Abstract: An information-recording medium having a substrate and a recording part formed on the substrate allowing three-dimensional formation of recording pits, the recording part, comprising multiple recording layers, in which the recording pits are formed with a converged recording light at a wavelength of ?2 and reproduced with a converged reproducing light with a wavelength ?1 shorter than the wavelength ?2, and intermediate layers alternately laminated between the recording layers, wherein the reflectance at the recording light wavelength of ?2 in the unrecorded region is smaller than the reflectance at the reproducing light wavelength of ?1 in the unrecorded regions of the recording layers.

Abstract: A laser beam 32 reflected by an information layer of a multilayer optical disc 26 is reflected and split by reflecting surfaces 31a?, 31b, 31c and 31d to be incident on a photodetector element 36 as laser beams 33, 34 and 35. The laser beam 34 is collected on a light receiving region 38 for RF detection to generate an RF signal. The laser beams 33, 35 are incident on light receiving regions 37a, 37b for focus detection, and a focus error signal is generated by an SSD method. A laser beam 65 reflected by an information layer adjacent to the above information layer partially transmits through the reflecting surface 31a? to be imaged on a light receiving region 66 for tracking detection, and a tracking error signal is generated.

Abstract: A confocal optical device and a spherical-aberration correction method reduce the generation of spherical aberration. This confocal optical device includes a drive mechanism which moves a sample board to change the distance between an objective lens and the sample board. A spherical-aberration correction element is disposed between a light source and the objective lens. A reference-position detection section, based on a detection result by a photo-detector, detects the position of the sample board when the focal position of the objective lens coincides with the surface of the sample. A movement-distance derivation section, based on a detection result by the photo-detector, calculates a distance by which the sample board is moved until the focal position of the objective lens coincides with an object to be measured inside of the sample, and derives the depth at which the measured object is located in the sample.

Abstract: In a confocal optical system provided with a light source 13, a first focusing means 14, a second focusing means 16, an aperture 17, and a detector 18, the detector has plural light reception regions. A position displacement is detected by detecting an intensity distribution of an image caused by a position displacement between the focusing spot of the second focusing means 16 and the aperture 17 by the detector 18, and the position displacement is corrected by controlling the aperture position using driving means 19 and control means 20. Also, a position displacement of the aperture 17 in the optical axis direction is detected and corrected on the basis of a change in output of the detector 18 by oscillating the aperture 17 in the optical axis direction.

Abstract: An optical head with excellent optical characteristics even when using a light source that substantially has a wavelength broadening is provided. The optical head includes a light source, an objective lens for focusing a light beam emitted from the light source on an information recording medium and a photodetector for detecting the light beam reflected from the information recording medium, wherein defocusing correction means and spherical aberration correction means are provided in an optical path between the light source and the information recording medium. Since both the defocusing correction means and the spherical aberration correction means are provided, while defocusing of a focused spot on the information recording medium caused by a wavelength broadening of the light source and chromatic aberration of the optical system can be corrected, the spherical aberration of the optical system caused by wavelength difference between a design wavelength and an incident wavelength also can be corrected.

Abstract: An information recording medium includes a substrate and a recording portion having recording layers on the substrate, wherein the recording portion is capable of three-dimensional recording by changing an optical constant of the recording layers by an irradiation of a recording light, and a first reflected-light reducing portion for reducing reflected lights of a reproducing light from the substrate side is provided at a side opposite to an incident side of the reproducing light with respect to the recording portion, and an optical information recording/reproducing apparatus records and reproduces information to and from the medium.

Abstract: An object of the present invention is to acquire optimum recording characteristics of an optical recoding medium having multiple data layers, with respect to each of the multiple data layers without increasing learning time required for learning a relation between aberration amount and optimum recording compensation with respect to each of the multiple data layers. The present invention includes a wavefront converter which is driven in such a manner as to reduce the aberration amount detected by an aberration detector. An output controller holds learned data as to the relation between the driving amount of the wavefront converter and the output of a light source, and controls the output of the light source based on the driving amount of the wavefront converter and the learned data.

Abstract: An information recording medium has a recording portion where three-dimensional information can be recorded. The recording portion includes at least one particle-containing layer (recording layer or a recording auxiliary layer) containing particles absorbing at least a part of light having a predetermined wavelength and substantially transparent to a recording light and a reproducing light having a wavelength longer than the predetermined wavelength and a particle holding material substantially transparent to the recording and reproducing lights. The mean particle size of the particles is preferably shorter than the wavelengths of the recording and reproducing lights.

Abstract: A diffractive optical element emits substantially zero order diffracted light when light with a wavelength of 0.35 ?m to 0.45 ?m is incident and emits substantially first-order diffracted light when light with a wavelength of 0.6 ?m to 0.7 ?m is incident. The diffractive optical element includes a substrate and a grating portion formed on the substrate. The grating portion has a step-wise cross section with any one of levels selected from four levels, five levels and six levels. The diffractive optical element emits substantially zero-order diffracted light when light with a first wavelength ?1 satisfying the relationship: 0.35 ?m??1?0.45 ?m is incident and emits substantially first-order diffracted light when light with a second wavelength ?2 satisfying the relationship: 0.6 ?m??2?0.7 ?m is incident.

