Optical element, optical head, optical information recording/reproduction device, computer, video recording device, video reproduction device, server, and car navigation system

An optical element, comprising:

• a substrate in which grooves are formed;
• wherein the expression:
• 380 nm≦(n−1)×d≦420 nm
• is satisfied, where n is a refractive index of the substrate at a wavelength of 400 nm, and d (nm) is a depth per step of the grooves;
• and
• wherein the grooves are formed in four steps of depth d, depth 2d, depth 3d and depth 4d.

An optical head, comprising:

• a first light source that emits light of a first wavelength that at least either records onto or reproduces information from a first information recording medium;
• a second light source that emits light of a second wavelength that at least either records onto or reproduces information from a second information recording medium;
• focusing means for focusing light that is emitted from the first light source and from the second light source;
• an optical element that passes light of the first wavelength and diffracts light of the second wavelength;
• and
• photodetecting means for detecting light of the first wavelength and light of the second wavelength;
• wherein light of the first wavelength and light of the second wavelength pass through the optical element, after which they are focused by the focusing means and are irradiated onto the information recording media;
• wherein the optical element is an optical element in which grooves are formed in a substrate;
• wherein the expression:
• 380 nm≦(n−1)×d≦420 nm
• is satisfied, where n is a refractive index of the substrate at a wavelength of 400 nm, and d (nm) is a depth per step of the grooves;
• wherein the grooves are formed in two steps of depth d and depth 2d;
• and
• wherein the photodetecting means detects light that is at least either reflected or diffracted by the information recording media.

An optical head, comprising:

• a first light source that emits light of a first wavelength, that at least either records onto or reproduces information from a first information recording medium;
• a second light source that emits light of a second wavelength, that at least either records onto or reproduces information from a second information recording medium;
• focusing means for focusing light that is emitted from the first light source and from the second light source;
• an optical element that passes light of the first wavelength and diffracts light of the second wavelength;
• and
• photodetecting means for detecting light of the first wavelength and light of the second wavelength;
• wherein light of the first wavelength and light of the second wavelength pass through the optical element, after which they are focused by the focusing means and are irradiated onto the information recording media;
• wherein the optical element is an optical element in which grooves are formed in a substrate;
• wherein the expression:
• 380 nm≦(n−1)×d≦420 nm
• is satisfied, where n is a refractive index of the substrate at a wavelength of 400 nm, and d (nm) is a depth per step of the grooves;
• wherein the grooves are formed in four steps of depth d, depth 2d, depth 3d and depth 4d;
• and
• wherein the photodetecting means detects light that is at least either reflected or diffracted by the information recording media.

An optical head comprising:

• a first light source that emits light of a first wavelength, that at least either records onto or reproduces information from a first information recording medium;
• a second light source that emits light of a second wavelength, that at least either records onto or reproduces information from a second information recording medium;
• a third light source that emits light of a third wavelength, that at least either records onto or reproduces information from a third information recording medium;
• focusing means for focusing light that is emitted from the first light source, from the second light source and from the third light source;
• a first optical element that passes light of the first wavelength and diffracts light of the second wavelength and light of the third wavelength;
• and
• photodetecting means for detecting light of the first wavelength, light of the second wavelength and light of the third wavelength;
• wherein light of the first wavelength, light of the second wavelength and light of the third wavelength pass through the optical element, after which they are focused by the focusing means and are irradiated onto the information recording media;
• wherein the first optical element is an optical element in which grooves are formed in a substrate;
• wherein the expression:
• 380 nm≦(n−1)×d≦420 nm
• is satisfied, where n is a refractive index of the substrate at a wavelength of 400 nm, and d (nm) is a depth per step of the grooves;
• wherein the grooves are formed in two steps of depth d and depth 2d;
• and
• wherein the photodetecting means detects light that is at least either reflected or diffracted by the information recording media.

