Abstract: Provided is a spatial light modulator SLM and a photodetector element CMOS sensor are placed on the same chip, and the alignment thereof and a relay lens system are eliminated, whereby an optical system is reduced in cost and made compact. Specifically, provided is an optical information recording and reproducing apparatus for recording information by allowing information light and reference light to interfere with each other and reproducing the information using the reference light including: a light source; a spatial light modulator for generating at least an information light with respect to a light beam from the light source; an objective lens for irradiating a recording medium with the light beam from the spatial light modulator; and a photodetector element for receiving a reproduction light from the recording medium, in which the spatial light modulator and the photodetector element are formed on the same semiconductor substrate.

Abstract: Provided is an optical pickup apparatus which has a function for correcting spherical aberration caused by a thickness error of a transparent substrate and which is sufficiently compact, wherein a collimator lens used in the apparatus is composed of two lens groups, an interval between the two lens groups is changeable, and therefore spherical aberration caused by the thickness error of the transparent substrate is corrected.

Abstract: The recording medium 12 is radiated with light beam from the second light source to obtain servo signal from the reflected light. At least one of the relay lenses 8 in the relay optical system is moved perpendicularly to the optical axis according to the servo signal to follow-up moving direction of the recording medium. The light beam from the second laser light source merges with an optical system from the first laser light source to the recording medium 12 between at least one of the relay lenses 8 and the spatial light modulator 3.

Abstract: There is provided an optical information recording/reproducing apparatus including a unit for detecting the focus error signal from the reflected light flux from a recording layer of an optical recording medium, and a unit for focusing the light flux on the recording layer of the optical disk on the basis of the focus error signal. In the case of detecting the focus error signal, the light flux of the effective numeric aperture NAeff<1 due to an objective lens and the SIL within a pupil is obtained by a splitting device as the focus error signal, whereby it is possible to suppress the reflected light from the bottom surface of the SIL from being mixed into the focus error signal as a noise.

Abstract: An apparatus for optically reproducing and recording information includes a light source, an objective lens, a light detecting element, and a processor. The objective lens focuses light beams emitted from the light source on an optical recording medium having tracks disposed at a track pitch. The wavelength of the light beams is greater than the track pitch of the medium. The light detecting element receives light beams reflected from the medium. The light detecting element includes a first region that receives substantially only light beams generated by interference between zeroth-order diffracted beams and first-order diffracted beams among the light beams reflected from the tracks of the medium and a second region that receives substantially only the zeroth-order diffracted beams. The processor generates focusing error signals using astigmatic focusing error detection on the basis of an output from the second region of the light detecting element.

Abstract: Provided is a spatial light modulator SLM and a photodetector element CMOS sensor are placed on the same chip, and the alignment thereof and a relay lens system are eliminated, whereby an optical system is reduced in cost and made compact. Specifically, provided is an optical information recording and reproducing apparatus for recording information by allowing information light and reference light to interfere with each other and reproducing the information using the reference light including: a light source; a spatial light modulator for generating at least an information light with respect to a light beam from the light source; an objective lens for irradiating a recording medium with the light beam from the spatial light modulator; and a photodetector element for receiving a reproduction light from the recording medium, in which the spatial light modulator and the photodetector element are formed on the same semiconductor substrate.

Abstract: A collinear system optical information recording-reproduction apparatus is provided which gives sufficiently high interference modulation degree even with inexpensive semiconductor laser as the recording-reproduction light source. Specifically in this apparatus, recording is conducted by introducing a light flux from a light source to a spatial light modulator having an information pattern area and a reference pattern area, introducing the produced information light and reference light to object lens to record the information to a recording medium by the object lens by holography; and reproduction is conducted by projecting the reference light only from the spatial light modulator to the recording medium, and introducing the light reflected by the recording medium to a light-receiving element. In this apparatus the average information light intensity and the average reference light intensity introduced into the object lens are made equal.

Abstract: The recording medium 12 is radiated with light beam from the second light source to obtain servo signal from the reflected light. At least one of the relay lenses 8 in the relay optical system is moved perpendicularly to the optical axis according to the servo signal to follow-up moving direction of the recording medium. The light beam from the second laser light source merges with an optical system from the first laser light source to the recording medium 12 between at least one of the relay lenses 8 and the spatial light modulator 3.

Abstract: The present invention provides an optical recording medium capable of detecting groove start signals and groove end signals with an inexpensive detection circuit and allowing quick, stable clock detection and tracking pull-in, which optical recording medium is constructed in such a way that the depth DG of the grooves satisfies DG/(?/N)<0.16, where ? is a wavelength of a light beam and N is an index of refraction of a substrate, and that the distance Ls between the groove edge and the pit closest thereto satisfies Ls>1.2 FWHM, where FWHM is a full width at half maximum of the light beam in the track direction.

