Measurements of Scene Spectral Radiance Variability
Detection performance of LWIR passive standoff chemical agent sensors is strongly influenced by various scene
parameters, such as atmospheric conditions, temperature contrast, concentration-path length product (CL), agent
absorption coefficient, and scene spectral variability. Although temperature contrast, CL, and agent absorption
coefficient affect the detected signal in a predictable manner, fluctuations in background scene spectral radiance have
less intuitive consequences. The spectral nature of the scene is not problematic in itself; instead it is spatial and
temporal fluctuations in the scene spectral radiance that cannot be entirely corrected for with data processing. In
addition, the consequence of such variability is a function of the spectral signature of the agent that is being detected
and is thus different for each agent. To bracket the performance of background-limited (low sensor NEDN), passive
standoff chemical sensors in the range of relevant conditions, assessment of real scene data is necessary. Currently,
such data is not widely available. To begin to span the range of relevant scene conditions, we have acquired high
fidelity scene spectral radiance measurements with a Telops FTIR imaging spectrometer. We have acquired data in a
variety of indoor and outdoor locations at different times of day and year. Some locations include indoor office
environments, airports, urban and suburban scenes, waterways, and forest. We report agent-dependent clutter
measurements for three of these backgrounds.............
Copyright 2006 Society of Photo-Optical Instrumentation Engineers. This paper was published in Chemical and Biological Sensing VII; Patrick J. Gardner, Augustus W. Fountain III; Eds., Proc. SPIE Vol.6218, 621807 (2006) and is made available as an electronic reprint with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commerical purposes, or modification of the content of the paper are prohibited.
author(s): Juliette A. Seeley, Edward C. Wack, Daniel L. Mooney, et al.
Performance of the FIRST, a Longwave Infrared Hyperspectral Imaging Sensor
Emerging applications in Defense and Security require sensors with state-of-the-art sensitivity and capabilities. Among these sensors, the imaging spectrometer is an instrument yielding a large amount of rich information about the measured scene. Standoff detection, identification and quantification of chemicals in the gaseous state are fundamental needs in several fields of applications. Imaging spectrometers have unmatched capabilities to meet the requirements of these applications.
Telops has developed the FIRST, a LWIR hyperspectral imager. The FIRST is based on FTIR technology to provide high spectral resolution and to enable high accuracy radiometric calibration. The FIRST, a man portable sensor, provides datacubes of up to 320x256 pixels at 0.35 mrad spatial resolution over the 8-12 µm spectral range at spectral resolutions of up to 0.25 cm-1. The FIRST has been used in several field measurements, including demonstration of standoff chemical agent detection. One key feature of the FIRST is its ability to give calibrated measurements. The quality of the calibrated measurements will be presented in this paper.
Sensitivity, spectral resolution and radiometric stability as obtained during field and laboratory measurements will be presented. Finally, images of chemical releases detected with the FIRST will be shown.
author(s): Vincent Farley, Alexandre Vallieres, Martin Chamberland, Andre Villemaire, Jeff Legault
Design and development of a cryogenic Michelson interferometer
A cryogenic Fourier transform infrared spectrometer (Cryo-FTS) was developed for the Low Background Infrared(LBIR) facility at the National Institute of Standards and Technology (NIST). This spectrometer was developed for the Missile Defense Agency Transfer Radiometer (MDXR) that will be used to calibrate infrared sources that cannot be transported to NIST for calibration. When used inside the MDXR, the Cryo-FTS is expected to be able to provide relative spectral measurements with an accuracy of < 0.3 % uncertainty of infrared sources with a spectral range from 4 µm_to 15 µm_and a spectral resolution of 0.6 cm-1.
