Abstract: An optical disk apparatus has an optical head having a lens of converging light from a light source onto an optical disk and a photodetector for detecting the light thus converged and then reflected from the optical disk. A tracking error signal is generated in order to perform tracking control on the basis of the detected light. A disk tilt DT is detected to indicate the amount of tilt of the optical head relative to the optical disk. A calculation is performed to calculate a lens shift LS indicating the amount of shift of the lens relative to the optical head, according to a predetermined rule on the basis of the generated tracking error signal and the detected disk tilt DT.

Abstract: An optical disk device is provided that can realize favorable recording/reproduction of signals on/from an optical disk having a plurality of signal planes arranged in proximity to each other. In this optical disk device, a hologram (4) is divided into n(n?2) regions Ak(k=1, 2, . . . , n) by a straight line that intersects with an optical axis, and a photodetector (7) is divided into at least two regions A and A?. Light emitted from a light source (1) is focused on a signal plane (6a) or (6b) included in a plurality of signal planes of the optical disk by an objective lens (5). Light reflected from a first signal plane (6a) and light reflected from a second signal plane (6b) pass through the objective lens (5) to turn into light beams a and a?, respectively, that enter the hologram (4).

Abstract: An optical disk apparatus including: a light source; an objective lens for converging light emitted from the light source toward an optical disk; a first photodetection device for detecting reflected light from the optical disk and outputting a first signal; a signal processing section for receiving the first signal and generating a signal containing information recorded on the optical disk; a second photodetection device for detecting a portion of the light emitted from the light source and outputting a second signal; a light source driving section for receiving the second signal, and based on the second signal, driving the light source so that output power of the light source equals a target value; and an amplitude fluctuation detection section for detecting an amplitude fluctuation amount of the second signal, and if the amplitude fluctuation amount exceeds a predetermined value, changing driving characteristics of the light source driving section.

Abstract: A first light ray with a wavelength ?1 emanating from the first emission light source passes through the transparent substrate and is condensed by the objective lens on a signal surface of a first optical disk with a substrate thickness t1, a second light ray with a wavelength ?2 (??1) emanating from the second emission light source passes through the transparent substrate and is condensed by the objective lens on a signal surface of a second optical disk with a substrate thickness t2, a step structure of at least one step is formed along a circle or an ellipse on a surface of the transparent substrate, and and by the step of the step structure, a phase of the first light ray is shifted by 2?n1+?1 and a phase of the second light ray is shifted by 2?n2+?2.

Abstract: An optical disk apparatus according to the present invention includes: a motor for rotating an optical disk; a light source; diffraction means for diffracting a portion of light emitted from the light source to form a main beam of 0th order light and a pair of sub beams composed of +1st order light and ?1st order light which are formed on both sides of the 0th order light; an objective lens for converging the main beam and the pair of sub beams onto the optical disk; a light receiving means for receiving the main beam and the sub beams reflected from the optical disk, and outputting electrical signals through photoelectric conversion; and a calculation section for, based on the electrical signals output from the light receiving means, providing a main push-pull signal MPP, a sub push-pull signal SPP, and a differential signal between the main push-pull signal MPP and the sub push-pull signal SPP.

Abstract: There is provided, in an optical disk apparatus which is capable of recording data to or reading data from a plurality of types of optical disks, a wavelength plate and an optical pickup which can reduce deterioration in signal quality even in the presence of a large birefringence of the substrate of an optical disk. A wavelength plate 6 according to the present invention is a wavelength plate to be placed in an optical path through which rays of a plurality of wavelengths travel back and forth, the plurality of wavelengths including a ray having a wavelength ?. The wavelength plate includes a two-dimensional array of a plurality of birefringent regions, the birefringent regions including first regions D1 and second regions D2 having different optic axis directions from each other. The relationship 240°??1?300° is true, where ?1 is a retardation of the wavelength plate 6 for the ray of the wavelength ?.

Abstract: An optical disk device is provided that can realize favorable recording/reproduction of signals on/from an optical disk having a plurality of signal planes arranged in proximity to each other. In this optical disk device, a hologram (4) is divided into n(n?2) regions Ak(k=1, 2, . . . , n) by a straight line that intersects with an optical axis, and a photodetector (7) is divided into at least two regions A and A?. Light emitted from a light source (1) is focused on a signal plane (6a) or (6b) included in a plurality of signal planes of the optical disk by an objective lens (5). Light reflected from a first signal plane (6a) and light reflected from a second signal plane (6b) pass through the objective lens (5) to turn into light beams a and a?, respectively, that enter the hologram (4).