An optical head, comprising:

• a first light source that emits light of a first wavelength, that at least either records onto or reproduces information from a first information recording medium;
• a second light source that emits light of a second wavelength, that at least either records onto or reproduces information from a second information recording medium;
• a third light source that emits light of a third wavelength, that at least either records onto or reproduces information from a third information recording medium;
• focusing means for focusing light that is emitted from the first light source, from the second light source and from the third light source;
• a first optical element that passes light of the first wavelength and diffracts light of the second wavelength and the third wavelength;
• and
• photodetecting means for detecting light of the first wavelength, light of the second wavelength and light of the third wavelength;
• wherein light of the first wavelength, light of the second wavelength and light of the third wavelength pass through the optical element, after which they are focused by the focusing means and are irradiated onto the information recording media;
• wherein the first optical element is an optical element in which grooves are formed in a substrate;
• wherein the expression:
• 380 nm≦(n−1)×d≦420 nm
• is satisfied, where n is a refractive index of the substrate at a wavelength of 400 nm, and d (nm) is a depth per step of the grooves;
• wherein the grooves are formed in four steps of depth d, depth 2d, depth 3d and depth 4d;
• and
• wherein the photodetecting means detects light that is at least either reflected or diffracted by the information recording media.

An optical information recording and reproduction apparatus, comprising:

• an optical head that includes;
• a first light source that emits light of a first wavelength, that at least either records onto or reproduces information from a first information recording medium;
• a second light source that emits light of a second wavelength, that at least either records onto or reproduces information from a second information recording medium;
• focusing means for focusing light that is emitted from the first light source and from the second light source;
• an optical element that passes light of the first wavelength and diffracts light of the second wavelength;
• and
• photodetecting means for detecting light of the first wavelength and light of the second wavelength,
• further comprising:
• moving means for moving the information recording medium and the optical head relative to each other;
• wherein light of the first wavelength and light of the second wavelength pass through the optical element, after which they are focused by the focusing means and are irradiated onto the information recording media;
• wherein the optical element is an optical element in which grooves are formed in a substrate;
• wherein the expression:
• 380 nm≦(n−1)×d≦420 nm
• is satisfied, where n is a refractive index of the substrate at a wavelength of 400 nm, and d (nm) is a depth per step of the grooves;
• wherein the grooves are formed in two steps of depth d and depth 2d;
• and
• wherein the photodetecting means detects light that is at least either reflected or diffracted by the information recording media.

An optical information recording and reproduction apparatus, comprising:

• an optical head that includes;
• a first light source that emits light of a first wavelength, that at least either records onto or reproduces information from a first information recording medium;
• a second light source that emits light of a second wavelength, that at least either records onto or reproduces information from a second information recording medium;
• focusing means for focusing light that is emitted from the first light source and from the second light source;
• an optical element that passes light of the first wavelength and diffracts light of the second wavelength;
• and
• photodetecting means for detecting light of the first wavelength and light of the second wavelength,
• further comprising:
• moving means for moving the information recording medium and the optical head relative to each other;
• wherein light of the first wavelength and light of the second wavelength pass through the optical element, after which they are focused by the focusing means and are irradiated onto the information recording media;
• wherein the optical element is an optical element in which grooves are formed in a substrate;
• wherein the expression:
• 380 nm≦(n−1)×d≦420 nm
• is satisfied, where n is a refractive index of the substrate at a wavelength of 400 nm, and d (nm) is a depth per step of the grooves;
• wherein the grooves are formed in four steps of depth d, depth 2d, depth 3d and depth 4d;
• and
• wherein the photodetecting means detects light that is at least either reflected or diffracted by the information recording media.

An optical information recording and reproduction apparatus, comprising:

• an optical head that includes;
• a first light source that emits light of a first wavelength, that at least either records onto or reproduces information from a first information recording medium;
• a second light source that emits light of a second wavelength, that at least either records onto or reproduces information from a second information recording medium;
• a third light source that emits light of a third wavelength, that at least either records onto or reproduces information from a third information recording medium;
• focusing means for focusing light that is emitted from the first light source, from the second light source and from the third light source;
• a first optical element that passes light of the first wavelength and diffracts light of the second wavelength and light of the third wavelength;
• and
• photodetecting means for detecting light of the first wavelength, light of the second wavelength and light of the third wavelength;
• further comprising:
• moving means for moving the information recording medium and the optical head relative to each other;
• wherein light of the first wavelength, light of the second wavelength and light of the third wavelength pass through the optical element, after which they are focused by the focusing means and are irradiated onto the information recording media;
• wherein the first optical element is an optical element in which grooves are formed in a substrate;
• wherein the expression:
• 380 nm≦(n−1)×d≦420 nm
• is satisfied, where n is a refractive index of the substrate at a wavelength of 400 nm, and d (nm) is a depth per step of the grooves;
• wherein the grooves are formed in two steps of depth d and depth 2d;
• and
• wherein the photodetecting means detects light that is at least either reflected or diffracted by the information recording media.

