| 摘要 |
PROBLEM TO BE SOLVED: To obtain a light scanner in which a scanning lens is excellent in machinable shape and a small diameter of a beam spot is realized. SOLUTION: The light scanner has a coupling optical system 2 which couples a light flux emitted from a light source 1, a linear image optical system 4 which turns the light flux emitted from the coupling optical system 2 into a long linear image along the main scanning direction, a deflection means 5 which deflects and scans the light flux emitted from the linear image optical system and a scanning optical system which guides the light flux emitted from the deflection means 5 on to a plane to be scanned 10. The scanning optical system is composed of a scanning lenses 7 and 8, the scanning lens 7, which is closer to a deflection reflection plane 10, has a face having a negative power in the subscanning direction on the side closer to the deflection means, and the face is a special toric surface of which the curvature radius in the subscanning direction varies along the direction from the optical axis of the lens surface to the periphery in the main scanning direction, the F-stop number of the scanning optical system in the subscanning direction for the light flux directed to a plane to be scanned 10 is larger at the peripheral part of an effective scanning width than at the central part of the effective scanning width. COPYRIGHT: (C)2005,JPO&NCIPI |
