| 摘要 |
1,260,257. Photo-electric apparatus. COMPAGNIE GENERALE D'ELECTRICITE. Oct.16, 1970 [Oct. 17, 1969], No. 49223/70. Heading G1A. In a photo-electric arrangement in which light is incident on a photo-detector 2, Fig. 2 through an optical filter 3, light from an auxiliary test source 4 is directed on to the photo-detector by reflection from the emergent face of the optical filter. Other optical elements may be included in the path between the filter and detector. |
