Abstract: A tilt can be detected highly accurately by minimizing the tilt detection error. An optical head includes: an objective lens for converging a light beam from a light source onto an optical disc; a photodetector section receiving the beam, reflected from the disc, at divided areas on its photodetection plane and outputting light detection signals from those areas; and a tilt detecting section for detecting a relative tilt between the lens and disc based on the detection signals.

Abstract: Provided are an optical head and an optical information device capable of inhibiting the temperature rise of a photodetector. An optical head (10) includes a semiconductor laser (101) which emits a luminous flux, an objective lens (105) which focuses the luminous flux emitted from the semiconductor laser (101) on the optical disk (21), and a photodetector (120) which detects the luminous flux reflected by the optical disk (21). The photodetector (120) includes a light receiving part (123) which receives the luminous flux reflected by the optical disk (21), a package (125) which covers the light receiving part (123), and a heat transfer adhesion layer (124) disposed between the package (125) and the light receiving part (123). The heat transfer adhesion layer (124) is formed in a region that is on the light receiving part (123) and includes a light path through which the luminous flux reflected by the optical disk (21) passes.

Abstract: To provide a polymer compound capable of forming an alignment film which has a sufficient aligning performance to a liquid crystalline compound and which is excellent also in adhesion with an optical anisotropic film obtainable by polymerizing a liquid crystalline compound in an aligned state, and a composition containing it, as well as an alignment film obtainable by using such a composition, an optical element and an optical information writing/reading device. Provided is a polymer compound comprising polymerized units derived from a fumaric acid diester and polymerized units having a radical polymerizable group in a side chain. By using this polymer compound, an alignment film is prepared. An optical element having this alignment film and an optical anisotropic film is used as a retardation plate 4 having mechanical strength and heat resistance, and good reliability without peeling. An optical information writing/reading device is constituted by using it.

Abstract: When ld0 denotes an initial optical path length that is a length of an optical path, along which the signal light travels, as converted using a refractive index in vacuum, lm0 denotes an initial optical path length that is a length of an optical path, along which the reference light travels, as converted using a refractive index in vacuum, ?l denotes a fluctuation width of a difference in optical path lengths between the signal light and the reference light as converted using a refractive index in vacuum, ?0 denotes a central oscillation wavelength of the wavelength-variable laser, and ?? denotes an oscillation wavelength variable range of the wavelength-variable laser, then an initial optical path difference |ld0?lm0| satisfies |ld0?lm0|>(?l/??)?0.

Abstract: Recording and reading method for optical information recording medium comprising: recording layer having thickness not less than 2?/n, where ? is wavelength of recording beam and n is refractive index of the recording layer, and configured to undergo a change in the refractive index by irradiation with the recording beam; and adjacent layer adjacent to the recording layer at a side opposite to an incident side, comprises the steps of: recording a recording spot by irradiating with the recording beam, while shifting focal position by offset amount d, which satisfies ?0d3?0, where ?0 is radius of the recording spot, from interface between recording layer and adjacent layer toward the incident side at a time of recording, whereby the refractive index of recording layer changes at a recording position to record recording spot; and reading out the information by irradiating with reading beam, while bringing it into focus on the interface.

Abstract: An optical information recording and reproducing apparatus includes an irradiation unit of a signal light beam and a reference light beam required for data recording, and a cure irradiation unit having at least one of a pre-cure irradiation that irradiates a predetermined light beam on to a desired position prior to irradiating the reference light bean and the signal light beam on to the desired position when information is recorded in the desired position on an optical information recording medium and a post-cure irradiation that irradiates a predetermined light beam on to the desired position so as to make the desired position non-recordable after the information is recorded in the desired position on the recording medium. The cure irradiation unit is disposed in one driving device in a freely movable manner in the driving device.

Abstract: An optical pickup device imparts different astigmatisms from each other to light fluxes in four light flux areas A through D formed around an optical axis of laser light, out of the laser light reflected on a disc. The optical pickup device also changes the propagating directions of the light fluxes in the light flux areas A through D to separate the light fluxes in the light flux areas A through D from each other. A signal light area where only signal light exists is defined on a detection surface of a photodetector. Sensing portions are arranged at a position corresponding to the signal light area. Accordingly, only the signal light is received by the sensing portions, thereby suppressing deterioration of a detection signal resulting from stray light.

