Abstract: A disc substrate inject-molded comprises; a first circular surface having an inner non-data region formed around a center hole thereof and an outer data region formed around the non-data region; a second circular flat surface opposite and parallel to the first circular surface; and a ring shaped stack-rib formed on the non-data region.

Abstract: Clamping apparatus for disk-shaped information medium having a central hole, the disk-shaped information medium having a surface upon which information is to be printed, including a baseplate having holes; a slider guidably mounted on the baseplate for centering the disk-shaped information medium with the central hole; stationary holding elements arranged on the baseplate, and movable holding elements arranged on the slider, in such a way that when an information medium is placed in the clamping apparatus, a predetermined number of the stationary and movable holding elements are arranged along the outer periphery of the information medium, and the remainder of the stationary and movable holding elements are arranged along the inner periphery of the central hole of the information medium; a bottom plate positioned under the baseplate and movable perpendicular thereto; and information medium contact elements which are formed on the bottom plate and adapted to pass through holes in the baseplate and contact the

Abstract: An optical disc has a pair of light-transmissible circular substrates each having an inner non-data region disposed around a center hole thereof, a data region disposed around the inter non-data region for bearing signals corresponding to information to be recorded and an outer non-data region disposed around the data region which are formed on a major surface of the substrate. The optical disc has a reflective layer formed on the data region and a protective layer made of an ultraviolet ray setting resin containing metal ions formed on the reflective layer. The optical disc has an adhesive layer made of an adhesive composition containing an ultraviolet ray setting component and an anaerobic hardening component disposed between the protective layers of the circular substrates for adhering the circular substrates.

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: In order to provide a laminated optical disc having a sufficient display portion and a reliable print display, a pair of disc substrates are bonded together to form an optical disc, in which one disc substrate is colored and contents of recorded matters are displayed on the surface thereof so as to eliminate the ground solid print layer for the print display layer and to avoid deformation or warping of the disc.

Abstract: A hard drive disk substrate is formed of a multi-phase ceramic-based material having at least two phases with amorphous phases being present in an amount less than about 1 volume percent based on the volume of the ceramic-based material or at least one phase being free metal. A process for producing the ceramic-based disk substrate is produced by forming a flat disk of a porous ceramic and then infiltrating the porous ceramic with a metal whereby a multi-phase ceramic-based computer hard drive disk is produced. Additionally, a step of passivating the porous ceramic by elevating it to a temperature of about 1300.degree. to about 1800.degree. C. before the infiltrating step may be performed, such that the surfaces are passivated and the reaction kinetics can be controlled during the infiltrating step. A preferred composite material is made of a multi-phase boron carbide composite material including grains having peaks with an average roughness value, Ra, of between about 1 to about 200.ANG.

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: 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: 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: The invention relates to a spin-transition parent compound in powdered form, comprising a network having molecules which are each formed from a complex in which a metallic ion M having an electronic configuration in d5 or in d6 or in d7, is bonded to at least one aminotriazole ligand of the formula ?L.sub.2 N-trz!, wherein L is an alkyl radical (C.sub.n H.sub.2n+1) and n is an integer which is equal to or greater than zero, each molecule also including a sulforganic anion comprising a sulfito radical (SO.sub.3.sup.-), and the network also including at least one water molecule (H.sub.2 O) per molecule of the metallic complex M, said water molecule(s) in the network only being bonded to the aminotriazole ligand by a hydrogen bond.In this compound, the anion may be, for example, a sulfito-aryl having a benzene radical or a sulfito-aryl derived from a benzene radical, or a sulfito-aryl having a saturated or unsaturated organic chain, an alkyl sulfito-halide or an aryl sulfito-halide.

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: Two disc bases D having different information are molded in a time by a pair of cavities formed when clamping the molds 1 and 2, which are filled with the molten resin by being injected. After taking out the disc bases from the mold by a product taking out apparatus, those are coated with a reflection layer by a sputtering apparatus and subsequently coated with a protection layer by a coating apparatus and finally bonded by a bonding apparatus to obtain a single disc VD. This disc VD can avoid the mechanical troubles such as distortion, bending, twisting or peeling off of the bonded portion in a time lapse after being bonded, because those disc bases VD are molded in a pair of cavities 3, 3 formed in a mold using the material of the same lot, i.e. under the same condition. Representative drawing FIG. 1.

Abstract: An information recording medium including a substrate, a recording layer, a protective layer, a print layer on the protective layer, and a barrier layer located intermediate the print layer and the recording 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: In advance of carbon coating, by injecting ions into the shaped surface of a metallic mold made of super-hard materials, it becomes possible to increase the adhesiveness of the carbon coat onto the mold material, and to increase the life of the mold. In a metallic pressing mold with the required flatness secured by carbon coating on the surfaces, the surface layer of the shaped surfaces is modified by ion injection in advance of carbon coating.

