Patent ID: 7355773
Filing Date: 2008-04-08
Classification: G02B

Abstract:
1. An optical scanning apparatus comprising: a light source device; a rotating polygon mirror; an incident optical system that causes a light beam emitted from a light emitter of the light source device to be incident on a deflecting surface of the rotating polygon mirror, the width of the incident light beam being larger than the width of the deflecting surface in the main scanning plane; and an imaging optical system that causes the light beam deflected by the rotating polygon mirror to form an image on a surface to be scanned, wherein when the number of deflecting surfaces of the rotating polygon mirror is N, the effective scanning width on the surface to be scanned is W (mm), the wavelength of the light beam emitted from the light source device is λ (μm), and the diameter in the main scanning direction of a spot formed by the light beam on the surface to be scanned is S (μm), the following conditions are satisfied: wherein when the magnification of the imaging optical system in the sub-scanning plane is βs, the angle of the light beam obliquely incident on the deflecting surface of the rotating polygon mirror in the sub-scanning plane is γ (°), and the amount of eccentricity, that is to say, the distance by which the deflecting surface of the rotating polygon mirror moves in the direction of the optical axis of the imaging optical system when the rotating polygon mirror rotates is δ (μm), the following condition is satisfied: