Fluorescent 75

Fluorescent 75: "Fluorescent Multilayer
The concept of multilayer, fluorescent cards/disks (FMD/C) is a unique breakthrough, solving the problems of signal degradation. Here the storage layer is coated with a fluorescent material. When the laser beam hits the layer, fluorescent light is emitted. This emitted light has a different wavelength from the incident laser light - slightly shifted towards the red end of the light spectrum - and is incoherent in nature, in contrast to the reflected light in current optical devices. The emitted light is not affected by data or other marks, and transverses adjacent layers undisturbed. In the read out system of the drive the light is filtered, so that only the information-bearing fluorescent light is detected, thus reducing the effect of stray light and interference. Theoretical studies, confirmed by experimental results, have shown that in conventional reflection systems the signal quality degrades rapidly with the number of layers. In fluorescent read out systems, on the other hand, the signal quality degrades much more slowly with each additional layer (see below). Research has shown that media containing up to a hundred layers are currently feasible, thereby increasing the potential capacity of a single card or disk to hundreds of Gigabytes. Use of blue laser techniques would increase the capacities to over 1 Terabyte. As the technology is developed, and the nonlinear mechanisms of light absorption are mastered, the objective is to reduce layer thickness toward molecular dimensions, potentially resulting in over 1,000s of layers per disk and capacities of 10s of Terabytes."