| 摘要 |
PURPOSE:To correct deviation of the light receiving angle characteristic from the law of cosine near 90 deg., by working a light diffusing plate in convexs and concaves to apply light shielding films on the bottoms of the concaves. CONSTITUTION:A light diffusing plate 1 is worked in convexes and concaves on the inner surface of a light receiving section and a light shielding film 6 is applied on the bottoms of the concaves of the worked surface. Light made incident into the light diffusing plate 1 passes gradually through a dimmer plate 3 and a visual sensitivity filter 4 and reaches a photoelectric conversion element 5 to be converted into electricity. Then, out of the incident lights from the direction smaller in the light receiving angle, the normal transmission component alone passing the light diffusing plate 1 at the longest distance is emitted reaching the back of the light diffusing plate 1 while the normal transmission component passing at the shortest distance is intercepted with the light shielding film 6. On the other hand, the incident light from the direction larger in the light receiving angle passes the light diffusing plate 1 at a smaller distance as compared with the normal transmission component from the direction smaller in the light receiving angle, making the attenuation less due to diffusion. Thereafter, the attenuation rate of the incident angle from the direction smaller in the light receiving angle becomes larger than that from the direction larger in the light receiving angle. This can correct deviation of the light receiving characteristic from the law of cosine relatively near 90 deg.. |
