Abstract: A disclosed imaging device may include an image sensor, a lens system, and an aperture filter. The aperture filter may include a first concentric region that passes light of a first wavelength range and that blocks light of a second wavelength range and a second concentric region that passes light of the first wavelength range and light of the second wavelength range. The lens system may direct received light through the aperture filter toward the image sensor. The lens system and the aperture filter may provide a first depth-of-field associated with the first wavelength range and a second depth-of-field associated with the second wavelength range. Associated systems and methods are also disclosed.

Abstract: A light irradiation unit forms an electrostatic latent image pattern on a photosensitive member by irradiating the photosensitive member and a shielding unit with light. A detection unit detects, in a rotation direction of the photosensitive member, timing at which a surface potential of the photosensitive member changes depending on displacement of the electrostatic latent image pattern in an axial direction of the photosensitive member.

Abstract: There is provided a playback device including a light source, an objective lens that radiates light emitted onto an optical recording medium, and onto which is incident reflected light obtained from a recording surface of the optical recording medium, a condenser lens that condenses the reflected light, a photodetecting section configured to, provided that a confocal position is a focal position of the condenser lens, ? is a wavelength of light radiated onto the optical recording medium, and NA is a numerical aperture of the objective lens, extract and detect light within a range of a diameter less than 1.5?/NA centered on an optical axis at the confocal position, and a phase difference imparting section that imparts a designated phase difference between a reflected light component from a readout track and a reflected light component from a track neighboring the readout track.

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: An optical head device includes a light blocking region disposed on a light flux of a reflected light beam resulting from reflection by a recording layer on which a blue light beam is focused, and blocks, when there are at least two recording layers on a blue light beam incident side of the recording layer on which the blue light beam is focused or on a side thereof opposite to the blue light beam incident side, reflected light beams resulting from reflection by the at least two recording layers which are incident on a region in a photodetector where the reflected light beams resulting from the reflection by the at least two recording layers interfere with each other. The light blocking region is not formed on an optical axis of the reflected light beam resulting from the reflection by the recording layer on which the blue light beam is focused.

Abstract: Provided is a holographic recording/reproducing apparatus including an aperture device having aperture of variable size. The holographic recording/reproducing apparatus includes a light source, an optical system to divide light emitted from the light source into a recording reference beam and a recording signal beam, and direct the recording reference beam and the recording signal beam to a same location of a holographic recording medium, a spatial light modulator (SLM) to modulate the recording signal beam into a two-dimensional signal pattern, a two-dimensional photodetector to detect a reproducing signal beam that is refracted via the holographic recording medium, and the aperture to limit a size of a spot of the reproducing signal beam, wherein the size of the aperture is variable.

Abstract: A recording and reproducing device that is capable of improving its reproduction quality by efficiently detecting a reproduction signal having small low frequency noises even when reproducing data on a super-resolution optical disk including recording marks smaller than a diffraction limit.

Abstract: An information recording medium of the present invention is an information recording medium characterized by and including a substrate; and a recording unit capable of recording three-dimensionally a recording pit on the substrate; in which the recording unit has n number of recording layers (n is an integer equal to or larger than 4) and a plurality of intermediate layers laminated with the recording layers one on another; the recording is performed by the condensed recording light using a two photon absorption phenomenon; each of the plurality of intermediate layers is substantially transparent at a wavelength ?1 of the recording light and at a wavelength ?2 of the reproduction light, respectively; the light intensity of the recording light incident into the recording layer nearest to the substrate is more than 0.707 fold as much as the light intensity of the recording light incident into the recording layer farthest from the substrate.

Abstract: A tilt sensor includes a photodetector having a photosensitive plane and detecting a light beam in multiple areas and outputting detection signals representing its intensities and a tilt detector for generating a tilt error signal, including information about the tilt of a disk, based on the detection signals. The light beam forms a beam spot on the photosensitive plane. The beam spot includes a +first-order light area in which zero-order and +first-order light rays, diffracted by a track on the disk, are superposed, ?first-order light area in which zero-order and ?first-order light rays are superposed, and a zero-order light area which is sandwiched between the +first-order and ?first-order light areas, includes neither the +first-order nor ?first-order light ray, but includes a zero-order light ray. The photodetector generates the detection signals except for light entering an opaque area provided for at least part of the zero-order light area.

