Patent ID: 6937373

Claim:
A scanning optical system for exposing a predetermined imaging area on a surface to be scanned to a plurality of laser beams, comprising: a plurality of light sources that emit a plurality of laser beams having different wavelengths, respectively; a single deflector which deflects the plurality of laser beams simultaneously; an imaging optical system that converges the plurality of laser beams deflected by said single deflector on the surface to be scanned; and a beam detector that receives the plurality of laser beams directed to outside of the predetermined imaging area via at least one lens element included in said imaging optical system, a synchronizing signal being generated upon detection of each of the plurality of light beams by said beam detector, an optical characteristic of said imaging optical system being configured such that the laser beams incident on said predetermined imaging area are aligned in a scanning direction with respect to one another, while the laser beams incident on said beam detector are shifted in the scanning direction with respect to one another.