Snapshot spectroscopy for stand-off detection of target chemicals using broadband infrared lasers

Christopher A. Kendziora; Tyler Huffman; Kristin M. DeWitt; Drew M. Finton; Geoffrey Smith

doi:10.1117/12.2663208

15 June 2023 Snapshot spectroscopy for stand-off detection of target chemicals using broadband infrared lasers

Christopher A. Kendziora, Tyler Huffman, Kristin M. DeWitt, Drew M. Finton, Geoffrey Smith

Proceedings Volume 12516, Next-Generation Spectroscopic Technologies XV; 125160C (2023) https://doi.org/10.1117/12.2663208
Event: SPIE Defense + Commercial Sensing, 2023, Orlando, Florida, United States

Abstract

We present further development of an eye-safe, invisible, stand-off technique designed for the detection of target chemicals (such as explosives) in a single “Snapshot” frame. Broadband Fabry-Perot quantum cascade lasers (FP-QCLs) are employed in the Mid-LWIR (long-wave infrared) in the range of 7 to 12 μm, to interrogate the spectral features from analytes of interest. We have developed a custom-built broadband laser source in the Mid-LWIR range. This “white” broadband laser source enables stand-off detection in a single snapshot frame. High power FP-QCLs with wide spectral coverage were collimated and aligned toward the target several meters away. The “backscatter” and absorption signals from target chemicals are spectrally extracted by an LWIR spectrometer based on the spatial heterodyne spectroscopy (SHS) technique or by a grating spectrometer. Both spectroscopic methods offer full spectral coverage in each single frame from an IR imaging array. This presentation will cover the implementation and optimization of FP-QCLs for this broadband spectroscopic application. We discuss the collection and processing of SHS images to extract spectral information. Finally, we present results of measurements using specific analytes to demonstrate the application of the method to stand-off detection of targets such as explosives and other chemical threats.

Conference Presentation

Citation Download Citation

Christopher A. Kendziora, Tyler Huffman, Kristin M. DeWitt, Drew M. Finton, and Geoffrey Smith "Snapshot spectroscopy for stand-off detection of target chemicals using broadband infrared lasers", Proc. SPIE 12516, Next-Generation Spectroscopic Technologies XV, 125160C (15 June 2023); https://doi.org/10.1117/12.2663208

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