Abstract: An optical pickup is provided for recording and reproduction of information onto and from an optical disk. In the optical disk, in a forward optical path, a single polarized optical beam is converted to plural polarized optical beams. Polarization modes of the plural polarized optical beams are then converted to a polarization mode suitable for one of the recording and the reproduction to produce polarization-converted optical beams and to radiate the polarization-converted optical beams to the disk. In the backward optical path, polarization modes of the polarization-converted optical beams reflected from the disk are returned to the same polarization mode as that of the plural polarized optical beams, so that plural polarized reflected optical beams are produced. Polarization modes of the plural polarized reflected optical beams are then returned to the same polarization mode as the single polarized optical mode.

Abstract: It is an object of the invention to record or reproduce information through the use of holography, attain a small configuration of the optical system for recording or reproduction, and improve the S/N ratio of reproduced information.

Abstract: The present invention includes a method and apparatus for reducing the effective spot size of a laser beam by selectively polarizing different regions of a light beam. By suitably dividing a beam into a plurality of regions and suitably changing the polarization of the regions in different directions, certain regions with opposite polarization cancel each other out, thereby effectively eliminating these regions from analysis by the detector. When focusing onto a high density optical disk, adjacent tracks do not see the canceled, circularly-polarized portions of the beam, but instead, only see the smaller, plane-polarized portion in the center of the beam. When reading from a high density optical disk, detectors using a known differential detection scheme similarly do not see the canceled, circularly-polarized portions of the beam, but instead, only see the smaller, plane-polarized portion in the center of the beam.

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

Abstract: It is an object of the invention to allow the use of a practical light source to record information in each information recording area of a recording medium having a plurality of information recording areas through the use of holography while moving the recording medium.

Abstract: An optical element supporting device has one ends of two parallel plate springs, which are extended in a tangential direction, fixed to a holder, has the other ends thereof fixed to a fixture member, and has a collimator lens locked in an opening of the holder. A base fixed to the bottom of the fixture member has two yokes formed thereon. Magnets each polarized in two directions are fixed to the insides of the yokes. Coils are fixed to two surfaces of the holder opposed to the magnets. A target is fixed to the holder, and a sensor is fixed to the bottom of the base. When a current flows into the coils, electromagnetic force is produced along an optical axis due to the interaction between the coils and the magnets opposed to the coils. This causes the parallel plate springs to loosen. Consequently, the holder, target, collimator lens, and coils move as a whole along the optical axis.

Abstract: An optical pickup apparatus comprises first, second and third light sources to emit light fluxes of wavelength &lgr;1, &lgr;2 and &lgr;3 for conducting recording and/or reproducing information for first, second and third optical information recording mediums having respective protective substrates of thickness t1, t2 and t3 and a diffractive optical element located on a common optical path for the first, second and third light sources. A converged-light spot is formed on the first optical information recording medium with m-th order diffracted-light ray of the wavelength &lgr;1, on the second optical information recording medium with n-th order diffracted-light ray of the wavelength &lgr;2, and on the third optical information recording medium with k-th order diffracted-light ray of the wavelength &lgr;3 generated by the diffractive optical element respectively, wherein one of m, n and k is different from one of other two numbers.

Abstract: An object of the present invention is to record and reproduce information through the use of holography, and achieve compact configuration of an optical system with no reduction in the amount of information. For recording, a spatial light modulator (25) generates information light and a phase spatial light modulator (17) generates recording-specific reference light having a spatially modulated phase. The information light and the recording-specific reference light are projected onto one side of an information recording layer (3) of an optical information recording medium (1) coaxially so as to converge on a reflecting surface. At the time of recording of information, P-polarized recording-specific reference light and S-polarized information light are each optically rotated by a two-way split optical rotation plate (21) in directions different between respective half areas of the cross section of the beam thereof.

Abstract: There is disclosed a storage apparatus which is of a system of utilizing a polarized state change by Kerr effect to read information from a storage medium and which easily and precisely performs adjustment to compensate for a phase deviation between both P, S polarized components attributed to an optical system. Phase plates 500, 510 are disposed between a fixed optical section 200 and a movable optical section 190 and the inclination angles of the phase plates are adjusted.

