Patent ID: 7646523
Filing Date: 2010-01-12
Classification: G02B

Abstract:
1. An optical scanning apparatus comprising: light source means; a condense optical system that condenses a light beam emitted from said light source means; an optical deflector that deflects a light beam emergent from said condense optical system for scanning; and an imaging optical system that images the light beam deflected and scanned by a deflection surface of said optical deflector on a surface to be scanned, wherein said imaging optical system comprises at least one imaging optical element made of plastic, wherein said optical deflector has a function of moving the deflection surface back and forth in a main scanning direction, the light beam emergent from said condense optical system converges in a sub scanning cross section, the convergence position being in an optical path between said condense optical system and the deflection surface of the optical deflector, and the following condition is satisfied: where, L 2 (mm) represents the distance from the convergence position of the light beam emergent from the condense optical system in the sub scanning cross section to the deflection surface of said optical deflector, β represents the imaging magnification of said imaging optical system in the sub scanning cross section, D (mm) represents the diameter of an image spot imaged on said surface to be scanned in the sub scanning direction, and λ represents the wavelength of the light beam emitted from said light source means.