Number 120 (Story #3), March 26, 1993 by Phillip F. Schewe and Ben Stein|
POLYMERS CAN BE USED TO MAKE HOLOGRAMS . At the APS meeting, W.E. Moerner of IBM Almaden reported on the optical properties of a new polymer, a composite chain molecule called PVK:F-DEANST:TNF. In this material the photorefractive effect---a nonlinear optical effect in which laser light causes the migration and then selective storage of charges in various parts of the polymer---is particularly strong, as strong as in some conventional inorganic photorefractive crystals. Moerner has already used the polymer to make a 125-micron-thick hologram in which two laser beams are combined to write and read information. If the diffraction efficiency, one measure of the brightness of the hologram image, could be improved from the current 1% to as high as 10%, then potential applications could ensue. These include erasable, high-density, rapid-access storage of information (eventually the Encyclopedia Britannica stored on a dime-sized hologram). Polymer holograms will be cheaper and more easily formable than inorganic crystalline holograms, said Moerner.