Abstract: An optical information medium measurement method measures a degree of modulation in an optical information medium of a multilayered structure having a plurality of information layers. The method includes measuring the modulation degree of each layer of the optical information medium, obtaining a thickness between layers of the optical information medium, obtaining a reflectance of each layer of the optical information medium, and converting the modulation degree of each layer. The modulation degree is measured based on a value indicative of the thickness between layers, and a value indicative of the reflectance of each layer.

Abstract: An optical information medium measurement method, for measuring a degree of modulation in an optical information medium of a multilayered structure having a plurality of information layers, includes a first step of measuring a modulation degree of each layer of the optical information medium, and a second step of obtaining a thickness between layers of the optical information medium. Further, the method includes a third step of obtaining a reflectance of each layer of the optical information medium, and a fourth step of converting the modulation degree of each layer, as measured in the first step, into a modulation degree at a reference optical system differing from the measurement optical system, based on a value indicative of the thickness between layers, the thickness being obtained in the second step, and a value indicative of the reflectance of each layer, as obtained in the third step.

Abstract: The present invention provides a recording medium and a recording/reproducing apparatus which enable the number of data units of recording pulse information to be reduced by dividing the recording pulse information into 1 byte-parameter information and differences from a value thereof, and the recording pulse information to be recorded on an existing DI area.

Abstract: A reproduction signal evaluation method according to the present invention relates to adjustment of an edge portion between a shortest mark and a shortest space in a data sequence including marks and spaces in combination that is recordable on an information recording medium. In a pattern including a shortest mark and a shortest space adjacent before or after the shortest mark, a shift amount of an edge of the shortest mark is obtained from a differential metric calculated regarding one of a first pattern in which a space adjacent to the shortest mark and not adjacent to the shortest space is longer than the shortest space; and a second pattern in which a mark adjacent to the shortest space and not adjacent to the shortest mark is longer than the shortest mark.

Abstract: When information is recorded or reproduced on or from an optical information medium having three or more recording layers using blue light, interference by another layer light is reduced and, when information is reproduced from an optical information medium using red light, an S/N ratio is held excellently high.

Abstract: Shape-wise thicknesses of a cover layer and first through (N?1)th intermediate layers of an optical recording medium having refractive indexes nr1, nr2 are converted into thicknesses t1, t2 of the respective layers having a predetermined refractive index which makes a divergent amount equal to a divergent amount of a light beam resulting from the thicknesses tr1, tr2, a difference DFF between the sum of a thickness “ti” through a thickness “tj”, and the sum of a thickness “tk” through a thickness “tm” is set to 1 ?m or more (where i, j, k, and m are each any positive integer satisfying i?j?k?m?N), and the thicknesses t1, t2 are calculated by products of a function f(n) expressed by the following formula (1), and the thicknesses tr1, tr2: f(n)=?1.088n3+6.1027n2?12.042n+9.1007??(1) in the formula (1), n=nr1, nr2, . . . , and nrN.

Abstract: A reproduction signal evaluation method according to the present invention relates to adjustment of an edge portion between a shortest mark and a shortest space in a data sequence including marks and spaces in combination that is recordable on an information recording medium. In a pattern including a shortest mark and a shortest space adjacent before or after the shortest mark, a shift amount of an edge of the shortest mark is obtained from a differential metric calculated regarding one of a first pattern in which a space adjacent to the shortest mark and not adjacent to the shortest space is longer than the shortest space; and a second pattern in which a mark adjacent to the shortest space and not adjacent to the shortest mark is longer than the shortest mark.

Abstract: Shape-wise thicknesses tr1, tr2, . . . , and trN of a cover layer and first through (N?1)-th intermediate layers of an optical recording medium having refractive indexes nr1, nr2, . . . , and nrN are converted into thicknesses t1, t2, . . . , and tN which are calculated by products of a function f(n)=?1.088n3+6.1027n2?12.042n+9.1007, where n=nr1, nr2, . . . , and nrN.

Abstract: A reproduction signal evaluation method evaluates the quality of a reproduction signal reproduced from an information recording medium based on a binary signal generated from the reproduction signal using a PRML signal processing system. The method includes a pattern extraction step of extracting, from the binary signal, a specific state transition pattern which has the possibility of causing a bit error; a step of computing a differential metric based on the binary signal; an extraction step of extracting the differential metric which is not greater than a predetermined signal processing threshold; a step of determining a mean value of the differential metrics which are not greater than the signal processing threshold and extracted in the extraction step; a standard deviation computing step of determining a standard deviation which corresponds to an error rate predicted from the mean value; and an evaluation step of evaluating a quality of the reproduction signal using the standard deviation.

