Abstract: An optical pickup apparatus for reading and recording information on recording media includes a semiconductor laser, a collimating lens, a half mirror, a reflecting mirror, and an objective lens. Further included therein are a super-resolution cutoff filter and an aperture control filter, one of which is appropriately selected and set right before the objective lens by a filter switching-over device. When reading the DVD, the super-resolution cutoff filter is set at the optical path, whereas when reading the CD, the aperture control filter is set thereat. The filter switching device is arranged separately from an actuator driving system having the objective lens integrally structured therewith.

Abstract: An optical-pickup slider is characterized in that a light-transmitting-property substrate is bonded to a surface of a layer having a tapered through hole, on which surface a larger opening of the tapered through hole exists. Thereby, it is possible to prevent the layer having an aperture from being destroyed. A method of manufacturing the optical-pickup slider comprises the steps of a) making a tapered through hole in a layer layered on a first substrate and having a thickness smaller than that of the first substrate; and, after bonding a light-transmitting-property substrate to a surface of the layer, removing the first substrate so as to expose an aperture at a tip of the tapered through hole.

Abstract: An auto-focus system for a DVD reader or other optical access unit which reads and/or writes information from/to at least two information layers on an optical storage medium such as a DVD or DVR. The auto-focus system includes an astigmatic lens. A confocal aperture is placed at the first focal line image generated by the astigmatic lens from light rays reflected from the addressed information layer. The placement of the confocal aperture allows extraneous out-of-focus light rays reflected from non-addressed information layers to be blocked from reaching the photo detector array which then creates a focus error signal (FES). The FES drives a servo assembly connected to an access head of the optical access unit, bringing the access head into focus. In some embodiments, the confocal aperture is “bow-tie” shaped, allowing for simplified assembly and easing in-plane rotational alignment.

Abstract: The present invention is capable of selectively reproducing an information signal from an optical disk with any of a plurality of types having different track pitches of recording tracks, that is, capable of selectively reproducing an information signal from an optical disk having a low or high recording density by determining the type of the optical disk, that is, determining whether a mounted optical disk is a low-recording-density optical disk or a high-recording-density optical disk. The present invention deliberately generates aberration in an optical beam by controlling a voltage applied to a liquid-crystal device in order to vary the diameter of the optical beam in accordance with the determined type of the optical disk.

Abstract: An optical element is provided in which in a lens surface substantially perpendicular to the optical axis of the lens, there is embedded a conductive member whose diameter or width is smaller than the diameter of an optical spot incident upon the lens surface. The optical element is used in an optical head which reads a signal by illuminating an optical recording medium with a reading light. The basic principle of this optical head is such that a subtle phase change of the light is detected which is caused by the electromagnetic interaction between the conductive member embedded in the optical element and a conductive material on the surface of the optical recording medium. For example, the interference between return light beams from the optical recording medium is used to read a signal.

Abstract: There is provided an optical reproduction apparatus and an optical recording and reproduction apparatus which can improve a CNR and can read at high speed. The center portion of a laser light emitted from a semiconductor laser is shaded by a light shading portion of a first light shade, and its peripheral portion is condensed and irradiates a super-resolution film of an optical disk. The center portion of a reflected light from the optical disk is mainly made of a signal component, and a noise component almost disappears. Thus, the reflected light from the optical disk is separated into the center portion and its peripheral portion, and the reflected light made of the signal component of the center portion is used for signal reproduction, so that the CNR can be increased.

Abstract: In a recording apparatus for reproducing information recorded on a recording medium by utilizing near-field light, the recording apparatus realizes reliable information reproduction with a simple structure. Illumination light 20 is illuminated to the recording medium 10 to create near-field light on a surface of the recording medium 10. The created near-field light is scattered by a microscopic aperture 12 formed in the aperture element 11 so that scattering light (propagation light) thereof is detected to create a reproduced signal. Derived from the created reproduced light a distance control signal representative of a distance between the microscopic aperture 12 and the recording medium 10. Based on the distance control signal, the aperture element 11 is controlled in position. Due to this, the microscopic aperture 12 is brought into proximity to the recording medium 10.

