Abstract: An phase-change optical disk comprises a substrate, a first protective layer, a first thermostable layer, a recording layer, a second thermostable layer, a second protective layer, an absorptance control layer, and a heat-diffusing layer which are provided in this order from a side on which a laser beam comes thereinto, wherein a recording layer material has composition ratios which are within a range surrounded by composition points of B3 (Bi3, Ge46, Te51), C3 (Bi4, Ge46, Te50), D3 (Bi5, Ge46, Te49), D5 (Bi10, Ge42, Te48), C5 (Bi10, Ge41, Te49), and B5 (Bi7, Ge41, Te52) on a triangular composition diagram. Recrystallization is not caused even when information is recorded on an inner circumferential portion, a reproduced signal is scarcely deteriorated even when rewriting is performed multiple times, and any erasing residue of amorphous matters scarcely appears at an outer circumferential portion.

Abstract: A phase-change optical recording medium capable of performing recording and reproduction at a high speed is provided, in which a reproduced signal output is not only sufficiently large but the phase-change optical recording medium also has excellent repeated rewriting performance. An interface layer 3, which is composed of a Ge—Si—N-based material, is formed on at least a surface of one side of a recording layer 4 of the phase-change optical recording medium 10. Accordingly, even when a phase-change material having a high melting point, for example, a Bi—Ge—Te-based phase-change material is used for the recording layer 4, it is possible to provide the phase-change optical recording medium in which the reproduced signal output is sufficiently large and the repeated rewriting performance is excellent.

Abstract: A write-once optical information recording medium is provided that is capable of realizing a high transfer rate and a method of recording and reproducing information on and from the optical information recording medium. The optical information recording medium is constructed by stacking a reflective layer 12, a first dielectric layer 13, a recording layer 14, a write-protect layer 15, a second dielectric layer 16 and a transparent cover layer 17 on a polycarbonate substrate 11. The recording layer 14 is made of a phase-change material, and the cover layer 17 is made of UV curing resin. The recording layer 14 is irradiated with a laser beam with a wavelength of 500 nm or less to change from a crystalline phase to an amorphous phase. The write-protect layer 15 prevents the recording layer 14 from changing back to the crystalline phase from the amorphous phase, formed by the phase change.

Abstract: An information recording medium includes a structure fabricated by successively depositing a first protective layer, a first interface layer, a recording layer, a second interface layer, a second protective layer, an absorptivity control layer and a thermal diffusion layer on a substrate which is placed on a laser-beam-incident side of the medium, in which the first interface layer and the second interface layer are formed so as to contain elements Bi, Sn, Pb, etc. having the effect of promoting the crystallization of the recording layer and the total content of the elements in the first interface layer is set lower than that in the second interface layer, thereby reducing playback signal deterioration after frequent rewriting.

Abstract: A phase-change optical recording medium capable of performing recording and reproduction at a high speed is provided, in which a reproduced signal output is not only sufficiently large but the phase-change optical recording medium also has excellent repeated rewriting performance. An interface layer 3, which is composed of a Ge—Si—N-based material, is formed on at least a surface of one side of a recording layer 4 of the phase-change optical recording medium 10. Accordingly, even when a phase-change material having a high melting point, for example, a Bi—Ge—Te-based phase-change material is used for the recording layer 4, it is possible to provide the phase-change optical recording medium in which the reproduced signal output is sufficiently large and the repeated rewriting performance is excellent.

Abstract: A write-once optical information recording medium is provided that is capable of realizing a high transfer rate and a method of recording and reproducing information on and from the optical information recording medium. The optical information recording medium is constructed by stacking a reflective layer 12, a first dielectric layer 13, a recording layer 14, a write-protect layer 15, a second dielectric layer 16 and a transparent cover layer 17 on a polycarbonate substrate 11. The recording layer 14 is made of a phase-change material, and the cover layer 17 is made of UV curing resin. The recording layer 14 is irradiated with a laser beam with a wavelength of 500 nm or less to change from a crystalline phase to an amorphous phase. The write-protect layer 15 prevents the recording layer 14 from changing back to the crystalline phase from the amorphous phase, formed by the phase change.

Abstract: An phase-change optical disk comprises a substrate, a first protective layer, a first thermostable layer, a recording layer, a second thermostable layer, a second protective layer, an absorptance control layer, and a heat-diffusing layer which are provided in this order from a side on which a laser beam comes thereinto, wherein a recording layer material has composition ratios which are within a range surrounded by composition points of B3 (Bi3, Ge46, Te51), C3 (Bi4, Ge46, Te50), D3 (Bi5, Ge46, Te49), D5 (Bi10, Ge42, Te48), C5 (Bi10, Ge41, Te49), and B5 (Bi7, Ge41, Te52) on a triangular composition diagram. Recrystallization is not caused even when information is recorded on an inner circumferential portion, a reproduced signal is scarcely deteriorated even when rewriting is performed multiple times, and any erasing residue of amorphous matters scarcely appears at an outer circumferential portion.

Abstract: An information recording medium includes a structure fabricated by successively depositing a first protective layer, a first interface layer, a recording layer, a second interface layer, a second protective layer, an absorptivity control layer and a thermal diffusion layer on a substrate which is placed on a laser-beam-incident side of the medium, in which the first interface layer and the second interface layer are formed so as to contain elements Bi, Sn, Pb, etc. having the effect of promoting the crystallization of the recording layer and the total content of the elements in the first interface layer is set lower than that in the second interface layer, thereby reducing playback signal deterioration after frequent rewriting.

Abstract: A magnetooptic recording medium which includes a substrate and a magnetooptic recording film thereon, the substrate having a surface comparted into a plurality of tracks on which magnetooptic recording signals are recorded, and a part of the tracks, selected from the plurality of tracks, including clusters of pre-pits wherein a variation of a change in light amount due to local birefringence in the vicinity of the pre-pits is not more than 20% with respect to a change in light amount in the absence of the local birefringence, when signals from the tracks with recorded magnetooptic recording signals are measured by changes in light amount on the basis of Kerr rotational angles of reflected light from the medium, which magnetooptic recording medium can be effectively used for a ZCAV system.