Optical relay whose target operates ferroelectrically

Claim 1

An optical relay which transmits light in dependence on an electric field parallel to the direction of propagation of the light, said relay comprising a target of electrically insulating material which becomes ferroelectric below a certain temperature, called the Curie temperature, in the proximity of which the optical relay operates, said target having said first face and an opposed second face, means for scanning said first face of said target with an electron beam, an anode for collecting electrons emanating from the first face of the target in response to the electron beam, a heat sink having a first face, an opposed second face, and a circumferential area extending therebetween, said first face of said heat sink being disposed against the second face of said target, cold transfer means in contact with said heat sink along the circumference of its second face and the adjacent portion of its circumferential area, said cold transfer means being effective to cool said target via said heat sink, means for assuring that a central area of said target is cooled before the corresponding peripheral area thereof, whereby as the temperature of the heat sink is lowered by said cold transfer means, said central area of said target will fall below the Curie temperature before said peripheral area, so that a ferroelectric domain can be formed in said central area while a paraelectric domain is sustained in said peripheral area and the advance of the ferroelectric domain into the peripheral area can be stopped before it breaks up into smaller domains.