Abstract: An optical data recording medium having a recording layer with or without an underlayer layered on a transparent substrate, wherein said recording layer is composed of a difficult-to-dissolve-in-water organic dye type material on which a thin layer composed of a surface active polymer as a hydrophilic material, which is denaturated by cross-linking.

Abstract: There is disclosed an optical information recording medium comprising forming at least a recording or reflecting film on one surface of a substrate, wherein an plasma-polymerized film of a halogen-containing resin is formed on at least one of the surface of the substrate or the outer surface of the recording or reflecting film. The medium may further include an additional UV-curing film which is formed on any of the surface of the substrate or plasma-polymerized film of halogen-containing resin on the surface of the substrate, the recording or reflecting film, or the peripheries of the substrate and protective film.

Abstract: A write-once type filled up with any fillers optical data recording medium provided with recording layers for a melting and diffusion recording system is disclosed, wherein a protective layer is formed between the recording layers or between the recording layer and another plate shaped member, the protective layer being composed of a member which is not adversely effected by a melting and recording operation and is not warped by changes of external conditions.

Abstract: An optical recording disc which includes a pair of recording disc substrates opposed to each other with a space therebetween, with a hub situated at the central portion of the disc substrates so that there is formed the closed space between the disc substrates, thereby providing a dual sided recordable optical recording disc. The hub may be formed by a pair of hub halves. There is disposed an annular inner spacer and annular outer spacer around the hub so as to separate the pair of recording disc substrates.

Abstract: A transparent substrate and a method of producing the same suitable especially for an optical system for an optical data recording medium using a linearly polarized light as a data reading light such as a magneto-optical recording medium drive unit and an optical data recording medium for reading data using a linearly polarized light.

Abstract: A cell using atmospheric oxygen as the depolarizer which is provided with a means for capture of carbon dioxide in the passage from the air inlet to the catalytic electrode whereby the air excluded carbon dioxide therefrom is supplied to the catalytic electrode. The cell shows good discharging property for a long duration.

Abstract: A transparent substrate and a method of producing the same suitable especially for an optical system for an optical data recording medium using a linearly polarized light as a data reading light such as magneto-optical recording medium drive unit and an optical data recording medium for reading data using a linearly polarized light.