Patent ID: 8144178

Claim:
An optical scanning apparatus comprising: a Vertical Cavity Surface Emitting Laser including a plurality of light-emitting portions that are spaced from each other in at least a sub-scanning direction, wherein the plurality of light-emitting portions emits a plurality of light beams; a first optical system including a light-condensing element that converts the plurality of light beams into a combined light beam in another state; a deflecting unit that reflects the combined light beam; and a second optical system that focuses the reflected combined light beam on a surface to be scanned, the second optical system including an imaging optical element having an optical surface with a non-arc shape in a sub-scanning cross section, wherein a principal ray of a light beam emitted from one of the plurality of light-emitting portions that is farthest from an optical axis in the sub-scanning cross section passes through a plurality of optical elements included in the first and second optical systems, the principal ray being farthest from the optical axis in the sub-scanning cross section when the principal ray passes through the optical surface of the imaging optical element, and wherein, when the focal length in the sub-scanning direction of the light-condensing element is Fcol (mm), the distance between the optical axis and the light-emitting portion that is farthest from the optical axis in the sub-scanning cross section is L 0 , the distance between the optical surface of the imaging optical element and the deflecting unit along the optical axis direction is SI, the imaging magnification of the first optical system in the sub-scanning direction is β 0 , and the F-number of the entrance side of the light-condensing element in the sub-scanning cross section is Fno, the following expression is satisfied: 0.10<|( SI/Fcol+β 0 )× L 0 /( SI /( Fno×β 0 ×2)|<5.43.