We report and analyze recent results obtained with the MoDDIFS sensor (Multi-option Differential Detection and Imaging Fourier Spectrometer) for the passive polarization sensing of liquid contaminants in the long wave infrared (LWIR). Field measurements of polarized spectral radiance done on ethylene glycol and SF96 probed at distances of 6.5 and 450 meters, respectively, have been used to develop and test a GLRT-type detection algorithm adapted for liquid contaminants. The GLRT detection results serve to establish the potential and advantage of probing the vertical and horizontal linear hyperspectral polarization components for improving liquid contaminants detection.
Standoff detection and identification (D and Id) of unknown volatile chemicals such as chemical pollutants and
consequences of industrial incidents has been increasingly desired for first responders and for environmental monitoring.
On site gas detection sensors are commercially available and several of them can even detect more than one chemical
species, however only few of them have the capabilities of detecting a wide variety of gases at long and safe distances.
The ABB Hyperspectral Imaging Spectroradiometer (MR-i), configured for gas detection detects and identifies a wide
variety of chemical species including toxic industrial chemicals (TICs) and surrogates several kilometers away from the
sensor. This configuration is called iCATSI for improved Compact Atmospheric Sounding Interferometer. iCATSI is a
standoff passive system.
The modularity of the MR-i platform allows optimization of the detection configuration with a 256 x 256 Focal Plane Array imager or a line scanning imager both covering the long wave IR atmospheric window up to 14 μm. The
uniqueness of its extended LWIR cut off enables to detect more chemicals as well as provide higher probability of detection than usual LWIR sensors.
MR-i is a dual band Hyperspectral Imaging Spectro-radiometer. This field instrument generates spectral datacubes in the MWIR and LWIR. MR-i is modular and can be configured in different ways. One of its configurations is optimized for the standoff measurements of gases in differential mode. In this mode, the instrument is equipped with a dual-input telescope to perform optical background subtraction. The resulting signal is the differential between the spectral radiance entering each input port. With that method, the signal from the background is automatically removed from the signal of the target of interest. The spectral range of this configuration extends in the VLWIR (cut-off near 14 μm) to take full advantage of the LW atmospheric window.
Detection and identification of Toxic industrial chemicals (TICs) represent a major challenge to protect and sustain first
responder and public security. In this context, passive Hyperspectral Imaging (HSI) is a promising technology for the
standoff detection and identification of chemical vapors emanating from a distant location. To investigate this method, the Department of National Defense and Public Safety Canada have mandated Defense Research and Development Canada (DRDC) – Valcartier to develop and test Very Long Wave Infrared (VLWIR) HSI sensors for standoff detection. The initial effort was focused to address the standoff detection and identification of toxic industrial chemicals (TICs), surrogates and precursors. Sensors such as the Improved Compact ATmospheric Sounding Interferometer (iCATSI) and the Multi-option Differential Detection and Imaging Fourier Spectrometer (MoDDIFS) were developed for this application. This paper presents the sensor developments and preliminary results of standoff detection and identification of TICs and precursors. The iCATSI and MoDDIFS sensors are based on the optical differential Fourier-transform infrared (FTIR) radiometric technology and are able to detect, spectrally resolve and identify small leak at ranges in excess of 1 km. Results from a series of trials in asymmetric threat type scenarios are reported. These results serve to establish the potential of passive standoff HSI detection of TICs, precursors and surrogates.
The MR-i spectroradiometer can support a wide range of applications from its architecture suited to multiple
configurations. Its modular 4-port FTIR spectroradiometer architecture allows the simultaneous use of two different
detector modules, direct or differential input(s) and multiple telescopes. In a given configuration, MR-i can combine a MWIR focal plane array and a LWIR focal plane array to provide an extended spectral range from the two imaging sensors. The two detector array modules are imaging the same scene allowing synchronized pixel-to-pixel spectral range combination. In another configuration, MR-i can combine two identical focal plane arrays with different attenuation factors and two interleaved integration times per detector array. This configuration generates four sets of hyperspectral data cubes with different dynamic ranges that can be combined to produce a single hyperspectral cube with unmatched dynamic range. This configuration is particularly well suited for high-speed, high-dynamic range characterization of targets such as aircrafts, flares, and explosions. In a third configuration, named iCATSI, the spectroradiometer is used in differential input configuration to provide efficient
optical background subtraction. The iCATSI configuration features an MCT detectors array with spectral cutoff near
14 µm. This extended spectral range and high sensitivity allows the detection and identification of a wide range of
chemicals.
