摘要:
An optical system for recording or reproducing of information to or from an optical information recording medium, includes: a light source; a coupling lens for converting a diverging light emergent from the light source to a converging light; and an objective lens for further converging the converted converging light and for focusing on an information recording surface of the optical information recording medium. A lateral magnification of the objective lens in which a wavefront aberration within a Marechal criterion is minimum, satisfies the following conditional expression,O