Optical scanning apparatus and image forming apparatus using the same

Abstract

Provided are an optical scanning apparatus, which keeps an oblique incident angle to be small with respect to a polygon mirror in a sub-scanning section to provide preferable optical performance with a compact and simple construction, and an image forming apparatus using the optical scanning apparatus. The optical scanning apparatus includes a plurality of light source means, an incident system turn back mirror that reflects light beams emitted from the plurality of light source means, a light deflector that deflects the plurality of light beams using the same deflecting surface, and an imaging optical system that guides the light beams deflected by the light deflector respectively onto a plurality of surfaces to be scanned. At the time of light-scanning of the plurality of surfaces to be scanned, the incident system turn back mirror is disposed in an effective scanning range in a main scanning section when it is projected in the main scanning section. Also, in the sub-scanning section, the multiple light beams are reflected by the incident system turn back mirror in mutually different directions with respect to the normal line direction of the incident system turn back mirror, and then made incident at mutually different angles with respect to the same deflecting surface of the light deflector.