ABERRATION CORRECTING ELEMENT, LENS DEVICE FOR OPTICAL PICKUP, AND OPTICAL PICKUP DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a lens device for an optical pickup which is easily manufactured and has a high performance even when it is used for the luminous flux of a wavelength in the short wavelength range such as a reference wavelength ≤420 nm, and to provide an aberration correcting element to be used for this lens device.

SOLUTION: This aberration correcting element 2 is arranged on the optical axis of the luminous flux and equipped with: a diffraction surface S1 having a power for deflecting the luminous flux by the diffraction; and a phase level difference surface S3 arranged on the optical axis at the position different from the diffraction surface S1 to include a plurality of annular areas stipulated by a concentric circle around the optical axis of the luminous flux and the phase level difference formed on a boundary section between the areas, and then the phase level difference generates the phase difference of integer multiple of 2π radian with respect to the reference wavelength between luminous fluxes passing through the areas different from each other.

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