Patent ID: 6233081
Filing Date: 2001-05-15
Classification: G02B

Abstract:
An optical scanning device, comprising:a light source which emits a light flux;a coupling lens which couples the light flux emitted by said light source;a optical deflector which has a deflection reflective surface, and deflects the light flux from the coupling lens at a uniform angular velocity;an aperture which is provided on an optical path between said light source and said optical deflector and is arranged to cut off a peripheral portion of the light flux deflected by the optical deflector to control a beam spot diameter on a surface to be scanned; anda scanning image-forming optical system converging the light flux deflected by said optical deflector to form a beam spot on said surface to be scanned so as to scan said surface to be scanned at a uniform velocity,wherein:the central wavelength of the light flux emitted by said light source is less than about 680 nm; andNAO, .kappa., .beta..sub.0 satisfy.beta..sub.0 /(NAO.cndot..kappa.)<100, (1)and NAO satisfies0.18<NAO<0.35, (2)where:NAO represents the light-source-side numerical aperture of the coupling lens;.kappa. represents the ratio A/D of the larger diameter A of the diameters, in a main scanning direction and a sub-scanning direction, of the opening of said aperture relative to the diameter D of the light flux emitted from the coupling lens; and.beta..sub.0 represents the larger one of the lateral magnifications, in the main scanning direction and the sub-scanning direction, of the entire optical system with respect to an optical path extending from said light source to said surface to be scanned, which optical path reaches a point of the image surface, at which point the image height is 0.