Background optics

There are many books covering the background optics and that by A. Yariv and P. Yeh [8] can be recommended. 

To appreciate properly how electro-optic ceramics function, it is first necessary to consider the nature of light and its interaction with dielectrics. 

James Clerk Maxwell (1831-1879), against a background of experimental and theoretical work by Andre Ampere (1775-1836). Karl Gauss (1777-1855) and Michael Faraday (1791-1867), developed the electromagnetic wave theory of 

Electroceramics Materials, Properties, Applications. 2nd Edition. Edited by A. J. Moulson and J. M. Herbert. 2003 John Wiley Sons, Ltd ISBN 0 471 49747 9 (hardback) 0 471 49748 7 (paperback) 

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Salganicoff, L., KraybUl, M., Mayer, D., and Legallais, V., Sensitive dual wavelength densitometer with suppression of the support introduced background optical density. J. Chromatog. 26, 434-441 (1967). 

R. Cubeddu, A. Pifferi, P. Taroni, A. Torricelli, G. Valentini, Imaging with diffusing light an experimental study of the effect of background optical properties, Appl. Opt. 37, 3564-3573 (1998)... 

ECL is also considered superior over other spectroscopic detection systems due to many distinct advantages [32], such as lack of a light source, the absence of a background optical signal, less sample volume, easy and simple instrumentation, precise control of reaction kinetics offered by controlling the applied potential, compatibility with solution-phase and thin-fihn formats, and opportunities to enhance intensity with nanomaterials such as metallic nanoparticles (NPs) and nanotubes (NTs), etc [33]. 

A detector system is presented in Fig. 2.2. A background optical flux is incident to the active area of a photodetector with a thickness d. Both in the case of solar cells and night vision photodetectors, the optical flux is blackbody radiation, described by the Planck s law. In a general case, the detector material may incorporate nanostructuring that could localize optical field and create hotspots with high density of states. A perfect mirror is placed at the rear side of the device—i.e., it is assumed that the incident light is unidirectional, while the internal radiation is bidirectional. 

Resolving the intrinsically low intensity lanthanide-based luminescence signals from the commonly much more intense background optical emission from other sources within the sample matrix. 

Fig. 5 Erosion pit inside a reducing pipe fitting, projection technique at 160 kV, profile plot with optical densities of the digitised film. The varying background caused by the geometrical set-up prevents a wall thickness calibration as in fig. 4...

In practice, the NEP of a room-temperature THz spectrometer is usually limited by fluctuations (shot-noise) in the ambient blackbody radiation. Usmg an optical bandwidth Av = 3 THz (limited by, for example, a polyethylene/diamond dust window), a field of view (at nomial incidence) 0 = 9 and a detecting diameter (using a so-called Winston cone, which condenses the incident radiation onto the detecting element) laboratory applications, the background-limited NEP of a bolometer is given by... 

The optical properties of metal nanoparticles have traditionally relied on Mie tlieory, a purely classical electromagnetic scattering tlieory for particles witli known dielectrics [172]. For particles whose size is comparable to or larger tlian tire wavelengtli of the incident radiation, tliis calculation is ratlier cumbersome. However, if tire scatterers are smaller tlian -10% of tire wavelengtli, as in nearly all nanocrystals, tire lowest-order tenn of Mie tlieory is sufficient to describe tire absorjDtion and scattering of radiation. In tliis limit, tire absorjDtion is detennined solely by tire frequency-dependent dielectric function of tire metal particles and the dielectric of tire background matrix in which tliey are... 

Thus we are challenged by the problem of measuring a small signal against the background of one much stronger. The problem is usually solved by one of two means (a) lock-in-amplifier detection and (b) a boxcar type of detection (to some extent we can include double-input optical multichannel detection in this category). 

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