| 摘要 |
PURPOSE:To enhance a light receiving or light projecting efficiency and make the light projecting receiving equipment thin, by arranging a small-diameter convex lens or the optical axis of the concave mirror of the light projecting and receiving equipment and by arranging a light projecting and receiving element in the common focus position of the concave mirror and the convex lens. CONSTITUTION:Parallel light beam l approximately equal to diameter D1 of concave mirror 2 is incident onto light receiver 1. Parallel light beam l inside diameter D2 is converged by convex lens 3 and is incident directly onto light receiving element 4 in common focus position F. Parallel light beam l outside diameter D2 is reflected by reflection surface 2a of concave mirror 2 and is incident onto element 4 in focus F also. Now, though light beam l1 in the range of light receiving angle alpha of element 4 is reflected to act effectively upon element 4, light beam l2 outside the range of light receiving angle alpha comes around to the back face of element 4 and is outside light receiving angle alpha. Since this light beam is converged directly by convex lens 3, all light beams l1 and l2 are stored in light receiving angle alpha though this equipment is thin. |
