OBJECTIVE LENS, OPTICAL HEAD AND OPTICAL DISK DEVICE

摘要

Provided are an objective lens, optical head, and optical disk device capable of improving refraction efficiency in the vicinity of an outermost periphery of an active region of an objective lens and suppressing light loss. A lens surface (22) of an objective lens (20) has an optical surface (221) of a substantially stair-step-configured cross-section comprising a plurality of annular optical surfaces (22a, 22b, 22c, and 22d) which have been annularly partitioned centered around an optical axis (OA) of the objective lens (20), and a plurality of connecting surfaces (251) for connecting the plurality of mutually adjacent partitioned surfaces. The plurality of connecting surfaces (251) include cylindrical connecting surfaces (25b and 25c) constituted by cylindrical surfaces centered around the optical axis (OA) and a conical connecting surface (26a) constituted by a conical surface centered around the optical axis (OA), wherein the conical connecting surface (26a) connects an annular optical surface (22c) with an annular optical surface (22d).