Abstract: The present invention is in the field of optical recording media, and is directed to an optical recording medium which comprises the following layers;a) a grooved transparent substrate (1), superposed byb) a recording layer comprising a partial mirror (2) of a material having a high complex index of refraction which is not within the pentagon defined by the vertices 7.15 - i3.93, 7.15 - i5.85, 8.96 - 6.28, 9.56 - i5.90, and 8.14 - i3.77 in the n,k plane, superposed by a buffer layer (3) comprising a nonliquid-crystalline high-molecular weight material and optionally a dye, superposed by a thick reflective layer (4), together forming a Fabry-Perot wherein the thickness (d) of the buffer layer within the grooves is set so that the reflection of the medium is in the high reflective state, optionally superposed byc) a protective coating (5).By virtue of the partial mirror, the buffer layer, and the thick reflective layer a Fabry-Perot etalon is created.

Abstract: An optical recording element is disclosed. The element has a transparent substrate and on the surface of said substrate, a recording layer and a light reflecting layer wherein recording layer comprises a mixture of a metallized formazan dye and cyanine dye and the unrecorded layer is such that the real part of the refractive (n) at 780 nm is greater than 1.8 and the imaginary part (k) is less than 0.15. The metallized formazan dye has a k value of 0.03 to 0.07.

Abstract: An optical recording medium having a phase-changing material layer served as a recording layer is composed to excellently repeat the rewrite of bits independently of the line speed of the writing light. The amount of the additive to be added to the phase-changing material layer is regulated in relation to the line speed for the write. The additive is added for suppressing the crystallization.

Abstract: A glass substrate manufacturing method advantageously applicable to magnetic recording disk glass substrates, LCD glass substrates, photomasks glass substrates, or optical memory glass substrates. The method includes the steps of forming a film of a solution on at least a principal surface of a sheet glass formed using a down-drawing method, the solution containing a water soluble inorganic material and a surface-active agent; sandwiching both sides of a single sheet glass on which the film is formed or of a laminated structure of two or more sheet glasses with a densified sheet with a high flatness to pressure the single glass or laminated structure; and heating and annealing the single sheet glass or laminated structure to flatten the same. The end side of the flatten glass substrate is treated with a treating solution containing a hydrofluosilicic acid.

Abstract: An information recording medium, a storage case for storing an information recording medium, or a sheet for use with an information recording medium, has a light-emitting area coated with a phosphorescent paint, and a luminous paint area coated with a luminous paint for emitting exciting light to stimulate the light-emitting area to emit light, the luminous paint area being disposed adjacent to or on the light-emitting area.

Abstract: A phase change optical recording medium in which writing, reading and/or erasing of information is conducted by utilizing change of phase of a recording layer by irradiation of a light beam, said recording medium comprising a substrate, a first transparent protecting layer of an amorphous dielectric material on the substrate, a recording layer of a chalcogen alloy on the first transparent protecting layer, an adhesive layer of a crystalline sulfide 10 to 30 nm thick on the second recording layer, a second transparent protecting layer of an amorphous dielectric material on the adhesive layer, and a reflection layer of a crystalline alloy mainly comprising aluminum on the adhesive layer.

Abstract: The invention provides a phase change type optical recording medium enabling an increased jitter concomitant with repeated overwriting to be restrained or substantially eliminated. In the optical recording medium comprising a phase change type recording layer on a substrate, the recording layer has a lower dielectric layer in contact with a lower side thereof and an upper dielectric layer in contact with an upper side thereof, and at least one of the upper and lower dielectric layers contains zinc sulfide, and further includes a metal element A that has a standard free energy for forming a sulfide thereof lower than a standard free energy for forming ZnS at 0 to 1,000.degree. C. The ratio of metal element A to all metal elements in the zinc sulfide-containing dielectric layer is less than 2 at %. Metal element A is typically Ce, Ca, Mg, Sr, Ba, and Na.

Abstract: A desired writable optical data recording medium has a transparent substrate 1 where a side wall of a recess is connected to a land surface by a curved surface. A data recording portion of a dye material may be placed only in recesses of a pre-formatted pattern on a transparent substrate, and a reflective layer may be formed on the data recording portion and on the exposed land area between neighboring recesses. The medium can show reflectivity of not less than 65% on reproduction and reduce the cost for manufacturing thereof.