Abstract: An apparatus for reproducing information stored in an optical recording medium which comprises marks or pits which are arranged at a pitch less than ?/2NA, wherein ? is a wavelength of light used for reproduction and NA is an numerical aperture of an objective lens. The apparatus generally comprises a laser diode, a polarization beam splitter, an objective lens, beam splitters, a low-frequency light detecting system with a photodetector, a high-frequency light detecting system with a photodetector, and a signal processing circuit for combining detection signals from the photodetectors. In the high-frequency light detecting system, before a convergent lens, a shielding band is provided so as to shield the middle of a bundle of rays of reproduction light.

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: A phase device for providing a phase difference between an inner radius portion and an outer radius portion of a light beam which is emitted from a light source is provided in an optical path between the light source of an optical pickup apparatus and an objective lens. The light beam to which the phase difference has been provided is converged by the objective lens and irradiated to an optical disc. An interference of an inner radius portion and an outer radius portion of the returning light beam caused when the light beam is diffracted by the optical disc with ±1 primary diffracted light caused by the diffraction is suppressed. Therefore, an intensity fluctuation of the returning light beam caused by the interference is suppressed. A spherical aberration error showing a thickness error of the optical disc and a focusing error having a high linearity can be detected with high precision on the basis of the returning light.

Abstract: An optical storage device capable of at least reproducing information recorded on first and second optical storage media different in distance from a medium surface on which a light beam is incident to a recording surface and in operating wavelength. The optical storage device includes a first light emitting element for emitting a light beam having a first wavelength, a second light emitting element for emitting a light beam having a second wavelength, a first photodetector for detecting a reproduction signal from a light beam reflected on the first optical storage medium, a second photodetector for detecting a reproduction signal from a light beam reflected on the second optical storage medium, and a beam splitter for combining optical paths of the light beams emitted from the first and second light emitting elements.

Abstract: The invention relates to materials and devices including these materials having non-erasable optical data capability, as well as to methods of storing optical data and to apparatus for carrying out these functions. In particular there is provided a method of storage of non-erasable optical data comprising exposing data storage material of a three-dimensional optical data storage device to focussed electromagnetic radiation wherein the radiation is of a wavelength and power appropriate to generate micro-cavity formation within the data storage material and wherein the location of micro-cavities encodes for stored data; the data storage material comprising a polymer matrix and a photosensitive agent dispersed through the polymer matrix.

Abstract: A beam splitting apparatus generates, from incident light having a specific polarization, first and second split light that has the specific polarization.

Abstract: An aperture limiting element that has a wavelength selectivity is disclosed wherein an aperture that is an open space of a specified size formed in a substrate and, in an area outside the aperture and that surrounds the aperture, a light filter is provided wherein light of a specified wavelength &lgr;1 is transmitted straight through, and light of a wavelength &lgr;2 is prevented from passing straight through. Alternatively, the light filter may be provided with an inner first region that transmits light of first and second wavelengths &lgr;2 and &lgr;2, respectively, and does not transmit straight through light of a third wavelength &lgr;3, where &lgr;1<&lgr;2<&lgr;3; and in an area outside of the inner first region, there is constructed an outer second region that transmits light of the first wavelength &lgr;1, and does not transmit straight through light of the second and the third wavelengths &lgr;2 and &lgr;3.

Abstract: Disclosed are a light emitting module, an optical detecting module, an optical pickup apparatus formed by coupling the ultra-minimized light emitting module and the optical detecting module, and manufacturing methods thereof. To this end, ultra-minimization, a micro machining technique fit to a mass production, and a semiconductor device assembly manufacturing process are applied, thereby reducing a component cost and increasing uniformity of components.

