase price being paid therefor by such underwriter or
underwriters and with respect to any other terms of an underwritten offering of
the securities to be sold in such offering, and



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<PAGE>
promptly make all required filings of such prospectus supplement or
post-effective amendment;

          (i) make available to each selling holder, any underwriter
participating in any disposition pursuant to a registration statement, and any
attorney, accountant or other agent or representative retained by any such
selling holder or underwriter (collectively, the "Inspectors"), all financial
and other records, pertinent corporate documents and properties of the Company
(collectively, the "Records"), as shall be reasonably necessary to enable them
to exercise their due diligence responsibility, and cause the Company's
officers, directors and employees to supply all information requested by any
such Inspector in connection with such registration statement subject, in each
case, to such confidentiality agreements as the Company shall reasonably
request;

          (j) enter into any reasonable underwriting agreement required by the
proposed underwriter(s) for the selling holders, if any, and use its reasonable
best efforts to facilitate the public offering of the securities;

          (k) request that each prospective selling holder be furnished a signed
counterpart, addressed to the prospective selling holder, of (i) an opinion of
counsel for the Company, dated the effective date of the registration statement,
and (ii) if and to the extent permitted by applicable professional standards, a
"comfort" letter signed by the independent public accountants who have certified
the Company's financial statements included in the registration statement,
covering substantially the same matters with respect to the registration
statement (and the prospectus included therein) and (in the case of the
accountants' letter) with respect to events subsequent to the date of the
financial statements, as are customarily covered (at the time of such
registration) in opinions of the Company's counsel and in accountants' letters
delivered to the underwriters in underwritten public offerings of securities;

          (l) use its commercially reasonable best efforts to cause the
securities covered by such registration statement to be listed on the securities
exchange or quoted on the quotation system on which the Common Stock is then
listed or quoted (or, if the Common Stock is not yet listed or quoted, then on
such exchange or quotation system as the selling holders of Registrable
Securities and the Company shall determine);

          (m) otherwise use its commercially reasonable best efforts to comply
with all applicable rules and regulations of the Commission and make generally
available to its security holders, in each case as soon as reasonably
practicable, an earnings statement of the Company (which need not be audited)
which will satisfy the provisions of Section 11(a) of the Securities Act and
Rule 158 thereunder (or any comparable successor provisions); and

          (n) otherwise cooperate with the underwriter(s), the Commission and
other regulatory agencies and take all reasonable actions and execute and
deliver or cause to be executed and delivered all documents reasonably necessary
to effect the registration of any securities under this Agreement.

     6. Expenses. All reasonable expenses incurred by the Company and the
Investors in effecting the registrations provided for in Section 2, Section 3


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and Section 4, including, without limitation, all registration and filing fees,
printing expenses, fees and disbursements of counsel for the Company and one
counsel for the Investors as a group (selected by a majority in interest of the
Investors who participate in the registration), underwriting expenses (other
than commissions or discounts), expenses of any audits incident to or required
by any such registration and expenses of complying with the securities or blue
sky laws of any jurisdiction pursuant to Section 5(d) hereof (all of such
expenses referred to as "Registration Expenses"), shall be paid by the Company.

     7.   Indemnification.

          (a) The Company shall indemnify and hold harmless the selling holder
of Registrable Securities, each underwriter (as defined in the Securities Act),
and each other Person who participates in the offering of such securities and
each other Person, if any, who controls (within the meaning of the Securities
Act) such seller, underwriter or participating Person (individually and
collectively, the "Indemnified Person") against any losses, claims, damages or
liabilities (collectively, the "liability"), joint or several, to which such
Indemnified Person may become subject under the Securities Act or any other
statute or at common law, insofar as such liability (or actions in respect
thereof) arises out of or is based upon (i) any untrue statement or alleged
untrue statement of any material fact contained, on the effective date thereof,
in any registration statement under which such securities were registered under
the Securities Act, any preliminary prospectus or final prospectus contained
therein, or any amendment or supplement thereto, (ii) any omission or alleged
omission to state therein a material fact required to be stated therein or
necessary to make the statements therein not misleading, or (iii) any violation
by the Company of the Securities Act, any state securities or "blue sky" laws or
any rule or regulation thereunder in connection with such registration;
provided, however, that the Company shall not be liable to any Indemnified
Person in any such case to the extent that any such liability arises out of or
is based upon any untrue statement or alleged untrue statement or omission or
alleged omission made in such registration statement, preliminary or final
prospectus, or amendment or supplement thereto in reliance upon and in
conformity with information furnished in writing to the Company by such
Indemnified Person specifically for use therein provided, further, that the
foregoing indemnity shall not inure to the benefit of any underwriter, with
respect to any preliminary prospectus, from whom the person asserting any
losses, claims, damages and liabilities and judgments purchased Registrable
Securities or any Person controlling such underwriter, if a copy of the
prospectus (as then amended or supplemented if the Company shall have furnished
any amendments or supplements thereto) was not sent or given by or on behalf of
such underwriter to such Person, if required by law so to have been delivered,
or prior to a written confirmation of the sale of the Registrable Securities to
such Person, and if the prospectus (as so amended and supplemented) would have
cured the defect giving rise to such liability, unless such failure to deliver
the prospectus (as so amended and supplemented) was a result of noncompliance by
the Company with Section 5(c) hereof. The Company shall reimburse each such
Indemnified Person in connection with investigating or defending any such
liability as expenses in connection with the same are incurred.

