Abstract: An optical glass includes P2O5, B2O3 and a rare earth oxide as essential components, and in a glass composition based on oxides, the P2O5 content is in the range of over 0 weight % and less than 0.79 weight %, the B2O3 content is in the range of 20-40 weight % and the total content of the rare earth oxide and an oxide selected from the group including of Ta2O5, WO3, TiO2, Nb2O5 and Bi2O3 is in the range of 35-70 weight %. Further, this optical glass has a refractive index (nd) in the range of 1.72-1.83, an Abbe number (?d) in the range of 45-55 and a glass transition temperature (Tg) of 640° C. or less.

Abstract: A method of manufacturing a perpendicular magnetic recording medium 100 that includes forming a magnetic recording layer 122 on a disk base 110, then forming a resist layer 130 on the magnetic recording layer, and a patterning step of processing the resist layer so as to vary the thickness of the resist layer partially, thereby forming a predetermined pattern having a recessed part and a projected part. Finally, the method includes implanting ions into a plurality of layers including the magnetic recording layer with the resist layer interposed. At the ion implanting step, (1) one or more of said plurality of layers to be implanted with ions is determined by selectively applying an energy amount to implant ions, and (2) a total amount of ions to be implanted into each of said one or more of said plurality of layers is determined by selectively applying said energy amount for a respective time period for said one or more of said plurality of layers.

Abstract: An optical glass includes P2O5, B2O3 and a rare earth oxide as essential components, and in a glass composition based on oxides, the P2O5 content is in the range of over 0 weight % and less than 0.79 weight %, the B2O3 content is in the range of 20-40 weight % and the total content of the rare earth oxide and an oxide selected from the group including of Ta2O5, WO3, TiO2, Nb2O5 and Bi2O3 is in the range of 35-70 weight %. Further, this optical glass has a refractive index (nd) in the range of 1.72-1.83, an Abbe number (?d) in the range of 45-55 and a glass transition temperature (Tg) of 640° C. or less.

Abstract: [Problem] An object is to provide a magnetic recording medium with improved HDI characteristics, such as impact resistance, and its manufacturing method. [Solution] A typical structure of a magnetic recording medium 100 according to the present invention includes, on a base, at least a magnetic recording layer 122, a protective layer 126, and a lubricating layer 128, wherein the magnetic recording layer 122 includes, in an in-plane direction, a magnetic recording part 136 configured of a magnetic material and a non-recording part 134 magnetically separating the magnetic recording part 136, and a surface corresponding to the non-recording part 134 protuberates more than a surface corresponding to the magnetic recording part 136.

Abstract: [Problem] An object is to provide a magnetic recording medium with improved HDI characteristics, such as impact resistance, and its manufacturing method. [Solution] A typical structure of a magnetic recording medium 100 according to the present invention includes, on a base, at least a magnetic recording layer 122, a protective layer 126, and a lubricating layer 128, wherein the magnetic recording layer 122 includes, in an in-plane direction, a magnetic recording part 136 configured of a magnetic material and a non-recording part 134 magnetically separating the magnetic recording part 136, and a surface corresponding to the non-recording part 134 protuberates more than a surface corresponding to the magnetic recording part 136.

Abstract: [Problem] The concentration distribution in a perpendicular direction of ions implanted in a magnetic recording layer of a perpendicular magnetic recording medium is made a suitable one corresponding to a layer implanted with ions.