Inverse analysis of NIR and SWIR reflectance spectra for dye mixtures in fabrics using analytical basis functions

Abstract

This study describes inverse spectral analysis of near-infrared (NIR, 0.7-0.9 μm) and shortwave infrared (SWIR, 0.9- 1.7 μm) reflectance spectra, which is for tailoring the NIR-SWIR reflectance of dyed fabrics. The parametric models used for inverse analysis are defined by linear combinations of gaussian functions, which are for modeling dyes in fabric whose absorption spectra span the NIR/SWIR spectral range. In general, these linear combinations are not unique, and thus suggest investigation concerning the concept of optimal linear combinations of analytical basis functions, which is in terms of analytical formulations, number of functions, and consistency of formulations with underlying physical processes. Prototype modeling is applied to NIR/SWIR absorbing dyes, and their mixtures, in fabric samples, which consist of a cotton blend. The results of this study demonstrate parametric modeling using linear combinations of gaussian functions for simulating NIR/SWIR spectral responses corresponding to variable dye and dye blend concentrations in fabrics.