Optical materials processing

High demands are placed on the substrate material of disk-shaped optical data storage devices regarding the optical, physical, chemical, mechanical, and thermal properties. In addition to these physical parameters, they have to meet special requirements regarding optical purity of the material, processing characteristics, and especially in mass production, economic characteristics (costs, processing). The question of recyclabiUty must also be tackled. 

A concise survey of where the broad domain of optical information processing had got to a few years ago is in a book issued by the European Commission (Kotte et al. 1989), while a good overview of non-linear optical materials is by Bloor (1994). 

The major optical coating process remains evaporation. However, sputtering, solgel, and CVD are making inroads because of the better properties they provide.fi l At this time, it is not clear which coating process will prove best but CVD, because of the excellent bond and hardness of the deposited materials and the relatively moderate cost of the equipment, is a good candidate. 

CuCl, especially in a single crystal form, is extensively used as an optical material for its special optical properties. Orel et al. [2] first proposed a new method to obtain CuCl particles by the reduction of Cu with ascorbic acid. Several dispersants were used in the reduction and monodispersed CuCl particles can be obtained by selecting the proper dispersant and reduction conditions. In this work, the above method was used to modify the traditional process of CuCl preparation, namely, by reducing the Cu " with sodium sulfite to obtain the highly active CuCl catalyst to be used in the direct process of methylchlorosilane synthesis. 

Klavs F. Jensen, Chemical Engineering in the Processing of Electronic and Optical Materials A Discussion... 

As this volume attests, a wide range of chemistry occurs at interfacial boundaries. Examples range from biological and medicinal interfacial problems, such as the chemistry of anesthesia, to solar energy conversion and electrode processes in batteries, to industrial-scale separations of metal ores across interfaces, to investigations into self-assembled monolayers and Langmuir-Blodgett films for nanoelectronics and nonlinear optical materials. These problems are based not only on structure and composition of the interface but also on kinetic processes that occur at interfaces. As such, there is considerable motivation to explore chemical dynamics at interfaces. 

We have described for a number of molecular single crystals the basic principles and techniques which were involved in the optimization of their nonlinear efficiency and crystalline quality. Certainly, other types of molecules or material processing techniques can be used. In particular, it could be worthwile to try and by-pass the difficulty of growing large single crystals for applications which are less demanding in terms of optical quality parametric oscillation. 

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