The Cryo-FTS spectral range is determined by the beamsplitter since all of its other optics use reflective materials. The compact interferometer uses a compensated Michelson configuration and has an operating temperature range between 10 K and 340 K with very low static beam redirection (< 215 µrad). The interferometer uses flat metal mirrors and KBr flat optics and maintains low wavefront distortion for infrared beams of up to 1.63 cm diameter. It integrates a digitally servo-controlled porchswing mechanism to provide an accurate and repeatable optical path difference and is supported by a Wavefront Alignment (WA) system to correct for wavefront residual tilt in real time using a fibre optic based metrology system. The interferometer is expected to provide modulation efficiency of better than 22% with limited power dissipation (< 2.8 W) during continuous operation.
author(s): Philippe Lagueux, Martin Chamberland, Frederick Marcotte, Andre Villemaire
Radiometric Calibration Stability of the FIRST a Longwave Infrared Hyperspectral Imaging Sensor
Vincent Farley, Systems Engineering, presented this paper at SPIE's Defense & Security Sympsium, Orlando in April 2006.
Emerging applications in Defense and Security require sensors with state-of-the-art sensitivity and capabilities. Among these sensors, the imaging spectrometer is an instrument yielding a large amount of rich information about the measured scene. Standoff detection, identification and quantification of chemicals in the gaseous state are fundamental needs in several fields of applications. Imaging spectrometers have unmatched capabilities to meet the requirements of these applications.
Telops has developed the FIRST, a LWIR hyperspectral imager. The FIRST is based on FTIR technology to yield high spectral resolution and to enable high accuracy radiometric calibration. The FIRST, a man portable sensor, provides datacubes of up to 320´256 pixels at 0.35 mrad spatial resolution over the 8-12 µm spectral range at spectral resolutions of up to 0.25 cm-1. The FIRST has been used in several field measurements, including demonstration of standoff chemical agent detection. One key feature of the FIRST is its ability to give calibrated measurements. The quality of the radiometric and spectral calibration will be presented in this paper.
During the field measurements, the FIRST operated under changing environmental conditions while many calibration measurements were taken. In this paper, we will present the stability of the calibration of the FIRST obtained during the field campaigns.
author(s): Vincent Farley, Martin Chamberland, Alexandre Vallières, André Villemaire and Jean-François Legault
High-Performance Field-Portable Imaging Radiometric Spectrometer Technology For Chemical Agent Detection
Martin Chamberland, Vice President at Telops, presented this paper at SPIE's Defense & Security in Optics & Photonics, in October 2005. Standoff detection, identification and quantification of chemicals in the gaseous state are fundamental needs in several fields of applications. To provide to best field imaging spectroscopy instrument, Telops has developed the FIRST, Field-portable Imaging Radiometric Spectrometer Technology, instrument.
author(s): Alexandre Vallières, Martin Chamberland, Vincent Farley, Louis Belhumeur, André Villemaire, Jean Giroux, Jeff Legault
Article published in the September issue of Photonics Spectra. Interest in the detection, identification and quantification of chemicals in the gaseous state from a safe distance has increased in the context of domestic defense aplications. One promising methot to achieve such standoff detection and quantification involves imaging spectroradiometry in the thermal infrared region. Compact and robust hyperspectral imagers based on Fourier transform spectrometers, such as FIRST, can offer the spectral resolution and sensitivity required for the passive standoff detection of gases.
author(s): Jeff Legault, Martin Chamberland, André Villemaire
Martin Chamberland, Vice President at Telops, presented this paper at SPIE's Defense & Security Sympsium in March 2005. It was part of the SPACEBORNE SENSORS II conference, Imaging and Optical Component Technology Advancements II session.
author(s): Martin Chamberland, Charles Belzile, Francoys Aubé, Jeff Legault
Use of spatial and spectral information for chemical detection from a hyperspectral imaging spectrometer
André Villemaire, Vice President at Telops, presented this paper at SPIE's Defense & Security Symposium in March 2005. It was part of the ALGORITHMS AND TECHNOLOGIES FOR MULTISPECTRAL, HYPERSPECTRAL, AND ULTRASPECTRAL IMAGERY XI conference, Emissive Remote Sensing session.
author(s): André Villemaire, Jeff Legault, Martin Chamberland, Vincent Farley, Karl Schwantes
This paper, presented at OSA FTS/HISE conference in January 2005, presents the design and performance of a LWIR imaging FTS. An overview of the key design features will be presented along with the test results.