Abstract: An optical information medium comprises a first disc forming information recording layer on a main surface thereof, a second disc being bonded to the first disc at the surface where the information recording layer is formed by way of an adhesive. A hydrophilic resin film is formed on the surface of the disc at the inner peripheral side extending from the center hole to the information non-recording area. The hydrophilic resin film is damp and is rough compared with the other portion formed of non-hydrophilic resin, and it is elastic. The characters, patterns or designs can be printed on the optical information medium using water-base ink, etc. after manufacturing the optical information medium. Further, the hydrophilic resin film is formed on the disc at the portion outside the information recording area.

Abstract: One object of the invention is to achieve a phase change type optical recording medium having high degree of modulation and recording sensitivity, and another object of the invention is to achieve a phase change type optical recording medium having already stable write/read characteristics at the time of the first overwriting. The optical recording medium comprises a recording layer made up of an optical recording material containing given amounts of In, Ag, Te and Sb. In one Raman spectrum embodiment of the optical recording there are a scattering peak I-1 having a Raman shift in a range of 113 to 117 cm.sup.-1 and a scattering peak I-2 having a Raman shift in a range of 123 to 127 cm.sup.-1, said scattering peak I-2 being larger in half-width than said scattering peak I-1. In another Raman spectrum embodiment, there are a scattering peak II-1 having a Raman shift in a range of 105 to 125 cm.sup.-1 and a scattering peak II-2 having a Raman shift in a range of 140 to 160 cm.sup.

Abstract: A recordable optical disk including a transparent substrate; a recording layer formed over the substrate; a reflective layer formed over the recording layer; and a thin metallic interlayer formed on the recording layer at the interface between the reflective layer and the recording layer wherein the thin metal interlayer includes materials selected from the group consisting of Pd, Ni, Sn, Au, In, Te, Si, Ge, and alloys thereof, the interlayer being selected so as to improve the optical disk recording stability without significantly affecting the reflection of a recording light beam passing through the substrate and the recording layer and which is reflected by the reflective layer.

Abstract: A phase-change type optical recording medium, wherein (1) recording, erasing and reading of information by irradiating light is possible, and the medium has a structure in which a first protective layer, a recording layer, a second protective layer, and a reflective layer are consecutively deposited in this order on a transparent substrate, (2) the thickness of the first protective layer is in the range of the thickness, where reflectivity of light on irradiating the layer from the side of the transparent substrate exhibits a minimum, .+-.30 nm, and (3) the second protective layer has the absorption coefficient k satisfying the equation as follows0.05.ltoreq.k.ltoreq.2.5.According to the present invention, unevenness of shapes and sizes of the recording pits can be reduced, irrespective of whether the state of the recording layer is crystalline or amorphous.

Abstract: An optical information recording medium includes a substrate, and a light absorption layer formed thereon which includes a phthalocyanine compound (I) having a thermal decomposition temperature in a range of 250.degree. C. to 350.degree. C., measured by thermogravimetry with a temperature elevation rate of 10.degree. C. and a phthalocyanine compound (II) having a thermal decomposition temperature in a range of 350.degree. C. to 450.degree. C., measured by thermogravimetry with a temperature elevation rate of 10.degree. C. This optical information recording medium can be produced by providing the light absorption layer, directly or via an intermediate layer, on a substrate with information pits and/or guide grooves being on the surface thereof by film formation coating, providing a light reflection layer, directly or via an intermediate layer, on the light absorption layer by vacuum film formation, and providing a protective layer on the light reflection layer.

Abstract: An information recording medium which comprises as a recording layer an information recording thin layer, formed on a substrate directly or via an underlayer, which records and/or reads back information through the use of atomic arrangement change caused by the irradiation of energy beams, a protective layer and at least two reflective layers, the reflective layers including a first reflective layer and a second reflective layer, the materials of which differ in refractive index or extinction coefficient or both, the aforesaid layers being laminated in the order, from the side of light incidence, of the protective layer, the recording layer, an intermediate layer, the first reflective layer and the second reflective layer.

Abstract: An information recording medium composed of 1) a transparent support, 2) a recording layer which is composed of an organic dye and an organic oxidizing agent having a reduction potential on the side nobler than -0.2, and 3) a light-reflecting layer on the recording layer shows improved light-resistance and endurance as well as good recording and reproducing characteristics.

