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: Provided is an optical pickup device that suppresses a fluctuation of a tracking error signal caused by stray light when recording/reproducing information on/from an optical disc including a plurality of recording layers and attains size reduction. It includes a laser diode emitting laser light of about 405 nm in wavelength, an objective lens irradiating the optical disc with an optical beam emitted from the laser diode and having a numerical aperture of about 0.85, and a detector including a detection part receiving the optical beam reflected from the optical disc. An optical magnification from the optical disc to the detector is set within a range from about 10× to 15×.

Abstract: In an embodiment, an optical pickup includes at least one light source for selectively emitting three light beams having blue, red, and infrared wavelengths, respectively, and an objective lens arranged so that each of the three light beams enters thereto. The objective lens includes a first grating, and a second grating formed in the same plane as the first grating. The first and second gratings each have phase steps arranged concentrically around a center axis of a lens in a region in which all the three light beams pass, and are different in phase step positions. The first grating diffracts the three light beams having the blue, red, and infrared wavelengths in a 2nd order, a 1st order, and the 1st order, respectively. On the other hand, the second grating diffracts the three light beams having the blue, red, and infrared wavelengths in the 1st order, the 1st order, and the 1st order, respectively.

Abstract: Provided is an objective optical element which can appropriately correct degradation from spherical aberration upon fluctuation of a light source wavelength while maintaining light use efficiency, just by changing the magnification of the objective optical element, and which can record/reproduce information to/from different optical discs. Also provided is an optical pickup device using the objective optical element. When a light flux having two different wavelengths ?11, ?12 (wherein ?11<?12 and ?12??11=5 nm) within a range of wavelength ?1 is introduced to the objective optical element to measure the wavefront aberration, the following third order and fifth order spherical aberrations in unit of ?rms are obtained: SA3(?11), SA5(?11), SA3(?12), SA5(?12). If ?SA3=|SA3(?12)?SA3(?11)|, ?SA5=|SA5(?12)?SA5(?11)|, the following expression is satisfied: 0.

Abstract: An optical component for an optical pick-up for converging a laser beam having a particular wavelength onto a recording layer of an optical disc. The optical component comprises a base material formed of a resin composition, an undercoating which is formed of three layers of thin films having a same main constituent and is formed on a top surface of the base material, and a functional thin film formed on a top surface of the undercoating. In this configuration, each of a first layer and a third layer of the undercoating is a thin film formed without introducing oxygen, and a second layer is a thin film formed while introducing oxygen. A film thickness of the undercoating falls within a range of 160 nm to 270 nm, and film thicknesses of the thin films constituting the undercoating are substantially equal to each other.

Abstract: New and useful methods and systems for reading optical discs, such as multi-layer Blu-ray discs are disclosed. For example, in an embodiment a device for reading two-layered optical discs includes a laser diode capable of emitting light, a set of optics including a fixed collimator, the set of optics providing a numerical aperture (NA) of substantially less than 0.85, and a detector for detecting laser light focused on a two-layer optical disc to produce a stream of detected bits.

Abstract: An optical pickup apparatus includes at least: a light emitting element capable of emitting at least first wavelength light and second wavelength light; and a diffraction grating configured to split the first wavelength light into at least a first main beam and a first sub-beam and to split the second wavelength light into at least a second main beam and a second sub-beam, a following expression (1) being satisfied: 1.05 < Yp ? ? 1 Yp ? ? 2 < 2.50 ( 1 ) where: Yp1 is an interval between the first main beam and the first sub-beam when a first media corresponding to the first wavelength light is irradiated with the first main beam and the first sub-beam, and Yp2 is an interval between the second main beam and the second sub-beam when a second media corresponding to the second wavelength light is irradiated with the second main beam and the second sub-beam.

Abstract: [Object] To provide a durable read-only optical recording medium having less variances in characteristics of a metal reflective film due to a temporal change. [Solving Means] Provided is a read-only optical recording medium (100) including: a substrate (101); an information recording surface onto which information is recorded by combining pits (P) and lands (L); and a metal reflective film (102) that is provided in contact with the information recording surface and represented by Al100-x-zXxZz, where x and z each represent an atomic %, X is constituted of an element including at least Ti, Z is constituted of an element including at least Fe, x is 1.0 to 3.0, and z is 0.05 to 1.0.