          (b) Each selling holder of any securities included in such
registration being effected shall indemnify and hold harmless each other selling
holder of any securities, the Company, its directors and officers,



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each underwriter and each other Person, if any, who controls the Company or such
underwriter (individually and collectively also the "Indemnified Person"),
against any liability, joint or several, to which any such Indemnified Person
may become subject under the Securities Act or any other statute or at common
law, insofar as such liability (or actions in respect thereof) arises out of or
is based upon (i) any untrue statement or alleged untrue statement of any
material fact contained, on the effective date thereof, in any registration
statement under which securities were registered under the Securities Act at the
request of such selling holder, any preliminary prospectus or final prospectus
contained therein, or any amendment or supplement thereto, or (ii) any omission
or alleged omission by such selling holder to state therein a material fact
required to be stated therein or necessary to make the statements therein not
misleading, in the case of (i) and (ii) to the extent, but only to the extent,
that such untrue statement or alleged untrue statement or omission or alleged
omission was made in such registration statement, preliminary or final
prospectus, amendment or supplement thereto in reliance upon and in conformity
with information furnished in writing to the Company by such selling holder
specifically for use therein. Such selling holder shall reimburse any
Indemnified Person for any fees incurred in investigating or defending any such
liability; provided, however, that such selling holder's obligations hereunder
shall be limited to an amount equal to the proceeds to such selling holder of
the securities sold in any such registration.

          (c) Indemnification similar to that specified in Section 7(a) and
Section 7(b) shall be given by the Company and each selling holder (with such
modifications as may be appropriate) with respect to any required registration
or other qualification of their securities under any federal or state law or
regulation of governmental authority other than the Securities Act.

          (d) If the indemnification provided for in this Section 7 for any
reason is held by a court of competent jurisdiction to be unavailable to an
Indemnified Person in respect of any losses, claims, damages, expenses or
liabilities referred to therein, then each Indemnifying Party under this Section
7, in lieu of indemnifying such Indemnified Person thereunder, shall contribute
to the amount paid or payable by such indemnified party as a result of such
losses, claims, damages, expenses or liabilities (i) in such proportion as is
appropriate to reflect the relative benefits received by the Company, the
selling holders and the underwriters from the offering of the Registrable
Securities or (ii) if the allocation provided By clause (i) above is not
permitted by applicable law, in such proportion as is appropriate to reflect not
only the relative benefits referred to in clause (i) above, but also the
relative fault of the Company, the other selling holders and the underwriters in
connection with the statements or omissions which resulted in such losses,
claims, damages, expenses or liabilities, as well as any other relevant
equitable considerations. The relative benefits received by the Company, the
selling holders and the underwriters shall be deemed to be in the same
respective proportions that the net proceeds from the offering (before deducting
expenses) received by the Company and the selling holders and the underwriting
discount received by the underwriters, in each case as set forth in the table on
the cover page of the applicable prospectus, bear to the aggregate public
offering price of the Registrable Securities. The relative fault of the Company,
the selling holders and the underwriters shall be determined by reference to,
among other things, whether the untrue or alleged untrue statement of a material
fact or the omission or alleged omission to state a material fact relates to
information supplied by the


                                       9
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Company, the selling holders or the underwriters and the parties' relative
intent, knowledge, access to information and opportunity to correct or prevent
such statement or omission.