Abstract: A magneto-optical recording medium is constructed by a reproduction layer which assumes an in-plane magnetization state at room temperature and becomes a perpendicular magnetization film at temperatures between room temperature and a Curie temperature, a recording layer for storing information, and an intermediate layer which is arranged between the reproduction layer and the recording layer and in which a Curie temperature is lower than those of the reproduction layer and the recording layer and which is iron group element sub-lattice magnetization dominant. Each of the layers is constructed by a rare earth-iron group element amorphous alloy and the intermediate layer is made of a material, as a main component, which satisfies ?Gd.sub.x (Fe.sub.100-y Co.sub.y).sub.100-x ! (8.ltoreq.x.ltoreq.15, 0.ltoreq.y.ltoreq.50). The reproduction layer has a compensation temperature between room temperature and the Curie temperature.

Abstract: A recordable optical disk including a transparent substrate; a recording layer formed over the substrate; a reflective layer formed over the recording layer; and a thin dielectric interlayer formed on the recording layer at the interface between the reflective layer and the recording layer wherein the thin dielectric interlayer includes materials selected from the group consisting of Ge--C--H, Si--N and InSnSb--O, the interlayer being selected so as to improve the optical disk recording stability without significantly affecting the reflection of a recording light beam passing through the substrate and the recording layer and which is reflected by the reflective layer.

Abstract: Multiple layer laminate element, such as DVD optical recording elements, are disclosed. The laminates include a cured cyanoacrylate adhesive layer in direct contact with a polymeric layer having a chemically bound cure accelerator for the cyanoacrylate.

Abstract: An optical information recording medium is here disclosed which comprises a transparent substrate, a recording layer comprising an organic dyestuff on which information can be written by a laser beam, a reflective layer and a protective layer formed in this order on the substrate, the aforesaid optical information recording medium being characterized by containing a pit.multidot.edge control agent for the formation of recording pits, particularly a dyestuff thermal decomposition accelerator in the recording layer. By the addition of the pit.multidot.edge control agent, deviation properties and jitter properties can be remarkably improved, whereby a CD-R medium having a low error rate and good recording properties can be provided. In consequence, stable compatibility with a commercial CD player can be secured.

Abstract: The optical information medium of the invention includes: a first substrate having a first information signal layer; a first reflective film formed on the first information signal layer of the first substrate; a second substrate having a second information signal layer; a second reflective film formed on the second information signal layer of the second substrate; and a photopolymer resin film provided between the first reflective film and the second reflective film for bonding the first substrate and the second substrate with each other.

Abstract: A dye mixture having, at 780 nm, a real refractive index not less than 1.8, and an imaginary part not greater than 0.15 and comprising (a) a tetra dye having a metallized azo dianionic dye with a cationic dye counterion and (b) at least one other dye having the structure according to formula I: ##STR1## wherein: A may be equal to or different from A.sup.1, in which each represents an aryl group having 6 to 10 carbon atoms;B may be equal to or different from B.sup.1, in which each ##STR2## R and R.sup.1 represent an alkyl group of C.sub.1 -C.sub.10 or an aryl group having 6 to 10 carbon atoms; andX represents halide, ClO.sub.4, BF.sub.4, PF.sub.6, tosylate and RCOO.

Abstract: A description is given of an reversible optical information medium comprising a substrate (1), a first dielectric layer (2), a phase-change recording layer on the basis of Ge-Sb-Te (3), a second dielectric layer (4), and a metal mirror layer (5). The recording layer (3) comprises an alloy having the composition Ge.sub.50x Sb.sub.40-40x Te.sub.60-10x, in atom %, wherein0.166.ltoreq.x.ltoreq.0.444and wherein the layer thickness d.sub.3 of said recording layer (3) ranges between 25 and 35 nm. Such a medium is suitable for high speed recording (i.e. at least twice the CD-speed), and has a large cyclability of at least 10.sup.5 direct overwrite cycles.

Abstract: A magneto-optical recording medium improved in reproduction stability and carrier-to-noise ratio by enlarging the magnetic anisotropy of a magnetic film. The magneto-optical recording medium is composed of a transparent substrate, a first dielectric film laminated on the transparent substrate, a magnetic film laminated on the first dielectric film, and a second dielectric film laminated on the magnetic film. The second dielectric film is formed from a material different from a material of the first dielectric film, and has film stress different from film stress of the first dielectric film. Accordingly, the coercive force and the magnetic anisotropy of the magnetic film can be enlarged.

