OPTICAL SYSTEM FOR OPTICAL PICKUP DEVICE, OPTICAL PICKUP DEVICE, AND OPTICAL INFORMATION RECORDING AND REPRODUCING APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide an optical pickup system for optical pickup apparatus that is used for an optical system for optical pickup apparatus which uses an objective with a large numerical aperture and corrects a spherical aberration of a convergence spot through an expander lens or coupling lens arranged in the optical path between a light source and the objective and has small deterioration in light converging performance even when a movable lens has an eccentricity error.

SOLUTION: The optical system OS1 for optical pickup apparatus is equipped with an expander lens EXP such that a coma aberration W2CM(λms) as an off-axis characteristic when an objective OBJ and the expander lens EXP are combined is smaller than a coma aberration W1CM(λms) as an off-axis characteristic of the objective lens OBJ alone. This optical system OS1 for optical pickup apparatus which is thus constituted can suppress an increase in coma aberration of a light convergence spot resulting of incidence of oblique luminous flux on the objective OBJ when a 1st lens group L1 of the expander lens EXP has an eccentricity error to the objective OBJ.

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