Optical information recording medium, and substrate and manufacturing method for the optical information recording medium

Abstract

In an optical disk including at least a rewritable phase change material and comprising a recording layer having a reflectivity of more than 15%, an address output value as an address pit signal component occupying in a reproduced signal in a non recording state is prescribed to be 0.18 though 0.27 or a numerical aperture of an address pit signal occupying in a reproduced signal in a non recording state is prescribed to be more than 0.3.

What is claimed is: 
     
         1 . An optical information recording medium comprising:
 a substrate formed with an area having sinusoidally deflected grooves;   a recording layer being recordable by a laser beam; and   a transmission layer being transparent to a laser beam and having a thickness of 0.1 mm and having birefringence;   wherein said recording layer is capable to record digital information marks modulated by a modulation code with minimum lengths of 2T.   
     
     
         2 . A reproducing method for reproducing an optical information recording medium, said optical information recording medium comprising:
 a substrate formed with an area having sinusoidally deflected grooves;   a recording layer being recordable by a laser beam; and   a transmission layer being transparent to a laser beam and having a thickness of 0.1 mm and having birefringence;   wherein said recording layer is capable to record digital information marks modulated by a modulation code with minimum lengths of 2T,   said reproducing method reproduces an optical information recording medium by irradiating a laser beam on said recording layer through said transmission layer as a light path, and reproduces said digital information marks modulated by a modulation code with minimum lengths of 2T.   
     
     
         3 . A method for reproducing an optical information recording medium, comprising:
 irradiating a laser beam through a transmission layer as a light path onto a recording layer to reproduce digital information marks modulated by a modulation code with a minimum length of at least 2T, wherein said transmission layer has a thickness of about 0.1 to 0.12 mm and is transparent to the laser beam, and   wherein said transmission layer has birefringence; and   filming the recording layer over a substrate, said substrate defining an area having sinusoidally deflected grooves.   
     
     
         4 . The method of  claim 3 , wherein the transmission layer has birefringence of less than 100 nm per double paths. 
     
     
         5 . The method of  claim 3 , wherein the transmission layer has a refractive index “n” of from 1.45 to 1.65. 
     
     
         6 . The method of  claim 3 , wherein the transmission layer comprises acetate resin.