| 摘要 |
PURPOSE:To monitor the amount of scanning light irradiated on a surface to be scanned, by measuring a loss of a laser light in a scanning optical system, through the detection of the intensity of emitting light from a laser light source and of the scanning light and the comparison of them provided with a circuit. CONSTITUTION:A emitted light from a laser light source 7 from a laser light source 7 having the detecting function of the intensity of emitted laser is detected at a photodiode 6 and converted into a level signal in response to the intensity of output of a monitor detecting circuit 11. On the other hand, the laser scanning light is detected at a photodiode 9, level conversion is made at a monitor detecting circuit 10 and compared with an output of the monitor detecting circuit 11 at a differential circuit 12. The output of the differential circuit 12 is amplified 12', outputted to an alarm connecting terminal 13, where a signal is outputted when the laser scanning light is decreased for a prescribed value or more in comparison with the emitted light. |
