Patent ID: 7450284

Claim:
An optical scanning apparatus, comprising: a light source unit; a deflecting unit; an incident optical system for guiding a light beam emitted from the light source unit to the deflecting unit; and an imaging optical system for imaging the light beam deflected by the deflecting unit onto a surface to be scanned, wherein the following condition is satisfied, 0.3 <Sd/L< 1, where L (mm) represents an interval between a deflecting surface of the deflecting unit and the surface to be scanned and Sd (mm) represents an interval between the deflecting surface of the deflecting unit and a natural convergent point, and wherein a scanning field angle region in which |θ 1 |<|θ 3 | and |θ 2 |<|θ 3 | are satisfied exists in an entire effective scanning field angle region, where in a main scanning cross section and for a finite scanning field angle θ 1 (deg.), θ 2 (deg.) represents an angle formed between a principal ray of a light beam incident on an imaging optical element LR included in the imaging optical system and an optical axis of the imaging optical system and θ 3 (deg.) represents an angle formed between a principal ray of a light beam emitted from the imaging optical element LR included in the imaging optical system and the optical axis of the imaging optical system.