DIAGNOSTIC METHOD OF OPTICAL SYSTEM IN LASER-BEAM SCANNING RANGE FINDER

PURPOSE:To realize a low-cost and high-reliability radar regarding the self- diagnostic method of an optical system-in a laser-beam scanning pulse radar. CONSTITUTION:A laser-beam scanning range finder is constituted in the following manner: its optical system scans, by using a laser-beam scanning part 2a, a laser beam LTX which is outputted by a laser-beam transmission part 1a; and a scanning laser beam LS is transmitted via a light-transmitting window 16a. The laser-beam scanning range finder performs a diagnostic operation in the following manner. That is to say, a laser beam LL which has been reflected regularly by the light-transmitting window 16a is detected by means of a photodetection element 20. When its intensity VL is lowered to a prescribed predetermined intensity VTH1 or lower, it is diagnosed that an abnormality which lowers a transmission output exists in the laser-beam transmission part 1a. On the other hand, when the intensity VG of a laser beam LG reflected in a diffused manner by the light-transmitting window 16a is raised to a prescribed predetermined intensity VTH2 or higher, it is diagnosed that a stain 17a exists on the light-transmitting window 16a.