Development of a real-time reflectance and transmittance monitoring system for the manufacturing of metaldielectric light absorbers

Badoil, Bruno; Cathelinaud, Michel; Lemarchand, Fabien; Lemarquis, Frédéric; Lequime, Michel

doi:10.1117/12.2308179

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“…A simulation (figure 1.39) based upon the change in compactness inside a metallic layer [91], including the Maxwell-Garnett model, has been successfully developed to fabricate a broadband absorber (absorptance A > 99%) which operates over the visible [91][92][93][94]. Figure 1.39: Simulation of optical constants, versus thickness of a Nickel layer at= 600nm [91] In conclusion of this section, measuring the refractive index is a more difficult task for a non-opaque metallic film than for a dielectric film.…”

Section: Optical Constant Determination By the Bilayer « Metallicdielmentioning

confidence: 99%

Refractive Index of Optical Materials

2019

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This chapter deals with the use of methods for measuring the refractive index of optical materials. It contains five sections: The first section recalls some bases of the electromagnetic theory of light leading to the main characteristics of the index of refraction, and their consequences in geometrical optics (Snell-Descartes laws), in the spectral transmission and absorption of optical media, or the polarization of light beams at interfaces between optical media. The second section describes the more or less classical panel of methods that have been devised to measure refractive indices of bulk materials: these are essentially based upon either the refraction or reflection of light inside prisms (minimum deviation angle, Littrow methods,…) polarizing properties of optical boundaries (ellipsometric, Brewster configurations). While the previous section consists of refractive index characterization at a given temperature, the third section is dedicated to the dependence of the refractive index upon the temperature: the normalized thermo-optic coefficient (NTOC) is defined here and an experimental setup specially designed for this purpose by one of the authors is described in detail. The last section is concerned with the fact that most optical components are thin film coated in order to improve their performances, in transmission, reflection or absorption. Since spectrophotometry is extensively used to characterize these coatings, the operating principle of spectrophotometers is recalled, as well as the main parameters of these deposited films that one can expect to extract by using this technology from spectrophotometric measurements. Also various spectrophotometric procedures are described to determine the optical constants of optical "systems" (bulk and thin film compounds) in the case of homogeneous or inhomogeneous films, slightly absorbing or not.

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