          The Company, the selling holders and the underwriters agree that it
would not be just and equitable if contribution pursuant to this Section 7 were
determined by pro rata or per capita allocation or by any other method of
allocation which does not take into account the equitable considerations
referred to in the immediately preceding paragraph. In no event, however, shall
a selling holder be required to contribute any amount under this Section 7(d) in
excess of the lesser of (i) that proportion of the total of such losses, claims,
damages or liabilities indemnified against equal to the proportion of the total
Registrable Securities sold under such registration statement which are being
sold by such selling holder or (ii) the net proceeds received by such selling
holder from its sale of Registrable Securities under such registration
statement. No person found guilty of fraudulent misrepresentation (within the
meaning of Section 11(f) of the Securities Act) shall be entitled to
contribution from any person who was not found guilty of such fraudulent
misrepresentation.

          (e) Promptly after receipt by an Indemnified Person of notice of the
commencement of any action involving a claim referred to in the preceding
paragraphs of this Section, such indemnified Person will, if a claim in respect
thereof is made against an indemnifying party, give written notice to the latter
of the commencement of such action.

          (f) The indemnification provided for under this Agreement will remain
in full force and effect regardless of any investigation made by or on behalf of
the Indemnified Person or any officer, director or controlling person of such
Indemnified Person and will survive the transfer of securities.

     8. Holdback Agreement. If the Company shall consummate a Qualified Public
Offering (as defined in the Shareholder Agreement) and the managing underwriter
for such registration shall request, the Investors shall not sell, make any
short sale of, grant any option for the purchase of, or otherwise dispose of any
Registrable Securities (other than those shares of Common Stock included in such
registration) without the prior written consent of the Company for a period
designated by the Company in writing to the Investors, which period shall not
begin more than ten (10) days prior to the effectiveness of the registration
statement pursuant to which such public offering shall be made and shall not
last more than one hundred eighty (180) days after the effective date of such
registration statement (the "Holdback Period"); provided that the Investors
shall be bound by this provision only if, and to the extent, the executive
officers of the Company owning Common Stock shall be bound by the same
provision; provided, further, that if any executive officer is permitted to sell
any shares of Common Stock prior to the expiration of the Holdback Period, then
the Investors shall also be permitted to do so.

     9. Underwriting Agreement. Notwithstanding the provisions of Sections 5, 8
and 13, to the extent that the Company and the Investors selling Registrable
Securities in a proposed registration shall enter into an underwriting or
similar agreement, which agreement contains provisions covering one or more
issues addressed in such Sections, the provisions contained in such Sections
addressing such issue or issues shall be superseded with respect to such
registration by such other agreement.


                                       10
<PAGE>
     10. Compliance with Rule 144. In the event that the Company (i) registers a
class of securities under Section 12 of the Exchange Act or (ii) shall commence
to file reports under Section 13 or 15(d) of the Exchange Act, the Company will
use its best efforts thereafter to file with the Commission such information as
is required under the Exchange Act for so long as there are holders of
Registrable Securities; and in such event, the Company shall use its best
efforts to take all action as may be required as a condition to the availability
of Rule 144 under the Securities Act (or any comparable successor rules). After
the occurrence of the first underwritten public offering of Common Stock
pursuant to an offering registered under the Securities Act on Form S-1 or Form
SA-1 (or any comparable successor forms), subject to the limitations on
transfers imposed by this Agreement, the Company shall use its reasonable best
efforts to facilitate and expedite transfers of Registrable Securities pursuant
to Rule 144 under the Securities Act, which efforts shall include timely notice
to its transfer agent to expedite such transfers of Registrable Securities.

     11.  Amendments.  The provisions of this Agreement may be amended, and
the Company may take any action herein prohibited or omit to perform any act
herein required to be performed by it, only with the written consent of the
Company and a Majority Interest of the Investors.

     12. Transferability of Registration Rights. The registration rights set
forth in this Agreement are transferable to each permitted transferee of
Registrable Securities provided, however, that the Company is given notice by
the Investor at the time of or within a reasonable time after the transfer,
stating the name and address of the transferee and identifying the securities
with respect to which such registration rights are being assigned. Subject to
the foregoing provision, this Agreement shall be binding upon, and inure to the
benefit of, the parties hereto and their respective successors and assigns;
provided, further, that the registration rights granted in this Agreement shall
not be transferred to Persons who received Registrable Securities pursuant to a
registration statement under the Securities Act or pursuant to a transaction
under Rule 144 or any successor provision thereto. Each subsequent holder of
Registrable Securities must consent in writing to be bound by the terms and
conditions of this Agreement in order to acquire the rights granted pursuant to
this Agreement.

