Patent ID: 8836744

Claim:
An optical scanning device, comprising: a light source which emits a light beam; a deflector including a deflective surface which reflects and then deflects/scans the light beam emitted from the light source; an incident optical system which causes the light beam emitted from the light source to enter the deflector from an oblique direction; and one scanning lens which includes a first face facing the deflector and a second face on an opposite side to the first face, and performs imaging of the light beam deflected/scanned on a surface to be scanned, wherein in a main scanning direction cross section of the scanning lens, when a scanning range is separated, with on axis as a reference, into an image height region of a first direction and an image height region of a second direction that is opposite to the first direction, the incident optical system is disposed on a side of the image height region of the first direction, curvature of the first face in a sub scanning direction cross section decreases from on axis toward off axis in a main scanning direction, and curvature of the second face in the sub scanning direction cross section gradually increases from the end part of off axis in the first direction of the scanning range to the image height region of axis in the second direction in the main scanning direction.