Patent ID: 7564607
Filing Date: 2009-07-21
Classification: G02B

Abstract:
1. A light source module for an optical scanning device including a deflecting unit that deflects an optical beam and an imaging optical system that focuses the optical beam on a scanning surface as a beam spot to optically scan the scanning surface, the light source module comprising: a laser light source that emits an optical beam; a coupling lens that collimates the optical beam emitted from the laser light source, and outputs a collimated optical beam having a desired beam spot size; an aperture that shields a peripheral light flux area of the collimated optical beam output from the coupling lens; a phase adjusting element that partially changes a phase of wavefront of the optical beam; and an auxiliary aperture formed on an outer side of a normalized aperture size, which is a size of the aperture when the beam spot formed on the scanning surface meets design values of a beam spot size and a depth allowance, in at least one of a main scanning direction and a sub-scanning direction, wherein the phase adjusting element is formed in a parallel plate, and changes at least a phase of wavefront of a peripheral portion of the optical beam to compensate decreases of the beam spot size and the depth allowance caused by the auxiliary aperture.