| 摘要 |
PURPOSE:To make it possible to achieve the compact configuration by simplifying the constitution with high focusing accuracy being maintained. CONSTITUTION:A rotary shaft 9a, which is intersected with a plane including the optical axis of a projecting lens 1 and the optical axis of a light receiving lens 3 at an approximately right angle, is provided between the light receiving lens 3 and a photodetector 4. A parallel planar transparent plate 9, wherein an extending member is formed as a unitary body, is attached to the rotary shaft 9a. A cam follower is formed at the tip of the extending member. The extending member is energized with an elastic member so that the cam follower is always pushed to a cam surface 6 of a focus ring. The parallel planar transparent plate 9 transmits only the infrared rays, which are emitted from a light emitting element 2 and reflected from an object 11. The plate 9 is arranged at a position, which is separated from the surface of the photodetector 4 by the distance about 1/3 of the focal distance of the photodetector 3. |