Abstract: A high density optical disc that can be driven changeably with the existent optical disc by the same driving apparatus. On the recording surface of the optical disc, a light transmissive layer with a thickness of about 0.2 to 0.4 mm is formed. The recording face is accessed by allowing a light beam with a wavelength of 395 to 425 nm in a spot shape to be irradiated onto it. Also, the light beam is converged in a spot shape by an objective lens having the numerical aperture of about 0.62 to 0.68.

Abstract: An optical head device includes a laser beam emitting element having a rectangular type body frame in which a semiconductor laser chip is accommodated, a light-emitting element holder having a first holder member and a second holder member, and a base portion to which the light-emitting element holder is mounted. The first holder member and the second holder member are fixed to each other so as to respectively about within part of the laser beam emitting element from both sides to hold the laser beam emitting element.

Abstract: An optical pickup apparatus for reproducing information from an optical information recording medium or for recording information onto an optical information recording medium, is provided with a first light source for emitting first light flux having a first wavelength; a second light source for emitting second light flux having a second wavelength, the first wavelength being different from the second wavelength; a converging optical system having an optical axis and a diffractive portion, and a photo detector; wherein in case that the first light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the first light flux is greater than that of any other ordered diffracted ray of the first light flux, and in case that the second light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the second light flux is greater than that of any other ordered diffracted

Abstract: An optical element structure allowing an increased power density of aperture-transmitted light while suppressing increase in temperature is disclosed. A conductive film has a sub-wavelength aperture formed therein and a periodic surface topography formed thereon. A lens focuses light onto the periodic surface topography with a predetermined diameter. The predetermined diameter of incident light on the conductive film and a period of the periodic surface topography are determined so that a power ratio of aperture-transmitted light to the light beam is greater than that of aperture-transmitted light which would be obtained if no periodic surface topography is provided in the conductive film.

Abstract: An optical head apparatus is provided with a first laser element, a second laser element and a polarized beam splitter. The first laser element emits a laser beam having a first wavelength. The second laser element emits a laser beam having a second wavelength. The second wavelength may be equivalent to the first wavelength, alternatively, it may be different from the first wavelength. The polarized beam splitter enables the laser beams of the first and second laser elements to be simultaneously radiated to the recording layer of an optical disk. When information are recorded in the optical disk, the laser beams of the first and second laser elements are used at the same time. At least one of the laser elements emits a laser beam having such a wavelength as enables the recording layer of the optical disk to absorb the largest possible amount of energy.

Abstract: In a disk drive for compensating the tilt between a disk including a first identification information area shifted radially outward by a predetermined distance from the center of a track, and a second identification information area shifted radially inward by the same distance, and a head for forming a light spot on the disk, there are provided a unit for determining a sum signal of an output signal from a photodetector obtained when the light spot traces the first identification information area and an output signal obtained when the light spot traces the second identification information area, and a tilt control unit for using the sum signal as an index to control the relative tilt between the disk and the head so as to cause the index to approach an extreme value.

Abstract: A high density optical disc that can be driven changeably with the existent optical disc by the same driving apparatus. On the recording surface of the optical disc, a light transmissive layer with a thickness of about 0.2 to 0.4 mm is formed. The recording face is accessed by allowing a light beam with a wavelength of 395 to 425 nm in a spot shape to be irradiated onto it. Also, the light beam is converged in a spot shape by an objective lens having the numerical aperture of about 0.62 to 0.68.

Abstract: An optical pickup apparatus for reproducing information from an optical information recording medium or for recording information onto an optical information recording medium, is provided with a first light source for emitting first light flux having a first wavelength; a second light source for emitting second light flux having a second wavelength, the first wavelength being different from the second wavelength; a converging optical system having an optical axis and a diffractive portion, and a photo detector; wherein in case that the first light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the first light flux is greater than that of any other ordered diffracted ray of the first light flux, and in case that the second light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the second light flux is greater than that of any other ordered diffracted

Abstract: An optical pickup apparatus for reproducing information from an optical information recording medium or for recording information onto an optical information recording medium, is provided with a first light source for emitting first light flux having a first wavelength; a second light source for emitting second light flux having a second wavelength, the first wavelength being different from the second wavelength; a converging optical system having an optical axis and a diffractive portion, and a photo detector; wherein in case that the first light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the first light flux is greater than that of any other ordered diffracted ray of the first light flux, and in case that the second light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the second light flux is greater than that of any other ordered diffracted

