US Patent 7330293 Optical scanning unit

An optical scanning unit designed to provide a sufficient optical path length between a light source and an exposed object while reducing the overall space it occupies. The optical scanning unit may include a light source that produces and emits at least one beam, a beam deflector that deflects and scans the beam emitted by the light source in main scanning direction of an exposed object, and a planar optical system (POS) that is disposed in an optical path between the light source and the exposed object. The POS is designed to maintain a sufficient optical path length of an incident beam while reducing the space occupied by the optical scanning unit.