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Hitachi Ltd
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Hitachi Ltd
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Application filed by Hitachi LtdfiledCriticalHitachi Ltd
Priority to JP7555876ApriorityCriticalpatent/JPS531459A/en
Publication of JPS531459ApublicationCriticalpatent/JPS531459A/en
PURPOSE: To measure the distance toward light axis with a good precision discontinuously and continuously, by converting the phase difference of the signal position of two video signals to the test piece into the distance toward the light axis.