| 摘要 |
PURPOSE:To reduce a distance error and to detect an object at high accuracy by allowing a pair of light receiving parts, which detect whether or not a distance up to the object to be detected lies within a set distance, to photodetect not only a zero point correcting optical signals having the same phases but also linearity correcting optical signals having the prescribed phase difference. CONSTITUTION:A pair of light receiving parts 2a and 2b photodetects a high frequency modulation optical signal from a light projecting part 1 and an optical signal reflected by the object to be detected M, and a light receiving detection means 3 detects whether or not the object M lies within the set distance from the phase difference between both light receiving signals. The optical signals having the same phases from a light projecting part 1a are projected to these light receiving parts 2a and 2b, and the light receiving signal is processed by the signal processing circuit 5 of the means 3, thereby correcting a zero point. In the same manner the optical signals having the prescribed phase difference correct automatically linearity through optical fibers 6a and 6b having optical path length different from the light projecting part 1b. Thus the error at the time of measuring a distance is minimized, and the object can be detected at high accuracy. |
