Abstract: In an optical recording medium having a plurality of recording layers on which information can be recorded by irradiating a laser beam from one side thereof, an optimum recording power to each of the recording layers can be determined. The optical recording medium has a plurality of recording layers on which information can be recorded by irradiating a laser beam from one side thereof, and each of the recording layers has a power calibration area (PCA) for optimizing the intensity of the laser beam.

Abstract: In an optical recording medium having a plurality of recording layers on which information can be recorded by irradiating a laser beam from one side thereof, an optimum recording power to each of the recording layers can be determined. The optical recording medium has a plurality of recording layers on which information can be recorded by irradiating a laser beam from one side thereof, and each of the recording layers has a power calibration area (PCA) for optimizing the intensity of the laser beam.

Abstract: In an optical recording medium of a single-sided incident type having a plurality of recording layers, recording/reading conditions (for example, tracking polarity, recording pulse strategy, recording recommended power, etc.) can be instantaneously switched according to each of the recording layer, and recording or reading of information can be accurately and surely performed under recording/reading conditions adapted to each recording layer. A control unit reads out layer information from one recording layer of the optical recording medium in which the layer information is recorded in each of the plural layers, on which recording or reading of information can be performed by irradiating a laser beam from one side thereof (layer information reading step), and controls so that recording or reading is performed under recording/reading conditions adapted to a recording layer specified on the basis of the layer information (recording controlling step).

Abstract: By use of a substrate which can be stably formed and has a relatively small groove depth, a very high density optical recording medium having good recording/reading characteristics is provided. In an optical recording medium of a surface incidence type, in which a reflective layer, a recording layer containing a dye as a main component and a cover layer are sequentially formed on a substrate having guide grooves formed therein, a guide groove part on a far side from a plane of incidence of a recording/reading light beam on the cover layer is set as a recording groove part, and reflected light intensity in a recorded pit portion formed in the recording groove part is increased by a phase shift and is set higher than reflected light intensity in unrecorded.

Abstract: An optical recording medium on which high-density recording and reading of optical information can be conducted by a short-wavelength light such as a blue laser beam is provided. In an optical recording medium comprising at least a substrate and a recording layer thereon that can record or read information by irradiation with light, the recording layer contains an azacyanine dye represented by general formula [I]: wherein R1 and R2 each independently represent a hydrogen atom or an optionally substituted linear or branched alkyl group having one to four carbon atoms; R3 represents a hydrogen atom or a hydrocarbon group; R4 represents a hydrogen atom or a linear or branched alkyl group having one to four carbon atoms; R5 represents an optionally substituted aromatic ring group or an optionally substituted unsaturated heterocyclic group; R4 and R5 may be combined together to form a ring; X? represents a counter anion; and the benzene ring A may be optionally substituted.

Abstract: In an optical recording medium having a plurality of recording layers on which information can be recorded by irradiating a laser beam from one side thereof, an optimum recording power to each of the recording layers can be determined. The optical recording medium has a plurality of recording layers on which information can be recorded by irradiating a laser beam from one side thereof, and each of the recording layers has a power calibration area (PCA) for optimizing the intensity of the laser beam.

Abstract: An information recording method allows optical information having a recording mark length smaller than a spot diameter of laser light to be recorded on an optical recording medium having a recording layer, at high density by laser light pulse application. The information recording method has: a power calibration step of determining a recording power for recording a signal having a predetermined signal length in the recording layer using the laser light; and a complementing step of complementing, based on the recording power determined in the power calibration step, a recording power for recording a signal having a signal length equal to or less than ½ of the spot diameter of the laser light in the recording layer using the laser light. In the information recording method, for example, an extremely small mark, such as a 2T signal, can be precisely formed.

Abstract: In an optical recording medium having a plurality of recording layers on which information can be recorded by irradiating a laser beam from one side thereof, an optimum recording power to each of the recording layers can be determined. The optical recording medium has a plurality of recording layers on which information can be recorded by irradiating a laser beam from one side thereof, and each of the recording layers has a power calibration area (PCA) for optimizing the intensity of the laser beam.

Abstract: In an optical recording medium having a plurality of recording layers on which information can be recorded by irradiating a laser beam from one side thereof, an optimum recording power to each of the recording layers can be determined. The optical recording medium has a plurality of recording layers on which information can be recorded by irradiating a laser beam from one side thereof, and each of the recording layers has a power calibration area (PCA) for optimizing the intensity of the laser beam.

Abstract: In an optical recording medium of a single-sided incident type having a plurality of recording layers, recording/reading conditions (for example, tracking polarity, recording pulse strategy, recording recommended power, etc.) can be instantaneously switched according to each of the recording layer, and recording or reading of information can be accurately and surely performed under recording/reading conditions adapted to each recording layer. A control unit reads out layer information from one recording layer of the optical recording medium in which the layer information is recorded in each of the plural layers, on which recording or reading of information can be performed by irradiating a laser beam from one side thereof (layer information reading step), and controls so that recording or reading is performed under recording/reading conditions adapted to a recording layer specified on the basis of the layer information (recording controlling step).

Abstract: The present invention provides a high level optical recording material which is capable of recording and reading by a blue laser with a short wavelength. An optical recording material comprises an organic dye compound A whose absorption maximum wavelength (?max) is not less than 340 nm and not more than 440 nm and a metal-complex compound B whose absorption maximum wavelength (?max) is not less than 500 nm and not more than 900 nm, the content of the organic dye compound A is higher than the content of the metal-complex compound B, and light resistance x determined by a predetermined method is not less than 30%.