Abstract: There is disclosed a near-field optical head having an microscopic aperture whose size can be varied. The optical head comprises a substrate of silicon. A hole in the form of an inverted cone is formed in the substrate. The top portion of this hole forms the microscopic aperture. A support portion for supporting an actuator is formed on the substrate. The actuator holds a light-blocking film in such a way that the light-blocking film stays in the hole and that the bottom surface of the light-blocking film is flush with the bottom surface of the microscopic aperture. The light-blocking film is moved by the actuator to change the aperture to desired size.

Abstract: In a magnetic recording medium to detect tracking error signals optically where an optical head and a magnetic head scan different tracks, two signals having phases different by &pgr;/2 are generated and added or subtracted. By changing the amplitude of the two signals with a changeable gain amplifying means, a phase of a tracking error signal is changed so that the servo operation is conducted at the middle of the amplitude of the tracking error signal to keep the magnetic head on track.

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.

Abstract: The present invention is directed to the provision of an optical device that can easily eliminate only side lobes or side lobe components from a super-resolution optical spot.

Abstract: In a recording apparatus for reproducing information recorded on a recording medium by utilizing near-field light, the recording apparatus realizes reliable information reproduction with a simple structure. Illumination light 20 is illuminated to the recording medium 10 to create near-field light on a surface of the recording medium 10. The created near-field light is scattered by a microscopic aperture 12 formed in the aperture element 11 so that scattering light (propagation light) thereof is detected to create a reproduced signal. Derived from the created reproduced light a distance control signal representative of a distance between the microscopic aperture 12 and the recording medium 10. Based on the distance control signal, the aperture element 11 is controlled in position. Due to this, the microscopic aperture 12 is brought into proximity to the recording medium 10.

Abstract: An optical scanning device comprising means for scanning optical record carriers of predetermined different formats, such as CDs and DVDs, using scanning at different numerical apertures provided by an optical diaphragm. The optical diaphragm comprises cholesteric liquid crystal material of one or more selected helical pitches which provide the diaphragm with desired wavelength- and/or polarization-selective characteristics.

Abstract: An optical-recording-medium playback apparatus includes a first optical member which focuses light emitted from a light-emitting unit on an optical recording medium, a second optical member which focuses light reflected by the optical recording medium, a light-receiving unit which receives the light focused by the second optical member, and a pinhole which is disposed between the second optical member and the light-receiving unit. The focal point of the light focused by the first optical member and that of the light focused by the second optical member correspond to each other. Accordingly, when the pinhole only transmits light which passes through positions around the focal point of the second optical member, stray light from positions around the focal point of the first optical member (in particular, light reflected by recording layers other than the one from which information is read out) can be removed.

Abstract: A laser beam emitted from a semiconductor laser enters an incident surface of a transparent condensing medium with a central part of the laser beam being shielded by a shading metal member, and a light spot is formed on a light-condensed surface of the transparent condensing medium. When this light spot is applied to a micro metal member, plasmon of the micro metal member is excited, and near field light leaks out therefrom. The near field light enters a recording medium of a disk as propagation light, and record into and reproduction from the recording medium is performed by this light. By shielding the central part of the laser beam, it is possible to prevent the propagation light from being generated from the light-condensed surface of the transparent condensing medium, and to prevent erroneous reproduction caused by the propagation light.

Abstract: An optical pickup includes: a first projector for projecting a first light beam of a first wavelength so as to record and reproduce information with respect to an optical disk having a first light transmissive layer; a second projector for projecting a second light beam of a second wavelength longer than the first wavelength so as to record and reproduce information with respect to an optical disk having a second light transmissive layer; an objective lens common to the first and second light beams; and a diffraction optical element made of a lens with a diffraction grating and a refracting face and disposed in an optical path between the first and second projectors and the objective lens. The diffraction optical element is set to satisfy a predetermined equation.

