Patent ID: 8730512

Claim:
An optical scanning device, comprising: a light source which emits a light beam; a deflector 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; 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 deflected/scanned light beam on a surface to be scanned, wherein in a main scanning cross section, when an angle relative to an optical axis of an incident light beam which enters the scanning lens from the first face is θin, and an angle relative to an optical axis of an outgoing light beam which is output from the second face toward the surface to be scanned is θout, in an entire scanning region, a condition of 0.9<θin/θout<1.3 is satisfied.