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.
MoDDIFS (Multi-option Differential Detection and Imaging Fourier Spectrometer) is a DRDC Valcartier technology built around a differential Fourier Transform Infrared (FTIR) spectrometer optimized for optical subtraction in the long wave infrared (LWIR). MoDDIFS is a dual use hyperspectral prototype offering two fore-optics configurations: "long range", specialized for the detection of small quantities of gaseous substances, and "polarization", built to investigate liquids and powders spills. We report and present a preliminary analysis of a series of measurement tests made with the polarization configuration. The tests were performed under indoor and outdoor environments. Different liquid and solid substances were deposited on different types of surfaces. Many liquid targets and some solid materials produce a noticeable linearly-polarized signal, with a more or less characteristic spectral modulation. For the liquids, the behavior of the observed radiance spectrum seems more predictable when the liquid is thick, or when it is deposited at any thickness on non-absorbing and weakly-reflective substrates. The behavior of the radiance spectrum observed becomes more complex when a thin layer of the liquid is deposited on a smooth and strongly-reflective substrate, or on an absorbing substrate. The parameter chosen to analyze the relative amount of polarization is the degree of linear polarization. When its value is noticeable, the polarized hyperspectral radiance measurements bring additional information on both targets and the backgrounds, as compared to standard unpolarized hyperspectral measurements. The tests performed can then help assess the materials for which the detection and the identification will be improved with polarized measurements.
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.
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.
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.
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.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.