COLLIMATE OPTICAL SYSTEM AND OPTICAL INFORMATION STORAGE DEVICE

摘要

A collimate optical system which is intended to improve stability against a temperature change and a light-source-output change, and is provided with an achromatic lens consisting of a glass-pasted structure or a diffraction lattice-attached plastic lens for canceling out a focal distance change, wherein the protrusion of the glass achromatic lens is such that the side opposite to a light source is bonded, and the protrusion of the diffraction lattice-attached plastic lens is such that the side facing the light source is bonded.