Abstract: A Beryllium disk drive substrate is prepared using a Beryllium metal having a starting modulus of elasticity (stiffness) of about 4.2 times that of Aluminum, in which the beryllium is separated into circular disks and processed by a sequence of lapping, heat-treating under pressure, cooling under pressure and polishing steps which retains the desirable metallurgical characteristics of the starting metal and provides sufficiently high quality surface finish, thermal conductivity and low mass density, to enable improved rotational speeds, acceleration/deceleration rates and information packing density for demanding disk drive applications.

Abstract: A magneto-optic memory and a magnetic material is described incorporating a polarized light beam directed towards a magnetic material and an analyzer for intercepting the polarized light beam after passing through the magnetic material or after being reflected by the magnetic material. The magnetic material includes a matrix of metal such as iron, cobalt, nickel, and alloys thereof and a plurality of separated phases distributed in the matrix such as EuS, EuO, EuOTb, PtMnSb, MnAs, MnBi, MnSb, CrO.sub.2, CrTe, GdN, Gd.sub.4 C, other compounds of a rare earth element and manganese compounds. Terbium or neodymium may be dissolved in the matrix of metal and in the plurality of separated phases. The invention overcomes the problem of providing a magnetic material having a Curie point above room temperature, a square perpendicular hysteresis loop at room temperature, a large magneto-optic rotation at the wavelength of interest and a deposition temperature suitable depositing on polymer substrates.

Abstract: An optical recording medium of phase change improves the erase ratio and the repeat writing characteristic by coexistence of an amorphous phase and a crystalline phase at the stage of initiation so as to reduce the size of crystalline grain in a recording layer and a method of fabricating the same. The optical recording medium of phase change comprises: a substrate; a first dielectric layer deposited on said substrate; a recording layer deposited on said first dielectric layer; a second dielectric layer deposited on said recording layer; a reflection layer and a protective film formed sequentially on said second dieletric layer; said recording layer being consisted of (GeSbTe).sub.x (In.sub.y Sb.sub.1-y).sub.1-x ; and a crystalline phase of said recording layer being a structure co-existing with a crystalline material of GeSbTe and an amorphous material of InSb.

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 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: Flexible optical medium comprising a flexible substrate having a surface. An imaging layer is carried by the surface and a protective overcoat of silicon dioxide is provided on the imaging layer to provide abrasion resistance for said imaging layer.

Abstract: An ultrahigh vacuum focused ion beam micromilling apparatus and process are isclosed. Additionally, a durable data storage medium using the micromilling process is disclosed, the durable data storage medium capable of storing, e.g., digital or alphanumeric characters as well as graphical shapes or characters.

Abstract: A magneto-optical recording medium includes a readout layer has in-plane magnetization at room temperature and in which a transition occurs from in-plane magnetization to perpendicular magnetization when temperature thereof is raised, and a recording layer for recording thereon information. The composition of the readout layer varies in a direction perpendicular to the surface thereof, and in the readout layer, the Co density on the light incident side is higher than the Co density on the interface between the readout layer and the recording layer. Therefore, the Curie temperature on the reproducing light incident side of the readout layer is high and the the polar Kerr rotation angle in reproducing increases, thereby achieving improvements in a reproducing signal quality.

Abstract: An electro-optical system is provided for the high speed storage and retrieval of digital information. In an exemplary embodiment, the system comprises pairs of closely coupled optical waveguides, with an intervening boundary storage layer. Data may be written to the storage layer during fabrication or by an external laser process. Data is read by injecting an input optical pulse which is lightly coupled through the storage layer to the data waveguide, where it may exit as an optical pulse train. This output may be converted to electrical signals.

Abstract: There is provided an optical detection method comprising the steps of preparing a solid body having an energy level structure constituted by at least three energy levels, and irradiating first and second coherent light on the solid body to optically detect the physical structure of the solid body, wherein the detection step satisfies the following conditions:min(.epsilon..sub.i31)<h.omega..sub.p /2.pi.<max(.epsilon..sub.i31),min(.epsilon..sub.i32)<h.omega..sub.c /2.pi.<max(.epsilon..sub.i32), andh.OMEGA..sub.c /2.pi.<max(.epsilon..sub.i31)-min(.epsilon..sub.i31)where the number of physical structures included in the solid body is N, the predetermined three levels of ith physical structure are called first, second, and third levels, and energies of the first, second, and third levels are .epsilon..sub.i1, .epsilon..sub.i2, and .epsilon..sub.i3, respectively, of the N physical structures, the maximum value of .vertline..epsilon..sub.i3 -.epsilon..sub.i1 .vertline. is max(.epsilon..sub.