Abstract: A multilayer optical disk having an information storage layer which can as well as be reproduced by a general-purpose reproducing apparatus, for example, a compact disk player, and from which information can be read from other information storage layers by using an exclusive reproducing apparatus. The multilayer optical disk having a plurality of information storage layers according to the present invention includes a plurality of information storage layers, wherein one of the plural information storage layers has a reflection factor of 70% or higher with respect to a wavelength of 770 nm to 830 nm which is a first wavelength of reproducing light, and other information storage layers are reproduced with reproducing light having a second wavelength which is different from the first wavelength of reproducing light. Each of the other information storage layers has a reflection factor of 20% or higher with respect to the second wavelength of reproducing light.

Abstract: A strip-shaped or wire-shaped compound material with a base material of copper or a copper alloy and with a moltenly applied surface coating of a tin alloy, whereby between both materials there is formed an intermetallic phase. The inventive additive of 0.001 to 0.5% cobalt to pure tin or a tin alloy results in a particularly fine-granular, smooth intermetallic phase and not only a higher total layer hardness, a better bendability, a higher shearing resistance and a lower elasticity module, but, in particular, also a high creeping resistance. The compound material can be utilized within a wide range for electromechanical and electrooptical structural elements, plug connectors and soldered structural parts.

Abstract: A stamper for manufacturing a base of an optical disc where grooves having a track pitch of 1.6 .mu.m and width of 1.3 .mu.m or less are formed by using synthetic resin material includes a plurality of projections for forming grooves and a plurality of recessed portions. The plurality of projections have a flat upper portion and a pair of rising portions provided on the both sides of the upper surface portion. The plurality of recessed portions are formed so that bottom surfaces provided continuously to the rising portions of the respective projections become flat. In this case, when width dimension of the rising portion is .epsilon./2, width .epsilon./2 of the rising portion is given by the following expression:0.05 .mu.m.ltoreq..epsilon./2.ltoreq.0.15 .mu.

Abstract: A memory media-ready substrate having a substrate, a hardening layer and a film made of a nonferromagnetic material that is disposed between the substrate and the film. A memory disk including the film and associated methods of making a hardening layer-ready substrate, the memory media-ready substrate and the memory disk are also provided.

Abstract: This invention is directed at the makings of glass-ceramic which is uniquely suited for use as a disc substrate for utilization in a magnetic memory storage device. The glass ceramic material exhibits a crystal phase assemblage comprised predominately of a mixture of lithium disilicate and tridymite which are uniformly interspersed with a residual glass phase and form an interlocked microstructure with the glass. The composition consists essentially, expressed in terms of weight percent on the oxide basis, of 75-95% SiO.sub.2, 3-15% Li.sub.2 O, 0-6% Al.sub.2 O.sub.3, and 0-6% K.sub.2 O. The nucleating agent for this glass-ceramic is selected from the group consisting of 0-0.1% Pd and 0-5% P.sub.2 O.sub.5 ; however if Pd is absent the P.sub.2 O.sub.5 amount is at least 0.5% and if P.sub.2 O.sub.5 is absent then the Pd amount is at least 0.005%. Additionally, up to 15% of optional ingredients may be added, including, B.sub.2 O.sub.3, Na.sub.2 O, ZnO, MgO, CaO, SrO, ZrO.sub.2, TiO.sub.2, F, Sb.sub.2 O.sub.3, As.

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: 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: A precursor for manufacturing a semiconductor thin film in which an oxide thin film comprising at least one element as a dopant, selected from a group which consists of Groups IA, IIA, IIB, VA, and VB elements, and Groups IB and IIIA elements which are main components of the semiconductor thin film are deposited on a substrate, or a precursor for manufacturing a semiconductor thin film which is formed by depositing a thin film of oxide comprising the Groups IB and IIIA elements on the substrate wherein the content of at least one of the Groups IB and IIIA elements is varied in the direction of film thickness, and a method for manufacturing a semiconductor thin film comprising the step of heat treating the precursor for manufacturing the semiconductor thin film in an atmosphere containing a Group VIA element.

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: The present invention provides a constrained layer damper having slits and/or cutout(s) therein, which provides improved vibration damping performance. The constrained layer damper of the invention is useful, for example, for damping rotatable spacer articles and also rotatable storage media such as compact disks.

Abstract: Sputter induced micro-texturing of thin film magnetic media discs entailing the formation of micro-texturing globules comprising a eutectic alloy of Indium and Bismuth.

Abstract: Method and apparatus for forming a first and a second component disk which are bonded together to produce a bonded composite disk, wherein a first mold for forming the first component disk includes first mutually concentric components cooperating to define a molding surface for forming a bonding surface of the first component disk, while a second mold for the second component disk includes second mutually concentric components cooperating to define a molding surface for forming the bonding surface of the second component disk, and wherein the first mutually concentric components are dimensioned such that at least one of first annular boundaries between adjacent ones of the first mutually concentric components, which boundaries are located on the molding surface, has a diameter different from that of the corresponding second annular boundary between adjacent ones of the second mutually concentric components.

