Optical data recording medium and method for reproducing recorded data

Abstract

An optical data recording medium, in which irradiation of a light beam is used for recording and/or reproducing data includes (i) a substrate having an a rise and/or a recess which are a light-incident surface, (ii) a reflective layer, provided on the light-incident surface of the substrate, for reflecting the light beam, (iii) a light absorption layer for converting, to heat, a light of the light beam to heat on the surface of the reflective layer, (iv) a reproducing layer, provided on the surface of the heat-light converting layer, having a transmittance that changes in accordance with a light intensity distribution of the light beam. The optical data recording medium is excellent in super-resolution property, and enables reproduction of a shorter mark length.

1 - 18 . (canceled) 
   
   
       19 . An optical data recording medium, in which irradiation of a light beam is used for reproducing data, comprising:
 a substrate;   pits indicative of reproduction position, provided in a light incident side of the substrate, the pits having a mark length shorter than a resolution limit of an optical system of a reproducing apparatus for reproducing the optical data recording medium; and   a reproducing layer, provided on the light incident side of the substrate, the reproducing layer for reproduction by the reproducing apparatus of a signal from a mark having a mark length shorter than a resolution limit of the optical system of the reproducing apparatus.   
   
   
       20 . The optical data recording medium as set forth in  claim 19 , wherein
 the reproducing layer is a most farthest layer from the substrate, among layers formed on the light incident side of the substrate.   
   
   
       21 . The optical data recording medium as set forth in  claim 19 , wherein
 the reproducing layer changes in transmittance in accordance with the light beam thus irradiated.   
   
   
       22 . The optical data recording medium as set forth in  claim 19 , further comprising
 a reflective surface provided between the substrate and the reproducing layer, the reflective surface for reflecting light transmitted through the reproducing layer.   
   
   
       23 . The optical data recording medium as set forth in  claim 22 , further comprising
 a reflective layer provided between the substrate and the reproducing layer, the reflective layer forming a reflective surface.   
   
   
       24 . The optical data recording medium as set forth in  claim 19 , wherein:
 the reproducing layer is made of a material whose transmittance changes in accordance with temperature.   
   
   
       25 . The optical data recording medium as set forth in  claim 19 , wherein:
 at least a part of a light-incident surface of the reproducing layer is exposed to air.   
   
   
       26 . The optical data recording medium as set forth in  claim 19 , further comprising:
 a light absorption layer for converting an incident light beam directed toward said light incident surface of said substrate to heat, the light absorption layer being contiguous to the reproducing layer.   
   
   
       27 . The optical data recording medium as set forth in  claim 19 , further comprising:
 a reflective layer for reflecting an incident light beam directed toward said light incident side of said substrate, the reflective layer being provided between said light incident side of said substrate and said reproducing layer.   
   
   
       28 . The optical data recording medium as set forth in  claim 19 , wherein:
 the reproducing layer is made of a metal oxide.   
   
   
       29 . The optical data recording medium as set forth in  claim 28 , wherein:
 the reproducing layer is made of a zinc oxide.   
   
   
       30 . The optical data recording medium as set forth in  claim 26 , wherein:
 the light absorption layer is made of one of silicon, germanium and an alloy of silicon and germanium.