Patent ID: 7061658

Claim:
A scanning image formation optical system for use in an optical scanner for scanning a scanned surface for one or more scanning lines by causing one or more coupled luminous fluxes from a light source to be incident on a deflecting reflective surface of a rotating optical deflector, which rotates around a rotary axis of the optical deflector, said rotary axis being parallel to the deflecting reflective surface, diagonally deflecting the luminous fluxes relative to a surface perpendicular to the rotary axis of the optical deflector, and converging the deflected luminous fluxes toward the scanned surface by the scanning image formation optical system so as to form an optical spot on the scanned surface, the scanning image forming optical system comprising: two or more optical elements, at least two different elements of the two or more optical elements each having at least one tilt surface, each said tilt surface formed such that a tilt amount of a sub-scanning cross-sectional configuration changes in a main scanning direction, each tilt surface formed so as to correct a scanning line curvature and a wavefront aberration on the scanned surface, one tilt surface having a different change in a tilt amount in the main scanning direction from another tilt surface, a first tilt surface partially correcting a scanning line curvature and a wavefront aberration, and a last tilt surface further correcting scanning line curvature and reducing a remaining wavefront aberration to a tolerable level.