Abstract: A transmission diffraction grating body including a base material being substantially transparent with respect to wavelength ?1 and having a refractive index n0; another base material being substantially transparent with respect to wavelength ?1 and having a refractive index n1, which is formed on the base material having a refractive index n0; and a relief diffraction grating formed on the base material having a refractive index n1; wherein the refractive indexes n1 and n0 satisfy the relationship: n1>n0. Thus, the base material having a refractive index n1 can be formed of a high refractive index material, and when the depth of grating of the diffraction grating is set so that the diffraction grating diffracts the light with wavelength ?1 and does not diffract the light with wavelength ?2, the depth of grating of the diffraction grating can be made to be shallow, thus preventing the loss of the amount of the light with wavelength ?1.

Abstract: An optical head device includes: an optical element collecting light reflected from a reproduction information layer (a target information layer in an optical information recording medium) and light reflected from information layers adjacent to the reproduction information layer at different positions; a light receiving element obtaining a detection signal from the reflected light collected by this optical element; and arithmetic circuitry obtaining a reproduction signal from this detection signal.

Abstract: An information recording medium is provided that includes a recording portion (3), which is irradiated with a recording light or a reproducing light so that information is recorded or reproduced thereto or therefrom. The recording portion (3) contains a first phosphor and a photon-mode photosensitive material. The first phosphor has a property of absorbing a first light having a wavelength of ?1/n and then emitting a second light having a wavelength longer than that of the first light, where ?1 is a wavelength of the recording light. The photosensitive material absorbs the second light and then exhibits a change in an optical constant thereof. A n-photon absorption sensitivity of the first phosphor with respect to the recording light is greater than a n-photon absorption sensitivity of the photosensitive material with respect to the recording light, where n is an integer not less than 2.

Abstract: An optical information reproducing method of the present invention is used for an optical recording medium. The optical recording medium includes a recording layer containing information and a mask layer that is located close to the recording layer and includes a nonlinear optical material whose optical properties are changed in accordance with incident light intensity. The method includes irradiating the optical recording medium with convergent light that is polarized in a first direction and dividing reflected light from the optical recording medium into a first polarized component that is polarized in the first direction and a second polarized component that is polarized in a second direction perpendicular to the first direction. The second polarized component is used to detect a reproduction signal.

Abstract: An optical head with excellent optical characteristics even when using a light source that substantially has a wavelength broadening is provided. The optical head includes a light source, an objective lens for focusing a light beam emitted from the light source on an information recording medium and a photodetector for detecting the light beam reflected from the information recording medium, wherein defocusing correction means and spherical aberration correction means are provided in an optical path between the light source and the information recording medium. Since both the defocusing correction means and the spherical aberration correction means are provided, while defocusing of a focused spot on the information recording medium caused by a wavelength broadening of the light source and chromatic aberration of the optical system can be corrected, the spherical aberration of the optical system caused by wavelength difference between a design wavelength and an incident wavelength also can be corrected.

Abstract: An optical head with excellent optical characteristics even when using a light source that substantially has a wavelength broadening is provided. The optical head includes a light source, an objective lens for focusing a light beam emitted from the light source on an information recording medium and a photodetector for detecting the light beam reflected from the information recording medium, wherein defocusing correction means and spherical aberration correction means are provided in an optical path between the light source and the information recording medium. Since both the defocusing correction means and the spherical aberration correction means are provided, while defocusing of a focused spot on the information recording medium caused by a wavelength broadening of the light source and chromatic aberration of the optical system can be corrected, the spherical aberration of the optical system caused by wavelength difference between a design wavelength and an incident wavelength also can be corrected.

Abstract: An information recording medium (21) of the optical information reproduction device of the present invention includes a recording unit (3) capable of recording information three-dimensionally and provided with a track, and information is recorded by forming a plurality of recording marks along the track of the recording unit by a mark length recording method. When the track direction of the recording marks is assumed to be their longitudinal direction and the direction perpendicular to the track direction is assumed to be their lateral direction, with the present invention, for recording marks located substantially in the same plane, the total area of elongated recording marks, whose longitudinal length is greater than their lateral length, is greater than the total area of recording marks having other than elongated shapes.

Abstract: An optical information recording carrier comprising a substrate and at least one recording film arranged on the substrate is disclosed. Information is recorded on the recording film through irradiation with a recording light having a predetermined wavelength (?). The recording film is composed of a heat generating layer and at least one dielectric layer arranged in contact with the heat generating layer. The heat generating layer and the dielectric layer are substantially transparent to the recording light with wavelength (?), and are respectively formed to have a predetermined thickness and a predetermined refractive index so that the field intensity of the recording light becomes maximum at the interface between the heat generating layer and the dielectric layer.

Abstract: A confocal optical device and a spherical-aberration correction method are provided which reduce the generation of a spherical aberration.

Abstract: The optical information recording and reproducing apparatus includes a light source for emitting a light beam, an objective lens for converging the light beam emitted from the light source to an information recording medium, and a light detector for detecting the light beam reflected from the information recording medium. The information bits are recorded into a recording member of the information recording medium in a three-dimensional arrangement by using a change in optical constant of the recording member. Furthermore, a thickness of the recording member is larger than a wavelength of the light beam and the information bits are sequentially recorded into the recording member in a three-dimensional arrangement in such an order that a converging light beam from the objective lens does not pass through information bits that have already been recorded.

Abstract: An information recording medium of the present invention includes a recording portion capable of storing information three-dimensionally. The recording portion (3) includes at least one recording layer (1a to 1f), and the recording layer (1a to 1f) contains titanium oxide. It is preferable that titanium oxide is at least one kind of an anatase type and a brookite type. The recording layer (1a to 1f) may be substantially made of titanium oxide, and may contain titanium oxide and a low refractive-index material having a refractive index smaller than that of titanium oxide.