| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent disabling of communication due to projection of transmission and reception light in different directions because even shimmering of the air is detected when a space where transmission and reception light is uneven is a transmission medium. <P>SOLUTION: The photodetector has a light-receiving element (8), an optical collection system which collects luminous fluxes incident from outside and forms spots of the luminous fluxes on the light receiving surface of the light-receiving element (8), information generating means (11 and 12) which generate information relative to the position of the spots according to the output from the light-receiving element (8). The optical collection system has an optical element array (21) provided with several optical element parts each of which has the function of collecting light. In this case, the plurality of spots formed by the plurality of optical element parts roughly overlap one another on the light-receiving surface. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