Toxic industrial chemicals (TICs) represent a major threat to public health and security. Their detection constitutes a real challenge to security and first responder's communities. One promising detection method is based on the passive standoff identification of chemical vapors emanating from the laboratory under surveillance. To investigate this method, the Department of National Defense and Public Safety Canada have mandated Defense Research and Development Canada (DRDC) - Valcartier to develop and test passive Long Wave Infrared (LWIR) hyperspectral imaging (HSI) sensors for standoff detection. The initial effort was focused to address the standoff detection and identification of toxic industrial chemicals (TICs) and precursors. Sensors such as the Multi-option Differential Detection and Imaging Fourier Spectrometer (MoDDIFS) and the Improved Compact ATmospheric Sounding Interferometer (iCATSI) were developed for this application.
This paper describes the sensor developments and presents initial results of standoff detection and identification of TICs and precursors. The standoff sensors are based on the differential Fourier-transform infrared (FTIR) radiometric technology and are able to detect, spectrally resolve and identify small leak plumes at ranges in excess of 1 km. Results from a series of trials in asymmetric threat type scenarios will be presented. These results will serve to establish the potential of the method for standoff detection of TICs precursors and surrogates.
MR-i is an imaging version of the ABB MR series Fourier-Transform spectroradiometer. This field instrument generates
spectral datacubes in the MWIR and LWIR. It is designed to acquire the spectral signatures of rapidly evolving events.
The MR-i is modular and can be configured in different ways. One of its configurations is optimized for passive standoff
measurements of gases in differential mode. In this mode, the instrument is equipped with a dual-input telescope to
perform optical background subtraction. The resulting signal is the differential between the spectral radiance entering
each input port. With that method, the signal from the background is automatically removed from the signal of the target
of interest. The spectral range of this configuration extends in the VLWIR (cut-off near 14 μm) to take full advantage of
the LW atmospheric window.
The passive standoff monitoring of vapor precursors emanating from a location under surveillance can provide relevant
information on the nature of products fabrication. Defence Research & Development Canada Valcartier recently
completed the development and field-validation of a novel R&D prototype, MoDDIFS (Multi-option Differential
Detection and Imaging Fourier Spectrometer), to address this remote sensing application. The proposed methodology
combines the clutter suppression efficiency of the differential detection approach with the high spatial resolution
provided by the hyperspectral imaging approach. This consists of integrating a differential CATSI-type (Compact
ATmospheric Sounding Interferometer) sensor with the imaging capability of the Hyper-Cam infrared imager. The
MoDDIFS sensor includes two configuration options, one for remote gas detection, and the other for polarization
sensing of surface contaminants. This paper focuses on the infrared spectral detection of gases. A series of measurements
done with MoDDIFS on selected laboratory solvents in vapor form are analyzed and discussed.
Homeland security and first responders are often faced with safety situations involving the identification of unknown
volatile chemicals. Examples include industrial fires, chemical warfare, industrial leak, etc. The Improved Compact
ATmospheric Sounding Interferometer (iCATSI) sensor has been developed to investigate the standoff detection and
identification of toxic industrial chemicals (TICs), chemical warfare agents (CWA) and other chemicals.
iCATSI is a combination of the CATSI instrument, a standoff differential FTIR optimised for the characterization of
chemicals and the MR-i, the hyperspectral imaging spectroradiometer of ABB Bomem based on the proven MR
spectroradiometers. The instrument is equipped with a dual-input telescope to perform optical background subtraction.