Abstract: An optical head which implements high recording density of a recording medium and which is miniaturized in size and improved in data transfer rate, a disk apparatus, and a method for manufacturing the optical head are provided. A laser beam is emitted from a semiconductor laser, the laser beam is collimated by the collimator lens to a collimated beam and reflected by a mirror, condensed by an condense lens, and incident to an incident surface of a transparent condensing medium. The condensed beam which was incident to the incident surface is refracted by the incident surface, the refracted beam is condensed on a condense surface, a beam spot is formed on the condense surface, and a near field wave leaks from a slit. The near field wave leaked from the slit propagates in a recording layer of a recording. The beam is served for recording/reproduction on the recording layer.

Abstract: An optical storage device capable of at least reproducing information recorded on first and second optical storage media different in distance from a medium surface on which a light beam is incident to a recording surface and in operating wavelength. The optical storage device includes a first light emitting element for emitting a light beam having a first wavelength, a second light emitting element for emitting a light beam having a second wavelength, a first photodetector for detecting a reproduction signal from a light beam reflected on the first optical storage medium, a second photodetector for detecting a reproduction signal from a light beam reflected on the second optical storage medium, and a beam splitter for combining optical paths of the light beams emitted from the first and second light emitting elements.

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 SIN (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 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 drive compatible with optical discs of different types, for example, is provided. For focusing, through an optical system used in common with the different types of optical discs, a laser beam emitted from a selected one of a plurality of light sources disposed apart from each other radially of the optical disc, the optical system is moved radially of the optical disc corresponding to the selection of the light source for emitting the laser light. Namely, it is possible to prevent the optical property from being deteriorated when a single optical pickup is used in common with such optical discs of different types.

Abstract: An optical head apparatus is provided with a first laser element, a second laser element and a polarized beam splitter. The first laser element emits a laser beam having a first wavelength. The second laser element emits a laser beam having a second wavelength. The second wavelength may be equivalent to the first wavelength, alternatively, it may be different from the first wavelength. The polarized beam splitter enables the laser beams of the first and second laser elements to be simultaneously radiated to the recording layer of an optical disk. When information are recorded in the optical disk, the laser beams of the first and second laser elements are used at the same time. At least one of the laser elements emits a laser beam having such a wavelength as enables the recording layer of the optical disk to absorb the largest possible amount of energy.

Abstract: An auto-focus system for a DVD reader or other optical access unit which reads and/or writes information from/to at least two information layers on an optical storage medium such as a DVD or DVR. The auto-focus system includes an astigmatic lens. A confocal aperture is placed at the first focal line image generated by the astigmatic lens from light rays reflected from the addressed information layer. The placement of the confocal aperture allows extraneous out-of-focus light rays reflected from non-addressed information layers to be blocked from reaching the photo detector array which then creates a focus error signal (FES). The FES drives a servo assembly connected to an access head of the optical access unit, bringing the access head into focus. In some embodiments, the confocal aperture is “bow-tie” shaped, allowing for simplified assembly and easing in-plane rotational alignment.

Abstract: An information recording and reproducing apparatus for at least one of recording and reproducing information on a recording medium utilizing near-field light has a suspension arm and a near-field light head mounted on the suspension arm. The near-field light head has a minute aperture, an optical waveguide for propagating light from a light source, and a reflection film for reflecting the light propagated by the optical waveguide and for irradiating the reflected light to the minute aperture to generate near-field light at the minute aperture for interaction with a recording medium. A light guiding structure guides light from the light source to the optical waveguide of the near-field light head.

Abstract: An optical pickup apparatus includes a wavelength selecting numeral aperture limiting element and a wavelength selecting beam splitter to record data on and reproduce data from three different optical discs, such as CD, DVD, and HD-DVD, each having different thickness of a protective layer and information recording density. The wavelength selecting numeral aperture limiting element of the optical pickup apparatus includes a first filter and a second filter disposed on respective sides of a transparent element to change a numeral aperture of an objective lens into three different numeral apertures in response to three different beams. The first filter disposed on an optical path to receive first, second, and third beams includes a first region transmitting the first laser beam and a second region disposed within the first region to transmit the first, second, and third laser beams.

