Holography data storage

Photopolymers and photothermoplasts are mentioned only in connection with holographic data storage (see Holography). The classical method of optical data storage in silver haUde films (photographic film, microfiche technique) is not discussed (see Photography). 

The purple membrane is harvested semiindustrially from halobacteria mutants which are bred in fermenters. The BR is then embedded into a polymeric matrix of poly(vinyl alcohol) or polyacrylamide. The BR films manufactured in this way are used for different applications, preferably in holography, for example, as a reversible transient data storage system for optical information processing (159). Another example is real-time interferometry by using the property of BR films to integrate over time (160). BR has been proposed also as a two-photon memory material because of its unusually large two-photon cross section. 

Dumont, M., Hosotte, S., Froc, G., and Sekkat, Z. (1994). Orientational manipulation of chromophores through photoisomerization. In Photopolymers and Applications in Holography, Optical Data Storage, Optical Sensors, and Interconnects. (R. A. Lessard, cd.), Proc. SPIE 2042,2-13. 

Photochromic polymers have played a pivotal role in the development of novel materials for optical data storage. Advances in holography have benefited from early research into PAPs. Although not based on PAPs, the first commercial holographic data storage devices are now available. 

The light-induced synthesis of polymers is the topic of Part III. While the various modes of photoinitiation of polymerization processes are discussed in Chapter 10, related technical applications are treated in Chapter 11. The latter include curing of coatings and dental systems, printing plates (used to print newspapers), holography (important for data storage), and the synthesis of block-and-graft copolymers. 

The term volume holography refers to recording plates with a thickness of up to a few millimeters. In such voluminous matrices, data storage in three dimensions is possible. This implies an enormous increase in storage capacity in comparison with other methods. If multiplexing techniques (see Section 12.1) are applied, thousands of holograms can be superimposed in the same plate. 

Holograms have many uses besides the display of three-dimensional images. Applications include industrial testing, precise measurements, optical data storage, and pattern recognition. A presentation of the applications of holography is given in Section V. 

Holography is also attractive for data storage. Because holograms record information in a distributed fashion, with no one point on the hologram corresponding to a particular part of the image, data recorded in holographic... 

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