Transparency, optical glasses

The main disadvantage is that at least one of the substrates must be transparent to the radiation initiating cure. This requirement prevents also the filling or pigmenting of such materials. Nevertheless, many applications are being developed—bonding glass, transparent plastics, jewellery, and optical fibres. 

For spectroelectrochemical and photoelectrochemical studies, optically semi-transparent electrodes have been fabricated by vapour deposition techniques on glass or quartz substrates (Chapter 12). Tin and indium oxides, platinum, and gold have been used. 

A schematic presentation of one of the most convenient modifications of these cells is given in Fig. 8.2. It represents a glass cuvette 1 (internal dimensions 5x3 cm and 7 x 1.7 cm), made of transparent optical glass, sintered glass filters 2 for creating a definite capillary pressure and electrodes 3 for measuring foam electrical conductivity. 

Due to the above requirements, typical optical ly-transparent materials, such as oxides (glass, quartz, alumina, zirconium oxide etc.) and halides (sodium chloride, lithium fluoride, calcium fluoride, potassium bromide, cesium bromide etc.) are usually unsuitable for use with fluoride melts. Therefore, no standard procedure exists at present for the spectral investigation of fluoride melts, and an original apparatus must be created especially for each particular case. 

Optical glass fiber is a thin, flexible, and transparent guide through which light... 

A photomask is a nearly optically flat glass (transparent to near UV) or quartz plate (transparent to deep UV) with a metal absorber pattern printed on one side. The metal pattern is typically a 0.1 /zm thick chromium layer. The metal absorber pattern on a photomask is opaque to ultraviolet radiation, whereas glass... 

Combinations of the intrinsic redox system of glass melts with several polyvalent ionic redox systems, which are often present as trace impurities, are of importance for the transparency of optical glasses [18]. An example of these homogeneous equilibria is the combination with the iron(III)/iron(II) ion system. 

Liquid samples (solutions) are normally contained in a rectangular quartz (UV) or optical glass (visible) cell (called a cuvette ), with transparent faces and defined path length. Disposable plastic cuvettes are also available for more routine work. The reference cuvette is used to measure the light transmitted in the absence of sample (/q). 

An important phenomenon observed in amorphous plastics (also observed in optical glass) is the development of optical anisotropy due to stress. The stress-optical characteristic of transparent plastics is the basis of the important technique of photoelasticity by which stress and strain in complicated shapes, for which no analytical solution is readily available, can be determined experimentally and simply. 

Optical properties Transparent but not as glass-clear as acrylics or polyesters. ... 

La20a, in proportions of up to 40%, is used in main optical glass (lanthanum heavy crown and heavy flint). The presence of this oxide endows the glass with a high transparency and improves its structural properties [5]. 

Broadband ultraviolet excitation light source causes easily difficulties with the choice of materials. UV is heavily absorbed by most of the optical materials. This naturally lowers transmission of the optical components, and also very easily causes unwanted luminescence emission. Suitable materials are often more expensive and harder to machine than the standard optical glasses. Mostly, the other demands for the optics are not very strict, and a single lens can replace the objective lens. This can be manufactured out of fused silica at relatively low cost. Fused silica is highly transparent at UV wavelengths above 300 nm and is usually quite pure with only minute traces of background creating luminescent materials. 

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