Abstract: 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.

Abstract: 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.

Abstract: In an optical dimension gauging instrument, commonly referred to as a laser micrometer, particularly for use in measuring the outside dimension of elongated cylindrical objects, such as coated wires or steel tubes, in hostile optical environments, including a laser for generating a beam of collimated light, means for directing the light through a measurement zone, photodetector means responsive to the light passing through the measurement zone, and a mirror mounted for rotation by a motor to cause the beam to be scanned repeatedly across the measurement zone, a beam expander is employed to enlarge the output of the laser to a diameter substantially greater than the maximum dimension of normally anticipated foreign objects which might intercept the beam outside the measurement zone, an anamorphic lens further expands the beam in one plane to a size greater than the size of normally anticipated foreign objects both within and without the measurement zone, and a lens system causes the beam to be focused in the o

Abstract: A narrow collimated light beam, such as a laser beam, is directed towards a mirror which is rotated to effect rotary planar scanning or sweeping of a lens constructed to convert the rotary scanning beam into a parallel scanning beam. An article to be measured is positioned in the path of the parallel scanning beam at generally the focal point of the lens, and interruptions of the parallel scanning beam, as produced by the article, are sensed by a photodetector. The photodetector controls transmission of pulses or signals to means for counting pulses produced by a high frequency generator so that the counted pulses correspond to the dimension of the article at the plane of the parallel scanning beam. In this invention a lens is positioned in the path of the light beam and changes a narrow substantially round light beam into an elongate or substantially flat light beam which is scanned across an object for measurement thereof.