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US 2002/0057641 A1Published application
Optical disc and apparatus for manufacturing a master disc therefor
AssigneePioneer Corporation
InventorMasahiro Katsumura
Life of this patent
Estimating the term…
Abstract
A master-disc-manufacturing apparatus includes an electron-beam emitting portion for emitting an electron beam, an electron-beam converging portion for converging an electron beam, a retarding voltage applying portion for applying a substrate with a negative potential having a magnitude of decelerating the electron beam, and a vacuum atmosphere producing portion for evacuating a chamber to produce a vacuum atmosphere therein.
Claims5
An apparatus for manufacturing a master-disc by irradiation of an electron beam on a disc substrate placed on a turntable disposed within a vacuum chamber, comprising:
- a beam source emitting an electron beam;
- a convergence device for converging the electron beam onto a disc substrate;
- and
- a shaping-aperture plate provided in said the convergence device and having an opening for shaping a transverse cross section of the electron beam, wherein said opening has a first internal diameter stretched in a radial direction of said disc substrate and a second internal diameter shorter than the first internal diameter and stretched in a tangential direction of said disc substrate.
1 more element
An optical disc comprising:
- a disc substrate;
- a land and a groove spirally or concentrically formed on the disc substrate wherein the groove has a line width stretched in a radial direction of said disc substrate;
- and prepits formed on the land or the groove, wherein each of the prepits has an internal diameter stretched in a tangential direction of said disc substrate, characterized in that said internal diameter of the prepit is shorter than said line width of the groove.
Dependencies are inferred from the claim text.