Patent ID: 6445482
Filing Date: 2002-09-03
Classification: G02B

Abstract:
An optical scanning apparatus for optically scanning a surface to be scanned at a constant velocity, the optical scanning apparatus comprising:a light source for emitting a light flux; a first optical lens system for coupling the light flux emitted by the light source to a following optical lens system; a second optical lens system for forming the light flux from the first optical lens system into a line image extending in a direction corresponding to a main scanning direction of the surface to be scanned which is perpendicular to a sub scanning direction; an optical deflector for deflecting the light flux formed as the line image via a deflecting reflective plane thereof, which is located near where the line image is formed; and a third optical lens system for condensing the deflected light flux as an optical beam spot on the surface to be scanned; wherein the second optical lens system includes a glass lens having positive power in the sub scanning direction and a plastic lens having power in both the main scanning and the sub scanning directions, with the power in the sub scanning direction being a negative power.