| 摘要 |
PURPOSE:To cut off completely backward scattered light due to oscillations of laser light and to improve reception efficiency by forming a passing window and a rotary detection hole for received laser light in a light shield board and synchronizing the rotation of the light shield board with transmitted laser light. CONSTITUTION:When a laser oscillator 6 oscillates the transmitted laser light 7, the light shield disk 1 is rotated by a pulse motor 2 operated at the same time in synchronism with the transmitted laser light 7, and a photodetector 8 is covered with the light shield surface 1A of the light shield board 1. When the received laser light 11 reaches a receiving mirror 12 and is converged, the light shield disk 1 is rotated by the pulse motor 2 and the received laser light passing window 9 of the light shield disk 1 is displaced to a position opposite the photodetector 8, so the received laser light 11 passes through the passing window 9 and operates on the photodetector 8. In this case, the light from the light source 4 is projected on a photodiode 5 through the rotary detection hole 10, thereby detecting the position of the passing window 9.
|
