| 摘要 |
Optical relay for projection television includes a target (12, 31) of an electrically insulating material which allows the light to pass in a manner depending on the electric field parallel to the direction or propagation of this light. An electron beam scans a first face of this target scanned by an electron beam and an anode (30) receives the secondary electrons emitted in response to the action of the beam. An optically transparent and electrically conducting plate 38 is provided against the second face of the target receive the electric signal conveying the video information. The target is made of a material which becomes ferroelectric, and a heat exchanger (18) is connected to a heat source which maintains the temperature of the target. In the normal mode of operation the target is formed by a useful central zone where it exhibits a single domain ferroelectric phase and a neutral peripheral zone, having a temperature much higher than the Curie temperature where it exhibits a paraelectric phase. The target is cemented to a plate (32) which is provided at its periphery with a collar (33) which is a very good heat conductor and is maintained at a temperature T1 by means of at least one thermal bridge (37) connected to the collar and to a reference source (39) kept at a temperature T0. The plate is cemented to a plate support (34) which is kept at a temperature T2 so that the plate has an annular zone in which a temperature gradient T1-T2 exists.
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