Riso National Laboratory

Consiglio Nazionale Della Richerche

P S Ramanujam

Rolf Henrik Berg

Gábor Szarvas

Pál Koppa

Soren Hvilsted

S&oslash;ren Hvilsted

Fulvio Andruzzi

Sören Hvilsted

Emöke Lörincz

Péter Richter

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 (). The recording of the information is in the form of data pages stored as thin Fourier holograms (). 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.

System and method for recording of information on a holographic recording medium, preferably an optical card

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. Optical anisotropy may reversibly be generated with polarized laser light whereby a hologram is formed. First order diffraction efficiencies of up to around 80% have been obtained.

Physically functional materials

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.

Optical storage medium

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Roskilde, Denmark

P S Ramanujam