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 electronic part comprising an amorphous thin film formed on a substrate; and a metal wiring formed on the surface of the amorphous thin film; wherein an interatomic distance corresponding to a peak of halo pattern appearing in diffraction measurement of the amorphous thin film approximately matches with a spacing of a particular crystal plane defined with the first nearest interatomic distance of the metal wiring. An electronic part provided with a metal wiring formed of highly orientated crystal wherein half or more of all grain boundaries are small angle grain boundaries defined by one of grain boundaries with a relative misorientation of 10.degree. or less in tilt, rotation and combination thereof around orientation axes of neighboring crystal grains; coincidence boundaries where a .SIGMA. value is 10 or less; and grain boundaries with a relative misorientation of 3.degree. or less from the coincidence boundary.

Abstract: An exposure master disc includes a photoresist laminate formed on a glass substrate. The photoresist laminate includes an i-line type, first photoresist layer and a g-line type, second photoresist layer consecutively formed on the substrate. The photoresist laminate is exposed by a scanning laser light while selecting the exposure power level, to thereby effectively expose the first and second photoresist layers or to effectively expose only the second photoresist layer. The resultant photoresist laminate has first pits revealing the substrate and second pits revealing the first photoresist layer, thereby forming two types of pits having different depths. Two type of pits and flat surface of the photoresist laminate provide three-valued data for a higher storage density.

Abstract: A magnetic recording tape or disk formed from a biaxially oriented laminated polyester base film which comprises a layer (A) of a polyester consisting essentially of 2,6-naphthalenedicarboxylic acid and ethylene glycol components and a layer (B) of a copolyester consisting essentially of 2,6-naphthalenedicarboxylic acid, ethylene glycol, and diethylene glycol components, wherein the copolyester contains 1-5% by weight of the diethylene glycol component, based on the weight of the layer (B) copolyester, layer (B) being present on one or both surfaces of layer (A).

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 near infrared light-absorbing dye comprising phthalocyanine compounds represented by the following formula (2): ##STR1## wherein in formula (2), M is two hydrogen atoms, a divalent metallic atom, a trivalent monosubstituted metallic atom, a tetravalent disubstituted metallic atom or an oxymetal atom, and L.sup.1, L.sup.2, L.sup.3 and L.sup.4 are each independently formula (a) or (b), ##STR2## in the formula (a) or (b), R.sup.1 and R.sup.3 are each a substituted or unsubstituted alkyl group, and R.sup.2 is a straight chain or branched halogenated alkyl or alkenyl group having 3 to 10 carbon atoms,X is a chlorine, bromine or iodine atom, and m is an integer of 1 to 12, provided that formula (2) represents a mixture of L.sup.1 =L.sup.2 =L.sup.3 =L.sup.4 =formula (a), L.sup.1 =L.sup.2 =L.sup.4 =formula (a) and L.sup.3 =formula (b), L.sup.1 =L.sup.4 =formula (a) and L.sup.2 =L.sup.3 =formula (b), L.sup.1 =L.sup.3 =formula (a) and L.sup.2 =L.sup.4 =formula (b), L.sup.1 =formula (a) and L.sup.2 =L.sup.3 =L.sup.

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 disk-shaped optical information medium of this invention includes: a first substrate having a center hole; a second substrate having a center hole; and a radiation curable resin interposed between the first and second substrates for bonding together the first and second substrates, wherein the optical information medium further includes a stopper for preventing the radiation curable resin from protruding into the center holes of the substrates, and a space between the first and second substrates of at least a half of a clamp region for clamping the optical information medium is filled with the resin.

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: 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 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 substrate according to the present invention is applicable to an optical disc on which an information signal is recorded. Formed on the substrate are prepits in the form of irregularities which generates a tracking error signal upon detected. The substrate serving as a electro-acoustic transducer comprises a flat surface portion including at least a portion on which a recording layer and/or a reflecting film layer are formed, and plural pairs of prepits formed on the portion. Two prepits constituting each pair of the prepits are disposed at positions offset from a center of a virtual recording track such that the center of the virtual recording track is interposed between the two prepits. The substrate is produced by injection-molding a synthetic resin material having a light-permeability and has a thickness of 1 mm or less at the portion on which the recording layer and/or the reflecting film layer are formed.

Abstract: An optical recording medium which is constructed in a manner such that a plurality of recording areas in which an information signal is recorded along vortical spiral tracks are arranged in a ring shape on a recording surface and a vortex direction of the spiral track of the outside recording area among the plurality of recording areas differs from that of the spiral track of the inside recording area. When the information signal is recorded to the recording medium, the first writing device executes the writing operation from the outer rim side toward the inner rim side of the spiral track of the outside recording area and the second writing device executes the writing operation from the inner rim side toward the outer rim side of the spiral track of the outside recording area.

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 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: 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: 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: 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: There is provided a WORM type organic optical recording media 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 of a thermosetting or photocuring resin. The organic optical recording medium can be prevented from being rewritten by heating up to 50.degree. C. or irradiating with a UV light, said dye being capable of absorbing near infrared rays and generating heat.The medium exhibits stable reading characteristics of at least 45 dB even after irradiating with a light with a short wavelength. In addition, it also has a function of record locking by curing the resin of the recording layer, so that, once recorded, rewrite or additional recording is not allowed therein.