Patent ID: 7586661

Claim:
An optical scanning device, comprising: a light source configured to emit light beams; a deflector configured to deflect the light beams in a main scanning direction; a coupling optical system configured to guide the light beams from the light source to the deflector; and a scanning optical system configured to scan the light beams on a target surface to form an image, wherein the coupling optical system includes at least one diffractive optical surface, and when linearly approximated, a temperature dependence dλ/dT of a wavelength of the light source satisfies dλ/dT<0.15, wherein an optical system including both the coupling optical system and the scanning optical system satisfies |βs|<|βm|, where βs is a lateral magnification in a sub-scanning direction perpendicular to the main scanning direction and βm is a lateral magnification in the main scanning, direction.