Abstract: A magneto-optical recording medium comprises: a readout magnetic film which is perpendicular magneto-anisotropy in a temperature range higher than room temperature and less than a second temperature Tsw2, and is in-plane magneto-anisotropy in a temperature range equal to or more than the second temperature Tsw2; an intermediate magnetic film which is in-plane magneto-anisotropy in a temperature range higher than the room temperature; and a recording magnetic film which is perpendicular magneto-anisotropy for holding recording magnetic domains. When the coercive force of the readout magnetic film is Hc, the exchange coupled force between the readout magnetic film and the recording magnetic film is Hs, and the readout magnetic field is Hr, in a temperature range equal to or higher than room temperature and less than a first temperature Tsw1 which is higher than room temperature and is lower than the second temperature Tsw2, a first relation .vertline.Hr.vertline.>.vertline.Hs+Hc.vertline.

Abstract: A resin composition for polymerization casting containing:20 to 60% by weight of a monomer (1) represented by the formula (1) ##STR1## wherein R.sup.1 stands for a hydrogen atom or a methyl group, R.sup.2 stands for an alkylene group having 2 to 4 carbon atoms, m and n each is an integer of 2 to 5;10 to 40% by weight of a monomer (2) represented by the formula (2) ##STR2## wherein R.sup.3 stands for a hydrogen atom or a methyl group, R.sup.4 and R.sup.5 are the same or different groups and each stands for an alkylene group having 2 to 4 carbon atoms, j and k each is 0 or 1; and5 to 70% by weight of a monomer (3), the monomer (3) being identical with neither monomers (1) nor (2), and containing at least one vinyl group in a molecule thereof.

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 index(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 0.00 to 0.02.

Abstract: A method for manufacturing an optical information recording medium having an excellent mechanical strength, thermal stability, and improved overwrite cycle property can be provided by forming the dielectric layer by using a mixed target comprising ZnS and SiO.sub.2 in an atmosphere comprising rare gas and at least oxygen at the side where the dielectric layer does not contact to the recording layer. The optical information recording medium is manufactured by using the substrate, the recording layer comprising a material that varies reversibly between the optically identifiable states by an irradiation of a laser beam, and the dielectric layer at least one side of which has a two-layered structure at the upper and lower sides of the recording layer. At least one of the dielectric layers that does not contact to the recording layer is formed by using a mixed target comprising ZnS and SiO.sub.2 in a mixed atmosphere comprising rare gas and oxygen.

Abstract: A medium suitable for the optical storage and retrieval of information comprising a substrate, an active layer for retention of the data, and an overlying optical layer, or layers for double-sided. The optical layer serves to produce an evanescent field in or adjacent to the active layer in response to an incident beam of radiation. The evanescent field is frustrated or attenuated by the data in the active layer and produces a signal.

Abstract: The object of the present invention is to provide an optical disc and a method of manufacturing thereof wherein defects and deterioration in the optical disc are minimized at the time of manufacture, during operation and storage thereof as well. The invention conceives an optical disc suitable for accomplishing the above object through spcifications such as providing a cross-sectional structure thereof comprising a pair of transparent substrates each provided with at least one layer of a recording film formed on the surface of information patterns thereof, with the pair being bonded and laminated with an adhesive, and further providing an instantaneous axial acceleration<2 G measured at room temperatures, a skew angle<5 mrad measured at room temperatures, and a skew angle<5 mrad measured after being left for one hour as heated to 80.degree. C. (otherwise, a shear mass<20 .mu.m measured after being left for one hour as heated to 80.degree. C.

Abstract: The optical disk writing system disclosed is one in which a data written on an optical data writing medium is verified essentially simultaneously with the writing on the medium. The written data is verified by detecting a timing of the light irradiated on the medium and by measuring return light doses at a rise and a fall of the light irradiated on the medium and comparing the doses thereof with predetermined reference values. The medium used is one which uses a phase transition reversible between a crystal state and an amorphous state for writing/reading/erasing of data on a data writing film and includes, a first protective film, a phase transition type data writing film, a second protective film, a reflection film formed in this order on a transparent substrate.