Abstract: A holder has walls defining a holding region for holding an optical element, and has a protrusion part overlapping the holding region. The protrusion part is formed at a deformable support part, and can be displaced in a direction away from the holding region by deformation of the support part. When the optical element is fitted into the holding region, the support part deforms and the protrusion part runs on a side surface of the optical element. In this state, the optical element is pressed until a back surface of the optical element abuts a support surface of the holder. The optical element is pressed against the wall and positioned by a return force of the support part.

Abstract: Provided is an optical pickup device which suppresses the decrease of light amount and performs conversion to circular polarization light, wherein the optical pickup device includes a beam splitter and a raising mirror on each of which a layered member is formed, and the optical pickup device satisfies conditional expressions relating to intensities of S-polarized light and P-polarized light with respect to the beam splitter of a laser beam emitted from a semiconductor laser element, reflectances of S-polarized light and P-polarized light on the beam splitter, a reflection phase difference obtained by subtracting a phase of S-polarized light from a phase of P-polarized light after the reflection, reflectances of S-polarized light and P-polarized light on the raising mirror, and a reflection phase difference obtained by subtracting a phase of S-polarized light from a phase of P-polarized light after the reflection.

Abstract: An exemplary optical pickup comprises: first, second and third photosensitive elements which are arranged to respectively receive a main light beam and first and second sub-light beams reflected from an optical storage medium; and fourth and fifth photosensitive elements which are arranged to receive the rest of the light that has also been emitted from a light source but has not been reflected from the optical storage medium. A signal that has been written on the optical storage medium with the main light beam for writing is read by performing an arithmetic operation on the signal output of the second or third photosensitive element and that of the fourth photosensitive element.

Abstract: To record information as an array of optically changed portions arranged along a track in an optical storage medium, a pulsed laser beam is emitted toward the optical storage medium while causing at least one of the optical storage medium and the pulsed laser beam to be moved relative to each other. A plurality of pulses of the pulsed laser beam are emitted during a time span in which one segment of the track having a length corresponding to a length of one optically changed portion is scanned with the pulsed laser beam. An intensity of light with which a segment of the track is to be illuminated to form each individual optically changed portion is adjusted by causing a shutter to selectively reduce the number of pulses of the pulsed laser beam with which the segment of the track is to be illuminated.

Abstract: An optical head 200 comprises: a light source 101 that emits a light beam; an objective lens 105 that condenses, in the form of converging light, the light beam emitted by the light source 101, onto an information recording medium; a cylindrical lens 115 onto which a reflected light beam that is reflected by the information recording medium is incident, and which generates astigmatism for forming a focus error signal; a light detector 120 that receives the reflected light beam passing through the cylindrical lens 115; and a holder 130 that holds the cylindrical lens 115 and the light detector 120. The holder 130 has a first main face and a second main face that extend in directions that intersect the optical axis of the reflected light beam. The cylindrical lens 115 is bonded to the first main face and the light detector 120 is bonded to the second main face.

Abstract: An optical disc apparatus records information onto plural disc shaped mediums of different standards or reproduces information from the plural disc shaped mediums. The optical disc apparatus includes an optical pickup equipped with a spherical aberration correcting unit using a movable lens, and a disc insertion unit for inserting and ejecting the disc shaped mediums. The spherical aberration correcting unit starts the movement of the movable lens to an initial position while the disc insertion unit inserts or ejects the disc shaped medium. As such, the present invention discloses the optical disc apparatus with a reduced disc recognition time for improving user convenience and a driving method thereof.

Abstract: An optical read/write apparatus as an embodiment of the present invention includes: a light-splitting element configured to split a light beam emitted from a light source into multiple light beams including a write beam and a read beam; an optical system configured to converge the write and read beams onto the same track on an optical storage medium; a photodetector including a light receiving element configured to detect the read beam reflected from the optical storage medium and output an electrical signal; and a divider configured to generate a read signal by dividing the signal detected by the light receiving element by a signal that represents a write modulated component and that is obtained by detecting a part of the light beam emitted from the light source.

