Glass 446 INDEX

See Henderson, Duchamp in Context, consulting especially her Large Glass Index, 368-74. 

Smithsonian Catalog of Basalt Glasses [http //www.nmnh. si.edu/minsci/research/glass/index.htm]... 

We assume the composite structure shown in Figure 1 fused silica glass (index 2) / water (index 1) / fused silica glass (index 2). Defining the optical axis as the x-axis and T and T2 as the temperatures of water and glass relative to the ambient temperature, respectively, diffusion of heat can be described by the differential equation... 

Despite the gains in internal quantum efficiency, the overall efficiency is still less than 19%. As much as 80% of the photons produced cannot get out because of the high index of refraction of the polymer material. Approaches such as texturing the surface of the glass, index matching or using low index substrate materials, and the use of arrays of microlenses have made increases in the extraction efficiency. 

Lead oxide is used in producing fine "crystal glass" and "flint glass" of a high index of refraction for achromatic lenses. The nitrate and the acetate are soluble salts. Lead salts such as lead arsenate have been used as insecticides, but their use in recent years has been practically eliminated in favor of less harmful organic compounds. 

For an air/glass interface, tan 0b = n, the refractive index of glass. In a gas laser, the light must be reflected back and forth between mirrors and through the gas container hundreds of times. Each time the beam passes through the cavity, it must pass through transparent windows at the ends of the gas container (Figure 18.10b), and it is clearly important that this transmission be as efficient as possible. 

Solution Polymers. Acryflc solution polymers are usually characterized by their composition, solids content, viscosity, molecular weight, glass-transition temperature, and solvent. The compositions of acryflc polymers are most readily determined by physicochemical methods such as spectroscopy, pyrolytic gas—liquid chromatography, and refractive index measurements (97,158). The solids content of acryflc polymers is determined by dilution followed by solvent evaporation to constant weight. Viscosities are most conveniently determined with a Brookfield viscometer, molecular weight by intrinsic viscosity (158), and glass-transition temperature by calorimetry. 

Viable glass fibers for optical communication are made from glass of an extremely high purity as well as a precise refractive index stmcture. The first fibers produced for this purpose in the 1960s attempted to improve on the quahty of traditional optical glasses, which at that time exhibited losses on the order of 1000 dB/km. To achieve optical transmission over sufficient distance to be competitive with existing systems, the optical losses had to be reduced to below 20 dB/km. It was realized that impurities such as transition-metal ion contamination in this glass must be reduced to unprecedented levels (see Fig. 

Fig. 6. Double crucible configuration showing core glass (upper crucible) flowing through molten cladding glass in lower crucible to yield graded-index...

Optical Properties. Teflon FEP fluorocarbon film transmits more ultraviolet, visible light, and infrared radiation than ordinary window glass. The refractive index of FEP film is 1.341—1.347 (74). 

Refra.ctlon, Optical glasses are usually described in terms of their refractive index at the sodium D line (589.3 nm), and their v value (or Abbe number) which is a measure of the dispersion or variation of index with wavelength, ie, v = ), in which is the refractive index at the... 

Fig. 11. Index of refraction vs dispersion and optical classification of glasses. The shaded area indicates the region of glass formation. BaF = barium flint BaK = barium crown BaLF = light barium flint BaSF = heavy barium flint BK = borosilicate crown F = flint FK = fluorcrown K = crown ...

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