| 摘要 |
A laser beam scanning apparatus provided with a first photosensor for detecting a laser beam which has passed through an optical member and a second photosensor for detecting the laser beam without passing through the optical member to prevent the breakage of the laser beam emitting source. The intensity of the laser beam is controlled on the basis of the output signal from the first photosensor and moreover, the supply of power to a laser beam emitting source is stopped when a difference between the intensities of the laser beam detected by the first and second photosensors exceeds a predetermined value due to any contamination of the optical member.
|