Abstract: A near field optical disc and a near field optical disc reading apparatus are provided. The near field optical disc has at least one light source and a near field optical pick-up head, and the near field optical disc includes a light guiding substance, a first reflection layer and a second reflection layer. The light guiding substance has a first surface, a second surface opposite thereto and at least one light entrance window. Light emitted from the light source enters the light guiding substance through the light entrance window. The second reflection layer is disposed on the second surface. The first reflection layer is disposed on the first surface and has a plurality of light pervious holes. A part of the light is transmitted through the light pervious holes and picked up by the near field optical pick-up head.

Abstract: A tracking error signal is generated with stability without being easily affected by a distribution fluctuation of light reflected from an optical disc or by a lens shift. An optical disc drive according to the present invention includes: an objective lens 5 with an aperture radius r0 for converging a light beam emitted from a light source 1; a polarizing hologram substrate 2 for dividing the beam reflected from the optical disc 6 into branched light beams; a photodetector substrate 6, on which at least some of the light beams are incident to generate signals representing the intensities of the light beams; and a shielding mask 16 for cutting off the beam partially.

Abstract: An optical pickup device has: a light source; an objective lens that condenses laser light emitted from the light source on a recording layer of an optical disc; and a movable lens that is disposed between the light source and the objective lens and that is movable along the optical axis. The movable lens is moved to correct for spherical aberration. Between the light source and the objective lens, a RIM intensity adjusting element is also disposed that adjusts the RIM intensity by changing the range within which, as the movable lens is moved, the intensity of the laser light incident on the objective lens can be varied.

Abstract: An optical information recording-reproducing apparatus for effecting at least one of recording of information on and reproducing of information from an optical recording medium. A light source emits a light beam. An objective lens and a solid immersion lens receive the light beam from the light source and approach the optical recording medium at a predetermined speed to focus the light beam onto the optical recording medium. An aperture element collects a portion of the light beam that is reflected by the recording medium, in which the portion of the light beam has a diameter that corresponds to an effective aperture number of the objective lens and the solid immersion lens of less than one. A detecting element detects the portion of the light beam collected by the aperture element and produces an output signal.

Abstract: An apparatus comprising a phase compensator and an optical condenser in communication with the phase compensator. The phase compensator provides for phase shifting a portion of an electromagnetic wave. The optical condenser is shaped to direct the electromagnetic wave to a focal region of the optical condenser.

Abstract: An optical pickup for recording or reproducing an information signal in an optical disc includes a light source for emitting a light beam toward the optical disc, an objective lens for focusing the light beam emitted from the light source onto a recording surface of the optical disc, and a photodetector for receiving the light beam reflected by the recording surface of the optical disc and outputting a signal corresponding to an intensity of the received light beam. A spot of the light beam received by the photodetector is asymmetric in both a radial direction and a tangential direction of the optical disc. A lens shift signal for the objective lens is detected by a controller on the basis of the signal output from the photodetector, the controller controlling the objective lens to follow the optical disc.

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

Abstract: On an optical path between a light source and an objective lens, there is provided an optical path changing section for changing a predetermined optical path of undesired light passing through, from the predetermined optical path to another optical path. The optical path changing section includes a plate having an aperture portion for allowing a laser beam emitted from the light source to pass through, and an aperture wall which defines the aperture portion of the plate includes a taper portion which is formed in a tapered-shape and slants so as to come close to an optical axis L1 of the light source in association with movement toward a laser beam outgoing direction. The undesired light from the light source is reflected by the taper portion to change the predetermined optical path of the undesired light passing through, from the predetermined optical path to another optical path.

Abstract: In a confocal optical system having a light source 13, a first focusing means 14, a second focusing means 16, an aperture 17, and a detector 18 including a plurality of light reception regions, a position displacement is detected by detecting an intensity distribution of an image caused by a position displacement between a focusing spot of the second focusing means 16 and the aperture 17, by the detector 18. Further, the position displacement is corrected by controlling the aperture position using driving means 19 and control means 20. Also, a position displacement of the aperture 17 in the optical axis direction is detected and corrected on the basis of a change in an output of the detector 18 by oscillating the aperture 17 in the optical axis direction.