     13. Rights Which May Be Granted to Subsequent Investors. Other than
transferees of Registrable Securities under Section 10 hereof, the Company shall
not, without the prior written consent of a Majority Interest of the Investors,
allow purchasers of the Company's securities to become a party to this Agreement
or grant any other registration rights to any third parties which are superior
to those registration rights granted to the Investors in this Agreement.

     14. Damages. The Company recognizes and agrees that each holder of
Registrable Securities will not have an adequate remedy if the Company fails to
comply with the terms and provisions of this Agreement and that damages will not
be readily ascertainable, and the Company expressly agrees that, in the event of
such failure, it shall not oppose an application by any holder of Registrable
Securities or any other Person entitled to the benefits of this Agreement
requiring specific performance of any and all provisions hereof or enjoining the
Company from continuing to commit any such breach of this Agreement.


                                       11
<PAGE>
     15. Information by Holder. Each Investor selling Registrable Securities in
a proposed registration shall furnish to the Company such written information
regarding such holder and the distribution proposed by such Investor as the
Company may reasonably request in writing and as shall be reasonably required in
connection with any registration, qualification or compliance referred to in
this Agreement.

     16.  Miscellaneous.

          (a) This Agreement shall bind and inure to the benefit of the Company
and the Investors and their respective successors and assigns.

          (b) This Agreement shall terminate and be of no further force or
effect upon the date on which there remains no Registrable Securities
outstanding. The indemnification provisions of Section 7 shall survive the
termination of this Agreement.

          (c) This Agreement contains the entire agreement among the parties
with respect to the subject matter hereof and supersedes all prior arrangements
or understandings with respect hereto.

          (d) All notices, requests, demands and other communications provided
for hereunder shall be in writing and mailed (by first class registered or
certified mail, postage prepaid), telegraphed, sent by express overnight courier
service or electronic facsimile transmission (with a copy by mail), or delivered
to the applicable party at the addresses indicated below:

     If to the Company:       IPG Photonics Corporation
                              660 Main Street; P.O. Box 519
                              Sturbridge, MA 01566
                              Attn:  Valentin P. Gapontsev

     With a copy to:          Winston & Strawn
                              1400 L Street, N.W.
                              Washington, D.C 20005
                              Facsimile:  (202) 371-5950
                              Attn: Barry Hart

     If to the Investors:     c/o TA Associates, Inc.
                              70 Willow Road
                              Suite 100
                              Menlo Park, CA  94025
                              Facsimile:  (650) 326-4933
                              Attn:  Michael C. Child

     With a copy to:          Goodwin, Procter, & Hoar LLP
                              Exchange Place
                              Boston, MA 02025
                              Facsimile:  (617) 523-1231
                              Attn:  John R. LeClaire, P.C.

     If to any other holder of Registrable Securities:

          At such Person's address for notice as set forth in the books and
          records of the Company.


                                       12
<PAGE>
or, as to each of the foregoing, at such other address as shall be designated by
such Person in a written notice to other parties complying as to delivery with
the terms of this subsection (a). All such notices, requests, demands and other
communications shall, when mailed, telegraphed or sent, respectively, be
effective (i) two days after being deposited in the mails or (ii) one day after
being delivered to the telegraph company, deposited with the express overnight
courier service or sent by electronic facsimile transmission, respectively,
addressed as aforesaid.

     (e) This Agreement shall be construed and enforced in accordance with and
governed by the laws of the State of New York (without giving effect to
principles of conflicts of law). All actions and proceedings arising out of or
relative to this Agreement shall be heard and determined in a Massachusetts
state or federal court sitting in the City of Boston. The parties hereby
irrevocably submit to the exclusive jurisdiction of any Massachusetts state or
federal court sitting in the City of Boston in any action or proceeding arising
out of or relating to this Agreement, and hereby irrevocably agree that all
claims in respect of such action or proceeding may be heard and determined in
such Massachusetts state or federal court. The parties hereby irrevocably waive,
to the fullest extent they may effectively do so, the defense of an inconvenient
forum to the maintenance of such action or proceeding. The parties agree that a
final judgment in any such action or proceeding shall be conclusive and may be
enforced in other jurisdictions by suit on the judgment or in any other manner
provided by law. TO THE EXTENT NOT PROHIBITED BY APPLICABLE LAW THAT CANNOT BE
WAIVED, EACH PARTY HEREBY WAIVES, AND COVENANTS THAT IT WILL NOT ASSERT (WHETHER
AS PLAINTIFF, DEFENDANT OR OTHERWISE), ANY RIGHT TO TRIAL BY JURY IN ANY FORUM
IN RESPECT OF ANY ISSUE, CLAIM, DEMAND, ACTION OR CAUSE OF ACTION ARISING OUT OF
OR PASSED UPON THIS AGREEMENT OR THE SUBJECT MATTER HEREOF, WHETHER NOW EXISTING
OR HEREAFTER ARISING AND WHETHER SOUNDING IN TORT OR CONTRACT OR OTHERWISE.