Abstract: By use of a substrate which can be stably formed and has a relatively small groove depth, a very high density optical recording medium having good recording/reading characteristics is provided. In an optical recording medium of a surface incidence type, in which a reflective layer, a recording layer containing a dye as a main component and a cover layer are sequentially formed on a substrate having guide grooves formed therein, a guide groove part on a far side from a plane of incidence of a recording/reading light beam on the cover layer is set as a recording groove part, and reflected light intensity in a recorded pit portion formed in the recording groove part is increased by a phase shift and is set higher than reflected light intensity in unrecorded.

Abstract: An answer sheet adapted for computer scoring has a first mark enclosing a space, printed on the sheet, and a second mark enclosing a space, printed on the sheet, wherein the second mark is encompassed by the first mark.

Abstract: In an optical recording medium having a plurality of recording layers on which information can be recorded by irradiating a laser beam from one side thereof, an optimum recording power to each of the recording layers can be determined. The optical recording medium has a plurality of recording layers on which information can be recorded by irradiating a laser beam from one side thereof, and each of the recording layers has a power calibration area (PCA) for optimizing the intensity of the laser beam.

Abstract: In an optical recording medium of a single-sided incident type having a plurality of recording layers, recording/reading conditions (for example, tracking polarity, recording pulse strategy, recording recommended power, etc.) can be instantaneously switched according to each of the recording layer, and recording or reading of information can be accurately and surely performed under recording/reading conditions adapted to each recording layer. A control unit reads out layer information from one recording layer of the optical recording medium in which the layer information is recorded in each of the plural layers, on which recording or reading of information can be performed by irradiating a laser beam from one side thereof (layer information reading step), and controls so that recording or reading is performed under recording/reading conditions adapted to a recording layer specified on the basis of the layer information (recording controlling step).

Abstract: An information recording method allows optical information having a recording mark length smaller than a spot diameter of laser light to be recorded on an optical recording medium having a recording layer, at high density by laser light pulse application. The information recording method has: a power calibration step of determining a recording power for recording a signal having a predetermined signal length in the recording layer using the laser light; and a complementing step of complementing, based on the recording power determined in the power calibration step, a recording power for recording a signal having a signal length equal to or less than ½ of the spot diameter of the laser light in the recording layer using the laser light. In the information recording method, for example, an extremely small mark, such as a 2T signal, can be precisely formed.

Abstract: To provide a rewritable compact disk having a rewritable area interchangeable with a CD-RW, that is, a RAM area (105), and an area available only for retrieving, that is, a ROM area (104), on the same disk surface, a phase-change recording layer is formed in each of the RAM area and the ROM area, with a wobble groove being made in the RAM area, irradiation is carried out with recording light so that an amorphous mark is formed to record information and information is recorded in the form of a pre-pit string (60) in the ROM area, and further when measured using a wavelength of 770 to 790 nm and an optical pickup whose objective lens numerical aperture is 0.49 to 0.51, a ratio |I1−I2|/|I1−I2|a of values of push pull signals before and after recording in the RAM area is set to be in a range from 1.05 to 2.

Abstract: To provide a rewritable compact disk having a rewritable area interchangeable with a CD-RW, that is, a RAM area (105), and an area available only for retrieving, that is, a ROM area (104), on the same disk surface, a phase-change recording layer is formed in each of the RAM area and the ROM area, with a wobble groove being made in the RAM area, irradiation is carried out with recording light so that an amorphous mark is formed to record information and information is recorded in the form of a pre-pit string (60) in the ROM area, and further when measured using a wavelength of 770 to 790 nm and an optical pickup whose objective lens numerical aperture is 0.49 to 0.51, a ratio |I131 I2|/|I1−I2|a of values of push pull signals before and after recording in the RAM area is set to be in a range from 1.05 to 2.

Abstract: An optical phase-change disc comprises a substrate having thereon a spiral groove or concentric grooves for guiding a focused light beam, and a layer structure including a recording layer and protective layers sandwiching therebetween the recording layer. The groove has wobble for recording ATIP (absolute time information) or ADIP (address information). The following relationship between the groove width GW, beam diameter R.sub.0 and wobble amplitude a.sub.w :0.25.ltoreq.GW/R.sub.0 .ltoreq.0.45 or 0.65.ltoreq.GW/R.sub.0 ; and0.03.ltoreq.a.sub.w /GW.ltoreq.0.08hold for preventing distortion of the groove caused by repeated overwriting operation to improve reliability of the optical disc.

Abstract: An optical phase-change disc comprises a substrate having thereon a spiral groove or concentric grooves for guiding a focused light beam, and a layer structure including a recording layer and protective layers sandwiching therebetween the recording layer. The groove has wobble for recording ATIP (absolute time information) or ADIP (address information). The following relationship between the groove width GW, beam diameter R.sub.0 and wobble amplitude a.sub.w :0.25.ltoreq.GW/R.sub.0 .ltoreq.0.45 or 0.65.ltoreq.GW/R.sub.0 ; and0.03.ltoreq.a.sub.w /GW.ltoreq.0.08hold for preventing distortion of the groove caused by repeated overwriting operation to improve reliability of the optical disc.