Improvements relating to apparatus for measuring small movements

Abstract

Abstract 782,831. Photo-electric measuring. ASSOCIATED ELECTRICAL INDUSTRIES, Ltd. July 6, 1955 [July 8, 1954], No. 20050/54. Drawings to Specification. Class 40 (3). [Also in Group XX] The image of one diffraction grating is projected on to the same or another grating so that the grating lines are slightly mutually inclined to produce moirÚ fringes. The emergent light may fall on a photo-cell so that the movement of the fringes varies the output of the cell. Non- cyclical variation of the output may be used to measure or control the relative movement of the grating and grating image and the cyclical variation may be used to measure the relative movement by fringe counting by means of an electronic counting arrangement. Optical arrangements (see Group XX) for measuring linear and angular movements are described.

Inventors

• 👤 James Dyson

Bibliographic Details