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

Abstract: An optical device including a light source for emitting diverging light, a polarizing beam splitter for transmitting or reflecting the diverging light according to a polarized light component, a collimator lens for converting the diverging light transmitted through the polarizing beam splitter into collimated light, and an objective lens for focusing the collimated light on an object. The optical device further includes an optical element arranged between the collimator lens and the objective lens for producing a phase difference of +90° ±15° or −90°±15° between P-polarized light and S-polarized light. The optical element has a principal axis perpendicular or parallel to a plane of incidence of the diverging light on the polarizing beam splitter. For example, the optical element is provided by a quarter-wave plate having an optic axis perpendicular or parallel to the plane of incidence of the diverging light on the polarizing beam splitter.

Abstract: The present invention provides a laser heterodyne interferometer based system for audibly producing sounds recorded on a cylinder recording, such as an Edison type wax cylinder, or a 33, 45 or 78 RPM LP (long play) record. The system generally comprises an optical system mounted on an optical platform, and an audio recording medium mounted on a platform operatively positioned relative to the optics platform. The optical system comprises an interferometer type structure that uses laser generated light propagated either through free space or through fiber, a platform on which the optical system is mounted, and a platform on which the recording media (e.g., cylinder or record) is mounted.

Abstract: An optical pickup includes a semiconductor laser for emitting light at a wavelength &lgr;1 and a semiconductor laser for emitting light at a different wavelength &lgr;2 from the wavelength &lgr;1. The light at the wavelength &lgr;1 transmitted through an objective lens forms a light-collecting spot on an optical disk to record/reproduce information thereon. The light at the wavelength &lgr;2 transmitted through the objective lens forms a light-collecting spot on an optical disk to record/reproduce information thereon, the two optical disks having different substrate thicknesses. Between the semiconductor laser and the objective lens is there provided a combination-type diffractive element fabricated by combining two raw materials having different refractive index behaviors in relation to wavelength at a combining plane shaped as a grating.

Abstract: An optical pickup performing recording, reproduction and deletion of information onto an optical recording medium, said optical pickup includes light sources of blue wavelength zone, red wavelength zone and infrared wavelength zone; a single object lens which condenses a light from any of the light sources; and a single aberration correction device disposed in a common light path between each of the light sources and the object lens.

Abstract: An optical disk apparatus includes a light source for emitting light in a prescribed wavelength range, an objective lens system for causing the light emitted from the light source to be focused onto a storage disk, and a reproduction signal system for causing return light from the storage disk to be conduced to a detector. The light emitted from the light source has a direction of polarization parallel to a recoding track of the storage disk. The objective lens system has transmission factors for s-polarized light and p-polarized light that are defined relative to the objective lens system. The transmission factor for s-polarized light is greater than the transmission factor for p-polarized light.

Abstract: An optical scanning device for scanning a recordable optical disk (20) with a laser beam having a linear polarisation. A quarter wave plate (16) is used to alter the polarisation of the beam on reflection from the disk. A partially polarising beam splitter (8) is used and arranged such that a proportion of intensity of the incident beam passed is greater than a proportion of intensity of the reflected beam. A relatively high optical signal power at the disk (20) can be achieved for recording purposes whilst allowing the beam splitter (8) to be manufactured in a relatively efficient manner.

Abstract: The above-discussed and other problems and deficiencies of the prior art are overcome or alleviated by the several methods and apparatus of the present invention for a block-by-block data retrieval method and system, wherein the data is stored in a multiple layer polarization selective, wavelength selective, or a combination of polarization selective and wavelength selective films.

Abstract: An optical pickup device for reading information recorded on an optical disc, the device having a semiconductor laser, a half mirror and a light-receiving element. The semiconductor laser and the half mirror are attached to each other via a grating, and the light-receiving element is attached on the surface of the half mirror.

Abstract: An optical recording medium allowing high-density recording, where a groove having a shallow U-shaped cross section wider than certain width, a master for manufacturing optical recording medium, a manufacturing apparatus thereof, and a manufacturing method thereof are provided. A exposure beam (61) and a exposure beam (62) are recombined together with a first exposure beam (60) in a second PBS (47) so that traveling directions thereof may be the same direction. At this time, the exposure beam (61) and the exposure beam (62) are arranged so that both optical axes may be aligned at certain distance. Thereby, a width of a spot formed by combining these beams can be extended, and light exposure of the spot can be proper to form a shallow groove, as typically showed in FIG. 3.