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: 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 optical recording medium having each of a land and a groove and comprises at least a recording layer, dielectric layers and reflection layer. Recording and erasing of data can be carried out on both land and groove by a phase change between amorphous and crystalline states. The mirror portion may have reflectance characteristics selected from at least one of a reflectance of more than 15% and no more than 35%, when in a crystalline state, and 10% or less, when in an amorphous state. Alternatively, additionally, the depth of the groove may be such as form an optical path length equal to 1/7 to 1/5 of the wavelength of the reproducing light and the photo-absorbance of the recording layer in the amorphous phase and the photo-absorbance in the crystalline phase may satisfy the following formula,Aa-Ac.ltoreq.10where Aa is the photo-absorbance (%) of the recording layer in the amorphous phase and Ac is the photo-absorbance (%) of the recording layer in the crystalline phase.

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 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: The present invention provides an optical disk 9 with a duplication preventing function, reproducing system 47 for the optical disk 9, optical disk reproducing method, method of fabricating an optical disk original record, and illegal program operation stopping method. An area in which a CP signal 24 is recorded is made after a signal having a constant pattern in the optical disk, the CP signal 24 being produced such that the center of an eye pattern is shifted from the center of the amplitude. In the reproducing system, CP signal arrangement information 25 or a CP preceding signal 26 is detected, before an offset voltage is applied to a threshold value to be used in demodulating an RF signal into a digital signal so that the threshold value varies, thus normally reproducing the signal in which center of the eye patter is shifted from the center of the amplitude. The reproducing system has a function whereby the reproduction is stopped when a predetermined offset signal is not reproduced.

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 a metallized carbamoylazo dye having an azo group linking a substituted 3-hydroxypyridine nucleus to a phenyl nucleus. The phenyl nucleus has a carbamoyl substituent ortho to the azo group. 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: This invention provides an optical disk whose recorded information cannot be easily copied to other recording media, with practically no degradation of strength. The optical disk of this invention has a ring-shaped signal layer made of radiation curable resin on a transparent substrate, a reflective layer formed on this signal layer, and a protective layer formed on this reflective layer; moreover, the above mentioned signal layer has a peel strength against the above mentioned transparent substrate in the range of about 20/100 to about 80/100 according to the JIS-K5400 test method; and if the outer and inner diameters of the mentioned signal layer are represented by Os and Is respectively, the outer and inner diameters of the mentioned reflective layer are represented by Or and Ir respectively, and the outer and inner diameters of the mentioned protective layer are represented by Op and Ip respectively, these diameters satisfy the relationships,Os<Or<OpandIp<Ir<Is.

Abstract: A multiple-recording-layer optical recording medium has a plurality of recording layers to be initialized by exposure to light, with a transparent layer interposed between the recording layers. Light is applied simultaneously to the to the recording layers to initialize the recording layers simultaneously.

Abstract: A method of making a multilayer optical disc of a type formed by laminating a plurality of signal layers each having a spiral or concentric pattern of a series of pits so that information can be read by irradiating any one of the signal layers with a playback laser from a surface of a substrate of the optical disc and reading waveforms reproduced therefrom. A master disc having a pit pattern formed thereon by exposing to a modulated exposure light pulse train is prepared for each of signal recorded layers. Based on this master disc, a mold is then prepared having a pit pattern which is a replica of the pit pattern on the master disc. Using the molds, respective replicas are formed and bonded together in face-to-face relation to thereby provide the multilayer optical disc.

Abstract: An information recording medium comprises at least a substrate, a recording layer which is installed on the substrate via a protection layer and in which the atomic arrangement is changed without the shape thereof being changed when a recording energy beam is irradiated and the optical constants are changed, and a reflection layer reflecting the recording energy beam and by making the information recording medium comprise a material such that the mean composition of the recording layer is expressed by a general expression of A.sub.w Ge.sub.x Te.sub.y Se.sub.z (where symbols w, x, y, and z indicate atomic percent and have the predetermined values and A indicates at least one of the predetermined elements Sb, Cr, Co, In, and Ag, etc.), an information recording medium in which the recording, erasing, and reproducing characteristics are satisfactory and the stability is kept superior for a long period of time can be obtained.

Abstract: An optical recording medium has deposited on a substrate a recording layer incorporating therein a cyanine dye, preferably an indoline dye, and optionally incorporating therein an autoxidizable compound or a thermoplastic resin and/or a singlet oxygen quencher.

