Optical disk and production method thereof

DETAILED DESCRIPTION The present invention provides improvements over the above-mentioned methods and overcomes the drawbacks of such conventional methods.
It provides optical disks that are inexpensive and have enhanced recording density without decreasing signal-to-noise ratios as well as being compatible with conventional disks.
Further, the present invention readily permits mass production and allows stampers and substrates to be produced by means of a simple method and simple facilities.
Moreover, the present invention provides a method for producing such optical disks that are inexpensive, have enhanced recording density without decreasing signal-to-noise ratios, and that are compatible with conventional disks.
Specifically, the present invention provides an optical disk comprising a disk-shaped substrate that is formed with a cyclic olefin polymer as its main component and a light-curing resin layer that is formed on the disk-shaped substrate, wherein a relief-and-indentation is formed on the light-curing resin layer based on given information.
Further, the present invention provides an optical disk comprising a disk-shaped substrate that is formed with a cyclic olefin polymer as its main component and a heat-curing resin layer that is formed on the disk-shaped substrate, wherein a relief-and-indentation is formed on the heat-curing resin layer based on given information.
The cyclic olefin polymer has the characteristics of low hygroscopicity as well as low gas adsorption.
Therefore, when a disk substrate of the present invention is processed, for example, using a vacuum device, workability can be improved without lowering the vacuum level inside the device.
The disk-shaped substrate can be produced by punching out a sheet formed with a cyclic olefin polymer as its main component.
Also, the disk-shaped substrate can be produced by injection molding of a material having a cyclic olefin polymer as its main component.
Furthermore, by applying an activation treatment to the surface of the disk substrate, adhesiveness with the light-curing resin or heat-curing resin can be improved