Image forming light scanning apparatus

摘要

A scanning apparatus has a luminous flux deflector and a single f theta lens. The deflector deflects a convergent luminous flux on a scanned surface at a uniform angular velocity. The f theta lens is arranged between the deflector and the scanned surface. The f theta lens is bi-convex in a main scanning direction and is made of a material having a refractive index of at most 1.6. One surface of the f theta lens in a main scanning direction is so curved that a radius of curvature in the main scanning direction A decreases as an angle of view in the main scanning direction increases.