Abstract: An irradiation method of applying a light spot or a light pattern to an object with high resolution is performed by disposing, in close vicinity to the object, a light-absorbing contrast-increasing layer whose transmittance or reflectivity with respect to an incident light thereto increases as the intensity of the incident light or the exposure thereof to the incident light increases; and applying light to the object through the light-absorbing contrast-increasing layer. This method is applied to an optical information recording and reproducing method using an optical information recording medium including an optical information recording layer and an auxiliary layer whose transmittance or reflectance increases in a real time manner correspondingly to the energy of an incident light thereto.

Abstract: Recording media made up of two discs bonded together back to back have one disc on which programming information is recorded in light-readable form (generally similar to conventional CDs or CD-ROMs) and a second disc bearing visible indicia regarding the recording media. At least some of the visible indicia on the second disc are generic (i.e., are not specific to the particular programming on the other disc). These generic visible indicia are preferably formed on the second disc prior to the bonding of the two discs together. Additional visible indicia that are specific to the particular programming on the other disc may be added to the second disc. The visible indicia may be provided in several ways such as by "pit art", thermal branding, laser scribing, printing, labelling, etc. The second disc may also contain some recorded, generic, light-readable information such as "Wrong side--turn disc over.

Abstract: A method for manufacturing a double-sided-multi-layered optical disc. An intermediate substrate having pits on both the major surfaces is previously prepared as well as first and second substrates. The method rotates the first substrate, the intermediate substrate and the second substrate with respect to the common center thereof so as to form unhardened radiation setting resin layers between adjacent substrates so that thicknesses of the unhardened resin layers are adjusted to predetermined values, and then the method irradiates a radiation onto the unhardened resin layer so as to harden the unhardened resin layers to solid resin layers.

Abstract: A system and method for recording data on an optical recording medium. One system in accordance with the invention includes an optical recording medium which absorbs less radiation at a first wavelength than at a second wavelength; a first optical source to generate a first radiation beam at the first wavelength; a second optical source to generate a second radiation beam at the second wavelength; and means for applying the first radiation beam and the second radiation beam, at least one of which is modulated by recording data, to the recording medium. The second radiation beam, which may have a shorter wavelength than the first radiation beam, induces a shift in the absorption response of a region of the medium. The region then absorbs an increased amount of radiation at the first wavelength such that a high resolution mark may be formed on the medium.

Abstract: Disclosed is a magneto-optical recording medium adapted for reproduction of a high resolution signal without the necessity of a reproducing magnetic field, whereby the magneto-optical recording medium comprises a transparent substrate, a reproducing layer, a switch layer and a recording layer formed on the transparent substrate successively. The reproducing layer is a perpendicular magnetization film at a room temperature but is turned to an in-plane magnetization film when heated beyond a predetermined temperature. Each of the switch layer and the recording layer is a perpendicular magnetization film. The respective Curie temperatures Tc1, Tc2 and Tc3 of the reproducing layer, the switch layer and the recording layer satisfy the relationship of Tc1>Tc3>Tc2.

Abstract: The present invention relates to a production process and a production apparatus for the optical information recording media comprising a material thin film which exhibits a reversible change of the optical characteristics by the irradiation of an energy beam such as a laser beam on the substrate. By dropping the emission strength instantly to the virtual zero level after having the emission for a specified time in conducting the initial crystallization process, both a large irradiation power and a short irradiation time can be achieved to reduce the various thermal damages. The charging time can be shortened.

Abstract: On one surface of a disk substrate, a first dielectric layer, a thin recording layer, a second dielectric layer and a reflecting layer are cumulatively formed. The second dielectric layer is thinner than the first dielectric layer and is 35-70 nm thick. The reflecting layer is 70-120 nm thick. The total thickness of the four layers is 250-430 nm. The compressive stress of the layers is offset by tensile stress generated by an overcoat resin protective layer, formed on the reflecting layer. A method of using the optical recording medium applies the MCAV (Modified Constant Angular Velocity) recording method which records information by changing recording frequencies in accordance with linear velocity. The linear velocity is 5-12 m/s. A ratio of an inner circumference recording pulse width to an outer circumference recording pulse width is 1.2 or more.

Abstract: The present invention relates to an optical recording medium having a recording layer, a reflective layer and a protective layer on a substrate, wherein a quinophthalone compound represented by the following formula (1) is contained in the above recording layer. The use of the quinophthalone compound or a mixture of the quinophthalone compound and a photoabsorbing compound having an absorption maximum in a wavelength falling in a range of 550 to 900 nm in the recording layer makes it possible to provide an interchangeable optical recording medium not only capable of recording and reproducing with a laser having a wavelength falling in a range of 480 to 600 nm, but is also capable of recording and reproducing with red lasers having wavelengths of 630 nm and 680 nm and a near infrared laser having a wavelength of 780 nm.