Abstract: A compound objective lens, an optical head device, an optical information device, and an information processing device that can inhibit the occurrence of aberration even when a light beam source wavelength shifts from the designed value. A diffraction structure having a sawtooth or stepwise cross section is formed in the region (R10) and region (R20). The height of the sawtooth or stepwise cross section formed in the region (R10) provides a light beam, which has a predetermined wavelength, with a difference in optical path length of N times the predetermined wavelength, as compared with a case of propagation in air. The height of the sawtooth or stepwise cross section formed in the region (R20) provides the light beam, which has the predetermined wavelength, with a difference in optical path length of J times the predetermined wavelength, as compared with a case of propagation in air.

Abstract: An objective lens includes: a diffraction area having a diffraction structure provided thereon concentrically around an optical axis of the objective lens; and a first non-diffraction area provided outward an outer circumference of the diffraction area, the objective lens being configured to focus first laser light on a signal recording surface of a first optical recording medium by refraction in the first non-diffraction area; focus second laser light, different in wavelength from the first laser light, on a signal recording surface of a second optical recording medium by diffraction in the diffraction area; and focus third laser light, different in wavelength from the first laser light and the second laser light, on a signal recording surface of a third optical recording medium by diffraction in the diffraction area.

Abstract: In an optical head device which performs recording or reading of data in/from a high-density optical disc using an objective lens with a large NA, a saw-tooth shape diffraction element is used for also performing recording or reading of data in/from a conventional optical disc, such as DVD, CD, or the like. A step difference that produces an optical path length for blue light which is equal to or longer than the wavelength of the blue light and optical path lengths for red and infrared light which are shorter than the wavelengths of the red and infrared light is utilized so as to exert an inverse action on the blue light to those exerted on the red and infrared light. The effect of increasing the working distances for CD and DVD enables multiple compatibility. The above optical element is integrally combined with the objective lens to perform a tracking servo following operation.

Abstract: An optical pickup is disposed which irradiates a laser beam onto an optical disc where a guide groove having characteristics of thermal interference (heat discoloration) is spirally formed. The optical pickup irradiates the laser beam along the guide groove to conduct one of data recording in which pits indicating a data length are formed, and visible-image formation in which a part of the optical disc is discolored. The laser beam irradiation position is controlled so that the data recording is conducted with starting from the inner peripheral side of the optical disc, and the visible-image formation is conducted with starting from the outer peripheral side of the optical disc.

Abstract: An optical pickup is disposed which irradiates a laser beam onto an optical disc where a guide groove having characteristics of thermal interference (heat discoloration) is spirally formed. The optical pickup irradiates the laser beam along the guide groove to conduct one of data recording in which pits indicating a data length are formed, and visible-image formation in which a part of the optical disc is discolored. The laser beam irradiation position is controlled so that the data recording is conducted with starting from the inner peripheral side of the optical disc, and the visible-image formation is conducted with starting from the outer peripheral side of the optical disc.

Abstract: It is an object of the present invention to provide a method for image processing and an image processing apparatus which are capable of performing repetitive forming and erasing of high-contrast images at high speeds by forming high-density, uniform images and uniformly erasing images in a short period of time, and in addition, suppressing the degradation of the thermoreversible recording medium due to repetitive forming and erasing is possible.

Abstract: A miniature optical disc drive includes a DVD-compatible optical controller and a cartridge load module designed to hold a cartridge containing a 32 mm optical data storage disc.

Abstract: A printing method applied to an optical recording medium including a recording/playback functional layer enabling recording or playback by a laser beam, an information recording/playback surface irradiated with the laser beam, and a printing layer separated from the information recording/playback surface by the recording/playback functional layer. Address information used for recording or playback is recorded on the recording/playback functional layer. The printing method detects the address information by irradiating the information recording/playback surface with the laser beam, and carries out printing on the printing layer using the detected address information.

Abstract: An information recording apparatus includes a multilayer information recording medium having a first layer containing an electro-chromic material, an electrode layer applying a voltage to the first layer to color the first layer, a second layer containing an electro-chromic material, a unit for applying the voltage to the first layer, a first optical irradiating unit for irradiating a first optical spot onto the first layer, and a second optical irradiating unit for irradiating a second optical spot onto the second layer after irradiating the first optical spot onto the first layer.