     (f) It is specifically understood and agreed that any breach of the
provisions of this Agreement by any party subject hereto will result in
irreparable injury to the other parties hereto, that the remedy at law alone
will be an inadequate remedy for such breach, and that, in addition to any other
legal or equitable remedies which they may have, such other parties may enforce
their respective rights by actions for specific performance (to the extent
permitted by law) and the Company may refuse to recognize any unauthorized
transferee as one of its stockholders for any purpose, including, without
limitation, for purposes of dividend and voting rights, until the relevant party
or parties have complied with all applicable provisions of this Agreement.

     (g) This Agreement may be executed in two or more counterparts, each of
which shall be deemed an original, but all of which together shall constitute
one and the same instrument.

     (h) If any provision of this Agreement shall be held to be illegal, invalid
or unenforceable, such illegality, invalidity or unenforceability shall attach
only to such provision and shall not in any manner affect or render illegal,
invalid or unenforceable any other provision of this Agreement, and this
Agreement shall be carried out as if any such illegal, invalid or unenforceable
provision were not contained herein.

     IN WITNESS WHEREOF, the parties hereto have caused this Registration Rights
Agreement to be duly executed as of the date first set forth above.


                                       13
<PAGE>
THE COMPANY:                                 IPG PHOTONICS CORPORATION


                                             By: /s/ Timothy P.V. Mammen
                                                 -------------------------
                                                Name: Timothy P.V. Mammen
                                                Title: Vice President


                 Signature page to Registration Rights Agreement

INVESTORS:                    TA IX, L.P.

                              By:  TA Associates IX LLC, its General Partner

                              By:  TA Associates, Inc., its Manager

                              By:          ***
                                 ----------------------------------
                                 Name:
                                 Title:

                              TA/ADVENT VIII L.P.

                              By:  TA Associates VIII LLC, its General Partner

                              By:  TA Associates, Inc., its General Partner

                              By:          ***
                                 ----------------------------------
                                 Name:
                                 Title:

                              TA/ATLANTIC AND PACIFIC IV L.P.

                              By:  TA Associates AP IV L.P., its General Partner

                              By:  TA Associates, Inc., its General Partner

                              By:          ***
                                 ----------------------------------
                                 Name:
                                 Title:

                              TA EXECUTIVES FUND LLC

                              By:  TA Associates, Inc., its Manager

                              By:          ***
                                 ----------------------------------
                                 Name:
                                 Title:

                              TA INVESTORS LLC

                              By:  TA Associates, Inc., its Manager

                              By:          ***
                                 ----------------------------------
                                 Name:
                                 Title:


                                       14
<PAGE>
                                  /s/ Kenneth T. Schiciano
                                  -----------------------------------
                                 Name:  Kenneth T. Schiciano
                                 Title:  Authorized Signatory

                Signature page to Registration Rights Agreement

                              MERRILL LYNCH KECALP L.P. 1999

                              By:  KECALP Inc., its General Partner

                              By: /s/  Margaret Monaco
                                  -----------------------------------
                                  Name:  Margaret T. Monaco
                                  Title: Vice President

                              KECALP INC.

                               By: /s/  Margaret Monaco
                                   ----------------------------------
                                   Name:  Margaret T. Monaco
                                  Title: Vice President

                              KECALP INC., as Nominee for Merrill Lynch
                              KECALP International L.P. 1999

                              By: /s/  Margaret Monaco
                                  -----------------------------------
                                  Name:  Margaret T. Monaco
                                  Title: Vice President

                              ML IBK POSITIONS, INC.

