Thursday, 4 June 2020

Contactless Terahertz Paint Thickness Measurements: specificity of aeronautics industry

Chopard, Adrien, J. Bou Sleiman, Q. Cassar, P. Fauché, J. P. Guillet, P. Mounaix, M. Pan, J. B. Perraud, and A. Susset. "Contactless Terahertz Paint Thickness Measurements: specificity of aeronautics industry." (2019).

Abstract 
We report on numerical developments for the analysis of multilayered structures and the extraction of individual layer properties obtained by terahertz time domain measurements. An iterative algorithm implements a connected propagation tree which denotes the occurrence of the incident pulse division for each reflection / transmission appearance at each interface encountered during the propagation. Each sub pulse is individually monitored and its carried proportion of the incident power is extracted. Such a process allows to obtain the specific dielectric properties of each layer but additionally permits to derive a parametric transfer function describing the whole interaction with an incident beam. Procedure results performed on aeronautics multilayered painting samples are reported. 



"The first step to achieve the simulations and the characterization, was to carefully extract the dielectric properties of each individual painting material (Tab. 1) via a basic inverse problem method thanks to measurements performed on a Teraview TPS 4000 system. Both the real and the imaginary part of the dielectric function are fitted with a first order Debye relaxation model. "

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