Systems Research Laboratories

Jack T Dehait

David C Dietz

Milo S Snyder

Francis M Talor

An optical micrometer includes circuit means for determining accurately the passage of a scanning beam of light across the edges of an article placed within the zone of measurement. By sensing the half power point of the beam as received by a photodetector, the accuracy of the measurement is made independent of the intensity of the scanning beam. The half power point is determined by comparing the amplitude of the photodetector output signal with its responsive half amplitude value. Since it is not possible to determine half-amplitude value until after full amplitude has been reached, delay means are provided, the amount of delay being determined by the dimensions of the beam and the scanning rate.

Half-maximum threshold circuit for optical micrometer

A method and apparatus for calibrating an optical micrometer utilizes a precisely dimensioned grate which is temporarily introduced into the optical path of the instrument within its zone of measurement. A beam of light is scanned through the zone of measurement and across the grate, and the information obtained therefrom is recorded in an electronic memory. Thereafter, articles subsequently placed within the zone of measurement are scanned by the beam, and the information obtained therefrom is compared against the calibration data to provide an accurate measurement of the article.

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Dayton, OH, United States of America

Jack T Dehait