| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a photodetector and an optical system with simple constitution for detecting light over a wide range without a loss. <P>SOLUTION: The photodetector 10 is provided with: an optical path splitting means 12 placed on an optical path extended up to a light collecting face 14 for collecting light beams; and a light receiving element 13 for receiving the light beams split by the optical path splitting means 12, and the optical path splitting means 12 is provided with an aperture 16 for passing the light beams when the optical axis of the light beams is coincident with a prescribed optical axis A directed to the light collecting face 14, and an optical element 17 located around the aperture 16 and for reflecting a part of the light beams toward the light receiving element 13 when the optical axis of the light beams is deviated from the prescribed optical axis A. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
