Patent ID: 6771407
Filing Date: 2004-08-03
Classification: G02B

Abstract:
An optical scanner comprising:a first optical system having a coupling lens that couples a light flux from a light source; a second optical system that forms the light flux into a line image extending in the horizontal scanning direction, on a deflector, the second optical system including a glass lens having a positive power in a vertical scanning direction, or a resin lens having a positive power in the vertical scanning direction; a third optical system having a scanning image formation device that condenses the light flux deflected by the deflector as an optical beam spot on a surface to be scanned, the third optical system including a first optical element made of resin, having a positive power in the horizontal scanning direction, and a second optical element made of resin, having a positive power in the vertical scanning direction; and a temperature distribution generation unit which controls atmospheric temperature T1 near the first optical element, and atmospheric temperature T2 near the second optical element such that T1>T2, wherein an absolute value of a lateral magnification in the horizontal scanning direction of an optical system, which includes the first optical system, the second optical system, and the third optical system, is set larger than an absolute value of a lateral magnification in the vertical scanning of the optical system.