Abstract: This invention provides phase change media for optical storage based on semiconductors of nitrides of the column III metals. The surface of thin films of these wide bandgap semiconductors may be metallized (by desorption of the nitrogen) by irradiating with photons of energy equal to, or greater than the band gap of these materials, and with power densities beyond a critical threshold value. As a consequence of such writable metallization, these materials are excellent candidates for write once, read many times storage media since the differences in the reflectivity between the metal and its corresponding wide gap nitride are very large. Furthermore, once the nitrogen is desorbed, the written metallic phase can no longer revert back to the nitride phase and hence the media is stable and is truly a write-once system.

Abstract: An optical recording medium comprising a substrate, a reflecting layer and a recording layer, which recording layer consists essentially of one or more than one dye of formula (I) or chlorination or bromation products thereof ##STR1## wherein R.sub.1 and R.sub.2 are each independently of the other C.sub.1 -C.sub.8 alkyl or C.sub.2 -C.sub.8 alkenyl;R.sub.3, R.sub.6, R.sub.9 and R.sub.12 are hydrogen, halogen, CN, CHO, C.sub.1 -C.sub.8 alkyl or unsubstituted or substituted C.sub.6 -C.sub.14 aryl;R.sub.4, R.sub.5, R.sub.7, R.sub.8, R.sub.10 and R.sub.11 are hydrogen, halogen, NO.sub.2, CHO, COOR.sub.13, CONR.sub.14 R.sub.15, CN or unsubstituted or substituted C.sub.1 -C.sub.8 alkyl or C.sub.2 -C.sub.8 alkenyl;or R.sub.4 and R.sub.5, R.sub.7 and R.sub.8 and/or R.sub.10 and R.sub.11 together are an unsubstituted or substituted 1,4-buta-1,3-dienylene, 2-buten-1,4-diylidene, 1,3-propylene or 1,4-butylene bridge, so as to form, optionally together with the shared C--C or C.dbd.

Abstract: A multilayer optical information medium provided with structure in which first and second substrates respectively provided with two to four layers of planar information areas are respectively arranged outside wherein the thickness of the above-described first and second substrates is set in the range of 0.52 to 0.65 mm. The above-described planar information area consists of embossed pits provided, for example on the surface of respective substrates or on the surface of a layer formed by transparent material and a semi-reflective layer provided on the embossed pits. A planar information area arranged in the farthest position from respective substrates is provided with a reflective layer in place of the above-described semi-reflective layer. The planar information area arranged in the farthest position from respective substrates may be constituted by a recording layer and a reflective layer provided on the recording layer.

Abstract: An optically readable data storage medium includes a thin film data carrier fabricated from first and second juxtaposed plastic layers. A microembossed data surface is positioned within an interface zone and includes physically displaced surface elements which encode digital data. An adaptor temporarily receives and supports the thin film data carrier from below and includes a centrally located aperture geometrically compatible with a standard CD player spindle to enable the adaptor to be supported and rotated by the spindle. The adaptor includes a refraction zone having an area and a location underlying the microembossed data surface to enable the light beam from the light source of the CD player to be focussed onto the rotatable data surface. The reflected light beam modulated by the digital data encoded within the microembossed data surface is intercepted and converted to an electrical signal by the CD player optical readout device.

Abstract: In an optical disk obtained by pasting two substrates, air bubbles and the like are removed from an adhesive layer between the substrates pasted together, and the thickness irregularity of the adhesive layer is suppressed to an allowable value or less. A spacer having a predetermined thickness is concentrically placed on a substrate. An adhesive is applied onto a surface of the substrate on which the spacer is placed. Another substrate is placed on the surface of the substrate on which the adhesive is applied. The substrates are rotated about the spacer at a high speed. The excessive adhesive sandwiched between the substrates is expelled, together with air bubbles and the like, by using the centrifugal force produced by the rotation. With this process, an adhesive layer having a thickness determined by the thickness of the spacer is left between the two substrates.

Abstract: Copolycarbonates having low intrinsic birefringence comprise structural units derived from hydroxyphenylindanol, from resorcinol, alkylenedioic acid or eugenolsiloxane, and, optionally, from a bisphenol, preferably bisphenol A. The copolycarbonates are useful for the fabrication of optical data recording media such as compact disks.