The resulting signal is the difference between the spectral radiance entering each input port. With that method, the signal
from the background is automatically removed from the signal of the target of interest. The iCATSI sensor is able to
detect, spectrally resolve and identify 5 meters plumes up to 5 km range. The instrument is capable of sensing in the
VLWIR (cut-off near 14 μm) to support research related to standoff chemical detection. In one of its configurations,
iCATSI produces three 24 × 16 spectral images per second from 5.5 to 14 μm at a spectral resolution of 16 cm-1. In
another configuration, iCATSI produces from two to four spectral images per second of 256 × 256 pixels from 8 to 13
μm with the same spectral resolution.
Overview of the capabilities of the instrument and results from tests and field trials will be presented.
The passive standoff detection of vapors from particular explosives and precursors emanating from a
location under surveillance can provide early detection and warning of illicit explosives fabrication. DRDC
Valcartier recently initiated the development and field-validation of a novel R&D prototype, MoDDIFS
(Multi-Option Differential and Imaging Fourier Spectrometer) to address this security vulnerability. The
proposed methodology combines the clutter suppression efficiency of the differential detection approach
with the high spatial resolution provided by the hyperspectral imaging approach. This consists of
integrating the imaging capability of the Hyper-Cam IR imager with a differential CATSI-type sensor. This
paper presents the MoDDIFS sensor methodology and the first investigation results that were recently
obtained.
KEYWORDS: Sensors, Signal to noise ratio, Telescopes, Interferometers, Spectral resolution, Black bodies, Standoff detection, Chemical detection, Imaging spectroscopy, Target detection
iCATSI is a combination of the CATSI instrument, a standoff differential FTIR optimised for the characterisation of
chemicals, and of the MR-i, the hyperspectral imaging spectroradiometer of ABB Bomem based on the proven MR
spectroradiometers.
The instrument is equipped with a dual-input telescope to perform optical background subtraction. The resulting signal is
the differential between the spectral radiance entering each input port. With that method, the signal from the background
is automatically removed from the signal of the object of interest. The instrument is capable of sensing in the VLWIR
(cut-off near 14 μm) to support research related to standoff chemical detection.
Standoff detection of explosives residues on surfaces at few meters was made using optical technologies based on
Raman scattering, Laser-Induced Breakdown Spectroscopy (LIBS) and passive standoff FTIR radiometry. By
comparison, detection and analysis of nanogram samples of different explosives was made with a microscope
system where Raman scattering from a micron-size single point illuminated crystal of explosive was observed.
Results from standoff detection experiments using a telescope were compared to experiments using a microscope to
find out important parameters leading to the detection. While detection and spectral identification of the micron-size
explosive particles was possible with a microscope, standoff detection of these particles was very challenging due to
undesired light reflected and produced by the background surface or light coming from other contaminants. Results
illustrated the challenging approach of detecting at a standoff distance the presence of low amount of micron or submicron
explosive particles.
ABB Bomem is expanding its line of infrared remote sensing products with the addition of a new imaging
spectroradiometer. The instrument is modular and support several configurations. One of its configurations is a multipixels
sensor optimised for differential acquisition in the VLWIR to support research related to chemical detection. In
that configuration, the instrument is equipped with a dual-input telescope to perform optical background subtraction. The
resulting signal is the differential between the spectral radiance entering each input port.
The other configuration is a general purpose imaging spectroradiometer designed to acquire the spectral signature of
rapid events and fast targets in infrared. Overview of the design and results from tests and first field trials will be
presented.
DRDC Valcartier recently completed the development of the CATSI EDM (Compact Atmospheric Sounding
Interferometer Engineering Development Model) for the Canadian Forces (CF). It is a militarized sensor designed to
meet the needs of the CF in the development of area surveillance capabilities for the detection and identification of
chemical Warfare Agents (CWA) and toxic industrial chemicals (TIC). CATSI EDM is a passive infrared double-beam
Fourier spectrometer system designed for real-time stand-off detection and identification of chemical vapours at
distances up to 5 km. It is based on the successful passive differential detection technology. This technique known as
optical subtraction, results in a target gas spectrum which is almost free of background, thus making possible detection of weak infrared emission in strong background emission. This paper summarizes the system requirements, achievements, hardware and software characteristics and test results.
