Abstract: Optical elements with anisotropic, patterned surface relief microstructures in which information is encoded in the distribution of the orientation of different zones. From the analysis of the distribution of the light scattered from the element, the orientation distribution in the element and therefore the encoded information can be evaluated. The elements are particularly useful for securing documents and articles against counterfeiting and falsification.

Abstract: An imaging system suitable to provide an image of a surface portion of an object is disclosed. The system includes a light source arranged to provide a light beam, at least a first optical waveguide having a first face and having a second face opposite to the first face, the first face having an incoupling surface. The optical waveguide includes an outcoupling surface, a first diffraction grating arranged on the optical waveguide, and an imaging subsystem arranged to the outcoupling surface. The first diffraction grating is arranged to outcouple at least a fraction of the light beam.

Abstract: A recording device of the present disclosure includes a light source, an objective lens, a beam splitter, an optical element, a detector and an operation circuit. The optical element divides a light beam into a first main region, a second main region, a first main end region, a second main end region, a first sub-region, and a second sub-region. The operation circuit generates a main signal in which a first main end region signal is multiplied by a coefficient a and added to the first main region signal, and a second main signal in which a second main end region signal is multiplied by the coefficient ? and added to the second main region signal.

Abstract: A data storage device comprises a substrate having oppositely disposed surfaces and a plurality of volumes arranged along tracks between the surfaces; a plurality of micro-holograms each contained in a corresponding one of the volumes; and, at least one groove in at least one of the surfaces and being operative to diffract light through the at least one surface and into the volumes; wherein, the presence or absence of a micro-hologram in a stacked layer in each of the volumes is indicative of a corresponding portion of data stored.

Abstract: The invention combines several techniques applying high-resolution photosensitive emulsions for the long-term, archival storage of data, images and text. Data is stored as vertical interference patterns of multiple frequencies in a photographic emulsion. Read-out of the stored data uses a precision mechanism to locate and decode stored data.

Abstract: In a small-sized optical pickup device for enabling to obtain a stable servo-signal, as well as, a focus error signal and a tracking error signal, without receiving ill influences of stray lights from other layers, when recording/reproducing a multi-layer optical disc, a reflection light from the multi-layer optical disc is divided into plural numbers of regions by a diffraction grating. And, it is divided into at least four (4) regions, by a division line in the tangential direction of the optical disc and a division line in the radial direction thereof. Light receiving parts, for detecting either one of grating diffraction lights, i.e.

Abstract: An objective optical system for information recording/reproducing, at least one of optical surfaces of the objective optical system comprising a diffraction surface including a first region contributing to converging first, second and third beams and including a diffraction structure formed such that use diffraction orders for the first, second and third beams are 1st-orders and a condition 0.03<(?B11??1)/?1<0.40 is satisfied; a second region contributing to converging only the first and second beams and including a diffraction structure formed such that the use diffraction orders are 1st-orders and a condition: ?0.35<(?B12??B11)/?1<0.35 is satisfied; and a third region contributing to converging only the first beam and including a diffraction structure formed such that the use diffraction order for the first beam is an odd order and a condition: ?0.23<m13 ((?B13??1)/?1)<0.23 is satisfied.

Abstract: For obtaining stable servo-signals without receiving ill influences of stray lights from other layers, on both a focus error signal and a tracking error signal, when recording/reproducing a multi-layer optical disc having small gap between layers thereof, a light beam is divided with using a first and a second diffraction gratings. The first diffraction grating is a polarization diffraction grating, and is mounted on an actuator. The second diffraction grating is disposed on a fixed portion. The first diffraction grating has a first region having a center of a light beam and other(s), and among signal lights reflecting from the disc, the light beam entering into the first region is diffracted, and the light beam entering into the second region transmits therethrough. The second diffraction grating transmits the light beam diffracting on the first region of the polarization diffraction grating therethrough, while diffracting the light beam diffracting on the second region.

