Patent ID: 8355037

Claim:
An optical element used in an optical scanning apparatus, the optical element comprising: a diffracting surface composed of a diffraction grating, wherein the diffracting surface includes a diffraction grating whose sectional shape of the diffracting surface is linearly formed, and wherein, if diffraction power in a main scanning direction on the diffracting surface received by an axial light flux is φDO and refractive power in the main scanning direction on a refracting surface on which the diffraction surface is formed received by the axial light flux is φref, the optical element satisfies the following conditions: 0 <φDO <1.8×10 −3 (1/mm), and 0.5 |φDO|<|φref |<1.5 |φDO|, where the diffraction power φDO and the refractive power φref have opposite signs.