Patent ID: 6052354
Filing Date: 2000-04-18
Classification: G11B,G11C

Abstract:
An optical data storage medium comprising a data storage area formed by a substantially transparent homogeneous base material and with a number of optically active structures in the form of diffractive optical elements (DOE) adjacent to one side of the data storage area, wherein the diffractive optical elements (DOE) each are adapted to focus a light beam incident on the data storage area onto one or more points which each corresponds to a uniquely adressable location of a data-carrying structure which is to be generated or a generated data-carrying structure in the data storage area and/or to focus a redirected light beam or emitted light radiation from this point or these points onto a point outside the optical storage medium, wherein that the diffractive optical elements (DOE) are formed with controlled, stepwise phase changes.