| 摘要 |
PURPOSE:To always detect the quantity of receiving light within the dynamic range of a detecting system so as to detect the light quantity with high accuracy in a short time by detecting the relative position of a light beam diffusing means and photoreception/detecting means, with the light beam being emitted from a light source, and calculating the light quantity of the light beam from the light source in accordance with the detected output and photoelectric signals. CONSTITUTION:A laser beam LB from an ultraviolet-band laser light source is diffused by a diffusing plate 1 and received by a detector 4 through a diaphragm 2. The relative position of the plate 1 and detector 4 is adjusted by a driving section 7a and control section 7b and detected by a position detector 8a of a linear scale, etc. A CPU 20 decides the damping factor of the optical beam corresponding to the detected relative position in accordance with supplied position detected signals by referring to a memory 12 and calculates the light quantity of the laser beam from the light source from photoelectric signals supplied through an AD converter 11. When such constitution is used, the light quantity of receiving light can always be detected within the dynamic range of the detecting system and, as a result, the light quantity detection can be performed with high accuracy in a short time. |
