Optical scanning apparatus

Abstract

An optical scanning apparatus in which a plurality of scanning light beams are deflected by a light deflector and the deflected light beams impinge onto a spherical lens having an f-.theta. characteristic at inclinations with respect to the optical axis of the lens so as to be focused on a scanning object. The apparatus is arranged to meet the following condition: ##EQU1## where, f represents the focal distance of the spherical lens (mm), .omega. represents the effective scanning rotation angle of the light deflector (deg), .DELTA.(.omega.) represents the amount of curve of the scanning line caused by the light deflecting element in the subscanning direction (mm), .rho. represents the resolution of the scan on the scanning object (lines/mm), .theta. represents the angle of inclination of any one of the light beams with respect to the optical axis of the lens within a plane which contains the optical axis of the lens and which is perpendicular to the scanning axis (deg), L represents the distance between the first reflection surface of the light deflector and the principal plane of the lens adjacent the scanning object along the optical axis (mm), and h represents the height of incidence of the any one of the light beams to the lens (mm).