Reticle calibrated diameter gauge

摘要

A non-contact optical gauging device in which a laser beam is deflected to produce a bidirectional scan. The beam is split; a measuring portion scans an object being inspected while the other portion scans a calibration reticle having alternating opaque and transparent bands. The alternating transmission and ocultation of the beam through the reticle is used to generate calibration pulses, each representing a predetermined increment of movement of the calibration beam. Ocultation of the measuring beam by the object being measured generates a signal which is used to control counting of the calibration pulses as an indication of the dimension being measured. Bidirectional averaging is employed to minimize errors due to object motion in the direction of beam scanning. Variations are disclosed in which two measuring beams and one or two calibration beams, are employed for measuring large objects or for dual axis measurement, the latter by orthogonal projection onto the object being measured.