| 摘要 |
PURPOSE: To reduce a DC drift over a long period of time, and maintain high detecting accuracy by impressing alternating voltage on an electrode by a voltage impressing device, and taking out output signals of light detectors when the alternating voltage becomes equal to a predefined value by a control device. CONSTITUTION: The reflected light propagated in a main trunk channel light wave guide passage 2 is branched off into respective branch channel light wave guide passages in a branch part 6, and among them, the light propagated in a left branch channel light wave guide passage 3 and a right branch channel light wave guide passage, is respectively detected by a left light detector 11 and a right light detector 12. A difference in output between both light detectors 11 and 12 is calculated by a main differential amplifier 32, and a control device 30 composites a reflecting surface of a detecting object 15 or an inclination of reflectance, that is, a differential image on the basis of this main differential signal SM, and displays it on a monitor 33. In this way, among a change in the intensity distribution of the light propagating in the light wave guide passage 2, an inclination of the reflceting surface of the detecting object 15 is detected from positional information, and an inclination of reflectance of the detecting object 15 is detected from amplitude information. |
