Patent ID: 8228581

Claim:
An scanning optical device that scans a light beam in two directions, the two directions being a main scanning direction and an auxiliary scanning direction, the optical scanning device comprising: at least one light source unit that emits the light beam; a first deflector that deflects the emitted light beam in the auxiliary scanning direction; a condensing optical system that generates an intermediate image of the light beam deflected by the first deflector; a collecting optical system that collects each chief ray corresponding each intermediate image formed by the condensing optical system; a second deflector that deflects the light beam collected by the collecting optical system in the main scanning direction; and a scanning optical system that scans the light beam, the light beam being deflected by the second deflector, on a surface to be scanned, wherein the condensing optical system is configured to have an f-θ characteristic, the collecting optical system is configured to have an f-sin θ characteristic, and the scanning optical system is configured to have an f-sin θ characteristic, respectively.