| 摘要 |
PURPOSE:To improve reliability when a laser output is monitored, by providing a screening means, which prevents receiving of laser beam by an optical sensor, between a returning mirror and the optical sensor, and providing linear relationship between the detected signal of the optical sensor and the laser output. CONSTITUTION:A screening means 18 is provided between a returning mirror 12 and an optical sensor 16. Laser beam P2, which is transmitted through a central part, is not received by the optical sensor 16 by a laser light absorbing body 21 in the screening means 18. Only laser light P1, which is transmitted through a peripheral part and has linear relationship with a laser output Pl, is received by the optical sensor 16. The detected signal from the optical sensor 16 has the linear relationship with the laser output Pl. Thus, a calibrating device is not necessary, different from a conventional device. the constitution as a whole can be simplified. The laser output Pl can be accurately monitored by an output monitor 23. |
