| 摘要 |
PURPOSE:To attain tracking with high reliability even if a moving distance of an unattended truck is changed by controlling an incident luminous amount of a feedback beam from an unattended truck mounting mobile station so as to be averaged by each photodetector so as to attain cost-down. CONSTITUTION:A light beam LB1 generated from a light beam generator 110 of a fixed station 10 is irradiated via a modulator 120, a splitter 150 and a mirror 131. A part of the light beam LB1 is reflected in the same direction as the incident direction via a splitter 220 and a corner cube 210 of a mobile station, becomes a feedback beam RB and is returned to the station 10. The light beam is made incident in any quadrant or the center of a 4-quadrant split lens 160 via the mirror 131 and the splitter 150, scattered and a photodetecting plane 171 of a photodetector 170 is irradiated. In this case, the light is controlled by the controller 134 so that the incident luminous amount to each photodetector is averaged, the received luminous intensity per unit area at the photodetecting plane of the photodetector is strengthened and the tracking with high accuracy is attained even when the moving distance of the unattended truck is changed. |