Abstract: An optical element for use in an optical pickup apparatus includes a substrate made of resin; an antireflection layer coating the substrate and having a low refractive index layer and a high refractive index layer, wherein the resin includes a polymer with an alicyclic structure, the low refractive index layer is formed of a material selected from the group consisting of silicon oxide; aluminum fluoride; yttrium fluoride; magnesium fluoride; a mixture of silicon oxide and aluminum oxide; and a mixture thereof, the high refractive index layer is formed of a material selected from the group consisting of scandium oxide; niobium oxide; lanthanum oxide; praseodymium titanate; lanthanum titanate; lanthanum aluminate; yttrium oxide; hafnium oxide; zirconium oxide; tantalum oxide; a mixture of tantalum oxide and titanium; silicon nitride; and a mixture thereof.

Abstract: An optical head device and an optical recording and reproducing apparatus using this optical head device, which can record information and reproduce the recorded information at any of optical recording media, such as a next generation optical recording medium, in which the wavelength of the light source is made to be shorter, the numerical aperture of the objective lens is made to be higher, and the thickness of the recording medium is made to be thinner, and conventional recording media of DVD and CD standards, are provided. A light having wavelength of 405 nm, emitted from one of optics, is inputted to an objective lens as a collimated light, and is focused on a disk having thickness of 0.1 mm. A light having wavelength of 650 nm, emitted from the other of optics, is inputted to the objective lens as a diverged light, and is focused on a disk having thickness of 0.6 mm.

Abstract: The present invention provides a first light source (21) that emits light of a first wavelength, that at least either records onto or reproduces information from an information recording medium (30), a light source (22) that emits light of a second wavelength that records onto or reproduces information from an information recording medium (33), a light source (23) that emits light of a third wavelength that records onto or reproduces information from an information recording medium (23), focusing means, an optical element (28) that passes light of the first wavelength and diffracts light of the second and third wavelengths, wherein the optical element (28) is an optical element in which grooves are formed in a substrate, wherein the expression: 380 nm?(n?1)×d?420 nm is satisfied, where n is a refractive index of the substrate at a wavelength of 400 nm, and d (nm) is a depth per step of the grooves, and wherein the grooves are formed in two steps of depth d and depth 2d.

Abstract: A light detecting apparatus includes a first photodetector for receiving 0th reflected light from a first information surface, a second photodetector proximate to the first photodetector for receiving the reflected light of a positive higher-order diffracted light from the first information surface, and a third photodetector proximate to the first photodetector for receiving the reflected light of a negative higher-order diffracted light from the first information surface. Light-receiving areas of the second and the third photodetectors include other-order light receiving areas that receive reflected light of the 0th order light from a second information surface where the 0th order light is not be focused, and wherein portions of the other-order light receiving areas of the second and the third photodetectors include light reception prohibited areas that prohibit the reception of the reflected light of the 0th order light from the second information surface.

Abstract: A near-field optical probe has a planar substrate formed with a through-hole and a phase shifter layer translucent to light having a wavelength of illumination light used to illuminate the substrate for producing near-field light. The phase shifter layer is effective to cause a shift of phase in the illumination light by 180 degrees and is provided on the substrate so as to cover one opening of the through-hole to form a microscopic aperture for producing near-field light.

Abstract: A near-field light-emitting element includes a transparent medium having a plane of incidence into which a laser beam enters, and a light-condensing plane on which the laser beam having entered the plane of incidence is concentrated, and a metal body provided on the light-condensing plane of the transparent medium having a first surface contacting the light-condensing plane, a second surface opposing the first surface, and an aperture which is formed to penetrate through the first and second surfaces at a position where the laser beam is concentrated and which emits a near-field light obtained from the laser beam. The metal body is arranged apart from a center of the aperture by a predetermined distance to connect together the first and second surfaces, and has a plasmon reflection plane that reflects toward the aperture a surface plasmon excited on the first and second surfaces by the laser beam concentrated at the aperture.

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 201 includes a light source 1, an objective lens group 13, a two-dimensional actuator 15, spherical aberration adding means 9, 10, and 16, a hologram element 17 for splitting the light beam from the optical disk 14 into a plurality of split light beams, and a photodetector 22 which includes at least one photoreceptor including a plurality of split light receiving areas and outputs an electric signal corresponding to the light amount of a split light beam entering each of the plurality of split light receiving areas or an electric signal corresponding to a combination of the light amount of split light beams entering the corresponding split light receiving areas, and the plurality of split light beams split by the hologram element 17 include one circular ray U1 and at least two annular rays U2 and U3.

