A volume radiation memory, nominally a 2.5 cm (1) diameter 6 mm thick optical disk, is preferably written in parallel by two-photon absorption within, and read with massive parallelism by a single-beam-induced fluorescence of, spherical voxels of nominal diameter 2 microns spaced 2 microns center-to-center...http://www.google.com.tw/patents/US6590852?utm_source=gb-gplus-share專利 US6590852 - Massively-parallel writing and reading of information within the three-dimensional volume of an optical disk, particularly by use of a doubly-telecentric afocal imaging system