Abstract: On one surface of a disk substrate, a first dielectric layer, a thin recording layer, a second dielectric layer and a reflecting layer are cumulatively formed. The second dielectric layer is thinner than the first dielectric layer and is 35-70 nm thick. The reflecting layer is 70-120 nm thick. The total thickness of the four layers is 250-430 nm. The compressire stress of the layers is offset by tensile stress generated by an overcoat resin protective layer, formed on the reflecting layer. A method of using the optical recording medium applies the MCAV (Modified Constant Angular Velocity) recording method which records information by changing recording frequencies in accordance with linear velocity. The linear velocity is 5-12 m/s. A ratio of an inner circumference recording pulse width to an outer circumference recording pulse width is 1.2 or more.

Abstract: A system for the optical writing/reading of a recording medium, the system including at least one light source emitting three beams that focus at three distinct points on the recording medium and a diffraction device creating three orders of diffraction, -1, 0 and +1, for each beam, the focusing points of the three beams being aligned in the direction of diffraction of the diffraction device and being at a distance from one another so that, at the focusing point of the 0 order diffraction of the central beam, there is focused the -1 order diffraction of one lateral beam and the +1 order diffraction of the other lateral beam.

Abstract: A multiple data layer dye-based optical disk drive uses a disk with a light transmissive substrate onto which the laser light at a single wavelength is incident. The disk substrate supports at least two spatially separated data layers formed of dye material. The disk is either an air-gap structure wherein each data layer is supported on a separate substrate and the substrates are separated by an air-gap, or a solid structure wherein a solid light transmissive spacer layer separates the data layers. The invention makes use of the characteristic anomalous dispersion absorption band of certain dye materials, in which at a specific wavelength the dye material exhibits a high index of refraction and low extinction coefficient. This allows the first data layer (the one nearest the incident laser light) and intermediate data layers to exhibit both sufficient absorption when the laser is focused on those data layers and high transmissivity when the laser is focused on the last or farther data layers.

Abstract: Disclosed is an optical disk having rows of pits, corresponding to information signals, formed on a transparent substrate, and a reflective film formed on this substrate. The reflective film is formed of amorphous silicon (a-Si) or indium antimonide (InSb), which exhibits a third-order non-linear optical effect. Thus, the reflectance of the reflective film formed of this material increases nearly in proportion to the intensity of the irradiated beam spot. The beam spot irradiated on the optical disk has the highest intensity at the center portion and this intensity becomes weaker as a point in the spot approaches the edge. Therefore, the effective spot size of the beam spot can be reduced, making it possible to reproduce from the reflection type optical disk information signals with a spatial frequency above the cutoff spatial frequency defined by the reproducing optical system. In other words, a row of pits recorded at a high density can be reproduced.

Abstract: An optical memory medium having a transparent substrate, a recording layer and a reflective layer, the recording layer and the reflective layer being formed in this order on the transparent substrate. The recording layer is a diarylethene derivative dispersed in a non-polar polymeric binder. The optical memory medium with such a recording layer fully utilizes advantageous properties of the diarylethene derivative, such as good thermal stability of recorded state, excellent durability against repeated color changes between colored and colorless states, and photosensitive property to semiconductor laser light with a wavelength of 780 nm. The optical memory medium enables high-density recording and non-destructive readout.

Abstract: An optical recording medium is provided with a surface layer which is obtained by curing a coating film containing a copolymerizable monomer and/or oligomer having at least one carboxyl group so that printing may be done with an ink containing a water-soluble dye, resulting in improved adhesion. Addition of smectite to the surface layer increases the drying rate and water resistance of printed characters.

Abstract: An optical data storage system comprises a multiple data surface medium and optical head. The medium comprises a plurality of substrates separated by a light transmissive medium. Data surfaces are located on the substrate surfaces which lie adjacent a light transmissive medium. The data surfaces are substantially light transmissive. The optical head includes an aberration compensator to allow the head to focus onto the different data surfaces and a filter to screen out unwanted reflected light.

