WAVELENGTH PLATE, OPTICAL ELEMENT AND OPTICAL PICKUP

摘要

PROBLEM TO BE SOLVED: To provide a wavelength plate and an optical pickup capable of reducing the signal quality degradations even if the substrate of an optical disk has a large birefringence in an optical disk drive which can read data from two or more kinds of optical disks.

SOLUTION: The wavelength plate 6 is used in a light path where light of multiple wavelengths including a wavelength λ passes back and forth, and has a birefringence area where a 1st area D1and a 2nd area D2each with different light axis are arranged 2-dimensionally. When Δ1represents the retardation of the wavelength plate 6 for the light of a wavelength λ, a relation 240°≤Δ1≤300° is satisfied.

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