Abstract: An optical pickup, photodetector, and optical drive adopting the optical pickup are provided. The optical pickup may include a light emitting system having a plurality of light sources corresponding to a plurality of mediums a light receiving system including a photodetector for converting light reflected from a medium into an electrical signal. The photodetector may include first and second light receiving sensors corresponding to the plurality of mediums, each of the first and second light receiving sensors comprising a plurality of regions, each region comprising a plurality of sectors. The plurality of regions of the first and second light receiving sensors may include shared sectors that are shared by the first and second light receiving sensors and exclusive sectors that are exclusively used in the first light receiving sensor or the second light receiving sensor.

Abstract: An optical pickup includes a light source emitting a light beam, a diffraction element diffracting the light beam to separate it into a main beam and a sub beam, an objective lens focusing the main and sub beams onto a desired recording layer of an optical disc, a lens moving section moving the objective lens in focusing and tracking directions, a light-separating element separating a reflected light beam, formed by reflecting each of the main and sub beams at the recording layer, into multiple beam components and allowing the reflected light beam to travel without rotating an image thereof, and a light-receiving element having multiple light-receiving regions that optically receive the reflected light beam and generating a light reception signal based on the amount of received light to allow a signal processing section to generate a focus error signal and a tracking error signal based on the light reception signal.

Abstract: An objective lens for an optical pickup device is provided with a light-source-side lens surface by which laser light is converged, and a disc-side lens surface by which the laser light converged by the light-source-side lens surface is converged. The first lens surface and the second lens surface are configured to guide a part of a light collecting portion of the laser light reflected on the second lens surface to a position on an outside of the first lens surface.

Abstract: The invention relates to three-dimensional optical memory devices and can be used in all areas of computing in which it is necessary to record large data files on compact carriers, and also for recording, erasing and reading video data, for example, in independent video viewing systems. The device comprises an optical disc positioning system, a source of radiation with two different wavelengths that is optically coupled to a focusing system, focusing system positioning means, and an optical sensor that is optically coupled to the focusing system via a spectrum splitter and an controlled spectrum selector placed between the source of radiation with two different wavelengths and the spectrum splitter, wherein the focusing system is designed with longitudinal chromatic aberration at the given wavelengths.

Abstract: An objective lens for an optical pickup device is provided with a light-source-side lens surface by which laser light is converged, and a disc-side lens surface by which the laser light converged on the light-source-side lens surface is converged. In this arrangement, assuming that a projection area S1 is an area of the light-source-side lens surface when the light-source-side lens surface is viewed from an optical axis direction of the objective lens, and a projection area S2 is an area of the disc-side lens surface lens surface when the disc-side lens surface lens surface is viewed from the optical axis direction of the objective lens, the projection area S1 and the projection area S2 satisfy the following formula: S1/S2?2.0.

Abstract: An optical pickup device has an astigmatism element which imparts astigmatism to reflected light of laser light reflected on a recording layer, and a spectral element into which the reflected light is entered, and which separates the reflected light. The spectral element is divided into four third areas by a first area having a certain width and formed along a straight line in parallel to a first direction, and by a second area having a certain width and formed along a straight line in parallel to a second direction. The spectral element is configured to guide the reflected light passing through the four third areas to respective corresponding sensors on a photodetector while making propagating directions of the reflected light different from each other, and to avoid guiding the reflected light entered into the first area and into the second area to the sensors.

Abstract: An optical pickup device includes a first optical system and a second optical system. The first optical system and the second optical system each include a mirror member that reflects light from a light source to change a direction of propagation of the light to a direction substantially perpendicular to the information storage surface of an optical disc. The first optical system and the second optical system are arranged such that a direction in which light from a first light source enters a first mirror member is substantially perpendicular to a direction in which light from a second light source enters a second mirror member.

Abstract: An optical phase controller includes an optical phase control element so that a phase of incident light applied to the optical phase control element is controlled. The optical phase control element includes a metal structure having anisotropy in a first direction and a second direction perpendicular to the first direction within an electric-field vibration plane of the incident light, the wavelength of the incident light includes a plasmon resonance wavelength possessed by the metal structure, and the incident light is linearly polarized light or elliptically polarized light simultaneously having polarized components in the first direction and the second direction perpendicular to the first direction.