An optical information recording and reproduction apparatus, comprising:

• an optical head that includes;
• a first light source that emits light of a first wavelength, that at least either records onto or reproduces information from a first information recording medium;
• a second light source that emits light of a second wavelength, that at least either records onto or reproduces information from a second information recording medium;
• a third light source that emits light of a third wavelength, that at least either records onto or reproduces information from a third information recording medium;
• focusing means for focusing light that is emitted from the first light source, from the second light source and from the third light source;
• a first optical element that passes light of the first wavelength and diffracts light of the second wavelength and light of the third wavelength;
• and
• photodetecting means for detecting light of the first wavelength, light of the second wavelength and light of the third wavelength;
• further comprising:
• moving means for moving the information recording medium and the optical head relative to each other;
• wherein light of the first wavelength, light of the second wavelength and light of the third wavelength pass through the optical element, after which they are focused by the focusing means and are irradiated onto the information recording media;
• wherein the first optical element is an optical element in which grooves are formed in a substrate;
• wherein the expression:
• 380 nm≦(n−1)×d≦420 nm
• is satisfied, where n is a refractive index of the substrate at a wavelength of 400 nm, and d (nm) is a depth per step of the grooves;
• wherein the grooves are formed in four steps of depth d, depth 2d, depth 3d and depth 4d;
• and
• wherein the photodetecting means detects light that is at least either reflected or diffracted by the information recording media.

An optical element, comprising:

• a substrate, in which steps are formed protruding from a flat surface thereof;
• wherein the expression:
• 760 nm≦(n−1)×d≦840 nm
• is satisfied when a refractive index of the substrate at a wavelength of 400 nm is n, and a height (nm) of one step is d;
• and
• wherein the height of the steps is an integer multiple of d.

An optical head, comprising:

• a first light source that emits light of a first wavelength that is in a range of 380 nm to 420 nm and that at least either records onto or reproduces information from a first information recording medium;
• a second light source that emits light of a second wavelength, that at least either records onto or reproduces information from a second information recording medium;
• an optical element that passes light of the first wavelength, and converts the phase of light of the second wavelength;
• focusing means for focusing light of the first wavelength and light of the second wavelength onto the information recording medium;
• detecting means for detecting light of the first wavelength and light of the second wavelength;
• wherein the optical element is an optical element comprising a substrate, in which steps are formed protruding from a flat surface thereof;
• and
• wherein the expression:
• 760 nm≦(n−1)×d≦840 nm
• is satisfied when a refractive index of the substrate at a wavelength of 400 nm is n, and a height (nm) of one step is d.

An optical head, comprising:

• a first light source that emits light of a first wavelength that is in a range of 380 nm to 420 nm and that at least either records onto or reproduces information from a first information recording medium;
• a second light source that emits light of a second wavelength, that at least either records onto or reproduces information from a second information recording medium;
• an optical element that passes light of the first wavelength, and converts the phase of light of the second wavelength;
• focusing means for focusing light of the first wavelength and light of the second wavelength onto the information recording medium;
• and
• detecting means for detecting light of the first wavelength and light of the second wavelength;
• wherein the position of the second light source is set closer to the focusing means than a position at which the aberration at the information recording surface of the second information recording medium, when the optical element is not present, is at a minimum;
• wherein the optical element is an optical element comprising a substrate, in which steps are formed protruding from a flat surface thereof;
• and
• wherein the expression:
• 380 nm≦(n−1)×d≦420 nm
• is satisfied when a refractive index of the substrate at a wavelength of 400 nm is n, and a height (nm) of one step is d.

