Optical scanner

摘要

An optical scanner is provided that reduces chromatic aberration (focus error) due to mode hopping of a semiconductor laser light source and that can give high-resolution output applicable to digital copiers and optical printers even when using an imaging optical system having only a few lens elements. At least one surface of the collimating lens includes a zone plate diffractive optical surface which meets specified design conditions to ensure that the focus error due to mode hopping is acceptably small.