Patent ID: 7369480
Filing Date: 2008-05-06
Classification: G11B

Abstract:
1. An optical pickup device comprising a first light source emitting a first light beam having a wavelength λ 1 within a range of from 390 nm to 420 nm and at least one optical element, the optical pickup device being capable of performing recording and/or reproducing of information of a first optical disk having a protective substrate thickness d 1 mm using the first light beam from the first light source, wherein the optical element is made of a mixed material produced by dispersing particles into a resin, a sign of a refractive index change Δn a spherical aberration SA where SA 1 denotes a sum of squares of a third order spherical aberration, a fifth order spherical aberration and a seventh order spherical aberration, Δn 3 /Δt denotes the refractive index change owing to the temperature change of the mixed material, and NA denotes a numerical aperture on an exit side of an optical element located nearest to an optical disk side among optical elements which the optical pickup device contains.