An optical head, comprising:

• a first light source that emits light of a first wavelength that is in a range of 380 nm to 420 nm and that at least either records onto or reproduces information from a first information recording medium;
• a second light source that emits light of a second wavelength, that at least either records onto or reproduces information from a second information recording medium;
• an optical element that passes light of the first wavelength, and converts the phase of light of the second wavelength;
• focusing means for focusing light of the first wavelength and light of the second wavelength onto the information recording medium;
• and
• detecting means for detecting light of the first wavelength and light of the second wavelength;
• wherein the position of the second light source is set further from the focusing means than a position that is substantially midway between the position of that light source at which the aberration at the information recording surface of the second information recording medium when the optical element is not present is at a minimum, and the position of that light source at which light of the second wavelength that is incident on the focusing means is collimated light;
• wherein the optical element is an optical element comprising a substrate, in which steps are formed protruding from a flat surface thereof;
• and
• wherein the expression:
• 380 nm≦(n−1)×d≦420 nm
• is satisfied when a refractive index of the substrate at a wavelength of 400 nm is n, and a height (nm) of one step is d.

An optical head comprising:

• a first light source that emits light of a first wavelength that is in a range of 380 nm to 420 nm and that at least either records onto or reproduces information from a first information recording medium;
• a second light source that emits light of a second wavelength, that at least either records onto or reproduces information from a second information recording medium;
• an optical element that passes light of the first wavelength, and converts the phase of light of the second wavelength;
• focusing means for focusing light of the first wavelength and light of the second wavelength onto the information recording medium;
• and
• detecting means for detecting light of the first wavelength and light of the second wavelength;
• wherein light of the second wavelength that is incident on the focusing means is collimated light;
• wherein the optical element is an optical element comprising a substrate, in which steps are formed protruding from a flat surface thereof;
• and
• wherein the expression:
• 380 nm≦(n−1)×d≦420 nm
• is satisfied when a refractive index of the substrate at a wavelength of 400 nm is n, and a height (nm) of one step is d.

An optical head, comprising:

• a first light source that emits light of a first wavelength that is in a range of 380 nm to 420 nm and that at least either records onto or reproduces information from a first information recording medium;
• a second light source that emits light of a second wavelength, that at least either records onto or reproduces information from a second information recording medium;
• a third light source that emits light of a third wavelength, that at least either records onto or reproduces information from a third information recording medium;
• an optical element that passes light of the first wavelength and light of the third wavelength, and converts the phase of light of the second wavelength;
• focusing means for focusing light of the first wavelength, light of the second wavelength and light of the third wavelength onto the information recording medium;
• and
• detecting means for detecting light of the first wavelength, light of the second wavelength and light of the third wavelength;
• wherein the optical element is an optical element comprising a substrate, in which steps are formed protruding from a flat surface thereof;
• and
• wherein the expressions:
• 760 nm≦(n1−1)×d≦840 nm
• and
• −10 nm<λ1/(n1−1)·λ3/(n3−1)/2<10 nm.
• are satisfied when a refractive index of the optical element at the wavelength of 400 nm is n, the third wavelength is λ3 (nm), a refractive index of the optical element at the wavelength λ3 is n3, and a height (nm) of one step is d.

An optical head, comprising:

• a first light source that emits light of a first wavelength that is in a range of 380 nm to 420 nm and that at least either records onto or reproduces information from a first information recording medium;
• a second light source that emits light of a second wavelength, that at least either records onto or reproduces information from a second information recording medium;
• a third light source that emits light of a third wavelength, that at least either records onto or reproduces information from a third information recording medium;
• an optical element that passes light of the first wavelength and light of the third wavelength, and changes the phase of light of the second wavelength;
• a liquid crystal element that passes light of the first wavelength and light of the second wavelength, and diffracts light of the third wavelength;
• focusing means for focusing light of the first wavelength, light of the second wavelength and light of the third wavelength onto the information recording medium;
• and
• detecting means for detecting light of the first wavelength, light of the second wavelength and light of the third wavelength;
• wherein the optical element is an optical element comprising a substrate, in which steps are formed protruding from a flat surface thereof;
• wherein the expression:
• 700 nm≦(n−1)×d≦840 nm
• is satisfied when a refractive index of the substrate at a wavelength of 400 nm is n, and a height (nm) of one step is d;
• and
• wherein the liquid crystal element comprises:
• a substrate that has a relief-shaped hologram pattern;
• a first transparent electrode, which is formed on the relief-shaped hologram pattern;
• and
• a second transparent electrode that is arranged opposite the first transparent electrode to sandwich the liquid crystal;
• wherein the liquid crystal element passes light of the first wavelength and light of the second wavelength, and diffracts light of the third wavelength by controlling a voltage that is applied to the first transparent electrode and the second transparent electrode.