Coatings optical properties

Functional Coatings. Whereas there are many types of functional coatings, the basic properties or characteristics that give a device utility are its electrical, magnetic, and optical properties. The electrical properties can be defined by the ability of the material to conduct or hinder flow of electrons. This characteristic resistance is expressed by... 

Hubicka, Z., Sicha, M., Pajasova, L., Soukup, L., Jastrabik, L., Chvostovd, D., and Wagner, T., CNx Coatings Deposited by Pulsed RF Supersonic Plasma Jet Hardness, Nitrogenation and Optical Properties, Surf. Coat. Technol., Vol. 142-144, 2001, pp. 681-687. 

Liu, (., Cankurtaran, B., Wieczorek, L., Ford, M.J. and Cortie, M.B. (2006) Anisotropic optical properties of semitransparent coatings of gold nano-caps. Advanced Functional Materials, 16, 1457-1461. 

Shankar, S.S., Rai, A., Ahmad, A. and Sastry, M. (2005) Controlling the optical properties of lemongrass extract synthesized gold nanotriangles and potential application in infrared-absorbing optical coatings. Chemistry of Materials, 17, 566-572. 

The measurement of 4 and A gives rP/rs via equation (2.74), for the coated electrode system, with both of these parameters highly sensitive to the properties of the film. However, whereas a knowledge of A and 4 allowed the direct calculations of the optical properties of an uncoated metal via equations (2.80) and (2.81), these equations no longer apply in the case of a coated substrate. At this point, the central problem in ellipsometry is encountered. To characterise the film completely, three parameters are required n, k and L, However, the above discussion includes only the determination of two parameters, a. and c, giving 4 and A. One of two approaches is commonly employed to solve the equations to give /i, k and L. 

The FPI principle can also be used to develop thin-film-coating-based chemical sensors. For example, a thin layer of zeolite film has been coated to a cleaved endface of a single-mode fiber to form a low-finesse FPI sensor for chemical detection. Zeolite presents a group of crystalline aluminosilicate materials with uniform subnanometer or nanometer scale pores. Traditionally, porous zeolite materials have been used as adsorbents, catalysts, and molecular sieves for molecular or ionic separation, electrode modification, and selectivity enhancement for chemical sensors. Recently, it has been revealed that zeolites possess a unique combination of chemical and optical properties. When properly integrated with a photonic device, these unique properties may be fully utilized to develop miniaturized optical chemical sensors with high sensitivity and potentially high selectivity for various in situ monitoring applications. 

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