Abstract: An optical data storage system comprises a multiple data surface medium and an optical head. The medium comprises a plurality of substrates, each supporting a data surface that contains optical media for the recording of data. The data surfaces are spaced apart so that each data surface can be accessed by focused laser light from the optical head. The type of optical media on each of the data surfaces may be ROM, write-once read-many (WORM), magneto-optic or phase change. At least one of the data surfaces includes recorded information located in a track header that identifies the type of optical media contained in the data surfaces.

Abstract: An information recording medium comprising a hygroscopic swelling layer having the hygroscopic swelling property formed on a recording layer. Also the hygroscopic swelling layer is hygroscopically swollen with the hygroscopic swelling of the substrate, so that the tilt (i.e. warping) of the information recording medium is suppressed as a whole, whereby the quantity of the tilted deformation due to the moisture absorption is reduced. As a result, the recording and regeneration of information are stably conducted even though the humidity is changed.

Abstract: An optical information recording medium comprising a substrate and formed thereon an information recording layer comprising at least two organic dyes having different chemical structures and continuous playback ability of 10.sup.5 times or more at a playback laser power of 0.5 to 1.5 mW, is excellent in readout light stability (durability) and reflectance.

Abstract: An optical disc comprises two facing disc units, at least one of which has a recording layer formed on its surface facing to the other disc unit. The disc units are bonded together by a layer of adhesive which may be a room-temperature curing thermosetting adhesive having a glass transition temperature higher than the upper limit of the range of temperatures of environments in which the disc may be used. Alternatively, the adhesive may be a room-temperature curing two-pack epoxy adhesive which comprises a bisphenol epoxy resin base agent and a modified aliphatic polyamine curing agent, and which has a viscosity of 100-1000 cps, a pot life of one hour or more, a cure shrinkage of 1.0% or less, a water absorption, after curing, of 0.2% or less, and a Shore hardness, after curing, of 80-90.

Abstract: There is disclosed a flexible optical recording element comprising a flexible support having thereon, in order, an SbInSn phase-change alloy optical recording layer and an overcoat layer, the overcoat layer being a silicon oxide layer having an index of refraction greater than about 1.8 at about 800 nm wavelength and a thickness of about .lambda./4, where .lambda. is the wavelength at which the element is read. The element of the invention provides for an advantageous optical tape with a well adhered abrasion resistant overcoat which also provides for excellent corrosion resistance.

Abstract: An optical recording medium according to the present invention includes a substrate, and a recording film formed on the substrate, when receiving a laser beam for recording, the recording film taking either a first structural state or a second structural state according to the intensity of the laser beam; when receiving a laser beam for reproducing, the recording film partially changing the optical phase of the laser beam for reproducing according to the structural state, thereby changing the intensity of the laser beam for reproducing, wherein the optical absorbance of the recording film in the first structural state is substantially equal to that of the recording film in the second structural state, and the refractive index of the recording film in the first structural state is substantially different from that of the recording film in the second structural state.

Abstract: An optical recording disk having an antistatic hard coat layer provided on at least one surface of the disk, wherein the hard coat layer comprises a fluorinated ionic salt; a polymer comprising a plurality of pendant fluorinated groups, and optionally a nonionic fluorinated surfactant. The polymer comprising a plurality of pendant fluorinated groups is preferably a copolymer derived from monomers comprising a nonfluorinated vinyl monomer; and a vinyl monomer comprising a fluorinated group.

Abstract: An optical recording medium has deposited on a substrate a recording layer incorporating therein a cyanine dye, preferably an indoline dye, and optionally incorporating therein an autoxidizable compound or a thermoplastic resin and/or a singlet oxygen quencher.

Abstract: An organic-optic recording tape of higher capacity and higher packing density of data. This tape comprises a backcoating layer, a base film coated on the backcoating layer, and a complex functional layer for writing, reading and erasing data. The complex functional layer is coated on the base film and selectively focused by laser beams of different powers outputted from a laser diode in order to write, read or erase data. This complex functional layer is made of a block polymer prepared by blending a thermoplastic elastomer and a viscoelastic transparent thermoplastic high-molecular resin or polymerizing them. Near infrared absorbing organic colorants are dispersed in the complex functional layer. The transparent thermoplastic resin has a glass transition temperature higher than that of the elastomer. The recording is effected by employing a laser beam of lower power capable of inducing thermal expansion of the elastomer and formation of a bump.