Abstract: An optical pickup device includes a polarization diffraction grating to diverge an optical beam reflected from an optical disc and an optical detector to receive the optical beam diverged by the polarization diffraction grating, a polarization of 0 order diffracted light diffracted through the polarization diffraction grating is substantially perpendicular to that of a +1 order diffracted light diffracted therethrough, and a polarization filter having a plurality of domains is mounted between the polarization diffraction grating and the optical detector.

Abstract: There is provided a diffraction grating including a convex portion and a concave portion which are used for lights having different wavelengths ?1, ?2 and ?3 and are alternately disposed on at least one surface of a substrate with a predetermined pitch. An average refractive index of the convex portion is smaller than an average refractive index of the concave portion. A phase difference in the lights having the wavelength ?1 which transmit the convex portion and the concave portion and a phase difference in the lights having the wavelength ?2 which transmit the convex portion and the concave portion are both substantially the integral multiple of 2?, and a phase difference in the lights having the wavelength ?3 which transmit the convex portion and the concave portion is substantially the non-integral multiple of 2?.

Abstract: There is provided a diffraction grating including a convex portion and a concave portion which are used for lights having different wavelengths ?1, ?2 and ?3 and are alternately disposed on at least one surface of a substrate with a predetermined pitch. An average refractive index of the convex portion is smaller than an average refractive index of the concave portion. A phase difference in the lights having the wavelength ?1 which transmit the convex portion and the concave portion and a phase difference in the lights having the wavelength ?2 which transmit the convex portion and the concave portion are both substantially the integral multiple of 2?, and a phase difference in the lights having the wavelength ?3 which transmit the convex portion and the concave portion is substantially the non-integral multiple of 2?.

Abstract: A visible pattern is obtained by modulating the digital sum value. Because the digital sum value modulation allows the choice of several different channel bits groups between DC control points, the selection of a group of channel bits resulting in a change of reflection. This creation of a visible pattern is highly suitable for Blueray as the parity preserving property of the channel code guarantees disparity inversion by the DC-control bit, which keeps the DSV excursions between hard limits. As a result only small DSV deliberate variations are required to produce a grating, which will not deteriorate the bit-detection margin of the optical disc.

Abstract: An optical pickup device is provided. The optical pickup device includes a first, second, and third light emitting portions emitting light beams having first, second, and third wavelengths, respectively; an adjusting element for optical axes enabled to control the optical axis of the return light beam reflected by the optical recording media after output from the light emitting portion, and a single photo detector receiving the return light beams passing through the adjusting element for optical axes. The first light emitting portion and the second light emitting portion are arranged in such a way that the optical axis of the first light beam and the optical axis of the third light beam approximately coincide with each other. The adjusting element for optical axes controls the axis of the return light beam of said second light beam and the single photo detector receives the return light beams of the first light beam, the second light beam and the third light beam.

Abstract: An optical pickup device has a semiconductor laser emitting light which is in turn branched via a diffraction grating into at least three beams of light including a main beam and two sub beams which are in turn condensed via an objective lens on an optical disk at a guide groove and reflected by the optical disk to provide three reflections of light which are in turn received by detectors, each divided into two regions, respectively, to generate a tracking error signal. The diffraction grating is divided into three regions including a first region, a second region and a third region located intermediate therebetween, each having a periodical structure out of phase, the periodical structure having grating grooves in a direction determined depending on the phase of the second region to incline relative to a direction perpendicular to the guide groove of the optical disk.

Abstract: An optical-pickup apparatus comprising: a laser-light source; a diffraction grating including first-and-second regions of periodic structures different in phase from each other and a third region whose periodic structure is different in phase from the first-and-second regions; an objective lens focusing main-and-sub-luminous fluxes generated by the diffraction grating on the same optical-disc track; and a photodetector to receive reflected light of the main-and-sub-luminous fluxes from an optical disc and output a detection signal for generating main-and-sub-push-pull signals, a relationship between an incident light width in the objective lens corresponding to the third region and pupil diameters of the objective lens corresponding to first-and-second wavelengths of laser lights being adjusted so that a ratio of minimum value to maximum value of a differential-push-pull-signal is at substantially 50% or more and a ratio of sub-push-pull-signal level to main-push-pull-signal level is at substantially 15% or m

Abstract: An optical controller includes a light source for emitting light, an object lens for condensing light emitted from the light source, a light detection unit for receiving light reflected on an optical information recording medium and outputting a signal corresponding to the amount of the light, and a laser control unit for controlling the amount of the light emitted from the light source to the information recording surface on which information is to be recorded or reproduced, based on the recording state of an information recording surface disposed closer to the object lens than an information recording surface on which the information is to be recorded or reproduced.