KEYWORDS: Sensors, Signal to noise ratio, Black bodies, Interferometers, Telescopes, Standoff detection, Chemical detection, Calibration, Collimators, Imaging spectroscopy
ABB Bomem is expanding its line of infrared remote sensing products with the addition of a new multipixel
imaging spectroradiometer. This hyperspectral instrument is based on the proven MR
spectroradiometers.
The instrument is modular and support several configurations. One of its configurations is optimised for
differential acquisition in the VLWIR (cut-off near 14 μm) to support research related to the stand-off
detection and quantification of chemicals. In that configuration, the instrument is equipped with a dualinput
telescope to perform optical background subtraction. The resulting signal is the differential between
the spectral radiance entering each input port.
A new generation of field-rated optical subtraction instruments for the standoff detection of chemicals will be presented.
It combines the latest ABB Bomem spectroradiometer technology and software with the concepts used in the design of
the original instrument designed and manufactured more than 12 years ago by ABB and Defence Research and
Development Canada - Valcartier.
This instrument is a Fourier-transform spectroradiometer with dual input beams. It is a passive, stand-off sensor that uses
one input port to interrogate a scene under investigation while the other input beam can be pointed at the background
scene. The instrument automatically measures the difference of spectral radiance between the target and the background
scenes by optical subtraction, hence achieving a real-time suppression of the background signal. The resulting
measurement is the unique spectral signature of the target measured in real time.
The system includes a software module to control the instrument and the acquisition parameters, a module for the
radiometric calibration and a module to perform the identification and quantification, in real time, of various gases.
An overview of the instrument design and initial results of tests are presented.
Defence Research and Development Canada (DRDC) - Valcartier is currently developing a ruggedized passive standoff
sensor for the detection of chemical warfare agents (CWAs) based on differential Fourier-transform infrared (FTIR)
radiometry. This system is referred to as the Compact ATmospheric Sounding Interferometer (CATSI) Engineering
Development Model (EDM). The CATSI EDM sensor is based on the use of a double-beam FTIR spectrometer that is
optimized for optical subtraction. A description of the customized sensor is given along with a discussion on the
detection and identification approaches that have been developed. Preliminary results of validation from a number of
laboratory measurements and open-air trials are analyzed to establish the capability of detection and identification of
various toxic and non-toxic chemical vapor plumes. These results clearly demonstrate the capability of the passive
differential radiometric approach for the standoff detection and identification of chemical vapors at distances up to a few
kilometers from the sensor.
A compact chamber was developed for the dissemination of biological aerosols. The chamber, measuring 110 cm in length, was designed according to short-range LIDAR principles, and will be used to simulate open-air releases of aerosols. Measurements, carried out by light-induced fluorescence (LIF) techniques, will be correlated with spectroscopic data obtained with a long-range lidar system owned by Defence Research and Development Canada (DRDC). The chamber allows complete control over environmental factors, such as humidity, pressure and temperature, thus facilitating the creation of a trustworthy signature database for the standoff detection of bio-aerosols. Studies will also include the influence of growth stage, stress and growth media on the fluorescence spectra of various biological aerosols.
A simple method is presented for quantitatively measuring the absorbance of chemical warfare (CW) agents and their simulants in the vapour phase. The technique is based on a standard lab-bench FTIR spectrometer, 10-cm gas cell, a high accuracy Baratron pressure manometer, vacuum pump and simple stainless-steel hardware components. The results of this measurement technique are demonstrated for sarin (GB) and soman (GD). A second technique is also introduced for the passive IR detection of CW agents in an open- air path located in a fumehood. Using a modified open-cell with a pathlength of 45 cm, open-air passive infrared measurements have been obtained for simulants and several classical CW agents. Detection, identification and quantification results based on passive infrared measurements are presented for GB and the CW agent simulant, DMMP, using the CATSI sensor which has been developed by DRDC Valcartier. The open-cell technique represents a relatively simple and feasible method for examining the detection capability of passive sensors, such as CATSI, for CW agents.