Abstract: An optical recording medium comprising a recording layer, a light interference layer, a reflective layer and a protective layer that are laminated on a substrate, characterized in that said recording layer and said light interference layer comprise at least one organic dye, and that a light absorbent and/or a thermal decomposition promoter are/is added to said light interference layer, wherein the optical recording medium has compatibility that allows good recording and/or reproduction by using lasers of different two wavelength ranges and has good recording properties.

Abstract: The invention relates to an optical recording medium comprising a substrate, a reflecting layer and a recording layer, which recording layer consists essentially of a dye of the formula (I), ##STR1## in which R.sub.1 and R.sub.6 are hydrogen or unsubstituted or substituted alkyl, alkenyl, alkynyl, aralkyl or aryl,R.sub.6 and R.sub.7 are unsubstituted or substituted alkyl, alkenyl, alkynyl, aralky or aryl,R.sub.3, R.sub.4, R.sub.8 and R.sub.9 are hydrogen, halogen, OR.sub.17, SR.sub.17, NR.sub.18 R.sub.19, NO.sub.2, alkyl, alkenyl or Alkynyl,R.sub.5 and R.sub.10 are hydrogen, halogen, OR.sub.17, SR.sub.17, NO.sub.2, NR.sub.18 R.sub.19 or unsubstituted or substituted alkyl, alkenyl, alkynyl or aralkyl, andR.sub.11 is hydrogen, (CH.sub.2).sub.1-10 COO.sup.-, (CH.sub.2).sub.1-10 COOR.sub.

Abstract: An optical disc having, as a recording layer, a first Sb--Se based thin film, a Bi--Te based thin film and a second Sb--Se based thin film, deposited in this order on a disc substrate, and a thin Al film deposited on the recording layer, is disclosed. Each of the first Sb--Se thin film and the second Sb--Se thin film has a composition such that Se accounts for not less than 70 atm % of the composition. The film thicknesses of the first Sb--Se based thin film and the second Sb--Se based thin film are set to not larger than 30 nm and to 15 to 25 nm, respectively, with the reflectance of the recording layer with respect to the laser beam with a wavelength of 680 nm being 10 to 25%. Alternatively, the first Sb--Se based thin film is of Sb.sub.2 Se.sub.3, the Bi--Te based thin film is of Bi.sub.2 Te.sub.3 and the second Sb--Se based thin film is of Sb.sub.2 Se.sub.

Abstract: For an optical recordable disk, a heat conductive gold layer can be deposited on a phase-change recordable layer to increase the writing threshold. This higher threshold improves the data stability during readout. However, it has been found that there is substantial inter-diffusion between the phase-change layer and the gold layer. The performance is degraded as a result. A barrier layer between the phase-change layer and the gold layer can effectively prevent diffusion and mixing. Using his barrier, the performance is preserved and the data stability is improved.

Abstract: An optical disk apparatus using an optical disk in which a layer (a reflectivity adjustment layer) in which the optical constants are changed by melting at the time of irradiation of light is provided separately from a recording layer using a phase change, and the reflectivity at a portion having a high reflectivity on the recording track is 40% or lower at the time of irradiation of strong light, and the reflectivity at the same portion is 60% or higher at the time of irradiation of weak light, wherein when the laser power is set to a power which is higher than the power at which the optical constants of the reflectivity adjustment layer are greatly changed at the time of rewriting and at which a high melting-point component is not melted, remaining of an unerased portion during rewriting due to a difference in reflectivity between the written mark portion and the other portions can be prevented and the possible number of rewritings can be increased, and hence an optical disk which has a high recording sensi

Abstract: A recordable compact disc comprises a 0.6 millimeter clear plastic or glass substrate on which is grown a thin-film image layer having several distinct recording planes. Each recording plane is separated from the next by a clear plastic layer. Each recording plane includes an organic dye layer in combination with another clear layer that has a different index of refraction. Different color dyes are used for each recording plane.A method for storing and reading data to and from a multilayer recordable compact disc with different color dye layers uses high powered color lasers to write each recording plane and low powered monochromatic reading lasers that are sensitive to the constructive and destructive light interference effects caused by micron variations in the clear plastic layers in each recording plane. The micron variations used for each recording plane are unique and chosen along with the monochromatic reading laser colors to have minimal crosstalk between recording-plane data channels.