Abstract: A recording medium, a recording/reproducing apparatus, and a recording/reproducing method are disclosed. The apparatus uses the number of record layers contained in a recording medium and a multi-wavelength light source including a plurality of optical signals having different wavelengths, and irradiates an optical signal emitted from a light source on each recording medium according to wavelengths of the light beams. As a result, the apparatus can effectively gain access to the recording medium including a plurality of record layers, such that it can simultaneously record/reproduce data in/from the recording medium.

Abstract: Multilayer optical disk is recordable or partly recordable. Parallel reading of information data from the group of layers by the same focused laser beam is possible. Only one layer of said group has the guide grooves for tracking. Alignment of the information data disposition on the layers of the group is provided. The signals reflected from the different layers of the group have different tilts and are directed onto the different photodetectors. Optical disk management for preventing its illegal use is proposed.

Abstract: An optical storage system includes a frame (e.g., a rack-mount drawer), an environmental assembly (e.g., a power and cooling subsystem) supported by the frame, and a set of optical storage devices coupled to the environmental assembly. Each optical storage device has a base, a storage medium (e.g., a sphere-shaped holographic data storage structure) disposed on the base, and an optical assembly coupled to the base. The storage medium has a curved surface configured to store data in a digital manner thereon. The optical assembly is configured to optically write the data to and read the data from the curved surface of the storage medium.

Abstract: A hologram recording medium including a substrate, a hologram recording layer that records an interference pattern formed by a first wavelength beam, a wavelength selecting reflection layer provided between the substrate and the hologram recording layer that reflects the first wavelength beam and transmits a second wavelength beam, a beam absorbing layer provided between the substrate and the wavelength selecting reflection layer that absorbs the first wavelength beam, and an information layer provided between the substrate and the light absorbing layer in which information is recorded and reproduced by the second wavelength beam, a second information layer provided between the substrate and the information layer and a second wavelength selecting reflection layer provided between the information layer and the second information layer that reflects the second wavelength beam and transmits a third wavelength beam.

Abstract: A diffraction element for an optical pick-up apparatus is provided that enables more accurate focusing control. The diffraction element for an optical pick-up apparatus is divided into first and second regions, each being formed with a grid pattern in which grids are repeated with a predetermined pitch P. The grid pattern in at least one of the first and second regions is tilted by a predetermined angle with respect to a virtual line VL substantially perpendicular to a division line DL that divides the first and second regions.

Abstract: A diffraction grating for plural wavelengths includes first grating regions which have periodic protrusions and depressions in sectional shape and are long formed in a depth direction perpendicular to a repeat direction of the protrusions and depressions, and second grating regions which have a configuration similar to that of the first grating regions and have depressions set to depths different from groove depths of the depressions of the first grating regions. The first and the second grating regions are alternately placed, and groove depths of each the depressions of both the grating regions are set so that the first grating regions transmit incident light of a first wavelength and also diffract incident light of a second wavelength different from the first wavelength and the second grating regions transmit incident light of the second wavelength and also diffract incident light of the first wavelength.

Abstract: An objective optical system is formed of a diffractive optical element with a diffractive surface formed on a virtual plane and an objective lens for focusing three light beams of three different wavelengths at three different numerical apertures onto desired positions of three different recording media with substrates that include different thicknesses, such as an AOD, a DVD, and a CD, that introduce different amounts of spherical aberration in the focused beams. The objective optical system provides compensating spherical aberrations to the three light beams, two of which are incident on the objective optical system as collimated beams and one of which is incident as a diverging beam. The objective optical system focuses second-order diffracted light of one wavelength and first-order diffracted light of the other two wavelengths. An optical pickup device includes the objective optical system, the recording media, and a light source that provides the three light beams.

