| 摘要 |
PURPOSE:To make the size of the titled device small and increase efficiency by using the first light detecting element that shows photo-conductivity in a specified wave length band and transmit light of other wave length band and the second light detecting element that receives the transmitted light. CONSTITUTION:A detecting element 21 is made by mirror polishing the both sides of an electroptical crystal plate such as BSO, EGO etc., and evaporating metallic electrodes 21A, 21B such as Al, In etc. on the incidence side. This has large photo-conductivity for blue light lambdaB and its sensitivity drops rapidly from red light to infrared light. On the other hand, a photo-electric element 25 detects the signal lambdaR of red side that passed the detecting element 21. Accordingly, light signals of two kinds of wave length lambdaR, lambdaB are sent into an optical fiber 20, the first detecting elememt intercepts and reacts the light signal of blue wave length and let flow the current, and a detecting circuit 24 detects the current. The light signal of red wave length that passed the detecting element 21 is detected by the photoelectric element 25 and a detecting circuit 26. |
