Patents by Inventor P. S. Ramanujam

P. S. Ramanujam has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 7315501
    Abstract: The invention relates to a method for the recording and reading of data with a holographic write/read apparatus onto a holographic recording medium with a thin holographic recording layer. The medium is preferably an optical card (2). The recording of the information is in the form of data pages stored as thin Fourier holograms (61). According to the invention, it is foreseen to use reflected transmission and polarisation holography with different write and read wavelengths, and to correct during reading the distortion in the readout channel caused by the difference between the write and read wavelengths. The invention further relates to an apparatus and system for performing the method. There is also disclosed a method of coding the recorded information.
    Type: Grant
    Filed: May 4, 1999
    Date of Patent: January 1, 2008
    Assignee: Riso National Laboratory
    Inventors: P. S. Ramanujam, Sören Hvilsted, Pál Koppa, Emöke Lörincz, Péter Richter, Gábor Szarvas
  • Patent number: 6376655
    Abstract: The invention relates to novel monodisperse or polydisperse compounds, in general named DNO (diamino acid N&agr;-substituted oligopeptides), preferably low molecular weight polypeptides, e.g., based on ornithine, lysine, diaminobutyric acid, diaminopropionic acid, aminoethylglycine or other amino acids or peptides having azobenzenes or other physicially functional groups, e.g., photoresponsive groups, as side chains. These compounds may be synthesized using solid phase peptide synthesis techniques. Materials, e.g., thin films, comprising such compounds may be used for optical storage of information (holographic data storage), nonlinear optics (NLO), as photoconductors, photonic band-gap materials, electrically conducting materials, electroluminescent materials, piezo-electric materials, pyroelectric materials, magnetic materials, ferromagnetic materials, ferroelectric materials, photorefractive materials, or materials in which light-induced conformational changes can be produced.
    Type: Grant
    Filed: December 2, 1997
    Date of Patent: April 23, 2002
    Assignee: Riso National Laboratory
    Inventors: Rolf Henrik Berg, Søren Hvilsted, P. S. Ramanujam
  • Publication number: 20020025401
    Abstract: The present invention relates a method for optical storage of information using materials comprising compound having at least two chromophores and a linkage connecting the chromophores. The optical storage method can be effected by use of light having a wavelength of from 100-1600 nm. The compound applicable for the method are typically dimers based on a skeleton made of peptides or amino acids, or alternatively peptide nucleic acid (PNA). The chromophores may thymine, N—(C1-6-alkyl)-thymine, anthracene, acridizinium salts, tetracene, etc.
    Type: Application
    Filed: June 18, 2001
    Publication date: February 28, 2002
    Inventors: Rolf Berg, P.S. Ramanujam
  • Patent number: 5496670
    Abstract: A macroscopically isotropic side chain liquid crystal polymer is described containing photochromic mesogenic groups and which through irradiation with light is capable of being permanently or substantially permanently converted into an optically anisotropic phase without having been pre-oriented. The polymer is preferably a polyester between on the one hand either an aliphatic, optionally substituted, .alpha.,.omega.-dicarboxylic acid having a total chain length of up to 24 carbon atoms, or an aryl-, in particular phenyl-, carboxylic acid, and on the other hand an optionally substituted 1,3-propanediol containing the mesogenic group, or a group containing the mesogenic group, attached to the carbon in the 2-position. Furthermore, an optical storage device comprising a film of the polymer.
    Type: Grant
    Filed: August 30, 1993
    Date of Patent: March 5, 1996
    Assignees: Riso National Laboratory, Consiglio Nazionale della Richerche
    Inventors: Soren Hvilsted, P. S. Ramanujam, Fulvio Andruzzi