Standoff photoacoustic spectroscopy for hazard detection

Abstract

Photoacoustic spectroscopy (PAS) is a versatile and sensitive chemical sensing method. This versatility allows for the construction of a variety of sensors that are optimized for specific sensing tasks. Current research at the U.S. Army Research Laboratory (ARL) is focused on the development of a standoff hazardous materials detection technique based on an interferometric sensor. The standoff detection paradigm increases operator safety and reduces sample preparation requirements as compared to traditional photoacoustic cell-based sensors. We demonstrate the collection of photoacoustic spectra of layered solid samples at a standoff distance of one meter. The layered samples are constructed via deposition of a thin layer of energetic or other hazardous substance upon a thick substrate. We will also discuss excitation source selection as it relates to the operating mode of the source (i.e., pulsed or continuous wave (CW) modulated).