author(s): Martin Chamberland, Vincent Farley, André Villemaire, Jean Giroux
Development of field-portable imaging radiometric spectrometer technology for hyperspectral imaging applications
Hyperspectral data has become the backbone of many chemical and biological detection applications. Advancements in infrared detector focal plan arrays combine with expertise in spectroscopy applications have spawned a new breed of hyperspectral imaging instruments. Telops has developped an instrument that provides an early warning for chemical agents and toxic chemicals, and also provides a "Chemical Map" of the field of view while being man portable.
author(s): Karl R. Schwantes, Martin Chamberland, Charles Belzile, Vincent Farley, Jean Giroux
Development and testing of a hyper-spectral imaging instrument for field spectroscopy
Standoff detection, identification and quantification of chemicals require sensitive spectrometers with calibration capabilities. Recent developments in LWIR focal plane arrays combined with the mastering of Fourier-Transform Spectrometer technology allow the realization of an imaging spectrometer specifically designed for chemical imaging. The spectral and radiometric calibration of the instrument enables the processing of the data to detect the chemicals with spectral signatures in the 8-12 µm region. Spectral images are processed and the contrast between different pixels is used to map the chemicals. Telops has built a field-portable instrument for this application. This paper presents the sensor and its performance test results.
author(s): Vincent Farley, Charles Belzile, Martin Chamberland, Jean-François Legault, Karl Schwantes
Design and Technical Demonstration of a Spectral Dispersive Module for an IR Hyperspectral Instrument for Earth Monitoring from
This paper presents the development of an instrumental prototype for IR hyperspectral imaging from geo-synchronous Earth orbit (GEO). Within the framework of collaboration and funding support from the Canadian Space Agency (CSA), Telops performed the development and technical demonstration of a Spectral Dispersive Module (SDM) with potential application for the US NOAA Hyperspectral Environmental Suite (HES). HES development will provide infrared and visible environmental data collection capabilities for the next GOES program series of geo-synchronous satellites that will collect weather and environmental data to aid in the prediction of weather and in climate monitoring. The design of the SDM is based on an Offner configuration and is adapted to a concentric reflective design. Such a design allows the gathering of high spatial and spectral resolution data while keeping the smile and keystone distortion smaller than the size of a pixel. A convex diffraction grating is used in the system as spectrally dispersing element.The targeted application of this Offner spectrometer configuration is weather sounding in the mid-IR spectral range. The design and demonstration phase of the SDM will be described. Test results, such as spectral/spatial resolution, distortion, transmission and efficiency, with the engineering laboratory model will be presented.
author(s): Eric Harvey, Jean Giroux, Martin Chamberland, Philippe Lagueux, Michel Dumais, Michael Maszkiewicz
Advancements in field-portable imaging radiometric spectrometer technology for chemical detection
Standoff detection, identification and quantification of chemicals require sensitive spectrometers with calibration capabilities. Recent developments in LWIR focal plane arrays combined with the mastering of Fourier-Transform Spectrometer technology allow the realization of an imaging spectrometer specifically designed for chemical imaging. The spectral and radiometric calibration of the instrument enables the processing of the data to detect the chemicals with spectral signatures in the 8-12 µm region. Spectral images are processed and the contrast between different pixels is used to map the chemicals.
Telops is building the field-portable instrument. This paper presents the requirements for chemical detection in the LWIR, how the system is broken down into different modules and the details of each of these modules: calibration, interferometer, datacube acquisition and processing, and the main controller. The system has real-time processing capabilities of the measured data. Performance prediction is presented as well.
author(s): Martin Chamberland, Charles Belzile, Vincent Farley, Jean-François Legault, Karl Schwantes
An operational fluorescence system for crop assessment
The development of precision farming requires new tools for plant nutritional stress monitoring. An operational fluorescence system has been designed for vegetation status mapping and stress detection at plant and field scale. The instrument gives relative values of fluorescence at different wavelengths induced by the two-excitation sources. Light-induced fluorescence has demonstrated successful crop health monitoring and plant nutritional stress detection capabilities.
