Mail Stop 0306

January 19, 2005



VIA U.S. MAIL AND FAX (860) 347-8372

Mr. Walter A. Shephard
Vice President, Finance and Chief Financial Officer
Zygo Corporation
21 Laurel Brook Road
Middlefield, Connecticut 06455

	Re:	Zygo Corporation
		Form 10-K for the year ended June 30, 2004


Dear Mr. Shephard:

      We have reviewed your filings and have the following
comments.
We have limited our review to only your financial statements and
related disclosures and will make no further review of your
documents. Where indicated, we think you should revise your
documents
in future filings in response to these comments.  If you disagree,
we
will consider your explanation as to why our comment is
inapplicable
or a revision is unnecessary.  Please be as detailed as necessary
in
your explanation.  In some of our comments, we may ask you to
provide
us with supplemental information so we may better understand your
disclosure.  After reviewing this information, we may or may not
raise additional comments.

      Please understand that the purpose of our review process is
to
assist you in your compliance with the applicable disclosure
requirements and to enhance the overall disclosure in your
filings.
We look forward to working with you in these respects.  We welcome
any questions you may have about our comments or on any other
aspect
of our review.  Feel free to call us at the telephone numbers
listed
at the end of this letter.


Form 10-K for the year ended June 30, 2004

Item 7. Management`s Discussion and Analysis of Financial
Condition
and Results of Operations

Results of Operations - Page 14

1. In future filings, where changes in financial statement line
items
are the result of several factors, each significant factor should
be
separately quantified and discussed.  For example, you say that
the
decrease in SG&A "is primarily related to increases in various
personnel costs including incentive programs and external
commissions."  However, you do not quantify the impact of each of
these factors. Refer to the Instructions to Item 303(a) of
Regulation
S-K.

2. MD&A should attribute increases or decreases in net revenue
among
price changes, volume changes, the introduction of new products,
etc.
In addition, MD&A should identify and quantify the contributing
factors when two or more items contribute to the material change
in a
line item. You should not merely state the increase was due to
general increases in the number of products sold across most
product
categories.  Rather you should explain the underlying reasons for
the
increase and any offsetting decreases. Please revise in future
filings. See Item 303(a)(3) of Regulation S-K.

Contractual Obligations - Page 18

3. Supplementally tell us the nature of the $10.5 million in
purchase
obligations. The tabular disclosure should be supplemented in
future
filings with additional information about cash requirements and
explain commitments for capital or other expenditures. Refer to
SEC
Release No. 33-8350.

Consolidated Financial Statements

Consolidated Balance Sheet - Page F-3

4. We noted the company`s critical accounting policy related to
self
insurance accruals, however, we did not note any discussion of
this
liability or disclosure of the amount of and the accounting for
such
liability in the footnotes. Supplementally tell us the amount of
this
liability at June 30, 2004 and where it is presented in your
balance
sheet.  In future filings consider the need to include a
discussion
of the liability in the significant accounting policies footnote.


Note 1. Summary of Significant Accounting Policies

Revenue Recognition - Page F-8

5. Tell us and expand your revenue recognition policy in future
filings to address the following:

* Explain whether any of your product sales include customer
acceptance, installation, rights of return, price protection
agreements, or other post shipment obligations and how you account
for them.

* Provide details of whether your revenue transactions have
multiple
deliverables and why the adoption of EITF 00-21 had no impact on
you.

* Explain how software is incorporated into your products or
otherwise sold.  Tell us how you account for sales of stand alone
software or software embedded in your products.

Note 2. Divestitures and Discontinued Operation

6. We note that your additional charges related to the disposition
of
TeraOptix in 2004 are primarily related to the impairment charge
related to the vacant facility. Supplementally tell us, and
disclose
in future filings, the facts and circumstances that led to the
impairment as well as the method (s) for determining the fair
value.
See paragraph 26 of SFAS 144.

7. In addition, supplementally tell us and enhance your discussion
in
future filings regarding the nature of the adjustment. We noted
the
impairment charge related to the building is $4.9 million of the
charge, what is the remainder of the charge? Also, tell us what
events have occurred in the past year that led to the additional
charges. See paragraph 44 of SFAS 144.

Note 7. Intangible Assets - Page F-12

8. We noted that the company`s intangible assets approximate $7
million and include patents, trademarks and license agreements.
Tell
us and revise future filings to disclose the gross carrying amount
of
each intangible asset, as well as the related accounting for each.
See paragraph 45 of SFAS 142.


Note 17. Segment Reporting - Page F-19

9. Please tell us, and investors in future filings, the factors
used
to identify the company`s reportable segments and the types of
products and services from which each segment derives its
revenues.
See paragraphs 25 and 26 of SFAS 131. Please include in your
discussion how these two segments relate to the two product
categories discussed in the business section.

Note 18. Related Party Transactions

10. In addition, we noted that "selling prices of products sold to
Cannon,..... are based, generally, on normal terms given to
distributors. Please tell us what you mean by generally and tell
us
the nature of the sales agreements when Cannon receives terms
other
than those normal terms given to distributors. We may have further
comments after reviewing your response.

*    *    *    *

      As appropriate, please respond to these comments within 10
business days or tell us when you will provide us with a response.
Please furnish a cover letter that keys your responses to our
comments and provides any requested supplemental information.
Detailed cover letters greatly facilitate our review.  Please file
your cover letter on EDGAR.  Please understand that we may have
additional comments after reviewing your responses to our
comments.

      We urge all persons who are responsible for the accuracy and
adequacy of the disclosure in the filings reviewed by the staff to
be
certain that they have provided all information investors require.
Since the company and its management are in possession of all
facts
relating to a company`s disclosure, they are responsible for the
accuracy and adequacy of the disclosures they have made.

      In connection with responding to our comments, please
provide,
in writing, a statement from the company acknowledging that

?	the company is responsible for the adequacy and accuracy of
the
disclosure in the filings;
?	staff comments or changes to disclosure in response to staff
comments in the filings reviewed by the staff do not foreclose the
Commission from taking any action with respect to the filing; and
?	the company may not assert staff comments as a defense in any
proceeding initiated by the Commission or any person under the
federal securities laws of the United States.

      In addition, please be advised that the Division of
Enforcement
has access to all information you provide to the staff of the
Division of Corporation Finance in our review of your filing or in
response to our comments on your filing.

      You may contact Julie Sherman, Staff Accountant, at (202)
824-
5506 or me at (202) 942-1812 if you have questions.  In this
regard,
do not hesitate to contact Martin James, the Senior Assistant
Chief
Accountant, at (202) 942-1984.



							Sincerely,



							Jay Webb

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Mr. Walter A. Shephard
Zygo Corporation
January 19, 2005
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