Patent ID: 8531738
Filing Date: 2013-09-10
Classification: G02B

Abstract:
1. An optical scanning apparatus, comprising: a light source unit; a deflection unit including a deflection surface; an incident optical system for guiding a light beam emitted from the light source unit to the deflection unit; and an imaging optical system for imaging, on a surface to be scanned, a light beam deflected for scanning on the deflection surface of the deflection unit, the imaging optical system including: the light beam deflected for scanning on the deflection surface of the deflection unit passes through the transmission type imaging optical element in order of the first transmission surface and the second transmission surface, and after being reflected on the reflection surface of the reflection optical element, passes through the transmission type imaging optical element again in order of the third transmission surface and the fourth transmission surface; in a sub-scanning section, the light beam entering the first transmission surface is bent at the first transmission surface in a direction in which the light beam reflected on the reflection surface of the reflection optical element passes through the third transmission surface; and the following condition is satisfied: where γ(°) indicates an angle defined, in the sub-scanning section, between a principal ray of the light beam entering a scanning center of the first transmission surface in a main scanning section and a normal to the first transmission surface at an intersection of the principal ray and the first transmission surface, and γ′(°) indicates an angle defined, in the sub-scanning section, between a principal ray of the light beam entering the scanning center of the first transmission surface in the main scanning section which is bent at the first transmission surface and the normal to the first transmission surface at an intersection of the principal ray and the first transmission surface.