Abstract: There is provided a WORM type organic optical recording medium comprising a recording layer, a reflective layer and a protective layer which are formed in sequence on a substrate, the recording layer consisting of near infrared absorbing dye able to absorb a laser beam and to generate heat and provided with a curing layer of thermosetting or photocuring resin thereon or thereunder. There is also provided a method for the prevention of rewrite in the organic optical recording medium, comprising subjecting the organic optical recording medium to heating up to 50.degree. C. or exposure to a UV light, to cure the curing layer. The organic optical recording medium requires reduced amounts of the dye and, thus, has improved reflectivity. By virtue of this improvement in reflectivity, a low-price metal may be employed in the reflective layer, bringing about additional economic benefit, along with lower requirements for dye.

Abstract: A dye mixture is disclosed. The mixture is useful in recording layers of optical recording elements. The mixture has:a) a real index of refraction of at least 1.8 in the 780 to 790 nm region of the spectra;b) an imaginary index (k) between 0.3 and 0.02 in the 780 to 790 nm region of the spectra;c) a metallized azo dye comprising an azo group linking a substituted 3-hydroxy-pyridine nucleus to a phenyl nucleus wherein the phenyl nucleus has an alkoxy or thioether substituent at its 2-position; andd) at least a second dye.

Abstract: In a phase change type of optical recording medium including on a substrate a lower dielectric layer, a recording layer, a first upper dielectric layer contiguous to said recording layer, a second upper dielectric layer and a reflective layer, the recording layer comprises a recording material containing an element A that represents silver and/or gold, an element B that represents antimony and/or bismuth, an element C that represents tellurium and/or selenium, an element indium, and an element M that represents at least one element selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, manganese, tungsten and molybdenum, with the atomic ratio of the elements in said recording material having the following formula:{(A.sub.a B.sub.b C.sub.1-a-b).sub.x (In.sub.0.5 C.sub.0.5).sub.y B.sub.1-x-y }.sub.1-z M.sub.zwherein 0.10.ltoreq.a.ltoreq.0.40, 0.10.ltoreq.b.ltoreq.0.40, 0.20.ltoreq.x.ltoreq.0.80, 0.01.ltoreq.y.ltoreq.0.60, and 0.001.ltoreq.z.ltoreq.0.20.

Abstract: An optical recording medium which has a recording medium and a light reflective film on a substrate. A top coat film made of organic material for adjusting reflectivity is formed on a surface of the substrate opposite to the other surface on which the at least one of the recording film and the light reflective film is formed. A reflectivity is remarkably enhanced without any adverse affect to a tracking error and an error rate. Also, it is easy to form the top coat. The top coat has an excellent weatherproof property.

Abstract: An optical information recording medium configured to prevent signal reproduction due to intermodulation as well as to ensure a compatibility to players that involve read lights with different wavelengths and improved data transfer rate with higher information recording density. The optical information recording medium comprises a first recording layer for reflecting first incident light of a first wavelength to change an optical characteristic thereof and passing second incident light of a second wavelength different from the first wavelength, and a second recording layer for reflecting the second incident light to change an optical characteristic thereof, the first recording layer and the second recording layer are laminated in the order of the first and second recording layers from a side where the first incident light enters.

Abstract: An infrared-absorptive compound is disclosed which has the structure represented by the following formula (I) or (II) ##STR1## Also, an optical recording medium having a recording layer containing the infrared-absorptive compound is disclosed.

Abstract: This invention relates to an optical recording method and apparatus, in which the intensity of a laser beam to be radiated onto an optical recording medium is raised from an intensity P.sub.pre for maintaining a pre-heat state in which the temperature of the medium surface becomes a predetermined temperature, to P.sub.W1 higher than P.sub.pre, the intensity is reduced to an intensity P.sub.LT lower than P.sub.W1 after P.sub.W1 is maintained for a time T.sub.W1, and thereafter, the laser beam is intensity-modulated between P.sub.LT and an intensity P.sub.W2 higher than P.sub.LT so as to form a mark on the optical recording medium. When at least one of P.sub.W2, P.sub.LT, and a time T.sub.W2 for maintaining P.sub.W2 is controlled, the medium temperature, after an elapse of T.sub.W1, at the peak temperature position or the spot center position of the laser beam radiated onto the medium surface is equal to the medium temperature after an elapse of T.sub.W2.