Patent ID: 8390908

Claim:
An optical scanning apparatus comprising: a first optical element configured to convert a light beam from a semiconductor laser light source into a light beam having a desired beam form; a second optical element configured to guide the light beam to an optical deflector; and a third optical element configured to focus the light beam deflected by the optical deflector into an optical spot on a scanned surface and configured to optically scan the scanned surface, wherein the semiconductor laser light source and the first optical element are fixed on a single continuous member, and the first optical element or the second optical element is a diffraction optical element, the diffraction optical element having a diffracting surface in which a plurality of elliptical grooves is formed, the diffracting surface having a diffracting portion power such that a change in a beam waist position in a main scan direction and in a sub-scan direction due to temperature variation in the optical scanning apparatus becomes substantially zero, wherein the member on which the semiconductor laser light source and the first optical element are fixed has a linear coefficient of expansion such that the change in the beam waist position becomes substantially zero even when there is temperature variation, and wherein a long-axis of the elliptical grooves is horizontally arranged so as to correspond to the main scan direction, and a short-axis of the elliptical grooves is vertically arranged so as to correspond to the sub-scan direction.