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Optical disc and optical system for reproducing the optical disc

  • US 5,436,885 A
  • Filed: 03/08/1994
  • Issued: 07/25/1995
  • Est. Priority Date: 03/12/1993
  • Status: Expired due to Term
First Claim
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1. An optical disc having a recording film disposed at a light receiving side and having information recorded thereon comprising:

  • a photochromic material film provided on the recording film at an information recorded side;

    a reflection film disposed on the photochromic material film; and

    the photochromic material film being made of a photochromic material which has a first state dependent on reading light having a first wavelength, where transmittance or reflectance of the material changes so as to enable reading of the recorded information, and has a second state dependent on auxiliary light having a second wavelength, where the transmittance or reflectance changes so as to disable the reading of the recorded information.

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