Abstract: A tracking error signal generation apparatus and method which utilizes confocal detection with a split detector and a differencing circuit for generation of tracking error signals. A first lens is positioned in the path of a light beam returning from an optical medium. A pinhole is positioned in the path of the light beam after the first lens and proximate to the focal plane of the first lens. A second lens is positioned in the path of the light beam after the pinhole, and a split detector, having equal halves is positioned in the path of the light beam after the second lens. A differencing circuit is operatively coupled to each of the halves of the split detector. In operation, a light beam is focused by an optical head onto a track in the optical medium, and the reflection of the beam from the optical medium is directed through the first lens, through the pinhole, through the second lens, and onto the split detector.

Abstract: It is an object of the present invention to provide an optical information storage device capable of performing stable information accessing at a high recording density, and an optical head, and the optical information storage device and the optical head of the present invention comprise: a light shielding body held in a position close to/in contact with a surface of a recording medium, and provided with a slit adapted to intersect a track of the recording medium by an angle &agr; of 45° or lower; condensing means for condensing a light emitted from a light source on the slit of the light shielding body; and moving means for moving the light S condensed on the slit by the condensing means along the slit.

Abstract: There is disclosed a compact optical information storage apparatus in which noise attributed to wobbling or the like is reduced and high-density recording is possible. An optical device 410 comprises a reflective surface 64 including a main portion for reflecting a signal light reflected by a separation surface 61 in a predetermined direction, and a mask portion 411 having an optical property different from the optical property of the main portion.

Abstract: An optical head includes a lens holder for carrying a biconvex lens and a plano-convex lens above a data storage disk. In data-writing or data-reading operation, the plano-convex lens comes closer to the storage disk than the biconvex lens. The plano-convex lens is accommodated in a through-hole formed in the lens holder. The lower opening of the through-hole is closed by a transparent plate attached to the bottom surface of the lens holder. The flat lens surface of the plano-convex lens is held in close contact with the transparent plate.

Abstract: In an optical pickup device for recording information onto and/or reading out information from an optical recording medium, comprising a light beam source for generating a light beam to be projected toward the optical recording medium, and a light beam detector for receiving the light beam reflected by the optical recording medium so that the information is read out from the light beam after reflected by the optical recording medium, a container houses therein the light beam source and includes an aperture through which the light beam proceeds toward the optical recording medium, and a light beam guide member is mounted on an outer surface of the container and covers the aperture to guide the light beam after reflected by the optical recording medium toward the light beam detector.

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 unit for scanning an optical disk includes a first optical branch including a first radiation source for emitting a first radiation beam of a first wavelength, and a dichroic mirror (8) located in the path of the first radiation beam for reflecting the first beam towards the disk, and a second optical branch including a second radiation source for emitting a second radiation beam of a second wavelength, different to said first wavelength, and a folding mirror (28) located in the path of the second radiation beam for reflecting the second beam towards the disk. The first and second branches are stacked in the axial direction of the disk, and are arranged substantially perpendicularly when viewed along the axial direction.

Abstract: An optical pickup device having a lead frame package and a detecting unit is provided. The lead frame package includes a sub-mount, a light source mounted on the sub-mount and emitting a beam, a reflecting element disposed to direct the beam toward an optical medium, a transmission-type diffraction gating element dividing the beam into three beams, and a hologram optical element diffracting the beams reflected from the optical medium, the lead frame package having an opening defined by the hologram optical element, the bottom of the lead frame package, and side walls of the lead frame package. The detecting unit having a substrate and a photo diode mounted on the substrate is disposed within the opening of the lead frame package. After the detecting unit is adjusted with respect to the lead frame package to a position to accurately receive the reflected beams from the hologram optical element, the detecting unit is fixed to the lead frame package.

Abstract: An exposure apparatus of an optical disk master having a laser source, a deflector for deflecting a recording laser beam obtained based on the laser beam of the laser source and an objective lens for focusing the recording laser beam on an optical disk master, has

Abstract: A magnetic disk unit which can provide a sufficient PD output of laser beams for optical tracking. The magnetic disk unit comprises a diffraction grating for splitting laser beams from a laser source into a plurality of beams; an aperture for narrowing a plurality of laser beams from the diffraction grating and light beams reflected from the recording medium; an objective lens for converging a plurality of laser beams, radiating the laser beams onto the recording medium, and guiding light beams reflected from the recording medium to the aperture; a beam splitter for splitting the reflected light beams having passed through the aperture; and a light receiver for receiving light beams split by the beam splitter. The objective lens is an objective lens telecentric to the image side.

