Opticator

(spring-optical measuring head), an instrument for measurement of linear dimensions in which the conversion mechanism of a mechanical comparator is combined with an optical system. An opticator differs from a mechanical comparator in that it uses an “optical lever,” consisting of a light source and a mirror bonded to a spring, rather than a pointer. As a light ray passes through an aperture with a filament mounted in its center and is reflected from the mirror as a spot of light, it transmits to the scale the image of the thread that functions as a pointer. The opticator offers all the advantages of a mechanical comparator, and also a larger range of measurement.

The first opticators were manufactured in the late 1940’s in Suhl, in the German Democratic Republic. Opticators made in the USSR have scale divisions of 0.1, 0.2, 0.5, and 1 micron (μ), with corresponding measurement limits of 24 (±12), 50 (±25), 100 (±50), and 250 (±125) μ. The error of an opticator in its vertical position does not exceed 0.5 of a scale division within the range of 100 scale divisions and is not more than one scale division for the total measurement range. Opticators are used for measurement by means of comparison with gauge blocks or certified parts. Opticators are usually equipped with adjustable tolerance indicators that consist of two light filters, which change the color of the light spot to red or green at the tolerance limits. During measurement, an opticator is mounted on a stand.

In the USSR, the opticator is being used as the basis for production of photoelectric converters (with additional photo-resistors mounted on the scale). Such instruments have scale divisions of 0.5, 1.2, and 5 μ and are used in automatic monitoring devices. Such photoelectric converters are capable of sorting the parts being checked into a large number of groups (up to 50).