The spectral response of the plants has first been measured with an hyperspectral imager using laser-induced fluorescence. A tabletop imaging fluorometer based on flash lamp technology has also been designed to study the spatial distribution of fluorescence on plant leaves. For field based non-imaging system, LED technology is used as light source to induce fluorescence of the plant. The operational fluorescence system is based on ultraviolet and blue LED to induce fluorescence. Four narrow fluorescence bands centered on 440, 520, 690 and 740nm are detected. The instrument design includes a modular approach for light source and detector. It can accommodate as many as four different light sources and six bands of fluorescence detection. As part of the design for field application, the instrument is compatible with a mobile platform equipped with a GPS and data acquisition system.
The current system developed by Telops/GAAP is configured for potato crops fluorescence measurement but can easily be adapted for other crops. This new instrument offers an effective and affordable solution for precision farming.
author(s): Charles Belzile, Marie-Christine Bélanger, Alain A Viau, Martin Chamberland, Simon Roy
Performance Model of Imaging FTS as a Standoff Chemical Agent Detection Tool
Standoff detection of chemical agent can be enhanced with the capability to give an image of the concentration of the agents. The use of an imaging Fourier-Transform Spectrometer to perform these measurements is extensively modeled in order to predict the performance. The model presented here allows one to determine the optimal configuration of the instrument taking into account the use of realistic and existing hardware.
The model is based on the calculation of radiative transfer from the scene into the instrument up to the imaging detector. The infrared focal plane arrays have their own constraints that are taken into account in the model. The model has been used to support the design of an imaging FTS to be used as a queuing device for another type of sensor. Comparison of the model results with actual data will be presented.
author(s): Martin Chamberland, Vincent Farley, Pierre Tremblay, Mike Dobbs, Merritt Webb, Jean-François Legault
This paper presents the numerical simulation of a thulium-doped ZBLAN fiber amplifier which provides gain for the 480nm window from an up-conversion pumping mechanism. The model includes ionic energy transfers (cross-relaxation processes).
author(s): Martin Chamberland, Philippe Lagueux, Réal Vallé
In this paper, we present a theoretical study, performed for the credit of the European Space Agency (ESA), on the validity of the concept of remote Raman spectroscopy from an orbiting spacecraft as a tool for planetary surface prospecting. The potential for measuring remote Raman spectra of chemical components from an orbiting spacecraft imposes stringent requirements on laser, optics, and detector technologies, leading to a discussion on the feasibility of such an approach with respect to the current or near future state-of-the-art technology.
author(s): Zahia Ichalalène, Jean-François Legault, André Villemaire, Martin Chamberland, James J. Sloan, Lucas Neil
1-12 µm Hyperspectral Optical Design: When no room is available, you must be creative... TELOPS provides a solution! An hyperspectral imager capable of sensing from 1 to 12 µm with three (3) possible field-of-views (FOV) steerable within a field-of-regard eight (8) times larger than the FOV is presented. This level of flexibility imposes several constraints on the front-end optics especially when the maximum etendue of the spectrometer must be maintained for all configurations. This paper presents the design approach and trade-offs leading to a high performance optical design. Other constraints such as mass and volume are also considered. An important limiting factor is the size of the window and its minimum distance to the primary mirror of the telescope. The design has been optimized by re-imaging the aperture stop on each component that are critical in size: the interferometer corner cubes, the steering mirror and the primary mirror of the telescope. A set of two (2) telescopes and two (2) afocal relays are interchanged to produce 3 FOVs with optimized etendue and minimum size on critical components.
author(s): Jean Giroux, Jean-François Legault, Yan Montembeault, Tracy Smithson, André Villemaire, Jean-Pierre Ardouin
FIRST,
is a sensor optimized to provide unparalleled spatial information
about the spectral characteristics of infrared targets. Measurements
available.