Abstract: An optical information recording/reproduction apparatus capable of eliminating a waste of learning time for spherical aberration learning and rationalizing the spherical aberration-correcting operation is provided. Specifically, the optical information recording/reproduction apparatus includes: a discrimination circuit for discriminating the kind of an optical disk, that is, whether a recording layer is a single-layer, or whether double-layers or an optical disk is a disk corresponding to red-laser or a disk corresponding to blue-laser; a correction device for correcting the aberration due to a change in thicknesses of the transparent substrate of an optical disk by changing intervals between a plurality of lenses; a learning circuit for searching a correction amount while changing intervals between the plurality of lenses; and a circuit for changing initial positions of intervals between the plurality of lenses at start of learning in accordance with a discrimination result by the discrimination circuit.

Abstract: The present invention provides a method of recording information on a magneto-optical recording medium of domain wall displacement type having a preformat area and a data area succeeding thereto, comprising the steps of generating a reproduction signal from said medium by utilizing a light beam, detecting a reference position based on said reproduction signal, determining, based on a result of the detection, a recording start timing at which a formation of a recording magnetic domain is started at a distance at least not shorter than a displacement amount of a domain wall away from a start position of said data area; and starting a recording with said determined recording start timing.

Abstract: Provided is an optical pickup apparatus which is inexpensive and has sufficient chromatic aberration correction performance, and which includes a chromatic aberration correction optical system composed of two lens groups having positive power and negative power, wherein the lens group having the positive power is constructed such that a focal distance thereof does not change or becomes shorter when a wavelength of a semiconductor laser lengthens, One of the lens groups is moved relative to the other lens group to correct chromatic aberration caused by a change in substrate thickness.

Abstract: Provided is an optical pickup apparatus which has a function for correcting spherical aberration caused by a thickness error of a transparent substrate and which is sufficiently compact, wherein a collimator lens used in the apparatus is composed of two lens groups, an interval between the two lens groups is changeable, and therefore spherical aberration caused by the thickness error of the transparent substrate is corrected.

Abstract: An optical information recording/reproducing device makes use of a differential push-pull (DPP) method. In the optical information recording/reproducing device, after amplification of a push-pull signal of first and second subbeams at a first predetermined ratio, a differential between the push-pull signal of the first and second subbeams and a push-pull signal of a main beam is determined in order to generate a tracking control signal. In addition, after amplification of the push-pull signal of the first and second subbeams at a predetermined second ratio, a summation of the push-pull signal of the first and second subbeams and the push-pull signal of the main beam is determined in order to generate an objective lens position signal. The first predetermined ratio and the second predetermined ratio are different.

Abstract: Two-dimensionally annular or spiral lands and grooves are formed in a magneto-optical disk having a magnetic layer composed of a magnetic domain wall displacement layer, a switching layer, and a record retaining layer. The lands and the grooves are each used as a recording and reproducing area. A side wall present between the land and the groove and its vicinity are annealed so as to change the physical properties of these areas. The width of the land is larger than the width of the groove by 0.5 to 4 times the width of the side wall. Further, the ratio of the width of the land to the width of the groove is 1.05 to 1.20. Furthermore, the grooves have a period of 1.0 to 1.2 microns.

Abstract: As a magneto-optical recording medium capable of obtaining stable tracking servo signals with a narrow tracking pitch with less influences of cross talk and cross write, a magneto-optical recording medium is provided which comprises a plurality of recording/reproducing tracks and wobble pits for a sample servo, wherein each of the wobble pits is provided between two adjacent tracks and used commonly by the adjacent tracks.

Abstract: An optical information reproducing apparatus for reproducing information by irradiating a recording medium with a reproducing light beam includes a light source for generating the reproducing light beam, a reproducing circuit for reproducing a reproduction signal by using the light beam, and an adjusting circuit for adjusting the light beam power. The adjusting circuit adjusts the beam power to a value larger than the light beam power at which a value obtained by normalizing the reproduction signal with the beam power is maximized.

Abstract: The present invention provides an optical recording medium capable of detecting groove start signals and groove end signals with an inexpensive detection circuit and allowing quick, stable clock detection and tracking pull-in, which optical recording medium is constructed in such a way that the depth DG of the grooves satisfies DG/(&lgr;/N)<0.16, where &lgr; is a wavelength of a light beam and N is an index of refraction of a substrate, and that the distance Ls between the groove edge and the pit closest thereto satisfies Ls>1.2 FWHM, where FWHM is a full width at half maximum of the light beam in the track direction.

Abstract: A domain wall displacement type magneto-optical recording medium is provided that can perform stable domain wall movement and prevent cross-write while adopting the land/groove recording to attain a narrow track pitch.

Abstract: The present invention provides a method of recording information on a magneto-optical recording medium of domain wall displacement type having a preformat area and a data area succeeding thereto, comprising the steps of generating a reproduction signal from said medium by utilizing a light beam, detecting a reference position based on said reproduction signal, determining, based on a result of the detection, a recording start timing at which a formation of a recording magnetic domain is started at a distance at least not shorter than a displacement amount of a domain wall away from a start position of said data area; and starting a recording with said determined recording start timing.