| 摘要 |
PROBLEM TO BE SOLVED: To align optical axes in a short time with loose accuracy in the range finding by retrieval of opposite receivers. SOLUTION: In a conventional embodiment, let a point at which an intensity of an intensity distribution curve C1 of a transmission beam at communication is P1 be P1 in the optical axis alignment in the case of placing the receivers opposite to each other, then the permissible deviation width of the transmission optical axis of a transmitter is within a range from the center O to the point R1. In this embodiment, the transmitter increases a transmission beam diameter being a projected light beam divergence angle to obtain an intensity distribution curve C2. Thus, the permissible deviation width of the transmission light in the intensity P1 is extended from the center O to a point R2. |
