Military Application of Differential FTIR Radiometry for Passive Standoff Detection

For the past six years Defence R&D Canada – Valcartier has been developing a method for the passive remote sensing of chemical vapours by differential Fourier-transform infrared (FTIR) radiometry. The originality of the method lies in the use of a double-input beam FTIR spectrometer (CATSI) optimized for optical subtraction. This configuration automatically reduces the clutter-to-signal ratio and permits realtime monitoring of chemical agents. The passive standoff results obtained with the CATSI instrument at several major open-air field trials have shown that the system can successfully detect, identify and quantify a number of chemical vapours at various distances. In particular, the detection method has been used at short range (105 m) to map the column amounts of ammonia, methanol and several binary mixtures with consistent results. At medium range (1.5 km), the measurement technique has been successfully used to detect and identify low, medium and high concentrations of vapour mixtures of DMMP and SF6 but appears to have limited quantification capabilities in its original form. At long range, CATSI has successfully measured SF6 gas amounts at a standoff distance of 5.7 km at DRDC Valcartier. Many of the measurements have been made for complex mixtures of gases exhibiting a strong overlap of spectral bands. In addition, the CATSI sensor has been applied to the problem of passively detecting bioaerosols at ranges of up to 3 km. The instrument has also been shown to demonstrate some capability in detecting and identifying liquid CW contaminants on surfaces at standoff distances of up to 60 m. Very recently, the CATSI system has been employed to detect, identify and quantify classical CW agents and their simulants in an open-air field trial. An initial effort in adapting the orthogonal background suppression (OBS) technique to the differential detection method has been undertaken with some success. The application of the OBS technique has been applied to differential radiance spectra of DMMP at a standoff distance of 500 m. All these experiments clearly show the relevance of the differential detection technique for on-line monitoring and surveillance of toxic chemical agents. 1.0 INTRODUCTION The military of modern Defense organizations are using a variety of electro-optical systems for the remote sensing of target characterization. The development of passive IR spectral sensors has grown to a point at which it is now considered a vital technology for the remote monitoring of battlefield environments, providing unique information concerning ongoing maneuvers. One of the most promising applications in surveillance is the passive standoff detection of chemical warfare agents and toxic vapours by Fourier-transform infrared (FTIR) radiometry (e.g. Refs. 1,2). In NATO countries, there is a growing need for fieldable, rapid-response surveillance systems that provide timely and accurate chemical threat assessments, thus ensuring prompt avoidance and deployment of countermeasures. Thériault, J.-M.; Puckrin, E.; Lavoie, H.; Bouffard, F.; Dubé, D. (2005) Military Application of Differential FTIR Radiometry for Passive Standoff Detection. In Emerging EO Phenomenology (pp. 23-1 – 23-12). Meeting Proceedings RTO-MP-SET-094, Paper 23. Neuilly-sur-Seine, France: RTO. Available from: http://www.rto.nato.int/abstracts.asp. Report Documentation Page Form Approved OMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE 01 OCT 2005 2. REPORT TYPE N/A 3. DATES COVERED 4. TITLE AND SUBTITLE Military Application of Differential FTIR Radiometry for Passive Standoff Detection 5a. CONTRACT NUMBER