PURPOSE:To perform accurate measurement, by obtaining the ratio of noises, which are measured when a light point is generated and when it disappears, and removing the noises from the output of a first light receiving means for obtaining the distance to the light point. CONSTITUTION:The image of light from a light point P is formed on the light receiving surface of a sensor 7. Its output is converted into a numerical value by an A/D converter 8, and the result is inputted to a computer CO. The inputted data is expressed by (St+Nt)n. At the same time, the output from a photodiode 10 is inputted as NMt through an A/D converter 11. The output NMt+Ts from the A/D converter 11 when the time Ts has elapsed is inputted and memorized. At the same time, the output from the image sensor 7 is inputted and (Nt+Ts)n is memorized. Then, NMt+Ts/NMt(St+Nt)n-(Nt+Ts)n is operated, and the data related to the intensity of the light at each (n) when the noises are approximately removed, is obtained.
展开▼