Abstract: Techniques are provided for placing atoms inside an appropriate nanocavity for enhancing two-photon absorption and quantum information processing based on the Zeno effect. Techniques for fabricating suitable nanocavities include: 1) a short length of optical fiber polished on the ends with the ends coated to form suitable mirrors; 2) a continuous length of fiber with the equivalent of mirrors being formed within the fiber using Bragg gratings; 3) a single filament of glass (such as fused silica) being suspended between two mirrors (without any cladding) and surrounded by an atomic vapor, solid, or liquid; 4) a small glass sphere (such as fused silica) that has been melted on the end of an optical fiber; and 5) a small toroid (ring) of glass bent in a circle surrounded by suitable atoms.

Abstract: Typical apparatus according to this invention comprises a host interface for receiving digital data interface input from a host computer and delivering digital data interface output to the host computer, the interface output data comprising a function of the interface input data; an optical storage device (herein sometimes called a “light drive”) for receiving the interface output data from the host interface and providing optical radiation (i.e. radiation of wavelength in the range at least of about ultraviolet to at least about infrared) to each of a series of pixels in a region of a member comprising an effective concentration of photoreceptive material (PRM) and wherein the wavelength and intensity of the radiation in each pixel are functions of the interface output data received from the host interface; and a transmission medium for providing a datum signal from each pixel via the host interface to the host computer.

Abstract: An optical memory device is specifically so designed that, when an reference beam is applied thereto, the entire information area of its core layer can receive the reference beam all at a time to surely reconstruct a correct image. The optical memory device includes a core layer and a cladding layer laminated on both surfaces of the core layer.

Abstract: A method and apparatus for increasing data storage capabilities by inserting quantum dots in the pits of disks like CD-RWs, DVDs, WORM disks, and CD-ROM disks, exciting them with a laser diode, and measuring their fluorescence is described. Carriers of different colors are placed in each pit via quantum dots. These dots are made up of multiple colors, or different shades of a color. The quantum dots are inserted using inkjet based technology, laser-induced technology, or holey fibers. A laser diode excites the dots, making them fluoresce, which is measured by a holographic multi-spectral filter (HMSF). The HMSF diffracts the collimated fluorescence before a lens focuses each spectral component onto a detector. A dichroic beam splitter is placed under the HMSF to prohibit the light from the laser diode to reach the detector yet allow the fluoresce through.

Abstract: A representative data storage medium includes: a substrate; and a plurality of elongate, carrier molecules anchored to the substrate. Each carrier molecule carries one or more luminescent groups and is alterable between a readable conformation in which the luminescent groups carried by the molecule are able to emit radiation and an inactive conformation in which the luminescent groups carried by the molecule are inhibited from emitting radiation. A writer to and reader of the data storage medium are also disclosed.

Abstract: In a multilayer recordable optical medium, each recording layer includes a luminophore that fluoresces under reading laser light and a quencher capable of quenching the luminophore fluorescence. Initially, the luminophore and the quencher are not intermixed, so that the default state of the luminophore is fluorescent. During writing, focused writing radiation heats a spot in the medium so as to cause the luminophore and the quencher to be intermixed, thereby quenching the fluorescence.

Abstract: An optical pickup is disposed which irradiates a laser beam onto an optical disc where a guide groove having characteristics of thermal interference (heat discoloration) is spirally formed. The optical pickup irradiates the laser beam along the guide groove to conduct one of data recording in which pits indicating a data length are formed, and visible-image formation in which a part of the optical disc is discolored. The laser beam irradiation position is controlled so that the data recording is conducted with starting from the inner peripheral side of the optical disc, and the visible-image formation is conducted with starting from the outer peripheral side of the optical disc.

Abstract: The present invention relates to an optical memory device and an operating process thereof. The optical memory device have a recording layer containing a photochromic compound and an electron-accepting compound which is a Lewis acid compound having a Lewis acid part and a long chain part having carbon atoms of C12 or more. One aspect of the operating process has a recording step which recording is performed on the optical memory device by irradiating visible light corresponding to the absorption band of the colored photochromic compound for recording using decolorizing, before and after recording, heating treatments are performed to control the decolorizing sensitivity of the photochromic compound, and an erasing step which ultraviolet light is irradiated to the area including the recorded portion in order to uniformly color the recording layer again.

Abstract: The present invention provides methods and apparatuses for writing information to, reading information from, and erasing information on a luminescent data storage medium comprising Al2O3. The method includes writing and erasing of the information using photo ionization via sequential two-photon absorption and non-destructive reading the information using fluorescent detection. The apparatuses for writing and reading the information incorporate confocal detection and spherical aberration correction for multilayer volumetric fluorescent data storage. The methods also allow multilevel recording and readout of information for increased storage capacity.