Abstract: An optical head is composed of a light source means (1) for generating a luminous flux (A), a polarization beam splitter (2), an object lens (11) opposed to an appropriate recording medium (12), and a power monitoring means (6) for monitoring the power of the luminous flux (A) output from the light source means (1). The power monitoring means (6) is adapted to utilize a luminous flux (B) other than a luminous flux (C) of the luminous flux (A) (the whole amount of light) in order to monitor the power of the luminous flux (A) output from the light source means (1). The luminous flux (C) is substantially used for reproducing predetermined information from the recording medium (12) or recording the predetermined information onto the recording medium (12).

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 head includes a light source for generating a luminous flux, a polarization beam splitter, an object lens opposed to an appropriate recording medium, and a power monitoring device for monitoring the power of the luminous flux output from the light source. The power monitoring device is adapted to utilize a peripheral portion of the luminous flux. This peripheral portion of the luminous flux is distinct from the portion of the luminous flux that is used for reproducing predetermined information from the recording medium and recording the predetermined information onto the recording medium.

Abstract: The focus light spot of the returned light is divided in halves so as the returned light from the points on the line perpendicular to the recording track at the center of the reading focus light spot is divided in halves;

Abstract: An optical pickup apparatus for recording and/or reproducing information for an optical information recording medium having a plurality of information recording layers, comprising: a light source to emit a light flux; and a converging optical system to converge the light flux emitted from the light source onto each information recording layer of the plurality of information recording layers. The converging optical system converges a light flux having an image side-numerical aperture of 1.0 or more onto the each information recording layer so as to conduct recording and/or reproducing information for the each information recording layer.

Abstract: A storage media for storage of data thereon is provided. The storage media including: a first layer, the first layer being substantially transparent to a predetermined radiant energy used for reading the data; and a second layer formed on the first layer and being substantially opaque to the radiant energy, the second layer having a pattern comprising a plurality of holes, each of the holes having a largest dimension which is greater than a wavelength of the radiant energy, the data being stored as the presence or absence of a hole in the pattern. Also provided are a method for fabricating the storage media as well as an apparatus and method for reading the data stored on the storage media.

Abstract: An optical pickup apparatus that can adaptive for a plurality types of optical discs different in the layout condition such as a recording density, etc. and an optical recording/reproducing apparatus employing the optical pickup apparatus. In the optical pickup apparatus, first and second light sources generate a different wavelength of light beams. An optical system allows a light beam generated from any one of the first and second light sources to be selectively irradiated onto the optical disc and have an aperture number controller allowing the number of aperture of a light beam to have a different value. A photo detector detects the light beam reflected from the optical disc to be accessed to convert the same into an electrical signal. The apparatus is capable of accessing three types of optical discs different in the layout condition by utilizing an appropriate combination of a wavelength of the light beam with the number of aperture.

Abstract: An optical head comprises a photodetector 8 having divided photosensitive areas to detect light 13 reflected from an optical disk 7, means 10, 11, 12 for obtaining tracking error signal by operating signals from the photosensitive areas. The photodetector 8 has a first division line 9a parallel to an information track on the optical disk and second and third division lines 9b, 9c perpendicular to the first division line 9f and symmetrical to the optical axis. Further, a light-shielding area 8i is provided for shielding a part of the reflected light between the division lines 9b and 9c. The signals are operated to reduce offset of the tracking error signal due to a shift of object lens and a tilt of the optical disk. Accordingly, the optical head of the present invention has a small offset of tracking error signal with a simple structure.

Abstract: A multiple channel scanning device has a scanning head with multiple columns of apertures that emit light which is projected to a small spot on the surface of a recorded medium. Light returned from the medium reenters the apertures and is conducted to detectors. In a preferred embodiment, the scanning head is rapidly oscillated (may be on the order of 100 kHz rate), in a direction parallel to the columns. The medium is moved in a direction perpendicular to the columns so that the same recorded regions pass beneath successive columns of apertures. The data from the detectors is image-processed to improve the quality of data reading using the successive readings of the same data regions. This allows errors to be corrected and throughput to be improved.

Abstract: The present invention has for its object to provide a compact and simplified optical pickup device which secures sufficient quantity of converged light required for recording and reproducing onto/from respective optical disks, can obtain required imaging magnification of respective optical systems, and does not generate performance degradation at lens shift, when recording or reproduction is performed onto/from optical disks with different base material thickness by plural optical systems of a single optical pickup device.

