Patent ID: 6995887

Claim:
A laser scanning apparatus comprising: a light source for emitting laser light; a polygon mirror for deflecting the laser light; and at least one plane mirror for reflecting the laser light deflected by the polygon mirror in the direction to a photosensitive member, wherein incident light to and reflected light on the polygon mirror are in a deflection plane perpendicular to the rotation axis of the polygon mirror, an angle formed between the deflection plane and the normal line to a most upstream side plane mirror in the optical path after the polygon mirror is in the range from 20 degrees to 70 degrees, an angle formed between the polarization direction of the laser light and the deflection plane is in the range from 15 degrees to 50 degrees, and a proportion of S polarized light contained in light incident on the most upstream side plane mirror after being reflected on the polygon mirror at one, formed at an end there of closest to the light source, of the two deflection angles corresponding to both ends of an image is smaller than a proportion of S polarized light contained in light incident on the most upstream side plane mirror after being reflected on the polygon mirror at the other, formed at an end there of farthest from the light source, of the two deflection angles.