Abstract: An optical information storage medium includes a multilayer structure formed on a substrate. The multilayer structure is formed by a sputtering process in a discharge gas and includes at least a first dielectric layer, a recording layer which shows reversible phase change between an amorphous phase and a crystal phase, and a second dielectric layer. The multilayer structure contains sufficiently small amount of the discharge gas so that a limited amount or less of voids of the discharge gas generates in the recording layer during repeated overwrite operations.

Abstract: A light beam modulated according to a data signal to be recorded is irradiates a magnetooptical recording medium while moving the recording medium. During a series of recording operations, a predetermined recording area of the recording medium is heated to a temperature of a second temperature T.sub.2 or higher in accordance with the data signal and at least a part of the area heated to the temperature of second temperature T.sub.2 or higher is once cooled down to a temperature of a third temperature T.sub.3 or lower. Then, it is heated to a temperature of a first temperature T.sub.1 or higher. Thus, the recording medium is locally heated or cooled, so that recording of information is performed.

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 optical disc comprising transparent substrate, a phase-changing material layer disposed on the transparent substrate and made of a material which is phase-changeable by radiation of a light beam, a reflecting film layer disposed on the phase-changing material layer, and a cooling layer disposed between the phase-changing material layer and the reflecting layer, wherein the cooling layer has a heat conductivity ranging from 0.25 J/cmKs to 20.00 J/cmKs. The optical disc of the present invention has such a structure that a crystal phase portion of the phase-changing material layer shows a higher light absorptivity than that of the amorphous phase portion and exhibits a high carrier to noise ratio (C/N ratio) irrespective of a line speed upon rotational driving of the optical disc.

Abstract: A recordable element with improved performance, and a method of making such element is disclosed. The recordable element includes a substrate and an optical recording layer deposited on the substrate, wherein the optical recording layer is formed of 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, and 15<(c+d)<65 and e.gtoreq.0; a metal layer over the optical recording layer; and the recording element having its properties changed by heat treatment for a time and temperature selected so as to significantly improve jitter, window margin, reflectivity, and recording sensitivity performance.

Abstract: An edge strengthened substrate of a data storage disk and a method for fabricating same is disclosed. A strengthening agent is preferably applied to selected portions of a disk-shaped glass substrate to increase the overall strength of the glass substrate. In one embodiment, a strengthening agent is preferably applied along an inner diameter portion of a disk-shaped glass substrate. A binder is preferably mixed with the strengthening agent to limit the mobility of the strengthening agent to the selected inner diameter portion of the substrate during the strengthening process. The glass substrate is then heated to a diffusion temperature for a sufficient duration of time to permit diffusion of the strengthening agent into the glass substrate. Selective application of a strengthening agent to an outer diameter portion of the glass substrate may be performed to further strengthen the glass substrate.

Abstract: A recording media comprises in cross-section, a substrate, a first dielectric layer, a recording section, a second dielectric layer and a reflector layer. The recording section comprises a plurality of thin magneto-optic recording layers interspersed with thin separating dielectric layers. The multiple magneto-optic layers act to average out the transition errors and results in improved signal to noise ratio performance.

Abstract: A mixture of low k metallized formazan dye with symmetrical and unsymmetrical cyanine dyes is disclosed. The mixture is useful in optical recording layers of optical recording elements.

Abstract: In a recordable/replayable optical recording medium having a thin metal recording layer and an optical recording method therefor, the optical recording medium includes a substrate, a thin metal film formed on the substrate, a reflective layer arranged on the thin metal film, a buffering layer interposed between the thin metal film deformed by heat, and a protecting layer for protecting the deposited layers. Recording is facilitated by adopting a buffering layer and compatibility with conventional CD players is possible. Since expensive organic dyes are not necessary, manufacturing costs can be reduced and productivity can be greatly improved.

Abstract: An optical recording medium is provided in which a first dielectric film, a second dielectric film, a recording film, a reflective film are sequentially stacked on a substrate, said first dielectric film and second dielectric film are formed of ZnO-BN. The optical disk has high recording sensitivity and high thermal stability.

Abstract: The optical recording medium has an optically transparent substrate having a center hole, a recording layer formed on the substrate, and a protective layer. The protective layer has an opening whose center coincides with a center of the center hole of the substrate, and the opening of the protective layer is larger than the center hole of the substrate. The optical recording medium is produced by a process including the steps of forming the protective layer for covering the recording layer so that the protective layer has an opening whose center coincides with a center of the center hole, and forming the opening of the protective layer so that it is larger than the center hole of the substrate. The step of forming the protective layer may be achieved using a spin coating method.