Abstract: The optical pickup device according to the present invention includes a feed screw (22) to move an optical pickup (11) having an objective lens (14) provided thereon radially of an optical disc D, a sliding member (24) provided slidably in relation to the optical pickup, and connected to the optical pickup (11) by a coil spring (25) which forces a shutter (47) in a direction of unmasking the objective lens, and a transmission (51) which connects the feed screw and sliding member to each other. As the feed screw is rotated, the sliding member moves the optical pickup radially of the optical disc D, and when the optical pickup has arrived at a position at the lead-in side of the optical disc D, the sliding member is further slid against the force of the coil spring to mask the shutter with the objective lens.

Abstract: An adhesive is coated on at least one surface of a thin film of organic material having birefringent properties and a phase-difference producing function, and a fixing substrate having transmitting or reflecting properties is bonded to the thin film of organic material by the adhesive, wherein materials satisfying relations of E1<E2 and E3<E2 where E1 is the linear expansion coefficient of the thin film of organic material, E2 is the linear expansion coefficient of the adhesive and E3 is the linear expansion coefficient of the fixing substrate, and the glass transition temperature of the thin film of organic material being 150° or more, are selected.

Abstract: An optical pickup device has one or a plurality of aperture restriction devices that are disposed in the optical path of a light beam that is emitted from a light source and illuminated onto an optical disk. The aperture restriction device restricts the cross-sectional shape of the light beam corresponding to the aperture in the time axis direction in comparison to that corresponding to the aperture in the radial direction and restricts the light beam in the radial direction of the optical disk by a pair of first partial arcs.

Abstract: A recording medium and near-field optical probe utilizing near-field light to achieve high density of information recording and hence enhance resolution in reproducing.

Abstract: The present invention relates to an optical head, a magneto-optical head, and a disk apparatus, that have high light efficiency, can realize high-density recording medium and perform high-speed recording and reproduction, and can prevent erroneous record or erroneous reproduction, and a manufacturing method of the optical head. When a converged beam enters an incident surface of a transparent condensing medium, its refracted beam is condensed on a light-condensed surface and forms a light spot. Since leaking out to an aperture formed on an outer surface of the light-condensed surface of this light spot, near field light is scattered by a micro metal member. In addition, since, also in the micro metal member, plasmon resonance occurs by the irradiation of a laser beam, near field light leaks out therefrom. This near field light becomes propagation light and enters a recording medium of a disk, and recording into the recording medium is performed by this light.

Abstract: An apparatus and method for reproducing signals from a multi-layer structured recording object wherein a linearly polarized laser beam illuminate the multi-layer structured object, such as a phase change recording medium via an objective lens system having an effective numerical aperture greater than 0.6. A light beam reflective from the object is passed to a filtering mask disposed to receive the reflected light beam. The filtering mask includes a first area that has a first transmissivity and a second area having a second transmissivity different than the first transmissivity. The reflected laser beam passed through the filtering mask is detected to reproduce signals from the recording medium.

Abstract: An objective lens for recording and/or reproducing information of an optical information recording medium, is a single lens having an aspherical surface on at least one surface.

Abstract: The present invention relates to a device for reading from or writing to optical recording media, which device has a scanning beam generation means, a focusing means and a photodetector comprising at least two detector zones and serving to receive zeroth- and first-order diffraction beams from the recording medium. The object of the invention is to obtain a reduction in interfering influences in a signal derived from signals of the photodetector, a signal such as, for example, a focus error signal or a track error signal. This object is achieved by virtue of the fact that a beam splitting means is provided, which splits a light spot falling onto the photodetector into two separate partial spots. The device is, for example, a CD or DVD player, but in particular a recording and reproduction device for so-called DVD-RAMs or similar optical recording media.