The passive remote monitoring of multi-gas vapour mixtures by FTIR spectroscopy is investigated experimentally. The spectral radiance data were collected with the CATSI interferometer for a variety of multi-gas plumes at a distance of 60 m. Two basic sets of mixtures were studied. The first set corresponds to mixtures formed of three gases with no overlapping spectral bands (C2H2, C2H4 and R14). The second set corresponds to mixtures formed of three gases having overlapping spectral bands (C2H4, R114 and R134a). For each mixture the flow rates of individual constituents were adjusted to yield specific constituent CL ratios. These ratios are compared to the CL ratios retrieved from infrared radiance spectra. Results of this study indicate that for both sets of multi-gas mixtures the CL ratios retrieved by the passive remote monitoring technique agree well with those derived from the release flow rates. This good level of agreement was achieved by introducing a simple correction scheme to compensate for the limited accuracy of the fast radiance model implemented in the GASEM monitoring algorithm.
A method for the passive remote monitoring of chemical vapours by differential Fourier-transform infrared (FTIR) radiometry is presented for determining the characteristics of chemical vapour plumes released from stacks at various horizontal distances from the FTIR sensor. The measurement technique is based on the use of a double-beam FTIR spectrometer that is optimized for optical subtraction. A description is given of the customized interferometer, along with a discussion of the analysis algorithm that has been developed for the on-line detection, identification and quantification of chemical vapour plumes. Experimental results are presented from a number of open-air trials that demonstrate the passive detection, identification and quantification of vapour plumes, which consist of DMMP, ammonia, methanol and sulphur hexafluoride gases probed at standoff distances of up to 1.5 km. In addition, recent results obtained at the open-air range at Defence Research and Development Canada (DRDC)-Valcartier are presented for the detection of a vapour plume of sulphur hexafluoride (SF6) measured at a standoff distance of 5.7 km. This work represents the first such measurement reported in the open literature for such a large standoff distance. These results clearly demonstrate the applicability of the differential radiometry approach for successfully detecting and identifying chemical vapour clouds located at long distances from the sensor.
Over the past year we have initiated a study into the passive standoff detection of radiological materials by Fourier-transform infrared (FTIR) radiometry. The preliminary work has shown that a number of radiological materials have an infrared signature in the 8-14 micron thermal infrared region. As well, through a series of simulations using the MODTRAN4 atmospheric transmission model, we have shown that these materials may potentially be detected at standoff distances of several kilometres. In this paper we present some results of our current work that focus on recent new measurements of spectral signatures, including the uranium oxides UO2 and UO3. Preliminary results from a measurement campaign held at Defence Research and Development Canada-Valcartier this year are also presented which address the passive detection of radiological materials in the field at standoff distances of 10-60 m. These results are analysed in view of determining the potential for measuring nuclear products with a passive standoff FTIR technique.
A selection of field trial results on the passive standoff detection by differential FTIR radiometry with the CATSI sensor is presented. This selection covers the seven-year development period (1998-2004) of the CATSI project. The results obtained with the CATSI instrument at two major field trials in Kansas (1998) and Nevada (2001) have shown the successful passive standoff detection of a number of chemical vapors at short and medium ranges of 100 m and 1.5 km, respectively. In particular, the detection method has been used at short range (100m) to map the column amounts of a methanol plume with an estimated uncertainty of the order of 15 - 30%. At medium range (1.5 km), the measurement technique has been successfully used to detect and identify low, medium and high concentrations of vapor 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 the 5.7-km range of DRDC Valcartier. The passive standoff detection of liquid contaminants on surfaces was tested with encouraging results. These results indicate that liquid contaminant agents deposited on high-reflectivity surfaces can be detected, identified and possibly quantified with passive sensors. For low-reflectivity surfaces, the presence of contaminants can usually be detected; however, their identification based on simple correlations with the absorption spectrum of the pure contaminant is not possible. In a field trial (Dugway Proving Ground, 2002) on the standoff detection of bio-aerosols, CATSI has detected large amounts of BG at ranges of up to 3 km. Recent field measurements for a standoff distance of 60 m suggests that the gas constituent ratios of complex mixtures can be properly retrieved from passive spectral measurements performed at 8 cm-1. These results from field experiments clearly show the relevance of the CATSI approach for the passive standoff detection by differential FTIR radiometry.
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