OPTICAL SYSTEM OF OPTICAL PICKUP DEVICE

摘要

PROBLEM TO BE SOLVED: To satisfy the RMS wave aberration and the ray aberration for both DVD and CD by using a means which shifts a part of the faces of lenses in the direction of the optical axis of optical elements including an objective lens in a region which is used for both DVD and CD.

SOLUTION: The optical system of the optical pickup device of the DVD and the CD is provided with a function which refracts the light which passes through a region used for recording or reproducing information both for the DVD and CD so that the spherical aberration becomes under on the DVD and over on the CD, and a function which gives optical path differences in which the light is divided into a plurality of ring bands coaxial with the optical path, and the adjacent ring bands are so formed dislocated in the optical axis direction from each other to make optical path differences approximately integer times prescribed wavelength λs (λ1<λs<λ2), and the optical path of the light gradually increases in the radial direction from the optical axis to the periphery.

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