Patent ID: 7224503

Claim:
An optical scanning apparatus for scanning a plurality of surfaces to be scanned, comprising: a plurality of light sources; an optical deflector for deflecting and reflecting a plurality of light beams emitted from the plurality of light sources; and an imaging optical system for guiding the plurality of light beams which are deflected and reflected by the optical deflector to the different surfaces to be scanned, wherein: the plurality of light beams incident on the optical deflector are incident on a deflection surface of the optical deflector at different angles to a normal of the deflection surface within a sub scanning section; the imagining optical system comprises a first optical element and a plurality of second optical elements; the first optical element is commonly used for the plurality of light beams; optical power of the first optical element satisfies 0≦|φ 1 s |<0.001 where φ 1 s represents optical power of the first optical element within the sub scanning section; a second optical element is provided for each of the plurality of light beams and each of the plurality of second optical elements has optical power in a sub scanning direction; optical power of the first optical element and optical power of each of the plurality of second optical elements within the sub scanning section are represented by φ 1 s and φ 2 s, respectively, and |φ1 s/φ 2 s|> 0.1 is satisfied; and an optical axis of each second optical element within the sub scanning section is eccentric in parallel to a deflection and reflection point side with respect to a principal ray position of a light beam incident on such second optical element within the sub scanning section; and a principal ray of a light beam is incident on each second optical element at an angle to an optical axis of such second optical element within the sub scanning section.