Probing chemical surface contaminants with a deep ultraviolet spatial heterodyne Raman system

Abstract

Physical Sciences Inc. has developed a standoff deep ultraviolet (DUV) Raman sensor for the detection of explosive residues. The sensor is based on a solid-state DUV excitation source coupled with a Spatial Heterodyne Spectrometer receiver. The sensor measures Raman signals across a ~830-2680 cm -1 spectral range from a 2.6 cm 2 interrogation area from a 1 m standoff in a single snapshot with a 17 cm -1 spectral resolution. Acquired spectra are processed through an onboard deep learning spectral correlation algorithm that provides real-time target identification. Developmental testing of the sensor has been conducted in a laboratory environment against explosive simulants including potassium chlorate, ammonium nitrate, and urea in bulk form as well as residues deposited on various substrates including plastic, glass, and metals. These measurements have demonstrated the system's ability to measure Raman spectra and identify targets in 1 to 120 seconds.