Patent ID: 8059149

Claim:
An optical scanning device that uses a light beam to scan a target surface for scanning, the optical scanning device comprising: a light source that emits the light beam; a pre-deflection optical system that is arranged in a path of the light beam and that includes at least one diffraction lens and at least one phase shifter, at least one surface of the diffraction lens being a diffractive surface, and at least one surface of the one phase shifter being a phase shifting surface; an optical deflector that deflects the light beam after the light beam has passed through the pre-deflection optical system to obtain a deflected light beam; and a scanning optical system that focuses the deflected light beam on the target surface for scanning, wherein the phase shifter has a finite focal length, and an absolute value of a focal length of the diffraction lens is longer than an absolute value of the focal length of the phase shifter.