Patent ID: 7052812
Filing Date: 2006-05-30
Classification: B82Y,G03H,G11B,G11C

Abstract:
1. A medium extending over an area having been selectively written by radiation at a writing time, the medium before writing consisting essentially of: a host matrix; containing a liquid monomer, in which monomer molecular mobilities are relatively higher, that can be photopolymerized into a solid polymer, in which polymer molecular mobilities are relatively lower, the monomer being at a time before photopolymerization substantially homogeneously doped with a dye that can be photoexcited to bind to at least the polymer, wherein upon selective exposure of certain areas of the matrix by radiation at the writing time, both (i) polymerization of the monomer into the polymer and (ii) fixing of the dye to the polymer occur in these exposed areas; wherein dye molecules that are photoexcited in the selected regions at the waiting time so as to bind to at least the polymer molecules become, due to the relatively lower molecular mobility in the polymer, relatively fixed in their bound locations while other un-photoexcited dye molecules not in the selected regions remain relatively more mobile, resulting in a migration and a redistribution of dye at the writing time from unexposed to photoexposed regions until, dye migration being substantially complete, photopolymerization occurs, locking the migrated and redistributed dye in place at a relatively higher concentration at the selectively photoexposed regions; wherein after the writing time a concentration gradient of dye molecules in the matrix exists from the unexposed to the exposed areas of the matrix, this concentration gradient resulting from diffusion of the dye from the unexposed to the exposed areas; wherein by radiation writing dye concentration is increased in the exposed areas relative to the unexposed areas; wherein, after radiation exposure in selected areas of the matrix stops, an excess concentration of dye molecules in these selectively exposed areas serves as a record of the selective radiation exposure.