Abstract: An optical pickup unit comprises a diffraction grating that divides light into at least three luminous fluxes and condenses the three luminous fluxes to apply at least three focusing spots, independent of each other, onto a signal side of a medium. The diffraction grating is divided into at least four regions, a first region, a second region, a third region, and a fourth region.

Abstract: In an information recording medium according to the present invention, in which an information recording medium has diffraction grating cells arranged therein, a plurality of types of the diffraction grating cells make up one information recording area. At least one type of the diffraction grating cells included in the diffraction grating cells making up the information recording area are information recording elements, while the other types of the diffraction grating cells included in the diffraction grating cells making up the information recording area are information hiding elements. The information is recorded by two-dimensional arrangement of the diffraction grating cells constituting the information recording elements in the information recording area.

Abstract: The present invention includes an optical disc whose informational units each contain a raised pad designed to reflect laser light at a compound angle which is 45 degrees from the disc surface and at one of 1024 preset angles between 0 and 360 degrees (with 0 degrees being oriented radially towards the disc center). Light reflected from the information units intersects with a ring of light detecting receptors arranged circumferentially around the laser/light source. When individual receptors are struck by reflected laser light: a signal is sent to a processor. This processor determines the order in which the receptors are stuck and outputs integers. Each integer corresponds to the receptor that was struck and this data, when streamed sequentially, reproduces the data stored on the optical disc.

Abstract: An optical pickup head device includes a diffraction grating for generating zero-order diffracted light and at least first-order diffracted light and provides a tracking error signal with a DPP method. The diffraction grating includes grating patterns with a nonuniform period or phase. The size of the first-order diffracted light converged on an optical recording medium is larger in the direction parallel to a tangent to the track than in the direction perpendicular to the tangent. P1/P0>PW2/PW1 is established, where PW1 represents the power that is required to record information on the optical recording medium, PW2 represents the maximum power that allows information recorded on the optical recording medium to be reproduced without being erased, P0 represents the light amount of the zero-order diffracted light converged on the optical recording medium, and P1 represents the light amount of the at least first-order diffracted light converged on the optical recording medium.

Abstract: There is disclosed an optical device in which a first light source for outputting a first wavelength light is apart from a second light source for outputting a second wavelength light by a predetermined distance. An information recording medium is irradiated with the first and second wavelength lights transmitted through a holographic optical element having first and second diffraction areas. The first and second diffraction areas are provided with grating arrangements in which grating axis directions are parallel to each other and grating pitches are different from each other. The first and second wavelength lights reflected by the information recording medium are transmitted through the holographic optical element and diffracted by the first and second diffraction areas.

Abstract: A multi-level optical recording medium according to the present invention is a multi-level optical recording medium (1) which is capable of recording record data according to multi-level recording that defines light reflection ratios of recording portions (12) into multiple levels by switching the irradiation amount of a recording laser beam between multiple levels, wherein light reflection ratio information enabling identification of a light reflection ratio dynamic range within which respective light reflection ratios of the recording portions (12) should be included is readably recorded.

Abstract: In an optical disc recording medium having formed thereon a first pit train and a second pit train, these pit trains are formed to be different in pit depth from each other and meet following two relations: Y ≥   ⁢ 0.5 ⁢ M + 73.0411 - 1098.4938 ⁢   ⁢ ( X - 0.5 ⁢ K ) +   ⁢ 6584.

Abstract: A hybrid disc whose ROM grooves are less than 170 nanometers deep, and whose pre-recorded ROM data pits are more than 350 nanometers or less than 250 nanometers deep, as measured from the effective land level. The ROM pits may be pre-recorded in ROM grooves that are shallower than the ROM pits, where the ROM pits are narrower, of equivalent width or up to approximately 10% wider than the ROM grooves, respectively measured at half-depth, although the transverse extent of the ROM pits will not typically exceed that of the ROM grooves. The ROM lands intervene between consecutive ROM pits, whether or not a ROM groove is provided. In the preferred embodiment, one beam of a dual beam apparatus records the ROM pits, while the other beam records the R-band pre-grooves, and also records the ROM groove, if present. In most embodiments a thermal mastering process provides smooth feature surfaces to facilitate replication of the hybrid disc masters.

