Proceedings of the Public Security S&T Summer Symposium 2009

CRTI 06-0202TD

Short-Range BioSpectra: A Device for the Surveillance of Bioaerosols in Large Indoor, Semi-Enclosed, and Outdoor Spaces

Project Lead: DRDC Valcartier

Federal Partner: DRDC Suffield

Industry Partners: INO; MacDonald, Dettwiler and Associates Ltd; Telops

Objectives

The objective of this project is to build a short-range light detection and ranging (LIDAR) system with command and control (C2) networking capabilities for the remote detection and classification of bioaerosols from laser-induced fluorescence. The moveable part of the device will be small (<50×40×30 cm). SR-Biospectra will have a range of 100-plus metres for detecting the presence of biothreats over indoor, semi-enclosed, and outdoor venues at minimal costs.

Based on work done at DRDC and INO, as well as first responder interviews conducted by INO and MacDonald, Dettwiler and Associates (MDA), an alpha model was designed, built, and tested at DRDC Valcartier in December 2008. Based on lessons learned, a beta prototype is being designed and built, and will be tested at DRDC Suffield by fall 2009. INO is designing and integrating the hardware; MDA is developing the C2 system; DRDC is providing the spectral exploitation algorithm and the testing and evaluation facilities; and Telops is providing commercialization feedback.

Relevance

SR-Biospectra, a short-range, compact spectrometric laser-induced fluorescence LIDAR system, will address operational deficiencies in bioterrorism prevention, surveillance, and alert capabilities. More specifically, SR-Biospectra will detect and classify biothreats in aerosol form over critical indoor, semi-enclosed, and outdoor venues. The technology will allow for continuous monitoring to detect unusual concentrations of fluorescing bioaerosols at a precise remote location, within seconds. Rapid detection of a bioaerosol release will permit timely implementation of measures to protect the public and minimize the extent of contamination.

Recent Progress and Results

The project is on track, having built and tested an alpha prototype at INO and at DRDC Valcartier. Analysis of the results shows that the prototype has sensitivity better than 1000 particles per litre (ppl) of Bacillus globigii, having 1 µm in diameter during nighttime conditions at a 100 m standoff distance. Based on modelling of targeted requirements, the prototype incorporated a 1 kHz, 100 µJ/pulse, eye-safe, 355 nm pulsed laser; a motorized adjustable focus collection optics of 20 cm diameter; and a high throughput spectrograph with a multi-anode linear photo-multiplier tube (PMT). Gating the charge collection from the 32-channel PMT with small form-factor 32-channel-gated integration electronics enables measurements to be taken. The channels span the range of 425 to 700 nm. INO demonstrated that this configuration could support photon counting. This first prototype is larger and heavier than the targeted final prototype, but the goal was to demonstrate that the low-cost hardware choices could provide the required sensitivity.

Testing and evaluation of the alpha prototype’s performance was completed by using solid targets along with return signals from air volumes. Noise analysis from these measurements showed single photon sensitivity and the impact of Raman returns from water in the sampled air volumes. Raman returns must be filtered for maximum aerosol fluorescence sensitivity. This will be improved in the beta prototype, enhancing sensitivity for a fixed laser power.

The prototype was then moved to the obscurant chamber at DRDC Valcartier used to contain inoffensive simulants of aerosolized biological agents and clouds of aerosols of interest for the public security community (e.g., tear gases, pepper spray). The produced clouds had their concentrations refereed with an aerosol particle sizer (APS), providing the concentrations orsizes of the aerosols as a function of time. Typical spectra will be shown. Comparing spectral data produced by SR-BioSpectra with data from the APS enables sensitivity limits to be derived as a function of the ranges and probed volumes.

While testing was taking place, MDA developed a C2 system compatible with the hardware. The hardware control and data collection is done remotely and several sensors can be networked.

Impact

SR-Biospectra is a novel bioaerosol detection and classification device that will significantly improve CBRNE detection, surveillance, and alerting systems over populated areas. This autonomous device will perform the remote, continuous monitoring of pre-programmed volumes having lines of sight over 360 degrees in azimuth and at ranges up to 100 m. Once networked under a C2 station, several devices can provide alert status for the presence of biothreats within seconds of an event over an area that may cover several square kilometres of varying geometric complexity. These characteristics result in a more effective and efficient response to a CBRNE event, aiding in both rapid determination of the scale of the event and evacuation planning. Additional characteristics, such as a moderate acquisition cost, small size, and eye safety, will facilitate the device’s deployment over a variety of sites that attract large populations over wide areas, such as subways, stadiums, malls, airports, and harbours.

Authors:

Nicolas Hô, INO, nicolas.ho@ino.ca

Jean-Robert Simard, DRDC Valcartier, jean-robert.simard@drdc-rddc.gc.ca

John McFee, DRDC Suffield, john.mcfee@drdc-rddc.gc.ca

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