                              By: /s/ Joseph Valenti
                                  -----------------------------------
                                  Name:  Joseph S. Valenti
                                  Title: Vice President

               Signature page to Registration Rights Agreement

As of August 31, 2000         BAYVIEW 2000, LP

                              By: Bayview 2000, GP, LLC, its General Partner

                              By: /s/ Dana Welch
                                  -----------------------------------
                                  Name:  Dana Welch
                                  Title: Authorized Signatory

               Signature page to Registration Rights Agreement

As of August 31, 2000         THE SOG FUND, LP

                              By: The Special Opportunities Group LLC, its
                              General Partner

                              By: /s/ Christopher Miller
                                  -----------------------------------


                                       15
<PAGE>
                                  Name:  Christopher G. Miller
                                  Title: Chief Executive Officer

                Signature page to Registration Rights Agreement

As of August 31, 2000         THE SOG FUND II, LP

                              By: The Special Opportunities Group LLC, its
                              General Partner

                              By: /s/ Christopher Miller
                                  -----------------------------------
                                 Name:  Christopher G. Miller
                                 Title: Chief Executive Officer


                Signature page to Registration Rights Agreement

As of August 31, 2000 WINSTON/THAYER PARTNERS, L.P.

                              By: /s/ Scott Andrews
                                  -----------------------------------
                                  Name:  A. Scott Andrews
                                  Title: Managing Partner

                Signature page to Registration Rights Agreement

As of Oct 6, 2000             APAX EUROPE IV - A, L.P.

                              By: APAX Europe IV GP, L.P., its Managing
                                  General Partner

                              By: APAX Europe IV GP Co. Limited, its Managing
                                  General Partner

                              By: /s/ C. A. E. Helyar
                                  -----------------------------------
                                  Name:  C. A. E. Helyar
                                  Title: Director

                               By: /s/ D. J. Banks
                                  -----------------------------------
                                  Name:  D.J. Banks
                                  Title: for and on behalf of INTERNATIONAL
                                     PRIVATE EQUITY SERVICES LIMITED AS
                                     SECRETARY

                              APAX EUROPE IV - B, L.P.

                              By: APAX Europe IV GP, L.P., its Managing
                               General Partner

                              By: APAX Europe IV GP Co. Limited, its Managing


                                       16
<PAGE>
                               General Partner

                              By: /s/ C. A. E. Helyar
                                  -----------------------------------
                                  Name:  C. A. E. Helyar
                                  Title: Director

                              By: /s/ D. J. Banks
                                  -----------------------------------
                                  Name:  D.J. Banks
                                  Title: for and on behalf of INTERNATIONAL
                                     PRIVATE EQUITY SERVICES LIMITED AS
                                     SECRETARY

                Signature page to Registration Rights Agreement

                              APAX EUROPE IV - C GMBH & CO., KG

                              By: APAX Europe IV GP, L.P., its Managing
                              General Partner

                              By: APAX Europe IV GP Co. Limited, its Managing
                                  General Partner

                              By: /s/ C. A. E. Helyar
                                  -----------------------------------
                                  Name:  C. A. E. Helyar
                                  Title: Director

                              By: /s/ D. J. Banks
                                  -----------------------------------
                                  Name:  D.J. Banks
                                  Title: for and on behalf of INTERNATIONAL
                                     PRIVATE EQUITY SERVICES LIMITED AS
                                     SECRETARY

                              APAX EUROPE IV - D, L.P.

                              By: APAX Europe IV GP, L.P., its Managing
                              General Partner

                              By: APAX Europe IV GP Co. Limited, its Managing
                                  General Partner

                              By: /s/ C. A. E. Helyar
                                  -----------------------------------
                                  Name:  C. A. E. Helyar
                                  Title: Director

                              By: /s/ D. J. Banks
                                  -----------------------------------
                                  Name:  D.J. Banks
                                  Title: for and on behalf of INTERNATIONAL
                                     PRIVATE EQUITY SERVICES LIMITED AS
                                     SECRETARY

                Signature page to Registration Rights Agreement

                              APAX EUROPE IV - E, L.P.


                                       17
<PAGE>
                              By: APAX Europe IV GP, L.P., its Managing
                              General Partner

                              By: APAX Europe IV GP Co. Limited, its Managing
                                  General Partner

                              By: /s/ C. A. E. Helyar
                                  -----------------------------------
                                  Name:  C. A. E. Helyar
                                  Title: Director

                              By: /s/ D. J. Banks
                                  -----------------------------------
                                  Name:  D.J. Banks
                                  Title: for and on behalf of INTERNATIONAL
                                     PRIVATE EQUITY SERVICES LIMITED AS
                                     SECRETARY

                              APAX EUROPE IV - F, C.V.

