Abstract: An optical recording method that performs recording by irradiating optical recording media with laser beam modulated in intensity based on a write waveform is provided. The write waveform has a plurality of write pulse blocks for forming write marks, and each write pulse block has at least one type of upward pulse. In the event that the width of said upward pulse is so narrow that the laser beam intensity corresponding to the peak intensity of that upward pulse cannot be obtained, the peak intensity of that upward pulse is increased so that, in said laser beam, the beam intensity it should have or a value close thereto is obtained. Thereby, good recording and playback characteristics can be obtained even when recording at a high transfer rate.

Abstract: A phase change optical recording medium is provided wherein the power of the laser beam per unit area required in the initialization is reduced. The optical recording medium has a phase change recording layer satisfying the relations: AI≦8.0%, and CI/AI≧3.0 when the medium is initialized with a light beam having a wavelength &lgr;I, and said recording layer exhibits a reflectivity AI in amorphous region and a reflectivity CI in crystalline region at said wavelength &lgr;I.

Abstract: The present invention has enabled to solve various problems associated with the optical recording medium of phase change type when high density recording is conducted by reducing the record marks. Provided is an optical recording method for an optical recording medium having a recording layer of phase change type wherein amorphous record marks are formed in the recording layer by irradiating the medium with a recording beam which is power-modulated between high power and low power. In this method, minimum record marks are formed such that at least a part of the rear end protrudes toward the forward end of the mark.

Abstract: A phase change optical recording medium is provided wherein the power of the laser beam per unit area required in the initialization is reduced.

Abstract: An information readout method for an optical information medium comprising an information recording layer having pits or recorded marks representative of information data involves the step of irradiating a laser beam to the information recording layer through an objective lens for providing readings of the pits or recorded marks. When the laser beam has a wavelength &lgr; of 400 to 410 nm, the objective lens has a numerical aperture NA of 0.70 to 0.85, and the pits or recorded marks have a minimum size PL of up to 0.36&lgr;/NA, readout is carried out at a power Pr of at least 0.4 mW for the laser beam. When the laser beam has a wavelength &lgr; of 630 to 670 nm, the objective lens has a numerical aperture NA of 0.60 to 0.65, and the pits or recorded marks have a minimum size PL of up to 0.36&lgr;/NA, readout is carried out at a power Pr of at least 1.0 mW for the laser beam. Pits or recorded marks of a size approximate to the resolution limit determined by diffraction can be read out at a high C/N.

Abstract: In a phase change optical recording medium, time required for recording the unrecorded area as well as jitter produced are reduced. Provided is an optical recording method for recording an optical recording medium having a phase change recording layer, wherein the recording is conducted such that: VW/Vo>1, and 0.

Abstract: An optical recording medium having at least a light-transmitting substrate, a recording layer recorded by heat mode recording, and a reflective layer comprising a metal or a semimetal disposed in this order exhibiting reduced signal noise in the reading and improved recording characteristics are provided. A method for producing such optical recording medium is also provided, and this method includes the step of changing bonding state of the element(s) constituting the reflective layer at least in the area to be recorded.

Abstract: High temperature reliability, and in particular, the high temperature reliability after repeated overwriting operations is improved in an optical recording medium wherein a material of Ag—In—Sb—Te system is used for the recording layer. Provided is an optical recording medium having a recording layer of phase change type, wherein said recording layer contains Ag, In, Sb, and Te as its main components, and Ge as its sub-component such that, when molar ratio of the elements constituting the main and sub-components is represented by formula (I): (AgaInbSbcTed) (1-e/100)Gee, 2≦a≦20, 2≦b≦20, 35≦c≦80, 8≦d≦40, a+b+c+d=100, and 1≦e≦15.

Abstract: The optical recording medium of the present invention has a phase change recording layer. This recording layer contains at least two elements selected from Sb, Te, Ge, and In as main elements, and at least one element selected from rare earth elements (Y, Sc, and lanthanoid), Zr, Hf, Ti and Sn as an auxiliary element, and also, a eutectic mixture can exist in the recording layer. The optical recording medium of the present invention can be operated at a high transfer rate, and has a high storage reliability.

Abstract: In an optical recording medium wherein a layer of nonlinear optical material and a recording layer of phase change type are formed extreme close to each other to enable reading of small record marks beyond diffraction limit, a high C/N is realized and decrease of the C/N in the reading is also suppressed. More illustratively, the optical recording medium has a mask layer (nonlinear optical material layer) and a recording layer of phase change type formed to sandwich an intermediate dielectric layer such that an optical aperture can be formed in the mask layer by irradiation of reading light beam from the side of the mask layer. The intermediate dielectric layer has a thickness of 5 to 70 nm; or near field light generated near the optical aperture is used in the reading. The recording layer contains Ag, In, Sb and Te as its main components and Ge and/or N as its sub-component.

Abstract: An information medium capable of recording the information at a high density in a convenient manner is provided. Also provided is a method capable of readily reproducing the information recorded at such high density, and a system which can be used therefor. In the present invention, the information is read by reading difference in crystallographic state, crystallographic phase or constituent material as a difference in surface potential or surface charge density.

