Optical pickup device and optical element

An optical pickup device comprising a first light source emitting a first light beam having a wavelength λ1 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 d1 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,
• the particles contain particles A and particles B,
• a sign of a refractive index change Δn2A/Δt of the particles A owing to a temperature change is opposite to a sign of a refractive index change Δn1/Δt of the resin owing to a temperature change, or an absolute value of the refractive index change Δn2A/Δt is smaller than an absolute value of the refractive index change Δn1/Δt, and
• a sign of a refractive index change Δn2B/Δλ1 owing to a wavelength change of the particles B is opposite to a sign of a refractive index change Δn1/Δλ1 by a wavelength change of the resin, or an absolute value of the refractive index change Δn2B/Δλ1 is smaller than an absolute value of the refractive index change Δn1/Δλ1.

An optical element to be used for an optical pickup device for performing recording and/or reproducing of information of a first optical disk having a protective substrate thickness d1 mm using a first light beam having a wavelength λ1 within a range of from 390 nm to 420 nm, the first light beam being emitted from a 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 Δn2/Δt of the particles owing to a temperature change is opposite to a sign of a refractive index change Δn1/Δt of the resin owing to a temperature change, or an absolute value of the refractive index change Δn2/Δt is smaller than an absolute value of the refractive index change Δn1/Δt, and
• a spherical aberration SA1 [λ rms] produced when an operating temperature of the optical pickup device rises by 30° C. satisfies a following relation,
• |(SA1/λ12)·(Δn3/Δt)·NA4·2d1·109|≦9.9
• where SA1 denotes a sum of squares of a third order spherical aberration, a fifth order spherical aberration and a seventh order spherical aberration, Δn3/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.

An optical element to be used for an optical pickup device for performing recording and/or reproducing of information of a first optical disk having a protective substrate thickness d1 mm using a first light beam having a wavelength λ1 within a range of from 390 nm to 420 nm, the first light beam being emitted from a first light source, wherein

• the optical element is made of a mixed material produced by dispersing particles into a resin,
• the particles contain particles A and particles B,
• a sign of a refractive index change Δn2A/Δt of the particles A owing to a temperature change is opposite to a sign of a refractive index change Δn1/Δt of the resin owing to a temperature change, or an absolute value of the refractive index change Δn2A/Δt is smaller than an absolute value of the refractive index change Δn1/Δt, and
• a sign of a refractive index change Δn2B/Δλ1 of the particles B owing to a wavelength change is opposite to a sign of a refractive index change Δn1/Δλ1 owing to a wavelength change of the resin, or an absolute value of the refractive index change Δn2B/Δλ1 is smaller than an absolute value of the refractive index change Δn1/Δλ1.

An optical pickup device comprising a first light source emitting a first light beam having a wavelength λ1 within a range of from 390 nm to 420 nm, a second light source emitting a second light beam having a wavelength λ2 within a range of from 1.5×λ1 to 1.7×λ1, 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 d1 mm using the first light beam from the first light source, and of performing recording and/or reproducing of information of a second optical disk having a protective substrate thickness d2 mm (0.8×d1≦d2) using the second light beam from the second light source, wherein

• the first light beam and the second light beam pass the optical element,
• the optical element is made of a mixed material produced by dispersing particles into a resin,
• a sign of a refractive index change Δn2/Δt of the particles owing to a temperature change is opposite to a sign of the refractive index change Δn1/Δt of the resin owing to a temperature change, or an absolute value of the refractive index change Δn2/Δt is smaller than an absolute value of a refractive index change Δn1/Δt, and
• a refractive index change Δn3/Δt of the mixed material owing to a temperature change satisfies a following relation,
• |Δn3/Δt|≦8.0×10−5 [° C.−1].

An optical element to be used for an optical pickup device for performing recording and/or reproducing information of a first optical disk having a protective substrate thickness d1 mm using a first light beam having a wavelength λ1 within a range of from 390 nm to 420 nm, performing recording and/or reproducing information of a second optical disk having a substrate thickness d2 mm (0.8×d1≦d2) using a second light beam having a wavelength λ2 within a range of from 1.5×λ1 to 1.7×λ1, the second light beam emitted from a second light source, wherein

• the first light beam and the second light beam pass the optical element,
• the optical element is made of a mixed material produced by dispersing particles into a resin,
• a sign of a refractive index change Δn2/Δt of the particles owing to a temperature change is opposite to a sign of a refractive index change Δn1/Δt of the resin owing to a temperature change, or an absolute value of the refractive index change Δn2/Δt is smaller than an absolute value of the refractive index change Δn1/Δt, and
• a refractive index change Δn3/Δt of the mixed material owing to a temperature change satisfies a following relation.
• |Δn3/Δt|≦8.0×10−5 [° C.−1]