Abstract: An optical information recording/reproducing optical system, comprising a light source; an optical element converting a laser beam into a substantially collimated beam; and an objective lens, wherein a wavelength ? (unit: nm) of the laser beam falls within a range of 400<?<410, the optical element and the objective lens are made of same resin materials or different resin materials having a glass transition temperature of Tg>115° C., each of optical surfaces is configured not to have an optical thin film which contains at least one of or elements of titanium, tantalum, hafnium, zirconium, niobium, molybdenum and chromium, each of optical surfaces of the optical element is provided with an antireflection film made of one of or a mixture of at least two of silicon oxide, aluminum oxide, aluminum fluoride and magnesium fluoride, and a following condition is satisfied ? i = 1 n - 1 ? ( 1 - R ( BL ) ? i 100 ) - ? i = 1 n - 1 ? ( 1 - R ( UV ) ? i 100 ) > 0.

Abstract: An optical information recording/reproducing apparatus using holography comprises a signal generation unit that modulates input data, adds at least one control bit to each group of N bits, performs an NRZI-modulation on the modulated data, determines the at least one control bit such that a digital sum value of the NRZI-modulated data is 0, performs NRZI modulation on the data whose at least one control bit was determined, and rearranges the data to generate 2-dimensional data; a pickup that records the 2-dimensional data in a hologram disc and reproduces the 2-dimensional data from the hologram disc; and a signal processing unit that corrects the 2-dimensional data reproduced by the pickup, performs NRZI-modulation on the 2-dimensional data that has undergone a binarization operation, removes the at least one control bit added during the recording, and demodulates the data according to a modulation rule used during the recording.

Abstract: A polymerizable compound represented by the following formula (1): wherein A is a hydrogen atom or a group selected from the following formulae (2) to (5): VwH(3-W)C—??(2) PhxY(3-x)Si—??(3) J-(CH2)m1—CHl(CH3)(2-l)—??(4) J-(CH2)n1—SiPhp1(CH3)(2-p1)—??(5); B is a group selected from the following formulae (6) and (7): J-(CH2)m2—CHk(CH3)(2-k)—??(6) J-(CH2)n2—SiPhp2(CH3)(2-p2)—??(7).

Abstract: A lens includes a lens portion which condenses light; a reflecting flat portion which is formed in a periphery of the lens portion and reflects parallel light to be irradiated to the reflecting flat portion in a direction opposite to the irradiation direction; and a flange portion which is adhered to a lens holder by an adhesive. An applied portion of the adhesive which is formed on the flange portion is inclined with respect to the reflecting flat portion.

Abstract: A spectral element separates first laser light in such a manner that an area including only signal light as reflected first laser light is formed on a photodetector. The photodetector is provided with a first sensor group which is disposed at an irradiation position of signal light of the separated first laser light, and a second sensor group which receives zero-th order diffraction light of a main beam and two sub beams of second laser light that has been transmitted through the spectral element. The second sensor group includes a four-divided sensor which receives the main beam. The four-divided sensor is disposed in an area surrounded by the first sensor group. Zero-th order diffraction light of the first laser light that has been transmitted through the spectral element is irradiated onto the four-divided sensor.

Abstract: An objective lens unit according to the present invention includes a first objective lens 41; and a first lens holder 2 for supporting the first objective lens 41. The first lens holder 2 is formed of a material which transmits ultraviolet. Preferably, the first lens holder 2 includes a through-hole, having first and second openings 2a and 2b, through which light incident on the first objective lens 41 passes, and an opening limiting section 3 provided along a circumferential direction of the through-hole and projecting toward a central axis of the through-hole. The first objective lens 41 is supported so as to block the first opening 2b. The opening limiting section 3 guides light incident thereon from the second opening 2a in a direction away from an optical axis of the first objective lens.

