Patent ID: 6975441

Claim:
A scanning optical apparatus, comprising: a laser diode that emits a laser beam; a collimating lens that collimates the laser beam emitted by the laser diode; a support member that holds and supports the laser diode and the collimating lens; a deflection member that dynamically deflects the laser beam collimated by the collimating lens in a main scanning direction; and a plastic scanning lens that converges the deflected laser beam onto a target surface, the scanning optical apparatus being configured to satisfy following conditions: 10 < f fc < 20 ; and ⁢ ⁢ fc · nc > t > fc ⁡ ( nc nc + 1 ) , where f denotes a focal length of the scanning lens in the main scanning direction; fc denotes a focal length of the collimating lens; nc denotes a refractive index of the collimating lens; and t denotes a thickness of the collimating lens along an optical axis.