Patent ID: 6091533
Filing Date: 2000-07-18
Classification: G02B

Abstract:
A scanning optical system comprising:a light source that emits a light beam;a deflector that deflects said light beam emitted by said light source to scan along a main scanning direction;a single mirror that reflects said light beam deflected bv said deflector towards a surface to be scanned, said single mirror being arranged such that said light beam deflected by said deflector and is incident on said single mirror and a light beam reflected by said single mirror forms a predetermined angle in the auxiliary scanning direction, said single mirror being formed to have a positive power both in said main scanning direction and in said auxiliary scanning direction, and a shape of said single mirror being asymmetric in said auxiliary scanning direction with respect to a reference line which extends in said main scanning direction and intersects an optical axis thereof,wherein when a three-dimensional coordinate system defined by a y-axis extending in the main scanning direction, a z-axis extending in the auxiliary scanning direction, and an x-axis orthogonal to said y-axis and z-axis is given, and when a sag amount, which represents a reflection surface of said mirror, in said x-axis direction with respect to a y-z plane is expressed by a function f (y, z) with respect to y and z coordinates, a condition:0.005<.vertline.g(0.8P,0)-g(0.0).vertline.<0.025is satisfied, wherein ##EQU12## and wherein, P represents a distance between said deflector and said single mirror.