LENS UNIT, ELEMENT FOR ABERRATION CORRECTION, AND DESIGNING METHOD OF ELEMENT FOR ABERRATION CORRECTION

摘要

PROBLEM TO BE SOLVED: To provide a lens unit capable of reducing wavefront aberration caused in an optical pickup objective lens even when the refractive index of a glass material is changed by the change of the temperature of the optical pickup objective lens, and to provide an element for aberration correction, and the design method of the element for aberration correction.;SOLUTION: In the lens unit having a pickup lens 15 and the element 14 for aberration correction disposed on the light source 11 side of the pickup lens 15 and having a plurality of zonal steps, the plurality of zonal steps have step quantities generating phase differences in a laser beam so that aberration caused in the pickup lens 15 is reduced when the temperature of the pickup lens 15 is changed.;COPYRIGHT: (C)2009,JPO&INPIT