Abstract: A recordable element including a substrate and having over its surface, in order, an optical recording layer and a light reflecting layer, the improvement includes an optical recording layer containing Te.sub.a Ge.sub.b C.sub.c H.sub.d O.sub.e where a, b, c, d, and e are atomic percents such that a+b+c+d+e=100, and wherein 10<a<40, 10<b<60, 5<c<35, 10<d<5, e.gtoreq.0; an the optical recording layer having one or more sublayers which can be of different compositions; and the thickness t of the optical recording layer is 0.7 Tmin<t<1.3 Tmin.

Abstract: An optical recording medium, wherein a recording layer is formed on a substrate to which a light beam is applied to record, erase, and read data with said recording and erasing of data being carried out by means of phase changes between amorphous and crystalline, and which recording medium has a laminated structure made up of a transparent substrate on which at least a first dielectric layer, recording layer, second dielectric layer, and reflecting layer are formed in this order; and the second dielectric layer not being transparent.Said optical recording media permit low-power recording and erasing, remain stable after repeated recording and erasing, and hardly suffer deterioration in performance or formation of defects. They are high in resistance to moist heat and oxidation and long in service life.

Abstract: The present invention is relative to an optical information recording medium having a reflective layer for reading out information signals by an optical technique. The optical information recording medium is formed as a plastic substrate. According to the present invention, the substrate is colored by admixture of a dyestuff for enabling instant judgment by the visual sense of the operator as to the contents of the optical information recording medium, for example, as to if the contents of the recording medium is a game program or the music information. If impurities such as dyestuffs are admixed, the optical system of the readout device is usually affected thus raising readout difficulties. Such ill effects on the optical system may be eliminated by setting the particle size of the dyestuff so as to be 50 .mu.m or less.

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 magneto-optical recording medium includes a readout layer having in-plane magnetization at room temperature and in which a transition occurs from in-plane magnetization to a perpendicular magnetization when temperature rises, and a recording layer for storing information thereon magneto-optically. In the readout layer made of GdFeCo by adding Nd thereto, an amount of Nd to be added changes in a direction perpendicular to its film surface, and an amount of Nd is larger on a light incidence side than on the other side. As a result, even when a laser with a short wavelength is used, high density recording can be achieved as undesirable recording and reproducing operations due to a change in a magnetic interaction is prevented and also deterioration in quality of a reproducing signal is prevented.

Abstract: An optical recording element having a transparent substrate and on the surface of said substrate, a recording layer and a light reflecting layer. The recording layer comprises (i) a metallized carbamoylazo dye having an azo group linking a substituted 3-hydroxypyridine nucleus to a phenyl nucleus wherein the phenyl nucleus has a carbamoyl substituent ortho to the azo group and (ii) a cyanine dye. The unrecorded recording layer has a refractive index, at a selected wavelength from 400 to 660 nm, comprising a real part (n) greater than 1.8 and an imaginary part (k) less than 0.2.

Abstract: An optical recording material of the following formula (1) and an optical recording medium excellent in recording sensitivity, light resistance and durability, having a recording layer containing the material,the formula (1), ##STR1## wherein each of X.sub.1 to X.sub.4 is a hydrogen atom, an alkyl group, an aryl group, an alicyclic residue, an aralkyl group, a heterocyclic ring, an alkoxy group, an aryloxy group or an alkylthio group, each of Y.sub.1 to Y.sub.4 is a hydrogen atom, a halogen atom, a nitro group, a phthalimidemethyl group or a sulfoneamide group, each of R.sub.1 and R.sub.2 is a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkylamino group, a dialkylamino group, an arylamino group or a diarylamio group, M is Al, Ga, In, Si, Ge or Sn, Z is an azo compound, an anthraquinone compound or a metal complex compound, n.sub.1 to n.sub.4 are 1 to 4, m.sub.1 to m.sub.

Abstract: This invention relates to a disk substrate consisting essentially of zirconia partially stabilized by a rare earth oxide, the disk substrate having a thickness of no more than 0.635 mm, a diameter of at least 10 mm, and a mean pore size of no more than 0.1 um.