Abstract: Blue color forming sub-layer (205), green color forming sub-layer (206) and red color forming sub-layer (207) which start to form colors upon application of different amounts of energy are superposed on the image surface of optical disc (D). The color forming sub-layer which requires the smallest amount of energy to form color is first illuminated with laser of the power required to realize color formation from that sub-layer; subsequently, this sub-layer is illuminated with ultraviolet radiation to fix the color it has formed. Then, the next color forming sub-layer is illuminated with laser of the required power and after fixing the color it has formed, the last color forming sub-layer is illuminated with the required laser to form color.

Abstract: A secure, optically readable data medium comprises a data-carrying zone readable by a read light beam, and at least a portion that is photosensitive, being provided with a photosensitive material and exposed to the read light beam. The photosensitive material contains an active compound taken from the family of diarylethenes.

Abstract: An optical recording medium of the present invention includes a recording layer, in which information is recorded in a three-dimensional manner in an in-plane direction and a thickness direction of the recording layer. The recording layer includes a thermochromic material whose color changes reversibly according to a temperature. The thermochromic material converts absorbed light into heat, increases its light absorptance as the temperature rises and, when the temperature reaches a first predetermined temperature or higher, changes irreversibly to a translucent substance whose color does not change according to a temperature change. In this optical recording medium, since only the position on which irradiated light is focused develops color so as to increase light absorptance, this property is utilized for recording and reproducing information.

Abstract: A recording medium comprises a substrate and a recording layer overlaid on the substrate. The recording layer comprises a material, which has properties such that, when recording light having a predetermined wavelength &lgr;1 is irradiated to the material, the material is capable of being caused to change into a fluorescent material and such that, when excitation light having a wavelength &lgr;2 is then irradiated to the thus formed fluorescent material, the fluorescent material is capable of being caused to produce fluorescence. The wavelength &lgr;1 of the recording light and the wavelength &lgr;2 of the excitation light may be identical or different. The substrate may be constituted of a material having properties such that, when the excitation light is irradiated to the material, the material does not produce fluorescence having a wavelength identical with the wavelength of the fluorescence produced by the fluorescent material.

Abstract: In a multilayer recordable optical medium, each recording layer includes a luminophore that fluoresces under reading laser light and a quencher capable of quenching the luminophore fluorescence. Initially, the luminophore and the quencher are not intermixed, so that the default state of the luminophore is fluorescent. During writing, focused writing radiation heats a spot in the medium so as to cause the luminophore and the quencher to be intermixed, thereby quenching the fluorescence.

Abstract: An optical memory system includes memory cells which utilize synthetic DNA as a component of the information storage mechanism. In the preferred embodiment, memory cells contain one or more chromophoric memory units attached to a support substrate. Each chromophoric memory unit comprises a donor, an acceptor and, at some time during its existence, an active quencher associated with the donor and/or the acceptor. The donor and the acceptor permit non-radiative energy transfer, preferably by Förster energy transfer. To write to the memory cell, the quencher is rendered inactive, preferably by illumination with ultraviolet light. To read, the chromophoric memory units in a read portal are illuminated, and the read illumination is detected. In the preferred embodiment, multiple chromophoric memory units having resolvable read properties are contained within a single read portal. In this way, a multibit word of data may be read from a single diffraction limited read portal.

Abstract: An apparatus and method for reproducing information stored in a fluorescent multilayer information carrier. The apparatus utilizes auto-focusing and auto-framing techniques when reading the information to enable parallel reading from uniformly moving carrier. To avoid discontinuity in motion, an actuator with an objective lens performs periodic motion following a specific moving information page and, after the end of reading of this page, returns back to follow the next page.

Abstract: A method and device for reproducing information from an optical recording medium having a recording layer containing a photochromic material for recording information and an optical recording medium, the method, device and medium being capable of utilizing the conventional method which reproduces information based on the amount of reflected light from the recording layer by irradiation of the recording layer with information-reproducing light, and being capable of reproducing information without destruction of the information recorded on the recording layer.

Abstract: The invention provides a near-field photochromic device for a supra-density optical memory, comprising a scanner carrying a data storage medium, an optical head having a tip, to be used for recording, readout and erasing, and located in close proximity to the data storage medium, and at least two lasers, alternatingly optically alignable with the optical head, wherein the data storage medium is a film consisting of a photochromic compound and wherein the distance between the tip and the data storage medium is within the limits of the near field of the optical head.

