Optical scanning apparatus.

摘要

In an optical scanning apparatus, a scanning lens (1) is composed of three lens elements. The centrally located lens element of the scanning lens (1) has a refractive power in the direction (y) for correcting the surface tilt, that is an inverted number of a focal length that is changed in accordance with the scanning view angle, whereby curvature of field is well corrected and RMS spot diameters on the scanning surface (17) may be small. In addition, even if the view angle is increased, imaging characteristics may be kept at a high resolving power.