Optical magnitudes

Piller, H. A Universal System for Measuring and Processing and the Characteristic Geometry and Optical Magnitudes of Microscope Objects, in ADVANCES IN OPTICAL AND ELECTRON MICROSCOPY, Barer. R. and Cosslett, V.G., Ed., 1973, 5, 95-114, Academic Press, New York. 

The optical density can be easily related to other well-known optical magnitudes that are also directly measurable by spectrophotometers, such as the transmittance, T = I//o, and the absorbance, A = I - I//q ... 

Our first task is to connect measurable optical magnitudes with the dielectric constant, which describes the response of a given material to an applied electric field. This... 

In the next section, we will develop a simple model to predict the frequency dependence of the relative dielectric constants si and 2 of a given material. At that point, we will be able to determine the measurable optical magnitudes defined in Chapter 1 at any particular wavelength (or frequency) if the relative dielectric constants (and thus n and k) are known at that wavelength. 

In the previous section we have demonstrated how the measurable optical magnitudes are related to the dielectric constants (si, 2)- Now we need to establish how these... 

F ure 4.3 The optical magnitudes, n and k, of an ideal metal (undamped free electrons) versus the light frequency. 

The book starts with a short introduction to the fundamentals of optical spectroscopy, (Chapter 1) describing the basic standard equipment needed to measure optical spectra and the main optical magnitudes (the absorption coefficient, transmittance, reflectance, and luminescence efficiency) that can be measured with this equipment. The next two chapters (Chapters 2 and 3) are devoted to the main characteristics and the basic working principles of the general instrumentation used in optical spectroscopy. These include the light sources (lamp and lasers) used to excite the crystals, as well as the instrumentation used to detect and analyze the reflected, transmitted, scattered, or emitted light. 

The primary driver for the expansion of optoelectronic teclmologies is optical communications [2]. It was realized in the second-half of the 20th century that an increase of several orders of magnitude in bandwidth would be possible if optical waves were used as the carrier for telephone signals. The basic configuration of an optical communication... 

Polarization which can be induced in nonconducting materials by means of an externally appHed electric field is one of the most important parameters in the theory of insulators, which are called dielectrics when their polarizabiUty is under consideration (1). Experimental investigations have shown that these materials can be divided into linear and nonlinear dielectrics in accordance with their behavior in a realizable range of the electric field. The electric polarization PI of linear dielectrics depends linearly on the electric field E, whereas that of nonlinear dielectrics is a nonlinear function of the electric field (2). The polarization values which can be measured in linear (normal) dielectrics upon appHcation of experimentally attainable electric fields are usually small. However, a certain group of nonlinear dielectrics exhibit polarization values which are several orders of magnitude larger than those observed in normal dielectrics (3). Consequentiy, a number of useful physical properties related to the polarization of the materials, such as elastic, thermal, optical, electromechanical, etc, are observed in these groups of nonlinear dielectrics (4). 

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