Mid Infrared Polarized Light Scattering Applications for the Remote Detection ofChemical and Biological Contaminations

摘要

A polarized IR scattering facility that measures all elements of the Muellermatrix was built here at the U.S. Army Chemical Research, Development and Engineering Center (CRDEC) for remote detection of contaminants (analytes) spread on natural and manufactured surfaces (background scattering interferent). The ellipsometer is a two-modulator design that when interfaced to a mathematical algorithm can be trained to emit beam CO2 laser energies at incident angles that best contrast various analyte target backscattering signatures from background signatures. For a probable detection event, sets of Mueller matrices are measured at beam energies coinciding with resonant IR absorptions by the analyte and at incident angle where backscattering by that analyte surface is strong. Identification of the contaminant(s) in situ is determined by another algorithm that operates on a vector whose N is equal or more than 16 components are the independent Mueller elements measured at the susceptible beam energy/angle parameters. This work documents the phase sensitive detection program at CRDEC from past developments to future applications.