Patent ID: 7236281

Claim:
An optical scanner comprising: a plurality of light sources configured to emit beams including first and second beams; a coupling optical system configured to couple beams emitted from the light sources; a line image focusing optical system configured to focus each beam coupled to a line image extending longer in a main scan direction; a deflector provided with deflecting reflective surfaces on focused positions of the line image and a common rotary axis for the deflecting reflective surfaces, and configured to be shared by the beams from the light sources and to deflect the beams focused; a scanning optical system provided with at least first and second scanning lenses, each configured to guide a corresponding beam deflected to a corresponding target surface of a plurality of target surfaces for optical scanning; and a photodetector configured to receive the beams deflected at the deflector, wherein the beams traveling toward the deflector have an open angle θ in a deflecting rotation plane, a scanning lens proximate to one of the target surfaces, among the at least first and second scanning lenses, passes only the beams traveling toward the one of the target surfaces, and the first and second scanning lenses are proximate to the target surfaces and are configured to guide the corresponding beams to different target surfaces, each scanning lens of the first and second scanning lens has a shape that asymmetrically varies along a line perpendicular to a corresponding optical axis, and the line of the first scanning lens is oriented at an angle different from the line of the second scanning lens relative to the corresponding optical axis.