Abstract: An optical information medium providing a protective layer above an optically transparent substrate to protect a recording part, and can record information which is optically readable by means of laser beam. An aqueous printing ink-fixable, hydrophilic resin film is formed on the protective layer. Given letters and patterns can be printed easily and satisfactorily. Such letters and patterns are printable by means of, for example, an ink jet printer.

Abstract: An optical recording medium of a multi-layer type comprises; a single or plural spacer layers each carrying pits and/or grooves; a single or plural reflective layers layered on the spacer layers; and a silane coupling treatment layer formed between the reflective layer and the spacer layer adjacent to each other.

Abstract: An optical recording medium comprising a substrate with grooves, a surface smoothing layer less than 1 .mu.m thickness deposited on the grooved substrate, and a recording layer. The medium reduces noise and improves sensitivity relative to media which do not have a surface smoothing layer.

Abstract: An optical disk records digital information in optically-reflective layers that each vary in thickness between constructive interference of a monochromatic light and destructive interference of the said monochromatic light. The difference in the intensity of a reflected light beam subjected to interferometric constructive and destructive interference is used to communicate digital data from the optically-reflective layers and a detector. The optical disk provides for multiple layers of digital information that are tuned for interferometric response at correspondingly different monochromatic wavelengths of light. Another embodiment of the present invention is a mass-production process for making such an interferometric optical disk. Another embodiment of the present invention is a variation that includes layers that are emitting or absorbing depending on dopants.

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: Disclosed is a phase-change optical recording medium which has a reflectance and a signal modulation conformed to the CD standard, and which is usable for recording at the same linear velocity as the reproducing velocity specified in the CD standard. The phase-change optical recording medium comprises a metallic layer, a first protective layer, a recording layer, a second protective layer, and a reflecting layer on a substrate, in which recording is performed through change from a crystalline state to an amorphous state in the recording layer. The recording layer comprises a recording material of a Ge--Te--Sb--Se system, and the recording layer has an average composition in a direction of thickness which satisfies the following relations as represented by atomic %:Ge.gtoreq.40%, and Sb+Se.ltoreq.

Abstract: On a substrate, a recording layer which reversibly transforms between two states with different optical properties--a crystalline phase and an amorphous phase--by the irradiation of a laser beam, a first and a second dielectric layer on the bottom and the top surfaces of the recording layer, and a third dielectric layer on one surface of the first or the second dielectric layers and on the opposite side with respect to the recording layer are successively laminated, thus preparing an optical information recording medium. The third dielectric layer has a smaller coefficient of thermal expansion than the first and the second dielectric layers, so that the thermal deformation of the first and the second dielectric layers is reduced and the mass transfer of the recording layer is controlled. As a result, the overwrite cycle characteristics of the optical information recording medium are excellent.

Abstract: The present invention provides an optical card which has an excellent suitability for embossing, i.e., causes neither warpage of the card nor cracking of the transparent protective layer upon application of pressure during embossing. The optical card includes a card substrate, an adhesive layer provided on one surface of the card substrate, an optical recording material layer provided on the surface of the adhesive layer, and a transparent protective layer optionally provided on the surface of the optical recording material layer. The optical recording material layer has an emboss area, to be embossed, provided in areas other than an optical recording section of the optical recording material layer. The adhesive layer comprises an adhesive having, in the form of a film, a breaking strength of not less than 50 kg/cm.sup.2 and an elongation at break of not more than 600%.

Abstract: A magneto-optical recording medium with wide operating margins is disclosed.The magneto-optical recording medium includes a vertical magnetic films of exchange-coupled liminated structure composed of a first magnetic layer with a high coercive force H.sub.H and a low Curie temperature T.sub.L and a second magnetic layer with a lower coercive force H.sub.L and a higher Curie temperature T.sub.H in comparison with those of the first magnetic layer. The first magnetic layer has a gradient of the Curie temperature along the direction of thickness of the layer so that the Curie temperature is higher at a position closer to the second magnetic layer.The recording method utilizing the recording medium according to the present invention is also disclosed.

