| 摘要 |
An optical type range finder apparatus for a motor vehicle. Dew condensation and deposition on an inner surface of an irradiation laser beam projecting window is prevented even in the environment where a front surface of the range finder is cooled down steeply, for ensuring a stable distance measuring performance. The apparatus projects outwardly an irradiation light beam (LE) from the motor vehicle and detects a distance between the motor vehicle and an object on the basis of known relation between the irradiation light beam (LE) and an echo light beam (LR) from the object existing in environment of the motor vehicle. An irradiation window (3a) includes a first light-transmissive panel (7) having a surface exposed to the exterior, a second light-transmissive panel (21) having a surface exposed to the interior of the range finder apparatus, and a heat insulation space (24) formed by an air layer confined between the first light-transmissive panel (7) and the second light-transmissive panel (21). |