Abstract: An optical disc apparatus is provided, which comprises a lens tilting section for tilting an objective lens to correct coma aberration occurring in a light beam spot focused on an information surface of an optical disc, a spherical aberration correcting section for correcting spherical aberration occurring in a light beam spot focused on the information surface, and a lens tilt-spherical aberration correction control section for controlling the spherical aberration correcting section to change an amount of spherical aberration correction performed by the spherical aberration correcting section depending on a tilt of the objective lens tilted by the lens tilting section.

Abstract: An LPF performs low-pass filtering for a light reception signal responsive to return light received by an optical pickup. A comparator makes a comparison between the level of the signal output from the LPF and a predetermined threshold value and outputs a high or low pulse signal MIR. A system control section determines the pulse signal MIR for each predetermined dot region. If the pulse signal MIR output from the comparator is high, the system control section writes “1” into buffer memory; if the pulse signal MIR is low, the system control section writes “0”into the buffer memory. The pixel string data recorded in the buffer memory is transferred to a host and an image responsive to pixel string data is displayed on a display.

Abstract: The present invention proposes an optical head apparatus provided with light-blocking structure that can reliably prevent nonessential light from reaching the photo detector, without being an impediment to miniaturization and flattening, moreover, without increasing manufacturing cost. In an optical head apparatus, and in a lens holder, light-blocking section is provided that blocks nonessential light from passing outside the effective diameter of objective lens. This light-blocking section is constructed so that it extends only in tracking direction T of objective lens 5. Further, light-blocking face of light-blocking section slants at an angle of 1° or more toward the face orthogonal to the optical axis, consequently, nonessential light is reflected in a direction other than the direction of photo detector.

Abstract: An object lens arranged on a light proceeding path to focus light on a recording medium includes a first surface that is an incident surface on which light is incident, a second surface from which light exits to be focused on the recording medium, and a diffractive optical element disposed on at least one of the first and second surfaces and which has a refractivity of fD/f<5, fD being a focus distance of the diffractive optical element and f being a focal distance of the object lens. The object lens has a numerical aperture of 0.75 or greater.

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: 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: A holographic ROM system of the present invention includes a lens unit for filtering and collimating an output radiation diffracted from a holographic disk in order to produce an output data beam. The lens unit includes an objective lens for collimating the output radiation and a filtering film for filtering the output radiation. The objective lens and the filtering film are formed in a single body.

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

Abstract: An 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 a lens system provided between the laser source and the deflector, which has a first lens for focusing the laser beam and a second lens for adjusting the focused laser beam to a desired beam diameter; and a pinhole placed at a practical focal position of the lens system.

Abstract: A light source outputs an optical beam. A condensing unit condenses the optical beam to a first information-recording layer. An optical detecting unit detects a reflected optical beam reflected from the optical storage medium. A limiting element inputs a first reflected optical beam reflected from the first information-recording layer to the optical detecting unit, and limits or shields an input of a second reflected optical beam reflected from a second information-recording layer to the optical detecting unit.

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 pickup apparatus comprises an orbicular zone forming lens group 14 for forming the section of the laser beam, which is irradiated to an optical disc DK having plural recording layers, into an annular shape, a condenser lens 35 that converges the reflected beam from the optical disc DK, and a pinhole plate 36 having formed thereto a pinhole 36a with a size corresponding to a flux diameter of the reflected beam converged by the condenser lens 35. The orbicular zone forming lens group 14 refracts the laser beam irradiated to the optical disc DK so as to form the section of the laser beam into an annular shape in order that the internal diameter of the annular converged flux formed on the pinhole plate 36a by the reflected beam from the recording layers other than the recording layer having an optical spot formed thereon becomes greater than the diameter of the pinhole 36a.

Abstract: In a holographic recording apparatus having a hologram medium for storing an interference pattern between a reference beam and a modulated signal beam, a double-layered mask for modulating a signal beam with data to generate the modulated signal beam has a first and a second opaque film and a transparent plate inserted therebetween. The first and the second opaque film face each other and have a plurality of first and second recording tracks, respectively. The first and the second recording tracks are alternately arranged, wherein the data to modulate the signal beam therewith are alternately embedded along the first and the second recording tracks such that one of two neighboring recording tracks is one of the first recording tracks and the other is one of the second recording tracks.

