Patent ID: 6850350
Filing Date: 2005-02-01
Classification: G02B

Abstract:
1. 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, wherein said imaging optical system comprises: a first cemented lens, formed by bonding a first lens and a second lens to each other, having negative refracting power; a second cemented lens, formed by bonding a third lens and a fourth lens to each other, having positive refracting power; and a fifth lens having positive refracting power successively from an entrance side for said light beam to satisfy the following expressions (1) and (2): where L represents the length between a plane of incidence of said first cemented lens and a plane of exit of said fifth lens along an optical axis direction, f represents the composite focal distance of said first cemented lens, said second cemented lens and said fifth lens in the above expression (1), r r