| 摘要 |
PURPOSE:To eliminate an irregularity in the quantity of light by providing a light source part control means which controls the quantity of light from a light source part according to the angle of scanning to a scanned surface and making a scan with a nearly constant quantity of light at any scanning angle. CONSTITUTION:A relay optical system 3 converges light from a light source part 2 on a rotary mirror 4 in a main scanning direction, the rotary mirror 4 makes a scan with the light beam from the relay optical system 3 in the main scanning direction, and a holographic ftheta lens 6 converges the converged light from the rotary mirror 4 on the scanned surface. Then a light source part control means 9 controls the quantity of light from the light source part 2 according to the angle of scanning to the scanned surface so that the surface can be scanned with the nearly constant light quantity at any scanning angle. Consequently, the irregularity in the quantity of light of the holographic ftheta lens 6 is eliminated. |