Abstract: A device for reading from or writing to optical recording media comprising 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.

Abstract: It is an object of the present invention to provide an optical information storage device capable of performing stable information accessing at a high recording density, and an optical head, and the optical information storage device and the optical head of the present invention comprise: a light shielding body held in a position close to/in contact with a surface of a recording medium, and provided with a slit adapted to intersect a track of the recording medium by an angle a of 45° or lower; condensing means for condensing a light emitted from a light source on the slit of the light shielding body; and moving means for moving the light S condensed on the slit by the condensing means along the slit.

Abstract: An optical recording/reproducing apparatus includes an irradiation optical system for irradiating a light beam from a light source onto a predetermined track of an optical recording medium having a plurality of neighboring tracks as a fine light spot so as to perform recording/reproduction of information or reproduction of information, and a detection optical system for detecting a returned light beam from the optical recording medium. A mask is arranged in a far field region sufficiently separated from a focal plane of the detection optical system, for masking marginal rays, in a direction perpendicular to the track, of the returned light beam, so that information reproduced from a track adjacent to the predetermined track upon reproduction of information on the predetermined track is reduced.

Abstract: In the apparatus for recording and reproducing high-density information using a multi-functional probe, media is locally heated not only by near-field optics come out of an aperture and but also by current induced from an end of an conducting cantilever, to record information and thereby increase a recording speed. The apparatus and method for recording and reproducing the high-density information using the multi-functional probe includes a conducting cantilever, in which a cantilever stage and a near-field optical aperture probe are formed in one body, the media is locally heated not only by the near-field optics from a near-field optical aperture probe but also by the current induced from the probe to the media or induced from the probe itself, and then the information is recorded; and an optical detector for reproducing the recorded information with a reflectivity of light come out of the near-field optical aperture probe or a transmission onto the media.

Abstract: Disclosed is an optical data recording/reproducing device which is provided with a laser diode for emitting laser beam, an illuminating optical system including an objective lens which converges the laser beam emitted by the laser diode on an optical disc, a monitoring optical system including a light receiving element which receives a part of the laser beam emitted by the laser diode, and a driving circuit which drives the laser diode in accordance with an output signal of the light receiving element. A coupling efficiency of the illuminating optical system and a coupling efficiency of the monitoring optical system are made substantially the same.

Abstract: A preferred microprocessor module includes a first wafer incorporating a storage medium. The storage medium is provided with storage areas that are configurable in one of a plurality of structural states to represent information stored in the storage areas. A second wafer is arranged proximate the first wafer and includes electron beam emitters that are configured to electrically communicate with the storage medium. The storage medium and the emitters are configured to move relative to each other so that each emitter may provide a beam of electrons to at least one of the storage areas. Additionally, a third wafer is provided which includes logic circuitry configured to enable extraction of data from the storage areas of the storage medium and execution of instructions embodied within the data. Processor-based systems also are provided.

Abstract: The present invention relates to a device for the reading and/or writing of optical recording media [(AT)] of various structures, which device operates with a single objective lens [(OL)]. The invention proposes to use a diaphragm varying in diameter, in particular a polarizing filter arranged in the optical path in order to adapt the aperture to each type of optical recording medium [(AT)] used. The wavefront can be corrected using a divergent lens [(SL)] which can also be positioned in the beam path. The Diaphragm formed by the polarizing filter PF is linked to the objective lens [(OL)]. The field of application of the invention relates to, in particular, devices for reading and/or writing optical recording media [(AT)] of various structure such as compact discs and digital video discs.

Abstract: An optical pickup device shares an objective lens for two different light sources so as to handle two kinds of optical recording media, that is, a first optical recording medium and a second optical recording medium, the second optical recording medium having a thickness larger than a thickness of the first optical recording medium. A first light source emits a first beam having a first wavelength. A second light source emits a second beam having a second wavelength. An objective lens converges the first beam and projects the converged first beam onto the first optical recording medium. The objective lens also converges the second beam and projects the converged second beam onto the second optical recording medium. A second coupling lens changes the second beam to a beam which matches the objective lens.