Abstract: An optical information-recording medium having in-groove pits, which is excellent in recording and reproduction characteristics and tracking characteristics, is provided. A method for producing the optical information-recording medium is also provided. Further, a stamper to be used for producing a substrate for the optical information-recording medium and a method for producing the same are also provided. In the optical information-recording medium of the present invention, the in-groove pits, which have flat bottom surfaces, are arranged on a groove which has a flat bottom surface.

Abstract: An optical recording medium includes a land track and a groove track formed as a recording track to record and write information. A prepit sequence is formed on a middle position between the land track and the neighboring groove track as a head part of each sector on the recording track. The groove track is continuously formed on the prepit sequence section. The land track and the groove track are mutually formed as one spiral line or respectively formed as two parallel spiral lines on a surface of the optical recording medium.

Abstract: In an optical disc recording medium having formed thereon a first pit train and a second pit train, these pit trains are formed to be different in pit depth from each other and meet following two relations: 1 Y ≥   ⁢ 0.5 ⁢ M + 73.0411 - 1098.4938 ⁢   ⁢ ( X - 0.5 ⁢ K ) +   ⁢ 6584.719 ⁢   ⁢ ( X - 0.5 ⁢ K ) 2 - 19632.4312 ⁢   ⁢ ( X - 0.5 ⁢ K ) 3 +   ⁢ 29119.8871 ⁢ ( X - 0.5 ⁢ K ) 4 - 17190.8276 ⁢   ⁢ ( X - 0.5 ⁢ K ) 5 Y ≤   ⁢ 0.5 ⁢ M - 27.1270 + 307.9548 ⁢   ⁢ ( X - 0.5 ⁢ K ) -   ⁢ 1283.3732 ⁢   ⁢ ( X - 0.5 ⁢ K ) 2 + 2358.2052 ⁢   ⁢ ( X - 0.5 ⁢ K ) 3   ⁢ - 1620.1442 ⁢   ⁢ ( X - 0.

Abstract: In an, optical disc recording medium having formed thereon a first pit train and a second pit train, these pit trains are formed to be different in pit depth from each other and meet following two relations: Y≧0.5M+73.0411−1098.4983(X−0.5K)+6584.7191(X−0.5K) 2−19632.4312(X−0.5K)3+29119.8871(X−0.5K) 4−17190.8276(X−0.5K)5 Y≦0.5M−27.1270+307.9548(X−0.5K)−1283.3732(X−0.5K) 2+235.2052(X−0.5K)3−1620.1442(X−0.5K)4 where X: Phase depth of first pit train Y: Phase depth of second pit train K and M: Arbitrary integers.

Abstract: A very-high-density memory device which utilizes a scintillating medium for data storage. In one mode, the device operates as a read-only-memory (ROM) unit. In another mode, the device functions as a one-time-write (OTW) and then read-only-memory unit. In an exemplary embodiment, information is read at high data rates from a rotating data-storage disk or cylinder with an electron beam and sensitive photodetector. Two methods of following the data tracks on the storage medium are provided. Masks are provided for use in patterning the data or data tracks. These masks may also be used to pattern very-high-density media for other applications such as magnetic memory and optical near-field memory. A method of patterning radially-periodic structures using interferometric lithography is also provided.

Abstract: A device for optically scanning an information plane having tracks. Radiation is supplied by a radiation source focused on the information plane by an objective system. The beam reflected by the information plane is incident on a dividing element, for example a grating which divides the beam into two halves along a dividing line. Two sub-gratings at both sides of the dividing line each form a detection beam from one half of the beam, which detection beams are detected each by a detector. A focus error signal is generated from the detector signals by forming a difference signal of the two detector signals and dividing this difference signal by the sum signal of the two detector signals. The focus error signal is relatively insensitive to the position accuracy of the detectors with respect to the detection beams.

