| 摘要 |
<p>A distance from an object to a light source (3) of a distance measuring apparatus is determined from a phase difference between a received signal which represents a reflected light beam from the object and a reference signal which is obtained directly from a transmitted light beam. The reflected signal and the reference signal are photoelectrically generated by a light-receiving unit (8). The level of the received signal is adjusted by a level adjustor (14) to the optimum level suitable to a phase difference detector (20). Consequently, the dynamic range of a phase difference detector (20) of the distance measuring apparatus can be made narrower. A light intensity regulator (19) is positioned between the light source (3) and the light-receiving unit (8) along a reference optical path (16), and the regulator (19) regulates the intensity of the reference light so as to be substantially equal to the intensity of the reflected light or within a prescribed range therefrom. Because the light intensity regulator (19) utilizes liquid crystal which has a relatively high attenuation rate, no mechanical drive is required. The phase difference detector (20) detects a phase difference between the received signal that has passed through the level adjustor (14) and the reference signal that has passed through the light intensity regulator (16). The distance measuring apparatus efficiently utilizes the intensity of a received light beam from a range-measuring optical path (30A) without attenuating the intensity. <IMAGE></p> |
