OBJECTIVE LENS AND OPTICAL PICKUP DEVICE

摘要

Provided is an optical pickup device which can appropriately record/reproduce information onto/from an optical disc having a plurality of information recording layers.  In an objective lens (OL1), a sinusoidal condition infringement amount when the incident light flux is parallel light is set so as to satisfy a conditional expression (1) as follows: 0.015 max/f max is the maximum value of the sinusoidal condition infringement amount and f is a focal distance. Accordingly, even when a modification is made on an information recording layer RL of the multi-layer optical disc MLD, the high-dimension spherical aberration is sufficiently small and it is possible to preferably perform recording/reproduction onto/from the multi-layer optical disc MLD.