Abstract: A dual layer pre-recorded optical disc includes a transparent substrate, a partially reflective layer, a transparent spacer layer, and a highly reflective layer. One pattern of data pits is provided on the substrate, adjacent the partially reflective layer, and another pattern of data pits is provided on the spacer layer, adjacent the highly reflective layer. The partially reflective layer may be made of silicon carbide. A substrate-incident beam can be used to read data encoded in either data pit pattern depending on which layer the laser is focused upon. The dual layer disc has twice the data storage capacity of conventional single layer discs.

Abstract: A recording layer contains a dye A having a complex index of refraction at 780 nm whose real part n is 1.8-2.8 and imaginary part k is up to 0.15 and forming a thin film exhibiting an absorption spectrum whose half-value width is up to 170 nm and a dye B having a complex index of refraction at 630 nm or 650 nm whose real part n is 1.8-2.8 and imaginary part k is up to 0.2. An optical recording medium capable of writing and reading in a conventional wavelength region of about 780 nm and a shorter wavelength region of about 630 to 680 nm is obtained.

Abstract: Disclosed are a phthalocyanine near infrared absorbing material having a phthalocyanine skeleton whose benzene rings contain a silyl group as a bulky substituent and an optical information recording medium containing the material.The phthalocyanine near infrared absorbing material has excellent association-preventing property and light resistance and exhibits a high index of refraction at a wave length of 770-830 nm and high stability, an optical information recording medium (CD-R recording medium) containing the phthalocyanine has high reflectance, excellent storage stability and excellent reproduction stability. The recording medium also shows strong light absorptivity and light reflectivity in a wave length of 630-700 nm and, thus, is applicable for the pick up with a semiconductor laser of 630-700 nm, permitting such high density recording as to provide 1.6-1.7 times as high recording density as that attained by currently employed recording media which are adapted to 780-810 nm.

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: 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 andr a singlet oxygen quencher.

Abstract: The present invention discloses an optical recording element having, in the following order, a transparent substrate, a recording layer and a light reflecting layer wherein the recording layer(A) has a real refractive index (N) at 780 nm not less than 1.8 and an imaginary part (k) is not greater than 0.15;(B) comprises a polymeric cyanine dye that (i) has both a weight-average molecular weight greater than 50,000 and a glass transition temperature (Tg) of less than 150.degree. C.; or (ii) has either (a) a weight-average molecular weight greater than 50,000 or (b) a glass transition temperature (Tg) of less than 150.degree. C.; and(C) a thickness greater than 200 nm.

Abstract: A magneto-optical disk having a four-layer structure formed of a first protective dielectric layer, a recording magnetic layer, a second protective dielectric layer and a reflective metal layer is disclosed. The constraints for the film thicknesses of the various layers are determined not only from the optical and magneto-optical aspects, but from the aspect of the dynamic thermal response.The recording magnetic layer is a magnetic layer mainly formed of TbFeCo and having a film thickness of not less than 180 .ANG. and not more than 280 .ANG.. The first protective dielectric layer is a nitride film having a film thickness such that the product of its refractive index and the film thickness is not less than 0.2 and not more than 0.35 times the wavelength of the laser light employed. The second protective dielectric layer is a nitride film having a film thickness such that the product of its refractive index and the film thickness is not less than 0.1 and not more than 0.

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. A layer of a semiconductor material is deposited onto each of the data surfaces. The thickness of the semiconductor layer determines the amount of reflectivity for each of the data surfaces.

Abstract: A magneto-optic recording medium with a transparent substrate, a first dielectric layer above the transparent substrate, a magnetic layer above the first dielectric layer, a second dielectric layer above the magnetic layer, and a reflecting layer above the second dielectric layer. The magnetic layer is made of a composition modulated material.

Abstract: A perpendicular magnetic recording medium is fabricated based on R.sub.21-60 (Fe.sub.1-y Co.sub.y).sub.z M.sub.0-10 wherein z is balance and at least 70 at % of R is Nd and/or Pr, the balance of R being one or more of other rare earth elements, and wherein y is less than 0.5 by atomic ratio. M is at least one of various additional metal elements. The Curie temperature Tc is between 70.degree. to 250.degree. C.; the saturation magnetization Ms is about 450 emu/cc or more; the uniaxial perpendicular magnetic anisotropy constant Ku of 2.5.times.10.sup.6 erg/cc or more is attained. Kerr rotation angle is 0.3 degree or more, which provides a magneto-optic recording medium. Since light rare earth elements having the collinear alignment of magnetic moment with Fe are used as a key element, it is possible to fabricate uniform perpendicular magnetic anisotropy thin films in a mass production scale at a low cost.

