Abstract: In a multilayer optical recording medium having three or more recording layers, when data is recorded on a recording layer far away from an incident surface of laser light, and especially on a recording layer farthest away from the incident surface of the laser light, by applying the laser light, the recording power margin of the farthest recording layer allows for a variation in the optimal recording sensitivity even if the transmittance of the recording layers located between the laser light incident surface side and the target recording layer is varied due to existing recordings and the amount of the laser light passing therethrough is also varied. In this case, the recording layer which is the farthest from an incident surface of laser light has a phase change recording film, and the recording layer which is the nearest from the incident surface of the laser light has a write-once read-multiple recording film.

Abstract: An optical recording medium has a five-layer structure including five recording layers, namely an L0 layer, an L1 layer, an L2 layer, an L3 layer, and an L4 layer in this order from a side farthest away from a laser light incident surface. The materials of the respective recording layers are selected so that the rate of change in transmittance Tb/Ta as taken from the laser light incident surface satisfies 0.93<Tb/Ta<1.07 when recording on the L0 layer among the recording layers, where: Ta is transmittance of laser light to reach the L0 layer when the L0 layer is irradiated with the laser light of optimum recording power after recording marks are formed on all the recording layers closer to the laser light incident surface (being the L1 to L4 layers); and Tb is transmittance of laser light to reach the L0 layer when the L0 layer is irradiated with the laser light of optimum recording power with no recording mark formed on any of the recording layers closer to the laser light incident surface.

Abstract: A multilayer recording medium has a three-layered structure for an increased capacity, including an L0 layer, an L1 layer, and an L2 layer in order from the side farthest away from the incident surface of laser light. The recording layers are made of respective recording film materials selected so that the recording films of the recording layers have respective recording-reaction temperatures T0, T1, and T2, where T0?T1?T2 and T0<T2. This makes the recording sensitivities of the respective recording layers substantially the same and, by extension, the optimal recording powers of the laser light for the respective recording layers substantially the same so that the recording power of the laser light necessary for recording information on the L0 layer in particular is prevented from becoming excessively high.

Abstract: An optical disc has a data management area in a region on a radially inward side. Management information is recorded in the data management area as recording marks and spaces. The optical disc also has a data recording area on the outside of the data management area. Data to be read is recoded in the data recording area as recording marks and spaces. The information readout density of the data recording area is higher than that of the data management area. The read power of a readout laser beam during readout can be set smaller in the data management area than in the data recording area. In this manner, the read stability is significantly increased without reducing the information readout density.

Abstract: A method and apparatus for measuring the read stability of an optical disc are provided. Specifically, readout of the optical disc is repeated at each of at least two read laser beams powers being different from each other. A graph is drawn in which the inverses of the read powers are plotted on a horizontal axis and in which on a vertical axis is plotted the logarithm of a repeated readout number for each of the read powers. Here, the repeated readout number is the number of repetitions of the readout when a characteristic value for the number of repetitions of the readout varies and reaches a predetermined value. The read stability of the optical disc is evaluated by using the gradient of the graph.

Abstract: A method for determining recording laser power on a super-resolution optical recording medium, on which information is recorded on a super-resolution optical recording medium by irradiating a laser beam modulated into a recording pulse train according to recording data to thereby form a recording mark train including recording marks and spaces smaller than the resolution limit of a reproduction optical system and recording marks and spaces equal to or larger than the resolution limit, is provided. At the time of recording, the method determines a minimum value and a maximum value of recordable laser powers determined by test-writing before recording, and determines a maximum value of a recordable range of laser power by adding to the minimum value one-third of a difference between the maximum value of the recordable laser powers and the minimum value. The method determines an optimal range of recording laser power from the minimum value of recordable laser powers to the maximum value of the recordable range.

Abstract: A method for recording information on a super-resolution optical recording medium is directed to a reproducing laser beam which moves during the reproduction of the super-resolution optical recording medium from a recording mark/space train smaller than the resolution limit to a recording mark, or mark/space train larger than or equal to the resolution limit. A pulse train employed by the method for forming a recording mark larger than or equal to the resolution limit immediately after a smaller space than the resolution limit of a reproduction optical system includes at least a first ON pulse T1 of recording power followed by a first OFF pulse and second ON pulses T21 and T22 in that order. The first OFF pulse includes an OFF pulse Pc of cooling power and an OFF pulse Pm of middle power in that order.

Abstract: When a recording mark and a space, each having a size depending on a modulation code corresponding to information to be recorded, are formed in a super-resolution optical recording medium which has at least a substrate and a recording layer, a super-resolution layer, and a light transmitting layer on the substrate, a space shorter than at least the resolution limit of a reproducing optical system is formed so that the space has a crescent shape when plan view from top surface and a convex section when viewed in a direction normal to a track, thereby allowing high carrier-to-noise ratio (CNR) recording of information.

Abstract: A method of optimizing a writing condition of an optical recording medium, including writing test pattern data with the writing condition on the optical recording medium, comparing an error pattern binary signal detected by reproducing the written test pattern data with a correct pattern binary signal of the test pattern data, and determining an optimum writing condition of the optical recording medium based on a result of the comparison.

