Outdoor chamber measurements of biological aerosols with a passive FTIR spectrometer

Abstract

Outdoor measurements of dry bacillus subtilis (BG) spores were conducted with a passive Fourier transform infrared (FTIR) spectrometer using two types of chambers. One was a large open-ended cell, and the other was a canyon of similar dimensions. The canyon exposes the aerosol plume to downwelling sky radiance, while the open-ended cell does not. The goal of the experiments was to develop a suitable test methodology for evaluation of passive standoff detectors for open-air aerosol measurements. Dry BG aerosol particles were dispersed with a blower through an opening in the side of the chamber to create a pseudo-stationary plume, wind conditions permitting. Numerous trials were performed with the FTIR spectrometer positioned to view mountain, sky and mixed mountain-sky backgrounds. This paper will discuss the results of the FTIR measurements for BG and Kaolin dust releases.

Optical Techniques for Detecting and Identifying Biological-Warfare Agents

“…A second technology that has been considered is passive infrared (IR) spectroscopy (single or multipixel), which offers no range information but has been exploited primarily as a detector for chemical vapor threats. 6 To date, passive IR has demonstrated a sensitivity to bioagents that is > 10 times higher (worse) than can be achieved with lidar [65]; however, if it is to be deployed as a chemical vapor sensor, it would be very useful to determine its use as a biosensor as well. There have been recent efforts to combine passive IR with lidar to provide a combined standoff detection system for both bio-and chem-agents [66].…”