Abstract: An objective lens for an optical information recording/reproducing optical system for an optical disc letting a laser beam impinge on a recording layer of the optical disc, and wherein a center wavelength ? (unit: nm) of the laser beam is in a range defined by a condition: 390???420, a base material of the objective lens is made of resin, the resin has a glass transition temperature Tg and light transmissivity T (unit: %) per a path length of 3 mm at a wavelength of 406 nm defined by conditions: Tg?115° C., 85?T?90, same antireflection films or different types of antireflection films are respectively formed on optical surfaces of the objective lens, and each of the antireflection films formed on the objective lens has a thickness of 100 nm or more in a vicinity of an optical axis of the objective lens.

Abstract: The present invention relates to an aberration correcting device comprising: an aberration correcting element which modulates the phase of incident light; and a position adjusting section which can move the aberration correcting element in a direction perpendicular to an optical axis of the incident light, wherein the aberration correcting element includes first and second aberration correction plates, each of which is disposed such that the phase of transmitted light beam differs with transmission position of the incident light beam with the same phase, and the aberration correcting element has a reference arrangement which is an arrangement of the first and second aberration correction plates in which the light beams transmitted through the aberration correcting element have the same phase, and assuming that a point on the first aberration correction plate crossing the optical axis is a point Oa and a point on the second aberration correction plate crossing the optical axis is a point Ob in the reference ar

Abstract: The relation between the cover layer thickness of a data recording surface and ratio ? of SCO to SCD is previously calculated and stored in a storage unit, where SCD denotes coma aberration which occurs when the data recording medium is tilted by unit angle and SCO denotes coma aberration which occurs when the objective lens is tilted by unit angle. When ?1 denotes ratio ? for a data recording surface corresponding to the smallest cover layer thickness, tilting angle ?1 of the objective lens is determined based on the ?1 and a tilt adjustment of the objective lens is made. Also, when ?2 denotes ratio ? for a target data recording surface, tilting angle ?2 of the objective lens is estimated based on the ratio of ?2 to ?1 and a tilt correction of the objective lens is made.

Abstract: Provided is an optical pickup including: a light-source emitting a light-beam; an objective lens collecting the light-beam on a desired recording layer among one or two recording layers or more installed in an optical disc and where spirally- or concentrically-shaped tracks are formed; a lens-moving unit moving the objective lens in a tracking direction toward at least an inner-circumference or outer-circumference side; a light splitting device splitting a reflected light-beam into reflected light-beams and propagating the light-beams; a light-detecting device generating central, inner-circumference-side, and outer-circumference-side light-detecting signals according to received light amounts thereof by central, inner-circumference-side, and outer-circumference-side light-detecting areas, receiving central, inner-circumference-side, and outer-circumference-side portions of an image of the reflected light-beam in the radial direction and allowing a signal processing unit to generate a tracking error signal by

Abstract: A recording/reproducing apparatus includes an optical source and a near-field light generating unit. The near-field light generating unit includes two conductors facing to each other at a predetermined distance and generating near-field light between the two conductors by irradiation of light from the optical source. These two conductors are arranged so that a direction along which the two conductors face to each other is substantially in parallel with the longitudinal direction of a recording mark region. Here, the recording mark region is prepared from a predetermined recording material and having shape anisotropy when information is recorded on a recording medium on which the recording mark is independently formed.

Abstract: An optical disc drive according to the present invention includes: a laser light source 2 for emitting a laser beam; a photodetector 10 for detecting a signal that has been supplied from an optical disc 100; and an optical system 200 for irradiating the optical disc 100 with the laser beam and guiding the light reflected from the optical disc 11 to the photodetector 10. The drive further includes a memory 300 for storing information defining a relation between the output value of the photodetector 10 and the output power of the laser light source 2 when the laser light source 2 is emitting the laser beam but the light reflected from the optical disc 100 fails to reach the photodetector 10; and a control section 400 for controlling the output power of the laser light source 2 based on the information stored in the memory 300 and the output of the photodetector 10 when the laser light source 2 is emitting the laser beam but the light reflected from the optical disc fails to reach the photodetector 10.

Abstract: A recording medium includes at least one recording layer on which information is recorded by multi-photon absorption, and a servo layer disposed in a laminated direction with respect to the recording layer and having a track for guiding a beam spot of laser light having a first wavelength and a beam spot of laser light having a second wavelength along a scanning trajectory. The servo layer and the at least one recording layer constitute a set of layers, and a plurality of sets of layers is formed in the laminated direction. The servo layer is made of a material having a high reflectance with respect to laser light having a third wavelength for generating a servo signal, and low reflectances with respect to the laser light having the first wavelength and the laser light having the second wavelength.