Abstract: An optical disk primarily includes a recording layer and a viscosity-variable material layer. When a laser beam is irradiated to reproduce a record written on the recording layer, part of the crystalline thin layer of the viscosity-variable material layer is softened to vary the optical constant of the softened region. Consequently, a plane having discontinuous optical constants is produced at the boundary between the softened region and the other region, so that a ring-shaped specific region is produced in a light spot. The ring-shaped specific region allows record patterns smaller than or equal to the resolution limit to be reproduced with the same signal intensity as that of the other record patterns larger than the resolution limit.

Abstract: A method of determining an optimum reproduction condition of a first mark recorded on an optical recording medium that is smaller than a resolution of a pickup to reproduce the first mark. The method includes obtaining an optimum reproduction condition of a second mark having a length which closely approximates the resolution of the pickup, and determining the optimum reproduction condition of the first mark using the obtained optimum reproduction condition of the second mark.

Abstract: A super-resolution optical recording medium has at least a recording layer and a super resolution layer on a substrate. A recording mark with the size of a resolution limit or less and a space with the size of the resolution limit or less are formed in the super-resolution optical recording medium by adjusting the intensity of a laser for recording or an emission pattern of the laser for recording such that at least the recoding mark with the size of the resolution limit or less out of recording marks in a modulation code is formed into a concave section with respect to a not-recorded section.

Abstract: It is an object of the present invention to provide an optical recording disc which can record data constituted by a recording mark train including recording marks and blank regions neighboring recording marks therein and reproduce the data therefrom in a desired manner even in the case where the lengths of a recording mark and a blank region between neighboring recording marks are shorter than the resolution limit and whose storage capacity can be markedly increased and a method for manufacturing such an optical recording disc.

Abstract: A multilayer optical recording medium enabled to retain an ideal signal regenerating property in spite of accidental adhesion of finger mark or alien substance is provided. The multilayer optical recording medium 1 is provided with a plurality of information-recording layers 20, 22, 24, and 26 capable of reading information with a reading light irradiated through a light incidence surface 38A on one side and is so adapted that the light incidence side information-recording layer 26 approximating most closely to the light incidence surface 38A may be set at a small recording capacity as compared with the recording capacities of at least one of the other information-recording layers.

Abstract: It is an object of the present invention to provide an optical recording disc which can record data constituted by a recording mark train including recording marks and blank regions neighboring recording marks therein and reproduce the data therefrom even in the case where the lengths of a recording mark and a blank region between neighboring recording marks are shorter than the resolution limit, thereby markedly increasing the storage capacity thereof and can improve a C/N ratio of a reproduced signal and the reproduction durability thereof.

Abstract: A super-resolution optical recording medium has at least a recording layer and a super resolution layer on a substrate. In the recording layer, a minimum recording mark is formed with spaces within a beam spot of a laser beam in recording. The minimum recording mark has a size of a resolution limit of a reproduction optical system or less, and can be reproduced by the reproduction optical system due to the existence of the super solution layer. The minimum recording mark in an AFM image takes the shape of a convex arc on a leading edge thereof and the shape of a concave arc on a trailing edge thereof (the AFM image is a plan view which can be observed on a surface when the light transmission layer is removed), and spaces have the similar shape to these.

Abstract: A method for recording information on an optical recording medium in which a laser beam modulated into one or a plurality of write pulses with one or a plurality of write powers in accordance with target data to be written is projected onto a recording layer of the optical recording medium to form a record mark. During recording the information on the optical recording medium, a data level and a weight index are assigned to each channel bit in reference data trains before and after the target data. Recording compensation of the target data is carried out in accordance with the sum totals of the products of the data level and the weight index in the reference data trains, so that it is possible to easily carry out high a real recording by writing fine mark/space trains.

Abstract: A super-resolution information recording medium, a recording/reproducing apparatus, and a recording/reproducing method uses an information recording medium provides a super-resolution effect by fluid bubbles. The fluid bubbles are formed in at least a portion of the medium by a light beam radiated to reproduce a signal from the information recording medium. Accordingly, the super-resolution information recording medium has improved optical characteristics, so that better recording/reproduction is possible.

Abstract: A supporting substrate 11 and a light-transmitting layer 12, and further between the light-transmitting layer and the supporting substrate 11 a dielectric layer 31, a noble metal oxide layer 23, a dielectric layer 32, a light absorption layer 22 and a dielectric layer 33 in this arranging order when viewed from the light-transmitting layer side are provided. The light absorption layer 22 contains as a main component a material that can be represented by (SbaTe1?a)1?bMAb (wherein MA is an element other than antimony (Sb) and tellurium (Te), 0<a<1 and 0?b<1), and besides, that is different from an intermetallic compound represented by {(GeTe)c(Sb2Te3)1?c)}dMB1?d (wherein MB is an element other than antimony (Sb), tellurium (Te) and germanium (Ge), c is ?, ½ or ?, and 0<d?1).

Abstract: An optical recording medium 10 is provided with a supporting substrate 11 and a light-transmitting layer 12, and further has between the light-transmitting layer 12 and the supporting substrate 11 a dielectric layer 31, a noble-metal oxide layer 23, a dielectric layer 32, a light absorption layer 22 and a dielectric layer 33. The second dielectric layer 32 contains as a main component ZnS or a mixture of ZnS and SiO2, and therein the proportion of ZnS to the sum of ZnS and SiO2 is set at a value from 60 mole % to 100 mole %. Since the material of the second dielectric layer 32 has both high hardness and elasticity, and high thermal conductivity besides, excellent balance of thermal conductivity with layer hardness can be achieved and makes it possible to form fine recording marks in true shapes.