Patent ID: 8462188

Claim:
An optical scanning apparatus comprising: first and second light sources configured to emit first and second divergent light beams respectively; first and second incident optical systems respectively provided in correspondence with the first and second divergent light beams; a deflecting unit having a first deflecting surface configured to deflect the light beams through the first and second incident optical systems respectively; and first and second imaging optical systems configured to guide the light beams deflected by the first deflecting surface of the deflecting unit onto first and second surfaces to be scanned respectively, wherein the first and second divergent light beams have a same wavelength, wherein the first incident optical system converts the first divergent light beam into a light beam with higher convergence than convergence of the first divergent light beam, and the second incident optical system converts the second divergent light beam into a light beam with convergence higher than convergence of the second divergent light beam and lower than the convergence of the light beam converted from the first divergent light beam, wherein an optical path length from a deflection point of the deflecting unit to the first surface to be scanned is shorter than an optical path length from a deflection point of the deflecting unit to the second surface to be scanned, and the following condition is satisfied: 0.85 <K 1 /K 2<0.98 where K1 is a Kθ coefficient of the first imaging optical system, and K2 is a Kθ coefficient of the second imaging optical system.