Abstract: The present invention is directed to a dye composition for use in CD-R recording media and having reduced wavelength dependence of the dye layer absorption, comprising:(1) a first cyanine dye having a peak absorption wavelength in the solid film form in the range of about 690 nm to about 730 nm, the amount of said first cyanine dye is about 90% to about 30% by weight, based on the total weight of the solid components in said dye composition; and(2) at least one noncyanine dye having a peak absorption wavelength in the range of about 900 nm to about 1200 nm, each noncyanine dye having an absorption coefficient greater than 30,000 cm.sup.-1 and said amount of noncyanine dye is about 10% to about 40% by weight, based on the total weight of the solid components in said dye composition. The invention is also directed to a recordable medium coated with the above dye composition, and a recording mechanism implementing the above dye composition.

Abstract: It is an object of the present invention to increase an amount of information recorded on an optical disk having at least two information recording layers. An optical disk having a plurality of information recording layers according to the present invention includes a transparent substrate, a transparent layer and at least two information recording layers formed on the transparent substrate. The information recording layers are provided so as to sandwich the transparent layer. At least one of the information recording layers has a transmittance varying layer. The transmittance varying layer is made of a material whose transmittance is changed at a predetermined temperature as a threshold value. The transmittance varying layer is made of a phase change material. The threshold value is within the temperature range from 700.degree. to 500.degree.. Crystallization speed of the transmittance varying layer is equal to or slower than 500 ns.

Abstract: An optical recording process for recording data on a recording medium of phase-change type employs laser power modulation scheme for mark-length modulation recording. The process selects one of pulse division schemes for modulating the laser power in accordance with a linear velocity on the disc. The recording laser includes m pulses for nT mark having a power level Pw and a duration of .alpha..sub.i T, with m intervals .beta..sub.i T sandwiched therebetween, wherein on condition that m=n-k and .SIGMA..alpha..sub.i +.SIGMA..beta..sub.i =n-j, .alpha..sub.i or bias power Pb.sub.i is changed in accordance with the linear velocity, Pb.sub.i being a bias power level for modulation, k and j being an integer and a real number, respectively, both selected between 0 and 2. A large range of the linear velocity margin can be obtained for the disc without changing either the composition of the phase-change material or multilayer structure on the disc.

Abstract: A magneto-optical recording medium comprises in combination: a magneto-optical recording layer capable of writing or erasing information by a laser beam and an external magnetic field and of reading the information by a Kerr effect; and a substrate having the magneto-optical recording layer formed thereon. The magneto-optical recording layer has at least two layers, including a first magneto-optical recording layer and a second magneto-optical recording layer which are magnetically coupled together. The first magneto-optical recording layer is a layer providing a greater magneto-optical effect in a short light wavelength range than the second magneto-optical recording layer though that having less perpendicular magnetic energy than this, as is provided on an irradiation side of the laser beam. It provides advantages in both the magneto-optical effect and perpendicular anisotropy in consideration of the thicknesses or compositions of the first and second magneto-optical recording layers.

Abstract: An optical information recording medium, which includes a substrate, and a recording thin film layer provided on the base material and adapted to form variation in an amount optically detectable by absorbing at least laser light so as to record information by partially varying the recording thin film layer and to reproduce the information by optically detecting the variation amount. The optical information recording medium further includes transparent layers each provided in contact with the recording thin film layer, and each of the transparent layers has optical thickness in which, in at least two different wavelengths .lambda., integral multiple of .lambda./2 is added to the thickness giving the large laser light absorption and large optical variation amount, respectively.More specifically, the optically detectable amount is of a reflectance factor variation, and in the different wavelengths .lambda.1 and .lambda.

Abstract: An optical disk has first and second substrates, at least one of which is provided with optically readable pits corresponding to record data, and a reflection film coated on the pits. In the optical disk, the first and second substrates are laminated on each other such that the surface on which the pits are formed, is located inside. Label information, indicative of the record data, is formed on at least one of the surfaces of the first and second substrates, which contact each other.

Abstract: An optical element is provide which has a durability enhancing layer. There is provided an optical disk comprising a support having on one surface thereof, in order:a) a recording layer such that said recording layer does not cover the entire surface of said disk but leaves an annular portion at the outer diameter;b) a reflective layer such that said reflective layer does not cover the entire surface of said disk but leaves an annular portion at the outer diameter;c) a first protective layer having a thickness between about 2-20 .mu.m, said protective layer being of a material having good adhesion to said support and covering a portion of the surface of said disk having said reflective layer, including at least a portion of said annular portion;d) a second protective layer having a thickness of at least about 3 .mu.m, said second layer covering at least the area of said surface having the reflective layer and having good adhesion to said first protective layer.