Abstract: The optical information recording and reproducing apparatus comprises a light source for emitting a light beam, an objective lens for converging the light beam emitted from the light source to an information recording medium, and a light detector for detecting the light beam reflected from the information recording medium. The information bits are recorded into a recording member of the information recording medium in a three-dimensional arrangement by using a change in optical constant of the recording member. Furthermore, a thickness of the recording member is larger than a wavelength of the light beam and the information bits are sequentially recorded into the recording member 11b in a three-dimensional arrangement in such an order that a converging light beam from the objective lens does not pass through information bits that have already been recorded.

Abstract: In a method, a light emitting portion of a light spot forming device is formed. The light emitting portion has a minute opening, and a light collecting portion for collecting the light coming from a light source for light spot formation to the minute opening. A light emitting portion base film and a resist film are successively formed on the light collecting portion. A light intercepting mask and a light amount detecting device are arranged. The position of the light intercepting mask is adjusted such that the light from the light source is collected by the light collecting portion onto the base film, and is received by the light amount detecting device, and the amount of light detected by the device takes on the maximum value. The resist film is exposed with the light from a light source for exposure through the through-hole in the mask to form a through-hole for etching.

Abstract: An optical pickup device that is able to record/reproduce information signals for first and second optical discs with different recording capacities. The optical pickup device includes an objective lens for converging first and second light beams of different wavelengths on the signal recording layers of first and second optical discs having different substrate thicknesses, a beam splitter having the same transmittance to the first and second light beams and configured for separating the first and second light beams radiated by first and second light sources to fall on the beam splitter via a first objective lens or a second objective lens, and a hologram element arranged between the objective lens and the beam splitter for limiting the aperture of one of the first light beam and the second light beam and for correcting the spherical aberration caused by difference in the disc substrate thickness of the first and second optical discs.

Abstract: An optical pick-up device for use in an information recording/reproducing apparatus for recording and/or reproducing information on an optical record medium. The device comprises a semiconductor laser, an information record medium having plural record layers laminated thereon, an outward route system for irradiating laser light from the semiconductor laser onto the information record medium through a beam splitter and objective lens, and an inward route system having a light detector for receiving the light reflected from the information record medium and transmitted through the objective lens, the beam splitter and pin-hole. The pin-hole has a radius, which is decided in such a manner that an expression Vp=2&pgr;r/(&lgr;/NA) satisfies following condition 3≦Vp≧6, wherein r is radius of the pin-hole, NA is lens aperture of the detection system, &lgr; is wave length of the laser light, and Vp is radius of Airy disc.

Abstract: An optical recording/pickup head having compatibility with a recordable compact disk (CD-R) and a digital video disk (DVD) transmits a first light beam having a wavelength of 635 nm for a DVD emitted from a first light source and a second light beam having a wavelength of 780 nm for a CD-R emitted from a second light source to an objective lens, using a holographic variable aperture. The holographic variable aperture totally transmits the incident first light beam to the objective lens, and transmits part of the incident second light beam to the objective lens. The objective lens focuses the incident first and second light beams on the information recording surfaces of the CD-R and the DVD. The sizes of the light spots which are focussed on the information recording surfaces of the DVD and the CD-R by the objective lens are approximately 0.9 &mgr;m and 1.4 &mgr;m, respectively, which appropriate for recording and reproducing the respective disks. The light spots have only a main lobe.

Abstract: An optical head and an optical disk apparatus are disclosed which are small-sized, permitting the attainment of a high recording density. A laser beam emitted from a semiconductor laser is shaped into a collimated beam by a collimator lens, then is folded mirror at right angles by a folding mirror and enters a light converging type hologram. A collimated beam thus incident on the light converging type hologram is focused to form a light spot on a surface for focusing of a transparent light converging medium. The light thus focused as the light spot on the focusing surface passes through an aperture having a width smaller than the diameter of the light spot and leaks out as a near-field light to the exterior of the transparent light converging medium. A recording layer of an optical disk is irradiated with the near-field light to effect recording or reproduction of information.

Abstract: An optical head, able to reduce thermal stress generated in an optical lens mounted on a bobbin, having a bobbin formed with a center hole and an optical lens mounted on the bobbin via a thermal expansion adjustment member 40 formed with an opening. The optical lens has a substrate formed by an optical material different from the bobbin in coefficient of thermal expansion. The substrate has a convex part functioning as a convex lens and a flat part positioned around the convex part. The flat part is fixed to the thermal expansion adjustment member so that the convex part fits in the opening. The optical lens is placed so that a center axis of the convex part or an extension thereof passes through the center hole of the bobbin and the center axis of the convex part coincides with a center hole of the bobbin.