Abstract: In a servo operation, position-controlling light, which is red light, is projected onto a recording medium so as to converge to a minimum diameter on a reflecting surface of the recording medium. In a recording operation, information light and recording-specific reference light, each of which is green light, are projected coaxially onto one side of an information recording layer of the recording medium so as to converge to a minimum diameter at an identical position located off the reflecting surface. Information is recorded in the information recording layer in the form of an interference pattern resulting from interference between the information light yet to impinge on the reflecting surface and the recording-specific reference light reflected by the reflecting surface and an interference pattern resulting from interference between the recording-specific reference light yet to impinge on the reflecting surface and the information light reflected by the reflecting surface.

Abstract: Two standard marks are set on two adjacent respective recording tracks, aligned in a direction perpendicular to the said recording tracks in the unit area for recording and reading that includes said the two recording tracks. Recording on the recording track is performed by forming round-marks that have information shown by which side of the two tracks they exist in and by what distance they are from each of the said two standard marks in the set area including the said two recording tracks. Reading information on the recording track is performed by reading two recording tracks at the same time or alternately.

Abstract: The magneto-optical recording and reproducing apparatus comprises a laser source, a collimator lens, an objective lens, a magneto-optical recording medium, a servo signal detector, a reproduction signal detector, a signal separating polarization beam splitter, a data recording polarization beam splitter and a data reproducing polarization beam splitter. The data recording polarization beam splitter and the data reproducing polarization beam splitter are disposed on a rotatable PBS holder so that the positions of the beam splitters can be changed according to whether the apparatus is for reproducing data or for recording data. With the apparatus, the quantity of light emitted from the laser source can be reduced since the optical path efficiency of the laser beam to the medium is enhanced at the time of recording, and carrier-output/noise ratio C/N can be increased at the time of reproducing.

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

Abstract: An optical system of an optical pick-up device 1 comprises a half mirror 13 and a prism 14 which serve to guide a first laser beam L1 for a CD and a second laser beam L2 for a DVD to the optical recording medium side and a common light receiving element 19. The half mirror 13 is set to have a ratio of a reflectance to a transmittance of 5:1 in the first laser beam L1 to be a P polarized light and the prism 14 is set to have a ratio of a reflectance to a transmittance of 1:3 in the first laser beam L2 having a P polarization component and an S polarization component mixed. The first laser beam for a CD can be guided to the optical recording medium without a light quantity loss. At the same time, a return light Lr can be sent in a sufficient light quantity back to the light receiving element 19 for servo signal generation. Therefore, it is possible to implement a reliable CD recording operation by using the first laser beam.

Abstract: A compatible optical pickup includes an optical disc, an objective lens, a diffractive device, and a divergent lens. The optical unit emits a short wavelength light beam corresponding to a high density optical disc and a long wavelength light beam corresponding to a low density optical disc. The objective lens forms a light spot on the high density optical disc and the low density optical disc and the diffractive device diffracts the short wavelength light beam to correct chromatism according to a change in a wavelength of the short wavelength light beam. The divergent lens refracts the long wavelength light beam toward the objective lens to increase a working distance with respect to the low density optical disc.

Abstract: The invention is a multiple wavelength optical pickup head. It contains at least three laser beam generating units for generating laser beams with different wavelengths, a beam guiding unit installed on the optical path of the pickup head to guide the propagation of the laser beams, and a photo-detector that converts light signals into the corresponding electrical signals. The beam guiding unit includes a diffractive optical element and a convergent objective lens. After the laser beam generating units send out laser beams, the beam guiding unit leads them to the diffractive optical element so that the laser beams have different diffraction angles and effects. Through the focus of the convergent objective lens, the laser beams are converged to the data surfaces of optical recording media and reflected to the photo-detector, retrieving data from at least three kinds of optical recording media each with a kind of data storage densities.

Abstract: An optical pickup for reading information from a recording medium having a plurality of prepits or for recording information onto the recording medium is provided. The optical pickup includes: a light emitting device for emitting a light beam to the recording medium; a dividing device for dividing the light beam reflected by the recording medium into a first divided beam and a second divided beam; an astigmatism producing device for producing astigmatism in the first divided beam; a first light receiving device for receiving the first divided beam from the astigmatism producing device; and a second light receiving device for receiving the second divided beam from the dividing device.

