| 摘要 |
PURPOSE:To measure only a reflected light from an object of measurement by a method wherein a lens whose surface in a prescribed region around the optical axis is covered with a non-reflective film is provided in the middle of an optical system. CONSTITUTION:A light from a light source LS is turned into an intermittent light by a chopper CP and applied to an object TG of measurement through an optical fiber FBO for the light source, a joint element JT, an optical fiber FB and a lens L. Since a circular region LR of the lens L is covered with a non-reflective film L1, the light applied to the lens L from the optical fiber FB is reflected on the surface of the lens L and does not enter an emission opening. Part of the light applied to the object TG of measurement is reflected by the object TG, passed through the lens L, the optical fiber FB, the joint element JT and optical fiber FB1 and FB2 for measurement and projected to filters F1 and F2, and a transmitted light is detected by photosensors S1 and S2. A direct-current component of a detection signal is cut by capacitors C1 and C2 and only the intermittent light from the light source is sent to amplifiers A1 and A2. |
