Abstract: An optical information recording medium (1) includes on a substrate (50), a ROM layer (20), a RE layer (40), an intermediate layer (30) separating the ROM layer (20) and the RE layer (40), and a light transmitting layer (10) provided farthest from the substrate (50). The RE layer (40) is an information recording layer provided most farthest from the light transmitting layer (10), and is a recording layer of BCA recorded in a format easily determinable as compared to an information recording format used in the ROM layer (20), and antifouling property of a surface of the light transmitting layer (10) is set based on the RE layer (40). This makes it easy for the recording and reproducing apparatus to confirm a disc type, allows for sharing one recording and reproducing apparatus with other types of optical discs, and simplifies the disc production.

Abstract: An optical information recording medium (1) includes on a substrate (50), a ROM layer (20), a RE layer (40), an intermediate layer (30) separating the ROM layer (20) and the RE layer (40), and a light transmitting layer (10) provided farthest from the substrate (50). The RE layer (40) is an information recording layer provided most farthest from the light transmitting layer (10), and is a recording layer of BCA recorded in a format easily determinable as compared to an information recording format used in the ROM layer (20), and antifouling property of a surface of the light transmitting layer (10) is set based on the RE layer (40). This makes it easy for the recording and reproducing apparatus to confirm a disc type, allows for sharing one recording and reproducing apparatus with other types of optical discs, and simplifies the disc production.

Abstract: A sputtering target for optical media is mainly composed of Al and contains 1 to 10 at % of one or two species of elements selected from the group consisting of Ta and Nb and 0.1 to 10 at % of Ag. An optical medium 100 comprises a substrate 10 and reflective layers 20A, 20B provided on the substrate 10. Each of the reflective layers 20A, 20B has a composition, mainly composed of Al, containing 1 to 10 at % of one or two species of elements selected from the group consisting of Ta and Nb and 0.1 to 10 at % of Ag.

Abstract: The present invention aims at providing a sputtering target for making an optical medium whose reflective layer is mainly composed of Ag and capable of attaining an optical medium which is excellent in surface smoothness and can sufficiently suppress noise and jitter, a method of making the same, an optical medium, and a method of making the same. The present invention provides a sputtering target for making an optical medium comprising 0.1 to 2 at % of one or two elements selected from the group consisting of Ta and Nb, 0.1 to 1 at % of Al, and the balance constituted by Ag and unavoidable impurities; and an optical medium comprising a reflective layer having this composition on a substrate.

Abstract: The present invention aims at providing a sputtering target for making an optical medium whose reflective layer is mainly composed of Ag and capable of attaining an optical medium which is excellent in surface smoothness and can sufficiently suppress noise and jitter, a method of making the same, an optical medium, and a method of making the same. The present invention provides a sputtering target for making an optical medium comprising 0.1 to 2 at % of one or two elements selected from the group consisting of Ta and Nb, 0.1 to 1 at % of Al, and the balance constituted by Ag and unavoidable impurities; and an optical medium comprising a reflective layer having this composition on a substrate.

Abstract: A sputtering target for optical media is mainly composed of Al and contains 1 to 10 at % of one or two species of elements selected from the group consisting of Ta and Nb and 0.1 to 10 at % of Ag. An optical medium 100 comprises a substrate 10 and reflective layers 20A, 20B provided on the substrate 10. Each of the reflective layers 20A, 20B has a composition, mainly composed of Al, containing 1 to 10 at % of one or two species of elements selected from the group consisting of Ta and Nb and 0.1 to 10 at % of Ag.

Abstract: A high-speed, write-once type optical recording medium, which utilizes laser light that is either blue or an even shorter wavelength, as well as an optical recording method and an optical recording apparatus for recording onto this optical recording medium. A high-speed, write-once type optical recording medium 10 having a recording layer 18 and a light transmission layer 22 formed sequentially on top of a support substrate 12, wherein the recording layer 18 is formed by laminating first and second vice-recording layers 18A, 18B which include Al and Sb respectively as primary components, and irradiation of a laser light of blue wavelength from a laser light source 24, through the light transmission layer 22 and onto the recording layer 18, causes diffusion and mixing of the Al and Sb contained within the first and second vice-recording layers 18A, 18B, and this mixing enables the formation of a recording mark based on an irreversible change in reflectance.

