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Information-recorded media and methods for reading the information

  • US 5,856,048 A
  • Filed: 07/26/1993
  • Issued: 01/05/1999
  • Est. Priority Date: 07/27/1992
  • Status: Expired due to Term
First Claim
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1. An information-recorded medium which includes a layer with a hologram recorded thereon that is composed of a hologram having interference fringes recorded in a transmittance profile or refractive index profile form in a thickness direction of the optical recording material, wherein spacings between interference fringes are made wide or narrow in a portion or portions of the hologram so as to conform to additionally written information, thereby making a wavelength reconstructed by the resultant portion different from that of another portion of the hologram.

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