Patent ID: 6922269

Claim:
A light scanning unit comprising: a composite light source in which a plurality of light sources for emitting coherent light having different wavelengths are arranged adjacent to one another and an optical axis of each light source is arranged almost parallel to each other and which emits light at a divergeing angle centering on each optical axis; and an optical system comprising a collimator lens arranged on an approximately central axis of an optical axis of each light source comprising the composite light source and collimates the light beam emitted from the composite light source, a cylinder lens for condensing the light beam emitted from the collimator lens, and a polygonal rotating mirror for scanning the light beam condensed by the cylinder lens in a main scanning direction on an exposed surface of an exposed object, wherein each light source is arranged adjacent to each other on a substrate having a gaseous layer between excitation light-emitting portions of each of the light sources.