Abstract: The optical recording medium of the present invention is a phase change optical recording medium which can be used as a write once medium and which can be recorded at a high recording density. The optical recording medium of the present invention is adapted for recording such that, when the recording beam has a wavelength of ?, and objective lens of recording optical system has a numerical aperture of NA, minimum record marks formed are circular or ellipsoidal marks having a length of 0.4 ?/NA or less; and the medium is a write once medium wherein the recorded information can not be erased or rewritten at the minimum linear velocity used.

Abstract: A high-speed, write-once type optical recording medium, which utilizes laser light that is either blue or an even shorter wavelength, as well as an optical recording method and an optical recording apparatus for recording onto this optical recording medium.

Abstract: It is an object of the present invention to provide an inspection method for judging whether or not a phase change type medium can be used as a write-once type medium.

Abstract: The optical recording medium of the present invention is a phase change optical recording medium which can be used as a write once medium and which can be recorded at a high recording density. The optical recording medium of the present invention is adapted for recording such that, when the recording beam has a wavelength of &lgr;, and objective lens of recording optical system has a numerical aperture of NA, minimum record marks formed are circular or ellipsoidal marks having a length of 0.4&lgr;/NA or less; and the medium is a write once medium wherein the recorded information can not be erased or rewritten at the minimum linear velocity used.

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: A method for recording a phase change optical recording medium under optimal conditions is provided. In the recording of a phase change optical recording medium which has a phase change recording layer and which has a data recording area and a test write area, the test write area is recorded before the recording of the data recording area, and the recording of the test write area is conducted corresponding to the recording history of the data recording area in order to determine optimal writing and erasing conditions for the data recording area on the basis of the quality of the read-out signal of the test write area.

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: A phase change optical recording medium has on a substrate a recording layer consisting essentially of a Sb base thin film and a reactive thin film. The Sb base thin film is formed by depositing a Sb base material containing at least 95 at % of Sb to a thickness of 70-150 Å. The reactive thin film is formed of a material which forms a phase change recording material when mixed with Sb. The reactive thin film is typically formed of an In—Ag—Te or Ge—Te material. Stable write/read characteristics are accomplished at the first overwriting, initializing operation is eliminated, and rewriting is impossible at the same linear velocity as recording.

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: A phase change optical recording medium has on a substrate a recording layer consisting essentially of a Sb base thin film and a reactive thin film. The Sb base thin film is formed by depositing a Sb base material containing at least 95 at % of Sb to a thickness of 70-150 Å. The reactive thin film is formed of a material which forms a phase change recording material when mixed with Sb. The reactive thin film is typically formed of an In—Ag—Te or Ge—Te material. Stable write/read characteristics are accomplished at the first overwriting, initializing operation is eliminated, and rewriting is impossible at the same linear velocity as recording.

Abstract: The invention provides an optical disc comprising a circular glass substrate (2) having information-carrying means (3) on one major surface. A protective member (4) of a resin includes a circular flat portion (42) and an annular rim (41) extending perpendicular from the periphery of the flat portion (42). The glass substrate (2) is integrally joined to the protective member (4) such that the information-carrying means (3) of the glass substrate (2) may face the covering portion (42) of the protective member (4). The outer side of the glass substrate (2) is surrounded by the protective member rim (41) to leave a shock absorbing space therebetween. The invention prevents the glass substrate from failure at its corner when impact is applied to the disc.

Abstract: A phase change optical recording medium has on a substrate a recording layer consisting essentially of a Sb base thin film and a reactive thin film. The Sb base thin film is formed by depositing a Sb base material containing at least 95 at % of Sb to a thickness of 70-150 Å. The reactive thin film is formed of a material which forms a phase change recording material when mixed with Sb. The reactive thin film is typically formed of an In—Ag—Te or Ge—Te material. Stable write/read characteristics are accomplished at the first overwriting, initializing operation is eliminated, and rewriting is impossible at the same linear velocity as recording.

Abstract: In a (Ge,Sb)-Te based optical recording medium of phase change type whose rate determining step in production has been initialization of the recording layer, the time required for production is reduced, and stable recording/reproducing properties are realized from the first overwriting operation. A phase-change type optical recording disc of write once read many-type requiring no initialization is also provided. The optical recording medium comprises a transparent substrate and a recording layer on the transparent substrate. The recording layer comprises at least one Te-based thin film and at least one reactive thin film, and the Te-based thin film is in contact with said reactive thin film. The Te-based thin film is formed from a Te-based material containing at least 95 at % of Te, and the reactive thin film is formed from a (Ge,Sb)-based material mainly comprising Ge and/or Sb. The optical change type material is formed by the mixing of the materials constituting the reactive thin film and Te.