Abstract: A device is disclosed herein which may comprise a chamber, a source providing a stream of target material droplets delivering target material to an irradiation region in the chamber along a path between a target material release point and the irradiation region, a gas flow in the chamber, at least a portion of the gas flowing in a direction toward the droplet stream, a system producing a laser beam irradiating droplets at the irradiation region to generate a plasma producing EUV radiation, and a shroud positioned along a portion of said stream, said shroud having a first shroud portion shielding droplets from said flow and an opposed open portion.

Abstract: There is provided an optical disc drive, which includes a light source emitting a light beam, a beam dividing element that divides the light beam into main and sub-beams, an objective lens, an astigmatism producing unit that gives astigmatism to the main and sub-beams, a signal generation unit that has sensors for the beams and generates a focus error signal based on output signals of the sensors; and an optical element that has a function of adjusting intensity distribution of the main beam such that the main beam incident on the optical disc has a predetermined intensity distribution where a maximum intensity level is positioned at a predetermined height within a range of 70% of a pupil diameter, the predetermined height is not equal to an optical axis, and an intensity of the main beam decreases gradually from the predetermined height to a peripheral portion of the pupil.

Abstract: An optical pickup apparatus comprising a first laser unit including a first laser light source and a second laser unit including second and third laser light sources, being respectively disposed on a reflection (transmitting) surface side and a transmitting (reflection) surface side of a first beam splitter, laser lights of the first, second, and third wavelengths being guided onto a common optical path through the first beam splitter and guided to the respective sorts of optical recording mediums, each of the laser lights being divided by a diffraction grating disposed on the common optical path into a main beam and sub-beams, a second beam splitter being disposed on the upstream side of the diffraction grating on a return path of each of the laser lights, the laser lights through the second beam splitter being branched from the common optical path and being received by a photodetector.

Abstract: An optical pickup device includes a semiconductor laser which emits a light beam, first and second objective lenses which focus the light beam onto a first and second optical disc, respectively, a grating which branches a light beam reflected from the second optical disc, an optical detector having a plurality of light receiving parts, which receives light beams branched by the grating, and an actuator which displaces the first and second objective lenses in a radial direction of the first optical disc and the second optical disc. The grating has a first area on which a 0-order diffraction light beam and a +1-order diffraction light beam upon reflection at the second optical disc enter, and a second area on which a 0-order diffraction light beam and a ?1-order diffraction light beam upon diffraction through the second optical disc enter.

Abstract: A light beam emitted from a laser source is divided into a first light beam and a second light beam. An optical divider is further provided to separate a combined light beam of the first and second light beams into a first light bundle near the optical axis and a second light bundle in the edge portion and to diverge the first and second light bundles so that the first and second light bundles are individually detected by plural detectors. The first light beam is signal light focused on an optical information recording medium by an objective lens and reflected off the medium, and the second light beam is reference light not focused on the optical information recording medium. A focus error signal is then detected for the first light bundle for compensating focus error.

Abstract: To provide an optical pickup and an optical information device, capable of obtaining excellent signal characteristics for an optical disk on and/or from which recording and/or reproducing are performed using a laser. The optical pickup includes an optical detector, a support holder for holding the optical detector, and an optical base for fixing the support holder. The support holder has at least two notches at its both ends, the optical base has convex portions corresponding to the notches of the support holder, the optical base and the support holder are fixed by photo-curable adhesives for bonding the convex portions and the support holder to each other, and the shortest distance between the side faces of the convex portions, which do not face each other, is equal to or less than the width of the support holder in the direction of right and left ends.

Abstract: An optical unit is provided with a light source; a light dividing means for dividing light emerging from the light source into a first light and a second light; a light converging means for converging the first and second lights at the same position in the recording layer in the manner that they face each other; a polarization state switching means for switching the polarization states of the first and second lights at the convergence point in the recording layer; and a light irradiation state switching means for switching between the state in which the optical cording medium is irradiated with both the first light and the second light and the state in which the optical recording medium is irradiated with only one of the first and second lights.