Abstract: An optical memory system includes memory cells which utilize synthetic DNA as a component of the information storage mechanism. In the preferred embodiment, memory cells contain one or more chromophoric memory units attached to a support substrate. Each chromophoric memory unit comprises a donor, an acceptor and, at some time during its existence, an active quencher associated with the donor and/or the acceptor. The donor and the acceptor permit non-radiative energy transfer, preferably by Forster energy transfer. To write to the memory cell, the quencher is rendered inactive, preferably by illumination with ultraviolet light. To read, the chromophoric memory units in a read portal are illuminated, and the read illumination is detected. In the preferred embodiment, multiple chromophoric memory units having resolvable read properties are contained within a single read portal. In this way, a multibit word of data may be read from a single diffraction limited read portal.

Abstract: An optical memory system includes memory cells which utilize synthetic DNA as a component of the information storage mechanism. In the preferred embodiment, memory cells contain one or more chromophoric memory units attached to a support substrate. Each chromophoric memory unit comprises a donor, an acceptor and, at some time during its existence, an active quencher associated with the donor and/or the acceptor. The donor and the acceptor permit non-radiative energy transfer, preferably by Forster energy transfer. To write to the memory cell, the quencher is rendered inactive, preferably by illumination with ultraviolet light. To read, the chromophoric memory units in a read portal are illuminated, and the read illumination is detected. In the preferred embodiment, multiple chromophoric memory units having resolvable read properties are contained within a single read portal. In this way, a multibit word of data may be read from a single diffraction limited read portal.

Abstract: An optical memory system includes memory cells which utilize synthetic DNA as a component of the information storage mechanism. In the preferred embodiment, memory cells contain one or more chromophoric memory units attached to a support substrate. Each chromophoric memory unit comprises a donor, an acceptor and, at some time during its existence, an active quencher associated with the donor and/or the acceptor. The donor and the acceptor permit non-radiative energy transfer, preferably by Forster energy transfer. To write to the memory cell, the quencher is rendered inactive, preferably by illumination with ultraviolet light. To read, the chromophoric memory units in a read portal are illuminated, and the read illumination is detected. In the preferred embodiment, multiple chromophoric memory units having resolvable read properties are contained within a single read portal. In this way, a multibit word of data may be read from a single diffraction limited read portal.

Abstract: A color separation prism in which are arranged, in the order according to the direction in which the light from the objective travels: a first prism which extracts a predetermined wavelength component; a first air gap; a second prism which extracts a predetermined wavelength component; a second air gap; and third and fourth prisms that are joined to each other, wherein, in particular, a light reflected by the joint plane is totally reflected by a surface adjacent the second air gap and guided to an image pickup device.

Abstract: The recording method and apparatus according to this invention is an "optical recording method utilizing a simulated photon echo" in which information is recorded by irradiating data a.d record excitation lights at the same time or at different times on the same location of a recording medium, and in which the delay time of a record excitation light electric field and a data light electric field is recorded as the information by use of a common incoherent light split into two equal parts: the data light and the record excitation light. In the reproducing method and apparatus according to this invention, reproducing excitation and probe lights are illuminated on the recording medium and the stimulated photon echo light emitted from the medium by illumination of the reproducing excitation light overlaps the probe light. The "stimulated photon echo" reproducing the information is utilized by converting the synthetic light obtained from the overlap into an electrical signal at a photo detector.

Abstract: An optical pickup system capable of improving productivity by facilitating the arrangement and assembly of components thereof and preventing an error caused by wavelength variation of a laser beam includes a laser diode used as a light source, a grating for classifying a beam from the laser diode into three diffracted lights of zero, +first and -first orders, an objective lens placed the grating and an optical disc for focusing the three diffracted lights passed through the grating on the optical disc while receiving the lights reflected from the optical disc, a photodetector divided-by-five formed of five split areas partitioned in the longitudinal direction to be arranged side by side in the sequence of fourth, first, second, third and fifth split areas to receive the lights reflected from the optical disc focusing on the respective split areas for detecting a focus error and a tracking error and reading out information recorded on the optical disc, and a hologram element divided-by-two formed of a first ho

Abstract: An optical data storage system is disclosed in which information is encoded and decoded in the spectrally resolved optical properties of the storage medium. An optical storage medium scatters an incident light excitation into both elastic and inelastic light beams. The inelastically scattered light serves as an optical data storage channel, whereby the inelastic light scattering properties of the medium are modulated in accordance with the information to be encoded or decoded. The elastically scattered light is also used as a data channel as in conventional optical storage systems, as well as for control functions. By increasing the optical processing gain, relatively weak inelastic scattering channels may provide a signal:noise ratio sufficient for storage applications. Furthermore, incorporation of a plurality of independently addressable inelastic scattering channels increases the storage density of the medium.

