Patent ID: 8670472

Claim:
An optical scanning device comprising: a vertical-cavity surface-emitting laser light source that emits laser beams perpendicular to a top surface thereof; a first optical system that couples the laser beams from the light source; a deflecting unit that deflects the laser beams; a second optical system that guides the laser beams from the first optical system to the deflecting unit; a third optical system that focuses the laser beams deflected by the deflecting unit into an optical spot on a scanned surface; and a light-quantity adjusting element disposed between the light source and the deflecting unit and having a substrate formed of a first surface and a second surface, wherein the first surface of the light-quantity adjusting element is coated with neutral density coating and the second surface of the light-quantity adjusting element is coated with antireflection coating so that reflectance of the second surface is made smaller than reflectance of the first surface, and wherein the vertical-cavity surface-emitting laser light source and the first optical system are configured such that the light-quantity adjusting element is disposed on an optical path of a divergent beam, with the divergent beam being incident on the neutral density coating of the light-quantity adjusting element, such that at least some diverging rays of the divergent beam have different optical path lengths within the light-quantity adjusting element, between the first surface and the second surface.