Abstract: A magnetic recording medium having a recording layer made up of a ferrimagnetic material whose compensation temperature is included within room temperatures and an information recording-reproduction method using the magnetic recording medium. During recording, while a light beam is projected on the recording layer so as to raise the temperature of a recording portion, information is recorded by applying a signal magnetic field from a magnetic head. During reproduction, while a light beam is projected on a reproducing portion of the recording layer so as to raise the temperature thereof, information is reproduced by detecting leakage flux from the reproducing portion by the magnetic head. Thus, during reproduction, no magnetic flux is generated from other portions of the recording layer not irradiated by the light beam. With the arrangement, crosstalk due to leakage flux from adjoining tracks not irradiated by the optical beam can be eliminated.

Abstract: An optical element which exhibits a great improvement in durability even after repeated use. The optical element comprising a substrate having thereon (a) a recording layer comprising a liquid crystal polymer composition and (b) a surface protective layer in this order, in which the protective layer comprises a plurality of layers laminated such that the hardness thereof increases from the layer adjacent to the recording layer toward the uppermost layer in order, or the protective layer comprises a plurality of layers laminated such that the glass transition point thereof becomes higher from the layer adjacent to the recording layer toward the uppermost layer in order. Furthermore, the layer adjacent to the recording layer preferably has a pencil hardness of HB or higher and the uppermost layer preferably has a pencil hardness of 3 H or higher.

Abstract: There is provided an optical memory medium comprising a flat plate modified on the surface thereof by a photolytic residual group, an optical recording apparatus comprising an optical probe having a microscopic aperture on the leading end thereof, a light source, X-Y-Z position control means, and a controller for controlling the apparatus as whole and an apparatus for reading the optical memory medium comprising the optical memory medium, a friction detecting probe, an X-Y-Z position control means and a controller for controlling the apparatus as a whole.

Abstract: A glass substrate manufacturing method advantageously applicable to magnetic recording disk glass substrates, LCD glass substrates, photomask glass substrates, or optical memory glass substrates. This 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 plural 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 comprising a substrate, a phase-change type recording layer and capable of storing information therein through a phase-change of a portion thereof upon being irradiated by light beam, a first dielectric protecting layer interposed between the substrate and the recording layer, a second dielectric protecting layer formed on the recording layer, a first light-absorptive protecting layer comprising a dielectric material and at least one material selected from metals, semimetals and semiconductor materials and interposed between the recording layer and the first dielectric protecting layer, and a second light-absorptive protecting layer comprising a dielectric material and at least one material selected from metals, semimetals and semiconductor materials and interposed between the recording layer and the second dielectric protecting layer.

Abstract: The present invention provides an information recording medium including a first recording film formed on a substrate and having an amorphous phase made of an alloy containing at least Ge and Te, and a second recording film formed on the first recording film and made of a material with a relatively large light absorption coefficient, wherein the alloy of the first recording film exhibits a Raman scattering spectrum having scattering peaks at 140 to 160 cm.sup.-1 and 120 to 130 cm.sup.-1 and no scattering peaks at 100 to 110 cm.sup.-1, and recording is performed by changing optical characteristics by alloying the materials of the first and second recording films by radiating recording light on the first and second recording films.

Abstract: Recording or erasing on a thermal recording medium is performed such a manner that a local region of a recording film on the recording medium is heated to a predetermined temperature to reversibly change the state of the local region between two states. In this method, the recording film is initialized in one of the two states. When the recording film is set in the other of the two states upon continuous or intermittent heating, a band-like region elongated in a recording direction on the recording film is formed to effect the erasing operation. In recording step, the local region of the recording film is heated to a predetermined temperature in accordance with information so as to include the band-like region in the local region to be heated and a state of the heated local region is caused to be identical with the state upon the initialization.

Abstract: A copolymer comprising 70 to 100 mole percent of repeating units comprising a formazan dye radical and a cyanine dye radical. The copolymers are useful in recording layers of optical recording elements.

Abstract: A magneto-optical memory element has a multi-layer construction in the order from a side first receiving light from a light-source which includes a first transparent dielectric film, a rare earth transition metal alloy film, a second transparent dielectric film and a reflective film. The magneto-optical device uses circular dichroism effect of a magnetic mater for reading information. The rare earth transition metal alloy film has a refractive index represented by n.+-..DELTA.n wherein n=3.2-3.55i and .DELTA.n=0.05-0.03i. The thickness of film is about 18 to 46 nm. The second transparent dielectric film has a refractive index of 2.0.+-.0.2 and a film thickness of 80 to 108 nm.