DIFFRACTION ELEMENT, OBJECTIVE LENS UNIT, OPTICAL PICKUP, AND OPTICAL DISK DRIVE

摘要

PROBLEM TO BE SOLVED: To provide a diffraction element having high durability, an objective lens unit using the diffraction element concerned, and an optical pickup and an optical disk drive.

SOLUTION: On the diffraction element 20, an upper layer separation prevention pattern PPa is formed so that a base layer 20C and an enclosure layer 20D may fit to an outside optics area EO through which an optical beam does not pass.

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