-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 TORPIDOukNCKREEsymF7jjO6V9jQkpGZjn8mqhFmapnaGA0CzE6hnZfH6sRYUC5i
 iWy0uhSLbJI506Yo68/lBg==

<SEC-DOCUMENT>0001179110-04-022244.txt : 20041130
<SEC-HEADER>0001179110-04-022244.hdr.sgml : 20041130
<ACCEPTANCE-DATETIME>20041130194800
ACCESSION NUMBER:		0001179110-04-022244
CONFORMED SUBMISSION TYPE:	4/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040720
FILED AS OF DATE:		20041130
DATE AS OF CHANGE:		20041130

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			COHERENT INC
		CENTRAL INDEX KEY:			0000021510
		STANDARD INDUSTRIAL CLASSIFICATION:	LABORATORY ANALYTICAL INSTRUMENTS [3826]
		IRS NUMBER:				941622541
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0930

	BUSINESS ADDRESS:	
		STREET 1:		5100 PATRICK HENRY DR
		CITY:			SANTA CLARA
		STATE:			CA
		ZIP:			95054
		BUSINESS PHONE:		4087644000

	MAIL ADDRESS:	
		STREET 1:		5100 PATRICK HENRY DRIVE
		STREET 2:		MAIL STOP P38
		CITY:			SANTA CLARA
		STATE:			CA
		ZIP:			95054

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	COHERENT RADIATION
		DATE OF NAME CHANGE:	19770604

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ROGERSON GARRY W
		CENTRAL INDEX KEY:			0001232125

	FILING VALUES:
		FORM TYPE:		4/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-05255
		FILM NUMBER:		041175699

	BUSINESS ADDRESS:	
		STREET 1:		C/O VARIAN INC INC
		STREET 2:		3120 HANSEN WAY
		CITY:			PALO ALTO
		STATE:			CA
		ZIP:			943041030
		BUSINESS PHONE:		6504243873

	MAIL ADDRESS:	
		STREET 1:		3120 HANSEN WAY
		CITY:			PALO ALTO
		STATE:			CA
		ZIP:			943041030
</SEC-HEADER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4/A -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2004-07-20</periodOfReport>

    <dateOfOriginalSubmission>2004-07-20</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000021510</issuerCik>
        <issuerName>COHERENT INC</issuerName>
        <issuerTradingSymbol>COHR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001232125</rptOwnerCik>
            <rptOwnerName>ROGERSON GARRY W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P. O. BOX 54980</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SANTA CLARA</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95056</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Non-Qualified Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>26.695</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2004-07-20</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>30000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>26.695</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2005-03-25</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-03-25</value>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>30000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>30000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Amended Form 3 to correct Date Exercisable due to a data entry error.  These shares become exercisable 10,000 shares 3/25/05, 3/25/06 and 3/25/07 , respectively.</footnote>
        <footnote id="F2">Amended Form 3 to correct Expiration Date due to a data entry error.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Scott H. Miller, by power of atty</signatureName>
        <signatureDate>2004-11-30</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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