Abstract: A holographic disc recording system for recording, in the form of holograms, information stored on a source disc onto a target disc includes a conical beam shaper which transforms a reference beam into a conical beam having a substantially cylindrically symmetrical shape and including light rays which travel along lines which intersect a beam axis of the conical beam at substantially the same angle with respect to the beam axis. The conical beam is incident on the target disc while the beam axis of the conical beam substantially coincides with a central axis of the target disc, so that substantially all of the light rays of the conical beam are incident on the target disc at substantially the same angle.

Abstract: The invention relates to a scanning apparatus for scanning information in an information carrier (16) comprising a plurality of layers for storing data on a material capable of generating an excited radiation when interacting with an exciting beam (13) produced by an exciting source (11). The scanning apparatus comprises an objective lens (15) for projecting the exciting beam in a layer of the carrier and collecting the excited radiation. The scanning apparatus also comprises a detector unit (19) for detecting the excited radiation collected on the objective lens. According to the invention, the exciting beam has a numerical aperture lower than the lens numerical aperture.

Abstract: An optical pickup actuator for use with a recording medium includes a swing arm pivoting in a tracking direction with respect to the recording medium, a first driving unit pivoting the swing arm, an optical pickup facing the recording medium, an elastic member having one end fixed to the swing arm and a free end portion elastically deformable in a focus direction with respect to the recording medium, wherein the optical pickup is coupled to the free end portion of the elastic member, and a second driving unit deforming and driving the elastic member.

Abstract: An optical disk apparatus includes a laser diode, and a light from the laser diode becomes a parallel light by a collimator lens, which is reflected toward an object lens by a reflection mirror. The parallel light transmitted through a through-hole provided on an object lens holder is reflected by a disk, and a reflected light is incident upon a light-receiving sensor via the collimator lens, a polarizing beam splitter and a prism. The parallel light reflected by the reflection mirror is reflected by a mirror integrated with the object lens holder, and incident upon the light-receiving sensor via the collimator lens, the polarizing beam splitter and the prism. A disk tilt and/or an object lens tilt are/is detected from output signals of divided light-receiving sensors of the light-receiving sensor.

Abstract: A optical device including conductive films having a first and second surfaces, one hole, surface specific shapes periodically, and a layer inserted as an intermediate layer between the first and the second surface of conductive films. The intermediate layer has the effect for improving surface roughness of the surface of conductive film. A light incident upon one surface enhances an intensity transmitted though the hole.

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 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 a lens system provided between the laser source and the deflector, which has a first lens for focusing the laser beam and a second lens for adjusting the focused laser beam to a desired beam diameter; and a pinhole placed at a practical focal position of the lens system.

Abstract: A drive current supply circuit is provided in which the speed of rise of the drive current to a laser diode is increased. In a drive current supply circuit for supplying drive current I to load 50 connected with the line 1R of two parallel lines 1R and 2R of a first current mirror circuit 1, this drive current supply circuit is provided with a control circuit CONT that controls the current i flowing in the other line 1L in accordance with first control signal ?ø1 and the first control signal ?ø1 comprises a steady DC component øD and a drive signal component ø1 added to the DC component øD when desired.

Abstract: The optical information recording and reproducing apparatus includes 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 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: An optical disk reader or read/write system for CD or DVD formats. First and second laser diodes operating at different wavelengths have their output beams collimated and directed at a single element objective lens, and are then reflected off the disk back through the lens to a photodetector. The single element objective lens has a central aperture zone and an outer aperture zone, the central zone being profiled to operate at a first numerical aperture at approximately 0.45 and the output beam of the first laser diode is confined to the central aperture zone. The outer aperture zone together with the central aperture zone are profiled to operate at a second numerical aperture, for example 0.60 wherein the output beam of the second laser diode has ray fans extending across the full aperture of the single element objective lens.

Abstract: An optical disk reader or read/write system for CD or DVD formats. First and second laser diodes operating at different wavelengths have their output beams collimated and directed at a single element objective lens, and are then reflected off the disk back through the lens to a photodetector. The single element objective lens has a central aperture zone and an outer aperture zone, the central zone being profiled to operate at a first numerical aperture at approximately 0.45 and the output beam of the first laser diode is confined to the central aperture zone. The outer aperture zone together with the central aperture zone are profiled to operate at a second numerical aperture, for example 0.60 wherein the output beam of the second laser diode has ray fans extending across the full aperture of the single element objective lens.