| 摘要 |
PROBLEM TO BE SOLVED: To reduce an correction error of optical axis shift which is generated by an uneven intensity distribution, even if there is an uneven intensity distribution in a light-receiving beam, and moreover, make it possible to conduct a stable space optical communication even if fluctuations in the extent of microns are generated in the atmosphere. SOLUTION: When the optical axis shift of the light-receiving optical axis of its own device from a light-receiving beam LB is detected on the basis of information on the positional shift of the beam LB from a reference position, and an optical axis shift correcting signal is sent to a variable part 20 in the optical axis direction on the basis of information on the optical axis shift to control the direction of the light- receiving optical axis of the own device, a plurality of diffracted lights are generated from the one beam LB by a diffraction grating of a hologram 21 provided in a light- receiving optical system and a plurality of diffracted light spots are formed on the light-receiving surface of a light-receiving beam spot position detection light-receiving element 22. Even in the case where an intensity distribution on an entrance pupil, which is the beam take-in port of the own device, is uneven, a correction of the optical axis shift is made by contriving so as to bring the center of the light intensity of a light-receiving beam spot closer to the center of a luminous flux. |