Abstract: An optical pick up apparatus includes: a first, a second and a third light emitting points for emitting light beams; an optical system for introducing the light beams emitted from the first, second and third emitting points to an objective lens; an objective lens for converging the light beams introduced by the optical system onto an information recording medium; and a light detector for detecting reflected light from the information recording medium, wherein a relationship of ?1<?2<?3 is satisfied, where ?1, ?2 and ?3 denote the respective wavelengths of the light beams emitted from the first, second and third light emitting points, and a relationship of either L1=L2<L3 or L1<L2=L3 or L1<L2<L3 is satisfied, where L1, L2 and L3 denote the respective distances between a reference axis which optically matches a center axis of the objective lens and the first, second and third light emitting points.

Abstract: A light emitting device according to the present invention includes: a first light source for emitting light having a first wavelength; and a second light source for emitting light having a second wavelength which is different from the first wavelength, wherein the first light source and the second light source are arranged in the same housing, and a relationship of ?h1>?h2 is satisfied, where ?h1 denotes an angle (full-width-half-maximum) of radiation of the light emitted from the first light source in the horizontal direction, and ?h2 denotes an angle (full-width-half-maximum) of radiation of the light emitted from the second light source in the horizontal direction.

Abstract: It is intended to provide an optical disk apparatus which detects a light amount greater than zero even when used in conjunction with an optical disk substrate having a large birefringence, so that it is possible to properly read a signal without errors and properly perform optical disk controls. The optical disk apparatus includes: a light source for emitting light; an objective lens for converging the light onto a signal surface of an optical disk; a polarized beam diffraction element for diffracting the light reflected from the optical disk; a photodetector for detecting the light diffracted from the polarized beam diffraction element; and a wavelength plate disposed between the optical disk and the polarized beam diffraction element.

Abstract: There is provided an information processing device which is capable of suppressing generation of stray light at the time of recording and reproduction of information, thus enabling quality information recording and reproduction. The information processing device includes: a radiation light source 2; and a converging section for converging rays emitted from the light source toward an information recording medium having a photosensitive layer 11b, wherein the converging section splits the rays into first and second rays 3? and 3 respectively traveling through first and second spaces as divided by a plane at least containing a point optical axis L, and converges the first and second rays 3? and 3 onto first and second points 12? and 12 in the information recording medium 11, the photosensitive layer 11b being interposed between the first and second points 12? and 12.

Abstract: An optical disk device has an aperture of an objective lens in an incoming path of a beam from a semiconductor laser to an optical disk formed larger than an aperture in a return path from the optical disk or an aperture is varied in recording and in reproduction. This configuration improves recording/reproducing ability since light is focused on an optical disk with high numerical aperture. In addition, since reflected light from the optical disk is detected with low numerical aperture, margins for tilt and defocus are not reduced. Furthermore, since unnecessary signal components contained in the reflected light can be eliminated, a S/N (signal-to-noise ratio) of an information signal also increases. Thus, a high-performance optical disk device can be obtained. Alternatively, by varying the aperture of an objective lens in recording and in reproduction, an optical disk device in which recording density and recording quality are increased without deteriorating reproduction quality can be obtained.

Abstract: An optical disk device has a light source which emits light; and light converging means of, in each of signal mark forming regions, each of lands, or each of grooves of an optical disk, converging the light from the light source onto a signal surface of the optical disk with selectively positioning a signal mark at any one of plural positions which are arranged in a direction that is substantially perpendicular to tracks, each of the signal mark forming regions surrounded by adjacent two of boarder lines which are between two the tracks on the signal surface of the optical disk, and which are substantially parallel to the tracks, and each of which substantially divides an area between adjacent tracks in two parts.

Abstract: An optical disk device has an aperture of an objective lens in an incoming path of a beam from a semiconductor laser to an optical disk formed larger than an aperture in a return path from the optical disk or an aperture is varied in recording and in reproduction. This configuration improves recording/reproducing ability since light is focused on an optical disk with high numerical aperture. In addition, since reflected light from the optical disk is detected with low numerical aperture, margins for tilt and defocus are not reduced. Furthermore, since unnecessary signal components contained in the reflected light can be eliminated, a S/N (signal-to-noise ratio) of an information signal also increases. Thus, a high-performance optical disk device can be obtained. Alternatively, by varying the aperture of an objective lens in recording and in reproduction, an optical disk device in which recording density and recording quality are increased without deteriorating reproduction quality can be obtained.