Abstract: An information recording medium includes a transparent substrate and a recording layer or a metal layer provided on the transparent substrate directly or via a ground layer. The information recording medium has a RAM area on which information is recorded, reproduced or erased, and a ROM area from which only reproduction is made, and an average thickness of the recording layer of said RAM area is larger than that of the recording layer or metal layer of the ROM area.

Abstract: An optical head device includes a light source for emitting at least one of a coherent beam and a quasi-monochromatic beam; a collection optical system for collecting the beam to an information memory medium having a track which has at least one mark and at least one space; a light detector having a plurality of detection areas for receiving the beam reflected by the information memory medium and outputting a signal in accordance with a light amount of the beam received; and a tracking error signal generator for receiving the signals output from the light detector and generating a tracking error signal based on the signals. The tracking error signal generator reduces a difference between a first signal amplitude and a second signal amplitude. The first signal amplitude is an absolute value of a difference between first and second signal levels. The second signal amplitude is an absolute value of a difference between the first and third signal levels.

Abstract: In a photodetector, the minimum size of the photodetection area for detecting a focus error signal from a light beam on the inner radius side of a hologram is made smaller than the minimum diameter of diffracted light beam spots (30, 31) for recording and reproduction, and when a CD is reproduced, a light beam close to the optical axis is made to significantly contribute to the focus error signal and the minimum size of the photodetection area for detecting the focus error signal from a light beam from the peripheral side of the hologram is made larger than the minimum diameter of diffracted light beam spots (130, 131) for recording and reproduction, whereby the focus error signal is made equal to the normal focus error signal when a DVD is reproduced, so that the focus offset variation caused when the base material thickness varies can be reduced.

Abstract: An optical recording medium used as a recording medium for information signals in which, in forming a groove along a recording track, a first groove and a second groove are formed to a first depth x to describe a double helix and a third groove having a second depth y shallower than the first depth x is formed between the first and second groves describing double helices. By setting the phase depths of these grooves to a pre-set range, signals required for tracking servo or seek are obtained to sufficient levels to realize stable tracking servo and seek.

Abstract: A disc having grooves and pits with different depths according to

Abstract: An optical disk has a lead-in region provided at the inner circumference side and a user region provided at the outer circumference side. Pit string 3 of pits of different depths is formed in the lead-in region. Light beam reflected from the pit string is detected by detector and TPP and RF signals are output by differential amplifier and addition amplifier. A ternary signal is restored from pits based on the TPP and RF signals. Information is recorded by pits of the same depth in the user region. Recording information in the depth direction in the lead-in region increases the recording capacity thereof. The information recorded in the depth direction in the lead-in region cannot be transferred to a user region of another optical disk.

Abstract: An optical recording medium which can precisely produce recording pits formed in pregrooves having a width narrower than the diameter of a reproducing beam spot, and which can reduce the jitter and the block error rate, wherein the following unequal equation satisfied:

Abstract: An optical disc of the present invention has a plurality of kinds of pre-pits with a correction size which have a length only uniformly shorter than a plurality of pre-pits with a specified size which have a constant width, a constant depth and a constant depth inclination and a different length in correspondence to the data thereby recording the data with the pre-pits with the correction size.

Abstract: An optical pickup head device includes a diffraction grating for generating zero-order diffracted light and at least first-order diffracted light and provides a tracking error signal with a DPP method. The diffraction grating includes grating patterns with a nonuniform period or phase. The size of the first-order diffracted light converged on an optical recording medium is larger in the direction parallel to a tangent to the track than in the direction perpendicular to the tangent. P1/P0>PW2/PW1 is established, where PW1 represents the power that is required to record information on the optical recording medium, PW2 represents the maximum power that allows information recorded on the optical recording medium to be reproduced without being erased, P0 represents the light amount of the zero-order diffracted light converged on the optical recording medium, and P1 represents the light amount of the at least first-order diffracted light converged on the optical recording medium.