Abstract: An information recording medium according to the present invention includes at least three information recording layers. If the readout power of a laser beam in reading information from an information recording layer L(n) is identified by Pw(n), and if the readout power of the laser beam in reading information from an information recording layer L(n+a) is identified by Pw(n+a), then a base thickness between the information recording layers is determined so that the intensity of the light when the information recording layer L(n+a) is irradiated with a laser beam having the readout power Pw(n) becomes equal to or lower than that of the light when the information recording layer L(n+a) is irradiated with a laser beam having the readout power Pw(n+a).

Abstract: A writing method according to the present invention is a method for writing a data sequence as a combination of marks and spaces on an information recording medium by condensing a laser beam through a lens. The writing method is characterized in that a cooling pulse for recording a mark that is even shorter than the limit of optical resolution of the laser beam and another cooling pulse for recording a mark that is still longer than the limit of the optical resolution of the laser beam are applied under mutually different conditions.

Abstract: Shape-wise thicknesses tr1, tr2, . . . , and trN of a cover layer and first through (N?1)-th intermediate layers of an optical recording medium having refractive indexes nr1, nr2, . . . , and nrN are converted into thicknesses t1, t2, . . . , and tN which are calculated by products of a function f(n)=?1.088n3+6.1027n2?12.042n+9.1007 where n=nr1, nr2, . . . , and nrN.

Abstract: A signal evaluation method according to the present invention is a method for evaluating a read signal, retrieved from an information recording medium, based on a binarized signal generated from the read signal by a PRML method.

Abstract: The optical disc apparatus according to the present invention includes a tilt detecting means; a coma aberration correcting means; and a spherical aberration correcting means. Based on the result of a tilt detection, the amount of the correction performed by the coma aberration correcting means is determined so that the amount of correction is constant for the whole circumference of an optical disc, and then a spherical aberration is corrected by the spherical aberration correcting means. Thus, it is possible to correct the spherical aberration that has occurred due to the coma aberration correcting means, while the tilt margin is secured, thereby improving the reliability of reproduction and recording by the optical disc apparatus. Further, the optical disc apparatus according to the present invention is configured, in the case where a thermal shock tilt has occurred during the activation of the apparatus, to wait until the thermal shock tilt has settled.

Abstract: An optical recording medium and an optical information device that improve the quality of a servo signal and a reproduction signal. In the optical recording medium, when shape-wise thicknesses tr1, tr2, tr3, and tr4 of a cover layer (42), a first intermediate layer (43), a second intermediate layer (44), and a third intermediate layer (45) are respectively converted into thicknesses t1, t2, t3, and t4 of the respective corresponding layers each having a predetermined refractive index “no”, a defocus amount with respect to a layer having a refractive index nr? and a thickness tr? (satisfying: 1???n (where ? is a positive integer and n is an integer of 4 or more)), and a defocus amount with respect to a layer having the refractive index “no” and a thickness t? (satisfying: 1???n (where ? is a positive integer and n is an integer of 4 or more)) are equal to each other.

Abstract: An information recording medium according to the present invention includes at least three information recording layers. If the readout power of a laser beam in reading information from an information recording layer L(n) is identified by Pw(n), and if the readout power of the laser beam in reading information from an information recording layer L(n+a) is identified by Pw(n+a), then a base thickness between the information recording layers is determined so that the intensity of the light when the information recording layer L(n+a) is irradiated with a laser beam having the readout power Pw(n) becomes equal to or lower than that of the light when the information recording layer L(n+a) is irradiated with a laser beam having the readout power Pw(n+a).

Abstract: The present invention aims to provide a reproduced signal evaluation method and a write adjustment method for offering a Blu-ray disc having a large storage capacity with excellent media compatibility. An evaluation index L-SEAT is calculated through signed addition using a Euclidean distance difference calculated from at least one of target signals in which a focused edge is shifted to the right and left, and the quality of the reproduced signal is evaluated based on the evaluation index. Write condition adjustment using the index enables write adjustment not depending on SNR and achieving high adjustment accuracy.

Abstract: An object of the invention is to provide an optical recording medium and an optical information device that enable to improve the quality of a servo signal and a reproduction signal.

Abstract: A method for inspecting an optical information storage medium includes the steps of: irradiating the storage medium with a laser beam and rotating the medium by a constant linear velocity control technique by reference to the radial location at which the laser beam forms a spot on the medium; changing the rotational velocities according to the radial location on the medium between at least two linear velocities that include a first linear velocity Lv1 and a second linear velocity Lv2 higher than the first linear velocity Lv1; generating a focus error signal and/or a tracking error signal based on the light reflected from the medium; performing a focus control and/or a tracking control on the laser beam that irradiates the medium based on the focus and/or tracking error signal(s); and passing the branched outputs of control loops for the focus and/or tracking error signal(s) through predetermined types of frequency band-elimination filters for the focus and/or tracking error signal(s) to obtain residual errors

Abstract: A signal evaluation method according to the present invention is a method for evaluating a read signal, retrieved from an information recording medium, based on a binarized signal generated from the read signal by a PRML method.