Abstract: In the recording of an optical recording medium of phase change type according to the present invention, favorable properties are realized even when the recording is effected in a wide range of linear velocity. The optical recording method of the present invention is a method for recording an optical recording medium comprising a substrate and a recording layer of phase change type on the substrate. A pulse train is used as the recording waveform for laser beam modulation during the formation of one recording mark. The pulse train includes at least one unit pulse comprising an upward pulse and a subsequent downward pulse, and the relation (I): 0.25≦(TclH/TclL)×n≦1.25  (I). is satisfied when width of the last downward pulse standardized by the reciprocal of linear velocity is TclH at a linear velocity of V and TclL at a linear velocity of V/n (n is a real number greater than 1).

Abstract: The present invention provides a method for determining optimal read power adapted for use in an optical information medium wherein super-resolution readout beyond diffraction limit is conducted. Also provided is an optical information medium adapted for use in such method. In this method, when the readout is conducted under the conditions: LMIN<&lgr;/4NA, and when reading light has a wavelength &lgr;, objective lens of readout optical system has a numerical aperture NA, and minimum mark of the marks constituting the information pattern has a length LMIN, a short mark having a length LS and a long mark having a length LL meeting the relations: LS<&lgr;/4NA, and LL≅&lgr;/4NA are preliminarily formed in the optical information medium, and the optimal power of the reading light is determined on the output when said short mark and said long mark are read.

Abstract: An information medium capable of recording the information at a high density in a convenient manner is provided. Also provided is a method capable of readily reproducing the information recorded at such high density, and a system which can be used therefor. In the present invention, the information is read by reading difference in crystallographic state, crystallographic phase or constituent material as a difference in surface potential or surface charge density.

Abstract: In an optical recording medium comprising a grooved light-transparent substrate, a phase change recording layer, a dielectric layer and a reflective layer, recording is carried out by irradiating a laser beam to the recording layer through an objective lens in an optical system. The recording is carried out in the grooves under the conditions: 0.48≦PT/(&lgr;/NA)≦0.74, and PT≦0.50 &mgr;m wherein &lgr; is a laser beam wavelength, NA is an objective lens numerical aperture, and PT is a track pitch, thereby forming a recorded mark having opposite ends extending out of the groove. This enables high density recording and increases the data transfer rate of a phase change optical recording medium.

Abstract: Increase of jitter in a phase change optical recording medium is suppressed with no extreme decrease in the crystallization speed of the recording layer when the medium is overwritten at a high linear velocity. In addition, in a disk-shaped medium operated at a constant angular velocity, the overwriting is accomplished with the increase of jitter suppressed over the entire area of the medium. Provided is an optical recording method for recording a disk-shaped optical recording medium having a phase change recording layer which is rotated at a constant angular velocity, wherein amorphous recorded marks are formed in the recording layer. In this method, the minimum recorded mark is formed such that WL/ML incrementally or gradually decreases from the radially inner side to the radially outer side of the optical recording medium, when the minimum signal has a length of SL, and when the minimum recorded mark corresponding to said minimum signal has its maximum width of MW, EW is 0.

Abstract: In an optical recording medium wherein grooves or lands formed on the supporting substrate are used for the recording tracks, and wherein prepits are also formed, production of the supporting substrate and high density recording are facilitated. This medium comprises a supporting substrate and a recording layer on the substrate wherein the surface of the supporting substrate on which the recording layer is formed is formed with alternating continuous convex portions and continuous concave portions which are substantially parallel to each other. The adjacent continuous convex portions are connected by bridging convex portions extending in transverse direction, and the bridging convex portion has a planar configuration that its width is minimum at or near the center between the adjacent continuous convex portions. The supporting substrate is produced by using a master disk which has a resist layer formed with mother patterns of each of the continuous convex portions, continuous concave portions, and prepits.

Abstract: In an optical recording medium comprising a phase change recording layer (4) containing Sb and optionally, Te and/or In as a main component, the recording layer is able to be crystallized to provide a crystallized region which contains rhombohedral crystals consisting essentially of Sb and is substantially free of a crystal phase other than the rhombohedral crystals. When the recording layer contains a rare earth element, Zr, Hf, Ti or Sn as an auxiliary component, the medium has a dielectric layer (31) composed of silicon oxide, silicon nitride, aluminum oxide, or a mixture of zinc sulfide and at least 30 mol % of silicon oxide, disposed contiguous to and in front of the recording layer (4) as viewed from the recording/reading beam incident side. The medium has a high transfer rate and improved thermal stability.

Abstract: In an optical recording medium having a phase change recording layer, recorded marks having a shortest length of up to 350 nm are formed in the recording layer which contains Sb as a main component. This enables formation of microscopic recorded marks which are stabilized in shape and size. The medium remains reliable in that the microscopic recorded marks are improved in thermal stability.

Abstract: When information is recorded in an optical recording medium having a recording layer by irradiating a laser beam thereto through an optical system, the recording is carried out under the conditions: &lgr;/NA≦680 nm and n·Tw≦22 ns wherein the laser beam has a wavelength &lgr;, the optical system includes an objective lens having a numerical aperture NA, the window margin is Tw, and a signal length corresponding to the shortest recorded mark is n·Tw. The method provides for a high transfer rate and minimizes the jitter.