| 摘要 |
The improved scanning optical system comprises a gas laser 10 for generating writing beam, a semiconductor laser 50 for generating monitoring beam of a different wavelength than the writing beam, a polygonal mirror 20 for deflecting and scanning the rays of light from each of the sources, a scanning lens 30 with which the rays of light deflected by the polygonal mirror 20 are focused on an image plane 40, a dichroic mirror 60 provided between the scanning lens 30 and the image plane 40 to isolate the monitoring beam from the optical path of the writing beam, and a signal generator A that receives the isolated monitoring light to generate a monitor signal. This optical system will not lower the energy of the writing beam, will not experience any change in the quantity of the monitoring beam due to leakage, and is free from the problem of curvature in the scanning lines of the monitoring beam.
|
