Scattering losses minimization

Backscattered electrons, however, do give some elemental information about the sample because they are more energetic than secondary electrons and escape from farther within the sample [45,46], On the molecular level, the electron beam can interact with the nucleus of an atom and be scattered with minimal loss of energy. These incident electrons may be scattered more than once and then ejected from the sample as backscattered electrons. The back-scattered electrons originate from a greater depth within the sample and are... 

Bulk Optical Absorption of Phthalocyanine Particles. The visible and near infrared optical absorption of the phthalocyanine pigments was measured on a Cary 17 spectrophotometer using the technique described in Reference 8. A thin film of phthalocyanine dispersed in the polymer was coated onto 3 mil Mylar substrate using wirewound rods. The dry films were index matched by overcoating with a thick film of polyvinyl alcohol. The differential absorption between two films with different thicknesses were recorded to minimize reflection and light scattering losses. The solution absorption spectra of some pigments were also measured in a-chloronapthalene. 

Optical power losses are very small, about 0.03 dB/km. This means that over 100 kilometres the optical power is halved this is an important requirement for telecommunications. Optical power loss is minimized near the wavelengths of 1300 nm and 1550 nm, where the minimum Rayleigh scattering or minimal infrared absorption is found. For sensing purposes, the losses in the fibre optics are irrelevant, but still 1550 nm is the preferred window, since the optoelectronic components are more readily available. 

Typical responses for second-order effects are values in the range of 0.2-20 X 10 esu. Williams (60) remarked that uniquely useful applications for organic and polymeric materials will require a of esu or greater. In addition, a variety of additional application-dependent properties and attributes must be present. These include uniform birefringence, minimized scattering losses, transparency, stability, and processibiUty. The relaxation time of the poled structures must be increased significantly. 

Reducing the number of surfaces to minimize light absorption and scattering losses. 

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