Abstract: This invention provides a multi-layer information medium wherein layer-specific information unique to the particular layer has been adequately recorded, and delay in the access to the recorded data associated with reading of the layer-specific information is suppressed. Such multi-layer information medium is also provided at low cost. The optical information medium has at least two information-storing layers each storing recorded information and/or tracking servo information, and at least one of the information-storing layers is a data layer storing recorded information, and at least one of said information-storing layers is recorded or read by the recording beam or the reading beam which has passed through other information-storing layer(s), and in this medium, the data layer has layer-specific information unique to the particular data layer recorded therein.

Abstract: An optical information disk with an excellent mechanical precision is provided. Also provided is a multi-layer optical disk having a plurality of data layers wherein every data layer exhibits sufficient properties in reading. In addition, such multi-layer optical disk is provided at a low cost. The optical information comprises a disk-shaped substrate or a pair of disk-shaped substrates, and at least one annular data layer for storing at least recorded information and at least one annular resin layer disposed on said disk-shaped substrate or between said pair of disk-shaped substrates. In this medium, at least one of the substrate(s) has a configuration such that its surface facing toward the data layer is convex, and at least one of said resin layer(s) is formed such that it is thicker near its outer periphery compared to the region near its inner periphery.

Abstract: An optical recording/reproducing apparatus includes an irradiation optical system for irradiating a light beam from a light source onto a predetermined track of an optical recording medium having a plurality of neighboring tracks as a fine light spot so as to perform recording/reproduction of information or reproduction of information, and a detection optical system for detecting a returned light beam from the optical recording medium. A mask is arranged in a far field region sufficiently separated from a focal plane of the detection optical system, for masking marginal rays, in a direction perpendicular to the track, of the returned light beam, so that information reproduced from a track adjacent to the predetermined track upon reproduction of information on the predetermined track is reduced.

Abstract: An optical pickup apparatus and method which can selectively perform optical pickup with respect to at least two types of optical disks, on which information recording surfaces are formed, having a different thickness. The optical pickup apparatus includes an optical path alteration unit for altering a path of a light beam so that the light beam emitted from each light source proceeds toward the disk, a numerical aperture adjustment unit, including an annular shielding region which is disposed concentrically about an optical path axis between the optical path alteration unit and the disk supporter, for providing different numerical apertures according to a characteristic of a light beam to be incident; and an objective lens for respectively focusing the light beams having passed through the numerical aperture adjustment unit on the information recording surfaces of the disks to form a beam spot. Accordingly, the apparatus provides a relatively simple structure thereby reducing fabricating cost.

Abstract: A multiple channel scanning device has a scanning head with multiple columns of apertures that emit light which is projected to a small spot on the surface of a recorded medium. Light returned from the medium reenters the apertures and is conducted to detectors. In a preferred embodiment, the scanning head is rapidly oscillated (may be on the order of 100 kHz rate), in a direction parallel to the columns. The medium is moved in a direction perpendicular to the columns so that the same recorded regions pass beneath successive columns of apertures. The data from the detectors is image-processed to improve the quality of data reading using the successive readings of the same data regions. This allows errors to be corrected and throughput to be improved.

Abstract: Disclosed is a near field optical recording head for use with light from a light source to read data from and to write data to a surface of an optical recording media. The recording head includes a slider body adapted to fly a first distance above the surface of the optical recording media, the first distance being less than one wavelength of the light from the light source. The recording head also includes separate read and write apertures having dimensions which optimize read and write functions, respectively.

Abstract: An optical head including a distributed feedback laser having first and second cladding layers, an active layer sandwiched between said first and second cladding layers, a first reflecting member having a periodic wave-shaped structure formed within said first cladding layer at an interface between said active layer and said first cladding layer or in close proximity to said active layer, a second reflecting member provided on a first end surface of an assembly of said first and second cladding layer and active layer and having an exit window formed by a fine aperture, a third reflecting member provided on a second end surface of said assembly, and first and second current injection electrodes electrically connected to said first and second cladding layers, respectively as well as to an injection current source for injecting a current modulated in accordance with information to be recorded on the optical record medium into the laser.

