| 摘要 |
PROBLEM TO BE SOLVED: To provide a reflection light condensing type photodetector capable of improving light-reception and photoelectric conversion efficiency of a light receiving element while preventing the light receiving element from being broken caused by concentration of intense light such as direct sunlight.SOLUTION: A reflection light condensing type photodetector 1, having a light receiving element 3, receives light by condensing reflected spatial light superimposed with information signal through a concave mirror 2 having a focal point. The light receiving element 3 is disposed on a substantial center axial line inside of the concave mirror 2 so that a light receiving surface 3a faces toward a mirror surface side of the concave mirror 2. The light receiving element 3 is disposed by having the position of the light receiving surface 3a displaced toward the mirror surface side or an opposite side of the mirror surface from the focal point of the concave mirror 2. A transparent synthetic resin is filled in a recess of the concave mirror 2, and a concave lens 15 is formed in a periphery of the transparent synthetic resin as a lens part. Light passing through the concave lens 15 in the periphery is reflected by the mirror surface and reaches the light receiving surface 3a of the light receiving element 3. |