Abstract: An optical pickup device includes: a first light source for emitting recording laser light; a second light source for emitting reproducing laser light having a wavelength different from a wavelength of the recording laser light; an objective lens for converging the recording laser light and the reproducing laser light. A quarter wavelength plate is disposed between the first light source and the second light source, and the objective lens. A wavelength-selective polarized beam splitter is disposed between the quarter wavelength plate, and the first light source and the second light source. The reproducing laser light alone out of the recording laser light and the reproducing laser light reflected on recording medium is guided to a photodetector.

Abstract: Provides an objective lens, an optical head and an optical disc apparatus (drive) capable of compensating for various types of aberrations including wavelength changes for a plurality of types of optical discs including high density optical discs, DVDs and CDs with a good wavelength dispersion compensation ability and thus capable of providing good recording or reproduction characteristics. The objective lens according to the present invention includes a first lens and a second lens substantially in close contact with each other such that optical axes thereof match each other, and acts as a convex lens as a whole. Each lens includes a central portion including the optical axis and a peripheral portion located in a periphery of the central portion. The central portion of the first lens acts as a convex lens; and the central portion of the second lens acts as a concave lens. Where the refractive index of the first lens at d line (wavelength: 587.

Abstract: Provided is a method for forming a near-field light generating element, which is capable of sufficiently suppressing the unevenness of a waveguide surface and the distortion within the waveguide. The forming method comprises the steps of: forming a first etching stopper layer on a lower waveguide layer; forming a second etching stopper layer; forming, on the second etching stopper layer, a plasmon antenna material layer; performing etching with the second etching stopper layer used as a stopper, to form a first side surface of plasmon antenna; forming a side-surface protecting mask so as to cover the first side surface; and performing etching with the first and second etching stopper layers used as stoppers, to form the second side surface. By providing the first and second etching stopper layer, over-etching can be prevented even when each etching process takes enough etch time, which allows easy management of etching endpoints.

Abstract: An object of the invention is to provide an optical element for use in an optical information recording and reproducing device or a like device for recording or reproducing information with respect to an information recording medium using laser light, wherein the optical element is a resin optical element capable of suppressing lowering in transmittance due to deterioration by irradiation of light having a high energy density, and maintaining a high transmittance for a long time. To realize the above object, used is an optical element made of a silicon resin cured material obtained by subjecting a silicon resin composition containing a silsesquioxane compound to a curing treatment.

Abstract: When information is recorded or reproduced on or from an optical information medium having three or more recording layers using blue light, interference by another layer light is reduced and, when information is reproduced from an optical information medium using red light, an S/N ratio is held excellently high.

Abstract: An optical disc device is provided with an optical head including a light source, a condensing optical system including an objective lens for receiving a light beam emitted from the light source and forming a microspot on a multilayer optical recording medium, a photodetector for receiving the light beam reflected by the multilayer optical recording medium and outputting an electrical signal corresponding to the amount of light and a coma aberration correcting element for correcting a coma aberration of the condensing optical system, and a processing circuit for controlling the condensing optical system and the coma aberration correcting element.

Abstract: There is provided an optical member 1 in which a fixation member 3 supporting the light emitting member 2 is fixed to a housing 5 supporting a light receiving member 4, so as to have clearances between the fixation member 3 and the housing 5, by photocurable resin 6 bridging the clearances, recesses 7 that adjoin positions where the photocurable resin 6 is deposited, that are opened so as to allow casting of light into the recesses 7, and that are to receive portions of the photocurable resin 6 are formed on the housing 5.

Abstract: An aspheric lens includes at least one aspheric lens surface, and an angle of inclination on the aspheric lens surface is smaller than or equal to 65°. The aspheric lens surface is given by the equation Z ? ( r ) = cr 2 1 + 1 - ( 1 + K ) ? c 2 ? r 2 + Lr 2 + Ar 4 + Br 6 + Cr 8 + Dr 10 + Er 12 + Fr 14 + Gr 16 + Hr 18 + Jr 20 where L?0, c is a curvature, r2=x2+y2, K is a conic integer, and L and A through J are aspheric coefficients.