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

摘要

PROBLEM TO BE SOLVED: To provide a diffraction element 20 capable of showing satisfactory characteristics.

SOLUTION: A cover layer 20D of the diffraction element 20 is constituted of a cover lower layer 20Du made of a second UV cured resin 100B and joined to a diffraction pattern PTc for a CD and a cover upper layer 20Do made of a third UV cured resin 100C and joined to the cover lower layer 20Du.

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