Optic relay for use in television

Claim 1

An optical relay device, comprising a plate of electrically insulating material positioned in an optical path between a polarizer and an analyzer, said material consisting of an acid salt which is ferroelectric below the Curie temperature thereof, said material being enriched with deuterium whereby the Curie temperature thereof is higher than in the absence of deuterium, means for applying a variable electric field across the plate with a direction parallel to the general direction of propogation of light in said path whereby the plane of polarization of the light is variably rotated in dependence upon said field, means for generating an electron beam, means for scanning the electron beam across a major face of said plate, an anode for collecting secondary electrons released from said plate by said electron beam, and a temperature control device for stabilizing the temperature of the plate at a value differing at most 5* from the Curie temperature of the plate, said temperature device comprising a capacitor as a temperature-determining element the capacity of which varies as a function of the temperature, the dielectric of the capacitor comprising a material having a Curie temperature differing from that of the plate by between 1* and 20*.