                              By: APAX Europe IV GP, L.P., its Managing
                              General Partner

                              By: APAX Europe IV GP Co. Limited, its Managing
                                  General Partner

                              By: /s/ C. A. E. Helyar
                                  -----------------------------------
                                  Name:  C. A. E. Helyar
                                  Title: Director

                              By: /s/ D. J. Banks
                                  -----------------------------------
                                  Name:  D.J. Banks
                                  Title: for and on behalf of INTERNATIONAL
                                     PRIVATE EQUITY SERVICES LIMITED AS
                                     SECRETARY

                Signature page to Registration Rights Agreement

                              APAX EUROPE IV - G, C.V.

                              By: APAX Europe IV GP, L.P., its Managing
                               General Partner

                              By: APAX Europe IV GP Co. Limited, its Managing
                                  General Partner

                              By: /s/ C. A. E. Helyar
                                  -----------------------------------
                                  Name:  C. A. E. Helyar
                                  Title: Director


                              By: /s/ D. J. Banks
                                  -----------------------------------
                                  Name:  D.J. Banks
                                  Title: for and on behalf of INTERNATIONAL
                                     PRIVATE EQUITY SERVICES LIMITED AS
                                     SECRETARY


                                       18
<PAGE>
                              APAX EUROPE IV - H, GMBH & CO. K.G.

                              By: APAX Europe IV GP, L.P., its Attorney

                              By: APAX Europe IV GP Co. Limited, its Managing
                                  General Partner

                              By: /s/ C. A. E. Helyar
                                  -----------------------------------
                                  Name:  C. A. E. Helyar
                                  Title: Director

                              By: /s/ D. J. Banks
                                  -----------------------------------
                                  Name:  D.J. Banks
                                  Title: for and on behalf of INTERNATIONAL
                                     PRIVATE EQUITY SERVICES LIMITED AS
                                     SECRETARY

                Signature page to Registration Rights Agreement

As of December 6, 2000            MARCONI CAPITAL LIMITED

                              By: /s/ M. Ablett
                                  -----------------------------------
                                  Name: Mark Ablett
                                  Title: Managing Partner

                              Address: c/o Marconi Ventures
                              890 Winter Street, Suite 310
                              Waltham, MA 02454-1204
                              Fax: 781-522-7477
                              Attn: Jim Goren


                                       19
<PAGE>
                                    AMENDMENT

      THIS AMENDMENT, dated as of July 31, 2006 (this "Amendment"), is made and
entered into by and among IPG Photonics Corporation, a Delaware corporation (the
"Company"), the persons designated as Investors on the signature pages hereto
and any assignees or transferees thereof (each, an "Investor" and collectively,
the "Investors"). Capitalized terms used herein but otherwise not defined shall
have the meaning given to such terms in the Series B Registration Rights
Agreement (as defined below).

      WHEREAS, the Investors and the Company have entered into that certain
Registration Rights Agreement, dated as of August 30, 2000 (the "Series B
Registration Rights Agreement"); and

      WHEREAS, the Investors and the Company desire to amend certain provisions
of the Series B Registration Rights Agreement;

      NOW, THEREFORE, in consideration of the mutual agreements contained herein
and for other good and valuable consideration, the receipt and sufficiency of
which are hereby acknowledged, the parties hereto agree as follows:

      1.  Amendment to Section 4.  Section 4 of the Series B Registration
Rights Agreement shall be amended and restated to read as follows:


            "Piggy-Back Registration. If the Company at any time proposes to
            register any of its Common Stock under the Securities Act for sale
            to the public either for its own account or for the account of
            another Person other than the Investors (except pursuant to a demand
            by the Investors under Section 2 hereof, which demand registration
            shall be governed by the terms of said Section 2, and except with
            respect to registration statements on Forms S-4, S-8 or any other
            form not available for registering the Registrable Securities for
            sale to the public), each such time it will promptly give written
            notice to each holder of Registrable Securities of its intention to
            effect such registration. Upon the written request of any such
            holder of Registrable Securities given within thirty (30) days after
            receipt by such holder of such notice, the Company will, subject to
            the limits contained in this Section 4, use its commercially
            reasonable best efforts to cause all Registrable Securities of such
            holder that such holder so requests to be registered under the
            Securities Act and qualified for sale under any state blue sky law,
            all to the extent required to permit such sale or other disposition
            of said Registrable Securities; provided, however, that in
            connection with a Qualified Public Offering (as defined in Article
            Fourth, Section B.6.2 of the Amended and Restated Certificate of
            Incorporation) that is consummated on or before February 15, 2007,
            the Investors shall not have any contractual, incidental or
            "Piggy-Back"
<PAGE>
            registration rights under this Section 4, except that, if and to the
            extent that, the Company shall not repurchase the Warrants (as
            defined in Article Fourth, Section B.6.2 of the Amended and Restated
            Certificate of Incorporation) in connection with such Qualified
            Public Offering and the holders of the Warrants are permitted to
            exercise all of the outstanding Warrants on a net exercise basis,
            the Investors shall be permitted to exercise their rights under this
            Section 4 with respect to the Registrable Securities issuable upon
            such exercise of the Warrants in such Qualified Public Offering;
            provided, further, that if the Company is advised in writing in good
            faith by the managing underwriter of the Company's securities being
            offered in an underwritten public offering pursuant to such
            registration statement that the amount to be sold by Persons other
            than the Company (collectively, "Selling Stockholders") is greater
            than the amount which can be offered without adversely affecting the
            marketability of the offering, the Company may reduce the amount
            offered for the accounts of Selling Stockholders (including any
            holders of Registrable Securities) to a number reasonably deemed
            satisfactory by such managing underwriter; and provided, further,
            that the securities to be excluded shall be determined in the
            following sequence: (i) first, securities held by any Persons not
            having any contractual, incidental or "Piggy-Back" registration
            rights, (ii) second, securities held by any Persons having
            contractual, incidental or "Piggy-Back" registration rights pursuant
            to an agreement which is not this Agreement and Registrable
            Securities held by the Investors and (iii) securities sought to be
            registered by the Company. If there is a reduction in the number of
            shares of Common Stock or Registrable Securities to be registered
            pursuant to clauses (i) or (ii) above, such reduction shall be made
            within each tranche on a pro rata basis (based upon the aggregate
            number of shares of Common Stock or Registrable Securities held by
            the holders in each such tranche and subject to the priorities set
            forth in the preceding sentence)."

      2.  No Waiver.  Nothing in this Amendment shall constitute a waiver by
the Stockholders or the Company of any breach or default on the part of the
other party to the Series B Registration Rights Agreement.

      3.  Governing Law.  This Amendment shall be construed and enforced in
accordance with and governed by the laws of the State of New York (without
giving effect to the principles of conflicts of law).

      4. No Other Agreements. This Amendment constitutes the entire agreement of
the parties with respect to the subject matter hereof and supersedes and
preempts all prior agreements, understandings or


                                       2
<PAGE>
representations, both written and oral, between the parties with respect to the
subject matter hereof.

      5.  Effect.  Except as amended hereby, the Series B Registration Rights
Agreement shall remain in full force and effect in accordance with its terms.

      6.  Counterparts.  The parties may execute multiple counterparts of
this Amendment.  Each executed counterpart shall be deemed an original, but
all of them together represent one and the same agreement.


                            [Signature Page Follows]


                                       3
<PAGE>

                  IN WITNESS WHEREOF, the parties hereto caused this Amendment
to be duly executed as of this 31st day of July, 2006.


COMPANY:

                            IPG PHOTONICS CORPORATION



                            By: /s/ Valentin P. Gapontsev
                                ----------------------------------------
                                Name: Valentin P. Gapontsev
                                Title: Chairman & CEO


INVESTORS:
                            TA IX, L.P.

                            By: TA Associates IX LLC, Its  General Partner

                            By: TA Associates, Inc., its Manager

                            By: /s/ Michael C. Child
                                ----------------------------------------
                                Name:  Michael C. Child
                                Title: Managing Director


                            TA/ADVENT VIII L.P.

                            By: TA Associates VIII LLC,
                                Its General Partner

                            By: TA Associates, Inc., its Manager

                            By: /s/ Michael C. Child
                                ----------------------------------------
                                Name:  Michael C. Child
                                Title: Managing Director


                            TA/ATLANTIC AND PACIFIC IV L.P.

                            By: TA Associates AP IV L.P., Its General Partner

                            By: TA Associates, Inc., its Manager

                            By: /s/ Michael C. Child
                                ----------------------------------------
                                Name:  Michael C. Child
                                Title: Managing Director

                                        4

<PAGE>


                            TA EXECUTIVES FUND LLC

                            By: TA Associates, Inc., its Manager

                            By: /s/ Michael C. Child
                                ----------------------------------------
                                Name:  Michael C. Child
                                Title: Managing Director


                            TA INVESTORS LLC

                            By: TA Associates, Inc., its Manager

                            By: /s/ Michael C. Child
                                ----------------------------------------
                                Name: Michael C. Child
                                Title: Managing Director

                            By: /s/ Michael C. Child
                                ----------------------------------------
                                Name:  Michael C. Child
                                Title: Authorized Signatory

                                       5