Abstract: An optical pickup which appropriately detects reflected light and return light reflected back from an information recording medium even if a laser light B1 emitted from a light source varies in wavelength. The transmittances of a half mirror to the laser light B1 emitted from the light source, and to the reflected light Bwr, Ber or the return light Brr reflected back from the information recording medium are preset according to a predetermined condition, i.e., Tpc(&lgr;c)/Tp(&lgr;)=(1−Ts(&lgr;)/(1−Tsc(&lgr;c))×(Tsc(&lgr;c)/Ts(&lgr;)).

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

Abstract: A pickup device has a light source, an objective lens for converging rays of light emitted from a light source onto a recording medium, a lens holder for holding the objective lens, and supporting element for movably supporting the lens holder. The pickup device is uniquely featured in that a part of the objective lens and a part of the lens holder are movable relative to each other so as to adjust an inclination of an optical axis of the objective lens.

Abstract: In an optical head apparatus, reflected light from the disk is diffracted by a hologram optical element, and received by an optical detector. A focusing error signal is detected from −1st-order diffracted light of the hologram optical element. A tracking error signal by the differential phase method, a tracking error signal by a push-pull method and the data signal recorded on the disk are detected from +1st-order diffracted light of the hologram optical element. A diffraction efficiency of the +1st-order diffracted light is higher than a diffraction efficiency of the −1st-order diffracted light.

Abstract: An optical pickup capable of reducing cross-talk due to signal interference of adjacent tracks of an optical medium during playback of a radio frequency (RF) signal from a main track of the optical recording medium. In the optical pickup, optical spots can be converged on the main track and the adjacent tracks of the recording medium without a time lag, wherein different polarized component beams are focused as a primary optical spot and secondary optical spots on the main and adjacent tracks, respectively, of the optical recording medium. Thus, the primary optical spot and the secondary optical spots, which have different polarized components, can be separately received by different light receiving portions. Also, the optical spots are photoelectrically converted in the light receiving portions and are differentially amplified through multiplication using a predetermined operation constant, thereby reducing cross-talk from a detected RF signal.

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

Abstract: In an optical head apparatus including a first light source for emitting a first light beam having a first wavelength, a second light source for emitting a second light beam having a second wavelength different from the first wavelength, an objective lens, a photodetector, and first and second optical combining/splitting elements, the first optical combining/splitting element receives the first light beam from the first light source to outgo most of the first light beam therefrom to the second optical combining/splitting element and receives the first and second light beams from the second optical combining/splitting element to outgo most of the first and second light beams therefrom to the photodetector.

Abstract: A polarizing beam splitter for separating an upstream beam from a downstream beam according to the polarization of an incident beam is provided between first and second light sources emitting laser beams at respective wavelength and an objective lens. A phase plate for providing a phase difference to a beam incident on the polarizing beam splitter is provided between the polarizing beam splitter and the light sources. A portion of the laser beam incident on the polarizing beam splitter is reflected by the polarizing beam splitter and caused to be incident on a photo-detecting unit, so as to prevent an unnecessary portion of the laser beam is incident on the photo-detecting unit. According to the invention, the laser beam is used efficiently and the cost of fabricating an optical disk apparatus is reduced by eliminating a need for a gain controlling circuit in the photo-detecting unit.

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

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

Abstract: An optical scanning device for scanning a recordable optical disk (20) with a laser beam having a linear polarisation. A quarter wave plate (16) is used to alter the polarisation of the beam on reflection from the disk. A partially polarising beam splitter (8) is used and arranged such that a proportion of intensity of the incident beam passed is greater than a proportion of intensity of the reflected beam. A relatively high optical signal power at the disk (20) can be achieved for recording purposes whilst allowing the beam splitter (8) to be manufactured in a relatively efficient manner.

