The idea of using holograms for storage of information was first suggested by van Heerden in 1963, who proposed to store data by recording the information carrying a light interference pattern in a holographic medium. He also predicted that the minimum volume necessary to record a bit of information is ~Î»3, where Î» is the wavelength used in the holographic recording. This involves an impressive density of data on the order of 10 Tbitsâcm3 for Î» ~ 400 nm. In addition to high-density storage, holography permits short access times to the data since the direction of propagation of a light beam changes rapidly without inertia, unlike magnetic disk heads. Furthermore, a high data transfer speed is achieved since the complete sheet of information is recorded or read at the same time. Nevertheless, despite these advantages, after more than 40 years of research and development there are still not holographic drives in our personal computers. This is due principally to the lack of an adequate recording material.
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