Patent ID: 7142339

Claim:
A method of adjusting a position of an image plane of an optical scanning apparatus, the optical scanning apparatus comprising light source means, deflecting means, an incident optical system for guiding a light beam emitted from a light emitting portion of the light source means to a deflecting surface of the deflecting means and an imaging optical system for imaging the light beam deflected on the deflecting surface of the deflecting means on a surface to be scanned, wherein the incident optical system includes a first optical element having refractive power in main and sub-scanning directions in an optical path between the light source means and the deflecting means and a second optical element having refractive power only in the sub-scanning direction, an incident side F-number of the incident optical system in the sub-scanning direction is smaller than that in the main scanning direction, and wherein a position of an image plane in the main scanning direction is adjusted by moving the first optical element in an optical axis direction of the incident optical system, and then a position of the image plane in the sub-scanning direction is adjusted by integrally moving the light source means, the first optical element and the second optical element in the optical axis direction of the incident optical system.