Abstract: An optical recording medium having a laminated structure portion(4) including a light-emission layer(3) and a recording layer(2). The light-emission layer(3) is made of a light-emission material excited by reproducing laser light to emit fluorescent light, and the recording layer(2) is made of a material in which at least a refractive index or an absorption coefficient can be changed relative to light emitted from the light-emission layer by recording laser light. The recording layer(2) is disposed to be closer to a side into which reproducing laser light is introduced than the light-emission layer(3). Then, recorded information recorded on the recording layer by the change of the refractive index or the absorption coefficient is read out from the recording layer as the change of intensity of light emitted from the light-emission layer(3) when it is irradiated with reproducing laser light. This optical recording medium can realize an optical memory which can generate a reproduced signal with a high S/N.

Abstract: An optical recording and pickup head having a flat plate lens of a staircase type diffraction grating structure is compatible with a DVD and a CD-RW.

Abstract: The invention relates to an optical information recording/reproduction apparatus and an optical pickup apparatus in which the configuration of a light receiving element is optimized particularly in a focus error signal and/or tracking error signal. Thereby, the offset due to the stray light generated from the light emitted from a light emitting element which is incident directly onto the light receiving element without incidence onto a recording medium is equalized approximately to 0.

Abstract: A liquid crystal element is provided as a polarization plane rotating means between a laser beam source and a beam splitter. Light emitted from the laser beam source passes through the liquid crystal element and the beam splitter, and is converted into parallel light by a collimating lens. The collimated light is incident on a first light-selection means, is reflected at a flat first reflecting surface or a concave second reflecting surface, and is then incident on a super-resolution cut-off filter as a second light-selection means. The light having passed through the second light-selection means is incident on an objective lens, and is converged onto a recording surface. The selection of the reflecting surface of the first light-selection means is determined based on an operation mode of the liquid crystal element.

Abstract: An optical information storage unit for reproducing information recorded on lands and grooves of a magneto-optical recording medium by means of a reflected light obtained from a luminous flux which has been emitted from a light source, irradiated onto the recording medium and reflected from the recording medium. The optical information storage unit includes a first wave plate on which the reflected light from the magneto-optical recording medium is incident; a diffraction grating on which the light having been transmitted through the first wave plate is incident; a second wave plate on which the light having been transmitted through the diffraction grating is incident; and a polarization detecting unit on which the light having been transmitted through the second wave plate is incident.

Abstract: A compatible optical pick-up device includes a first light source to emit a first light, a second light source to emit a second light and having a wavelength that is different from that of the first light, a first optical path converter to reflect the first light irradiated from the first light source onto an optical path, a second optical path converter to reflect the first light from the first optical path converter and transmit the second light irradiated from the second light source onto the optical path, an objective lens to converge the light received from the second optical path converter towards an optical recording medium, and a photo-detector to receive an incident light reflected by the optical recording medium. The compatible optical pick-up device reduces the difference between transmissivities depending on the polarization status of the incident light by adopting a transmission-type optical path converter such that the optical recording medium is minimally affected by the birefringence.

Abstract: A 3-beam-generating grating 2, a collimating lens 3, a polarizing beam splitter 4, a rising mirror 5 and an objective lens 6 are arranged sequentially in the optical path between a semiconductor laser device 1 and an information recording medium 7. The reflecting face of the polarizing beam splitter 4 has a reflection characteristic such that the reflectance is minimum for return light L2 at an angle of 45 degrees whereas the reflectance increases as the incident angle of the return light L2 deviates from 45 degrees. This realizes an optical head device that is not likely to cause the decrease in tracking error signals even if the objective lens shifts in radial directions of the recording medium.

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: A hologram 48 as optical path branching element has two hologram areas 48b and 48c for diffracting a return light beam into different directions, and a boundary 48a between them is inclined at a predetermined angle with respect to the direction corresponding to the direction of radius of the optical disc 11. The light diffracted by the one hologram area 48b is received by light-receiving sections A1 and A2 of a photodetector IC 44, and the light diffracted by the other hologram area 48c is received by light-receiving sections A3 and A4. With the above-described structure, a position deviation of an objective lens 27 at the time of access to a desired recording track on an optical disc 11 can be detected by finding the difference between the light quantity of the light received by the light-receiving sections A1 and A2 of the photodetector IC 44 and the light quantity of the light received by the light-receiving sections A3 and A4.

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

Abstract: An optical pickup for recording and reproducing information on a plurality of record media respectively, the pickup has

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.