GB1024473A - - Google Patents

Abstract

1,024,473. Photo-electric measuring devices. ZAVODY V. I. LENINA PLZEN NARODNI PODNIK. Oct. 22, 1962 [Oct. 20, 1961], No. 39831/62. Heading G1A. The dimension or position of an object 2 in a direction parallel to a diffuse planar light source 1 of greater area than the object and emitting light of a specific wavelength is given by the output from a photo-electric cell 3a as modified by the interposition of the object 2 between the cell 3a and the source 1, the cell 3a being responsive only to light of said specific wavelength. As shown light from the source 1 is focused on to the cell 3a by an optical system comprising a lens 3b and filter 3c and the photo-cell 3a forms part of a bridge circuit 4 whose output controls a servo motor 7 which adjusts the position of the combined photo-cell and optical system unit 3 in a direction parallel to the surface of the source 1 to reduce the output from the bridge circuit to zero, the resultant position of the unit 3 as given by a remote indicator coupled to the servo motor 7 by a selsyn 5 giving the required object data. Alternatively the position of the unit 3 may be adjusted manually or the unit 3 may be stationary, the required data being then given by the output from the bridge circuit 4.