basics of holographic data storage

Many holotechnology information storage media have a ray splitter that splits a laser ray into two rays. One of the rays, called the object beam, goes by means of a Spatial Light Modulator (SLM), especially a Liquid Crystal Display (LCD), that imprints data into the ray. The object ray intersects the second ray, called the reference beam, inside optically sensitive encoding media -- like a photopolymer. The intersection of these rays, called an interference configuration, is a hologram that is saved in the storage material. When a reference beam is shown into the storage media at the identical angle and wave phase used to store the hologram, then the hologram is recreated and the information configuration may be extracted and changed into electronic pulses. Information bits on holotechnology storage disks are expected to last as long as a half century, while data on magnetic tape can degrade in less than 10 years. Accordingly, uses for which long-term durability is critical may increasingly switch from tape to holodisks. Write up on Technology Review: Holographic Memory .

With holotechnology data encoding, a laser ray called the "object beam" contains the information to be stored. The object beam is intersected with a reference ray. The optical interference configuration that results from this intersection contains the data inside a holographic image. When this intersection happens inside optically sensitive media, then the hologram with the data is burned within the storage material for later retrieval. Multiple, intersecting holograms can be recorded throughout the thickness of the photosensitive media. A sensitizing or gating laser with a shorter wavelength than the reference and signal rays can sensitize the storage media as part of the information recording process. When a reference beam with the same angle and wavelength as the original reference ray is shone onto the hologram at a later time, then the data configuration of light of the object ray is retrieved. A light detector reads the information from this recreated object ray in parallel. Movement of laser beams for holotechnology information storage and retrieval requires fewer moving parts than traditional data storage. Accordingly, it is possible to access data much faster using holographic technology. Sub-page Simulation Games covers additional information.

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