Abstract: To implement light quantity monitoring with high frequency responsivity and correction of astigmatic differences of a semiconductor laser with a simple configuration with a fewer parts. Of the light beam output from a semiconductor laser light source 101, a peripheral beam component is entered by a light reflection element 107 into an anterior light monitoring photodetector 103 formed in the vicinity of a semiconductor laser light source 101. Furthermore, the surface of the reflection sphere of the light reflection element is formed anamorphic, and thus condensed to an appropriate size on the photodetector without being focused, providing high frequency responsivity. Furthermore, the light reflection element 107 is placed inclined at a predetermined angle so as to cancel out astigmatic difference of the optical semiconductor laser light source 101.

Abstract: An optical disk device has a light source which emits light; and light converging means of, in each of signal mark forming regions, each of lands, or each of grooves of an optical disk, converging the light from the light source onto a signal surface of the optical disk with selectively positioning a signal mark at any one of plural positions which are arranged in a direction that is substantially perpendicular to tracks, each of the signal mark forming regions surrounded by adjacent two of boarder lines which are between two the tracks on the signal surface of the optical disk, and which are substantially parallel to the tracks, and each of which substantially divides an area between adjacent tracks in two parts.

Abstract: An optical disk device has an aperture of an objective lens in an incoming path of a beam from a semiconductor laser to an optical disk formed larger than an aperture in a return path from the optical disk or an aperture is varied in recording and in reproduction. This configuration improves recording/reproducing ability since light is focused on an optical disk with high numerical aperture. In addition, since reflected light from the optical disk is detected with low numerical aperture, margins for tilt and defocus are not reduced. Furthermore, since unnecessary signal components contained in the reflected light can be eliminated, a S/N (signal-to-noise ratio) of an information signal also increases. Thus, a high-performance optical disk device can be obtained. Alternatively, by varying the aperture of an objective lens in recording and in reproduction, an optical disk device in which recording density and recording quality are increased without deteriorating reproduction quality can be obtained.

Abstract: An optical disc apparatus capable of mounting an optical disc includes a light source for emitting light; an objective lens for collecting the light emitted by the light source on the optical disc; a first light distribution section integrally movable with the objective lens, the first light distribution section including a first area and a second area, the first light distribution section outputting the light reflected by the optical disc and transmitted through the first area or the second area as transmission light, outputting the light reflected by the optical disc and diffracted by the first area as first diffraction light, and outputting the light reflected by the optical disc and diffracted by the second area as second diffraction light; a transmission light detection section for detecting the transmission light and outputting a TE1 signal indicating an offset of the detected transmission light; a first diffraction light detection section for detecting the first diffraction light and the second diffrac

Abstract: An optical disk device has an aperture of an objective lens in an incoming path of a beam from a semiconductor laser to an optical disk formed larger than an aperture in a return path from the optical disk or an aperture is varied in recording and in reproduction. This configuration improves recording/reproducing ability since light is focused on an optical disk with high numerical aperture. In addition, since reflected light from the optical disk is detected with low numerical aperture, margins for tilt and defocus are not reduced. Furthermore, since unnecessary signal components contained in the reflected light can be eliminated, a S/N (signal-to-noise ratio) of an information signal also increases. Thus, a high-performance optical disk device can be obtained. Alternatively, by varying the aperture of an objective lens in recording and in reproduction, an optical disk device in which recording density and recording quality are increased without deteriorating reproduction quality can be obtained.

Abstract: An optical pickup device, a signal processing method for the optical pickup device, and an optical disk drive unit are provided which are capable of eliminating or lessening the influence on the RF signal by a variation in the emission power of a laser, without changing the structure of the laser or varying reproduction power. A signal processing circuit 19 of an optical pickup device 2, which converges light emitted from a laser 11 upon an optical disk through an objective lens and executes recording and reproduction of information on the optical disk, comprises: a photo-detector 18 which receives reflected light from the optical disk; a former-light detector 17 which receives a part of emitted light from the laser 11; a division circuit 22 which divides an RF signal outputted from the photo-detector 18 by a former-light signal outputted from the former-light detector 17; and an RF detection circuit 23 which detects an RF signal from the signal obtained by a division of the division circuit 22.