Abstract: The purpose of the invention is to fabricate a near field optical head capable of recording and reading high density information at high speed with excellent mass production. In the invention, stoppers having almost the same height as that of a tip of conical or pyramidal shape are disposed around the tip, a part of a pressing body covering the tip and the stoppers is displaced by an external force, a part of the pressing body having displaced is allowed to come into contact with an opaque film near the point of the tip and thereby an aperture is formed. According to a fabricating method of the invention, multiple apertures can be formed in the block. Thus, the near field optical head is excellent in mass production and the formed aperture has a structure of high optical efficiency and high resolution. Therefore, the near field optical head capable of performing recording/reading in high density and at high speed can be fabricated in excellent mass production.

Abstract: An optical reading and writing system including a base; an optical disk rotatably mounted on the base; an optical pickup including an objective lens, focusing a light beam to form a light spot on a recording surface of the optical disk; an actuator arm mounted on the base such that the actuator arm can pivot in the radial direction of the optical disk by a voice coil motor; a load beam supported by the actuator arm, and capable of moving slightly up and down and in the radial direction of the optical disk by an external force; a flexure attached to the load beam, supporting a slider to enable the slider to contact the recording surface; and a driving unit mounted on free ends of the actuator arm and the load beam, providing a driving force in the radial direction to the free end of the load beam.

Abstract: An optical disk recording/reproduction apparatus includes a semiconductor laser, an objective lens provided opposite an optical disk, an optical system for supplying a laser beam from the semiconductor laser to the objective lens, an aperture for not intercepting the laser beam in reproducing from a digital video disk and intercepting an outermost portion of the laser beam in reproducing from a compact disk, and a tracking servo mechanism for moving the objective lens in a tracking direction orthogonal to the running direction of a track of the optical disk. The aperture has an oblong opening that is longer in the tracking direction than in the track running direction.

Abstract: An optical disc can increase an information storage capacity by reducing the track width of the optical disc. An optical pickup for a narrow track optical disc includes an optical shielding portion having a desired light intensity distribution with respect to a target track and the tracks adjacent to the target track on the optical disc. The optical shielding portion is disposed on the optical path between the light source and the optical disc and shields part of the light beam proceeding toward the optical disc, to provide a light intensity distribution such that only the beam spot focused on the target track is used to detect information stored in the target track. Thus, the beam spot focused on the target track of the optical disc has track crosstalk having a magnitude by which information can be read from the target track. The optical pickup can provide an excellent performance even in the case that the optical pickup is adapted in a high-definition DVD to be commercialized in the future.

Abstract: The present invention is an optical pick-up head with a single objective lens, which discloses an optical pick-up head that can retrieve data from CD and DVD with different thickness using a single objective lens and a special optical element on the optical path of the optical pick-up head. This optical element is a three-beam grating which is formed a reflective film thereon, for example, by coating a metal or dielectric layer to achieve the goal of controlling the numerical aperture. Thus, this invention provides a single objective lens optical pick-up head with simple structure, low cost, easy assembling, and applications to multi-wavelength systems.

Abstract: An improved focus error signal generator device and an optical data delivery and detection system including an optical lens disposed in the path of a return read beam and a birefringent plate disposed in the path of the return beam of light after the optical lens, wherein the birefringent plate provides for a first and second focal plane of corresponding first and second polarization. A pinhole is disposed in the path of the return read beam after the birefringent plate and in close proximity to first and second focal planes. A polarizing beam splitter is positioned after the second focal plane and serves to split the return read beam into two light beams of first and second polarization. First and second detectors are disposed in the path of corresponding first and second polarization light beams. The detectors are connected to the inputs of an electrical differencing circuit that has an output to an optical head servo system.

Abstract: An optical recording/reproducing apparatus includes an irradiation optical system for irradiating a light beam from a light source onto a predetermined track of an optical recording medium having a plurality of neighboring tracks as a fine light spot so as to perform recording/reproduction of information or reproduction of information, and a detection optical system for detecting a returned light beam from the optical recording medium. A mask is arranged in a far field region sufficiently separated from a focal plane of the detection optical system, for masking marginal rays, in a direction perpendicular to the track, of the returned light beam, so that information reproduced from a track adjacent to the predetermined track upon reproduction of information on the predetermined track is reduced.

Abstract: An optical scanning device can scan two different types of optical record carrier (1; 25), requiring a scanning beam (15) having different numerical apertures. The device has two stops (33; 32) at different positions along the optical axis of the path followed by the radiation beam for both types of discs. The first stop (33) limits the numerical aperture of the radiation beam when scanning the first type of record carrier (1). The second stop (32) limits the numerical aperture when scanning the second type of record carrier (25).