Patent ID: 6771429
Filing Date: 2004-08-03
Classification: G02B

Abstract:
An optical scanner comprising:a light deflector periodically reflecting a light beam emitted from a light source to periodically deflect said light beam; and an imaging optical system having such a distortion characteristic that the product of a focal distance and a half angle of view defines an ideal image height for imaging said light beam deflected by said light deflector on an objective surface, said imaging optical system comprising a first lens having negative refracting power, a second lens having positive refracting power and a third lens having positive refracting power successively from an entrance side for said light beam to satisfy the following expressions (1) and (2): Lf<0.100(1)0.10&leq;r1r3&leq;0.26(2)whereL represents the length between a plane of incidence of said first lens and a plane of exit of said third lens along an optical axis direction, f represents the composite focal distance of said first lens, said second lens and said third lens in the above expression (1), r1 represents the radius of curvature of a refracting interface on the entrance side for said light beam in said first lens, and r3 represents the radius of curvature of a refracting interface on the entrance side for said light beam in said second lens in the above expression (2).