US 2002/0057359 A1 · Aberration detection device, aberration detection method, and optical pick-up device

Abstract

An aberration detection device which can detect a spherical aberration sensitively by separating a light beam appropriately so as to enlarge a difference in the positions where the respective separated light beams have the minimum spot diameters, and thus to enlarge a deviation amount of the focus positions of the separated light beams, is provided. A hologram for separating a light beam reflected from an optical disk and passing through a dual element objective lens into a first light beam and a second light beam, and a detection device for receiving the first and the second light beams and detecting the deviation of focus positions of the first and the second light beams, are equipped. The light beam directed to the hologram is separated into the first light beam and the second light beam, by a first region and a second region of the hologram which are obtained by being separated at a boundary drawn at an extreme value of a curve representing a wave front when the light beam has a minimum beam diameter on an information recording layer of the optical disk.

Claims20

Dependent claims

An aberration detection device comprising:

light beam separation means for separating a light beam passing through a focusing optical system into a first light beam which includes a light axis of the light beam and a second light beam which does not include the light axis of the light beam, at a boundary drawn at an extreme value of a curve representing a wave front when the light beam has a minimum beam diameter on an information recording layer of an optical recording medium;
and
spherical aberration detection means for detecting a spherical aberration of said focusing optical system, in accordance with at least one of focus positions of the two light beams separated by said light beam separation means.

An aberration detection device comprising:

light beam separation means for separating a light beam passing through a focusing optical system into a first light beam which includes a light axis of the light beam and a second light beam which does not include the light axis of the light beam;
and
aberration detection means for detecting a spherical aberration of said focusing optical system, in accordance with at least one of focus positions of the first light beam and the second light beam separated by said light beam separation means,
said aberration detection means including:
a first focus error detection section for detecting a focus position deviation of the first light beam from the first light beam, and outputting a first error signal;
and
a second focus error detection section for detecting a focus position deviation of the second light beam from the second light beam, and outputting a second error signal,
wherein said aberration detection means obtains a spherical aberration error signal SAES showing an amount of the spherical aberration of said focusing optical system, from an equation:
SAES=F1−FES×k1(k1:
a coefficient),
where F1 is the first error signal, F2 is the second error signal, and FES, which is a focus error signal showing an amount of a focus error of said focusing optical system, is F1+F2, and
said aberration detection means detects the spherical aberration by the spherical aberration error signal SAES.

9 more elements

An aberration detection device comprising:

light beam separation means for separating a light beam passing through a focusing optical system into a first light beam which includes a light axis of the light beam and a second light beam which does not include the light axis of the light beam;
and
aberration detection means for detecting a spherical aberration of said focusing optical system, in accordance with at least one of focus positions of the first light beam and the second light beam separated by said light beam separation means,
said aberration detection means including:
a first focus error detection section for detecting a focus position deviation of the first light beam from the first light beam, and outputting a first error signal;
and
a second focus error detection section for detecting a focus position deviation of the second light beam from the second light beam, and outputting a second error signal,
wherein said aberration detection means obtains a spherical aberration error signal SAES showing an amount of the spherical aberration of said focusing optical system, from an equation:
SAES=F2−FES×k2(k2:
a coefficient),
where F1 is the first error signal, F2 is the second error signal, and FES, which is a focus error signal showing an amount of a focus error of said focusing optical system, is F1+F2, and
said aberration detection means detects the spherical aberration by the spherical aberration error signal SAES.

9 more elements

An optical pick-up device comprising:

a light source;
a focusing optical system for focusing a light beam emitted from said light source onto an optical recording medium;
light beam separation means for separating a light beam reflected from said optical recording medium and passing through said focusing optical system, into a first light beam which includes a light axis of the light beam and a second light beam which does not include the light axis of the light beam;
focus position deviation amount detection means for detecting a deviation amount of at least one of focus positions of the first light beam and the second light beam separated by said light beam separation means;
and
correction means for correcting a spherical aberration of said focusing optical system in accordance with the deviation amount of the focus position detected by said focus position deviation amount detection means, said focus position deviation amount detection means including:
a first focus error detection section for detecting a focus position deviation of the first light beam from the first light beam, and outputting a first error signal;
and
a second focus error detection section for detecting a focus position deviation of the second light beam from the second light beam, and outputting a second error signal,
wherein said focus position deviation amount detection means obtains a spherical aberration error signal SAES showing an amount of the spherical aberration of said focusing optical system, from an equation:
SAES=F1−FES×k1(k1:
a coefficient),
where F1 is the first error signal, F2 is the second error signal, and FES, which is a focus error signal showing an amount of a focus error of said focusing optical system, is F1+F2, and
said correction means corrects the spherical aberration in accordance with the spherical aberration error signal SAES obtained by said focus position deviation amount detection means.

11 more elements

An optical pick-up device comprising:

a light source;
a focusing optical system for focusing a light beam emitted from said light source onto an optical recording medium;
light beam separation means for separating a light beam reflected from said optical recording medium and passing through said focusing optical system, into a first light beam which includes a light axis of the light beam and a second light beam which does not include the light axis of the light beam;
focus position deviation amount detection means for detecting a deviation amount of at least one of focus positions of the first light beam and the second light beam separated by said light beam separation means;
and
correction means for correcting a spherical aberration of said focusing optical system in accordance with the deviation amount of the focus position detected by said focus position deviation amount detection means,
said focus position deviation amount detection means including:
a first focus error detection section for detecting a focus position deviation of the first light beam from the first light beam, and outputting a first error signal;
and
a second focus error detection section for detecting a focus position deviation of the second light beam from the second light beam, and outputting a second error signal,
wherein said focus position deviation amount detection means obtains a spherical aberration error signal SAES showing an amount of the spherical aberration of said focusing optical system, from an equation:
SAES=F2−FES×k2(k2:
a coefficient),
where F1 is the first error signal, F2 is the second error signal, and FES, which is a focus error signal showing an amount of a focus error of said focusing optical system, is F1+F2, and
said correction means corrects the spherical aberration in accordance with the spherical aberration error signal SAES obtained by said focus position deviation amount detection means.

12 more elements

Dependencies are inferred from the claim text.

Aberration detection device, aberration detection method, and optical pick-up device

Life of this patent

Aberration detection device, aberration detection method, and optical pick-up device

Life of this patent

Abstract

Claims20