| 摘要 |
1,231,029. Photo-electric displacement measurement. NATIONAL RESEARCH DEVELOPMENT CORP. Dec.8, 1969 [Dec.13, 1968], No.59477/68. Heading G1A. [Also in Division H1] In an apparatus for measuring relative movement between a "scale grating" 3 and an "index grating" 4 in the presence of a collimated beam of light, opaque elements of the latter grating, which elements alternate with transparent elements across the grating, constitute parts of a photo-electric device 4b and are adapted to respond to light incident upon the left-hand surface thereof in the configuration shown, but not to light incident upon the righthand surface. This permits the grating 4 to be used under near-normal incident light conditions in conjunction with a reflective scale grating 3, the light passing first through the index grating 4 from its non-responsive surface, being reflected from the scale grating 3, and finally striking the responsive surface of the index grating 4 and producing a cyclic output from the photo-electric device 4b. The index grating 4 may also be used in conjunction with a transmissive scale grating Fig.3 (not shown). The index grating 4 preferably comprises a glass substrate 4a on which is deposited an array of parallel strips of opaque metal linked at one end by a common transverse strip serving as an output terminal. The active medium of the device comprises an evaporated CdS layer having its upper surface doped with cuprous ions to produce a photovoltaic effect, and covered with an evaporated transparent conductive layer of Au or tin oxide. A photo-resist method is used to shape the CdS and overlying conductive layers into strips overlying the opaque metal strips and interconnected by a common transverse strip serving as a common output terminal at the opposite end to that at which the opaque strips are interconnected. If the photoresist is transparent it may be left on the device, but otherwise it is removed. |