Abstract: A method for recording and reproducing information using an optical memory device being constituted by a transparent substrate, a recording film formed on the substrate and made of a resin containing a photochromic material dispersed therein, the photochromic material being capable of reversibly changing its state from achromatic to chromatic and absorbing light of at least 780 nm wavelength in the chromatic state, and a reflecting film formed on the recording film for reflecting light, the method including the steps of: applying a visible light beam of a long wavelength onto the optical memory device to turn said recording film into the achromatic state for initialization, applying thereafter a visible light beam of a short wavelength onto the optical memory device to turn the recording film into the chromatic state in accordance with binary-coded data of information for recording the information, and applying another visible light beam of a long wavelength having a light intensity lower than that of the vis

Abstract: An optical pickup for use in various optical recording/reproducing apparatus includes a general-purpose lamp producing a wide range of light wavelengths, a converging device for converging the light of the lamp, and a pinhole and color filter for enhancing the temporal/spatial coherence of the light. The lamp radiates light containing the intensity of a laser and spectral distribution characteristic of a laser.

Abstract: The invention relates to an optical computing element for use in an optical computer utilizing computing light rays having a plurality of wavelength components. The optical computing element comprises a photo-chemical hole burning element which functions as a wavelength selecting filter of the computing light rays. Therefore, the optical computer using the photo-chemical hole burning element of the invention can perform arithmetic operations by taking advantage of differences in optical wavelength. The computer can efficiently perform bulky arithmetic processing, and can also speedily perform arithmetic operations through simultaneous parallel processing for information.

Abstract: A three-dimensional optical recording medium is made of a photo-induced refractive index-changing material or two-photons absorbing material, which is based on photo-dissociation or photopolymerization. An optical information recording apparatus comprises a device for loading a three dimensional recording medium; a device for generating a high coherent optical pulse or a train of partially-coherent optical waves; a device for splitting the optical pulse into two pulse components and causing the two pulse components to propagate in the recording medium from opposite directions to meet at a predetermined three-dimensional position; a device for converging a light beam in the recording medium into a parallel beam; and a device for discretely scanning the meeting position of the pulse components to ensure three-dimensional recording in accordance with information to be recorded.

Abstract: A photochromic optical disk read/write apparatus is provided having, in addition to the beams of light for reading and writing, a tracking light beam which is used for tracking during the reading, erasing, and writing of information signals and a standby state so that deterioration in the recording medium quality can be lessened.

Abstract: An array of diode lasers selected to emit at certain fixed wavelengths is assembled to temperature stabilzed Bragg reflectors to assure maintenance of the selected wavelength within 1 .ANG.. One laser is included in the array for each wavelength at which absorption will occur within a photochemically active optical storage medium. Each temperature stabilized laser is focussed by a lens onto an optical storage medium containing photoactive chemical components containing guest and hose molecules, as is known in the art. Light emitted by each laser will be used to burn a pit for each bit of data at the locations of the storage medium. One or more photodetectors located on the opposite side of the sotrage medium to detect the presence or absence of a hole with respect to the selected wavelength with which the hole was initially burned. A similar device is available with a temperature stabilized tunable laser which accurately controls the selected wavelength withing 1 .ANG..

Abstract: An apparatus in accordance with the present invention sequentially fixes the wavelength of a light beam irradiated from a light source whose oscillation wavelength sequentially varies to a plurality of different wavelengths to a recording medium to required wavelengths each capable of forming a hole at absorption spectrum of the recording medium, synchronizes timing of change of the wavelength of the light source with timing of recording or regenerating each bit of information, records the optical hole formed in a manner that each bit of information corresponds to the wavelength varying in sequence, and detects the formed hole to regenerate information.

Abstract: Recording medium having islands of light-emitting material in regions formed between a transparent substrate, and a reflective layer disposed on one principal surface thereof. The islands of light-emitting material are sensitive to illuminating light incident thereupon, and in response thereto, emit light having a different wavelength than said illuminating light. Reproducing apparatus separates an overall reflected light from the recording medium into first reflected light corresponding to a reflected scanning light, and second reflected light corresponding to emitted light from the light emitting material.