Anamorphic single lens for use in an optical scanner

摘要

An anamorphic single lens has its radii in respective directions determined by the transfer efficiency of beams and imaging positions in respective directions, as required by the overall optical scanner. The anamorphic single lens satisfies the following formulae: <IMAGE> (Formula 1) S' < S (Formula 2) where fm is the focal length of the lens in the direction of beams diverged at a larger angle, TH is the thickness, S is the distance from a light source side principal point position (6) to the light source (5) in the direction of the beams diverged at the larger angle, and S' is the distance from a light source side principal point position (8) to the light source in the direction of beams diverged at a smaller angle.