KEYWORDS: Cameras, Sensors, Imaging systems, Optical filters, Digital cameras, Commercial off the shelf technology, Image processing, Power supplies, Data acquisition, Global Positioning System
Digital cameras and imaging/non-imaging spectrometers covering the ultraviolet through long-wave infrared
wavelengths are readily available and affordable for use by scientists and emergency responders. An
important addition that will enhance the value of these precision sensors as tools in the hands of scientists and
emergency responders is the capability to produce automated geo-registered or ortho-rectified imagery maps
from their data. This paper describes the Mapping System Interface Card (MSIC), a low cost, compact, realtime
precision metadata annotator with embedded INS/GPS designed specifically to convert commercial-offthe-
shelf (COTS) sensors with Camera Link standard data streams into mapping systems for airborne remote
sensing applications.
On April 28, 2010, the Environmental Protection Agency's (EPA) Airborne Spectral Photometric
Environmental Collection Technology (ASPECT) aircraft was deployed to Gulfport, Mississippi
to provide airborne remotely sensed air monitoring and situational awareness data and products in
response to the Deepwater Horizon oil rig disaster. The ASPECT aircraft was released from
service on August 9, 2010 after having flown over 75 missions that included over 250 hours of
flight operation. ASPECT's initial mission responsibility was to provide air quality monitoring
(i.e., identification of vapor species) during various oil burning operations. The ASPECT airborne
wide-area infrared remote sensing spectral data was used to evaluate the hazard potential of
vapors being produced from open water oil burns near the Deepwater Horizon rig site. Other
significant remote sensing data products and innovations included the development of an
advanced capability to correctly identify, locate, characterize, and quantify surface oil that could
reach beaches and wetland areas. This advanced identification product provided the Incident
Command an improved capability to locate surface oil in order to improve the effectiveness of oil
skimmer vessel recovery efforts directed by the US Coast Guard. This paper discusses the
application of infrared spectroscopy and multispectral infrared imagery to address significant
issues associated with this national crisis. More specifically, this paper addresses the airborne
remote sensing capabilities, technology, and data analysis products developed specifically to
optimize the resources and capabilities of the Deepwater Horizon Incident Command structure
personnel and their remediation efforts.
The EPA Airborne Spectral Photometric Environmental Collection Technology (ASPECT) Program provides airborne
ortho-rectified imagery, video, chemical and now radiological information directly to emergency response personnel via
a commercial satellite link onboard the aircraft. EPA initiated the ASPECT Gamma Emergency Mapper GEM Project in
2008 to improve its airborne gamma-screening and mapping capability for monitoring any ground-based gamma
contamination. This paper will provide an overview of the system, which can be configured to carry six 2"x4"x16"
NaI(Tl) detectors and two 3"x3" LaBr3(Ce) detectors or eight 2"x4"x16" NaI(Tl) detectors. The paper will provide an
overview of the analysis of gamma radiation spectra, system limitations, and emergency response applications.
Airborne passive hyperspectral infrared spectral measurements of chemical vapors in the
atmosphere have been completed over a wide variety of locations throughout the United States.
These measurements are part of the US EPA emergency response chemical disaster mitigation
capability. Analysis and regional comparison of these atmospheric measurements reveals a glycol
constituent, which has been noted during flooding conditions along the Southern Gulf Coast Region
and the Midwestern United States. This discussion will describe several differences in the natural
atmospheric background for vapor species identified in various regions of the country. There are
two possible sources for this constituent in these regions one is a natural source the other is an
anthropogenic source. The paper will highlight the usefulness of passive infrared spectral
measurements to determine key atmospheric indicators correlated with locations of major flooding
along with the identification of naturally occurring species.
A longwave-infrared (LWIR) passive-spectrometer performance was evaluated with a short-pathlength gas cell. This
cell was accurately positioned between the sensor and a NIST-traceable blackbody radiance source. Cell contents were
varied over the Beer's Law absorbance range from the limit of detection to saturation for the gas analytes of sulfur
hexafluoride and hexafluoroethane. The spectral impact of saturation on infrared absorbance was demonstrated for the
passive sensor configuration. The gas-cell contents for all concentration-pathlength products was monitored with an
active traditional-laboratory Fourier Transform Infrared (FTIR) spectrometer and was verified by comparison with the
established PNNL/DOE vapor-phase infrared (IR) spectral database. For the passive FTIR measurements, the blackbody
source employed a range of background temperatures from 5oC to 50oC. The passive measurements without the presence of a gas cell permitted a determination of the noise equivalent spectral noise (NESR) for each set of passive
gas-cell measurements. In addition, the no-cell condition allowed the evaluation of the effect of gas cell window
materials of low density poly(ethylene), potassium chloride, potassium bromide, and zinc selenide. The components of
gas cell, different window materials, temperature differentials, and absorbances of target-analyte gases supplied the
means of evaluating the LWIR performance of a passive FTIR spectrometer. The various LWIR-passive measurements
were found to simulate those often encountered in open-air scenarios important to both industrial and environmental
monitoring applications.
KEYWORDS: Fourier transforms, Digital signal processing, Spectroscopy, Data acquisition, Sensors, Interferometers, Control systems, Analog electronics, Signal detection, Field programmable gate arrays
Advance of digital electronic technology into the signal processing domain facilitates significant advancement in the ability to control the scanning mechanisms of Fourier Transform Spectrometers (FTS). A generic digital controller for FTS has been developed and is now being offered as a commercial product to upgrade most commercially available FTS that use a He-Ne laser as their metrology system. This controller replaces the conventional analog signal from the laser fringes with a digital signal using a dedicated DSP and creates a more precise feedback control of the FTS scan mechanism.
Infrared airborne spectral measurements were collected over the Gulf Coast area during the aftermath of Hurricanes Katrina and Rita. These measurements allowed surveillance for potentially hazardous chemical vapor releases from industrial facilities caused by storm damage. Data was collected with a mid-longwave infrared multispectral imager and a hyperspectral Fourier transform infrared spectrometer operating in a low altitude aircraft. Signal processing allowed detection and identification of targeted spectral signatures in the presence of interferents, atmospheric contributions, and thermal clutter. Results confirmed the presence of a number of chemical vapors. All detection results were immediately passed along to emergency first responders on the ground. The chemical identification, location, and vapor species concentration information were used by the emergency response ground teams for identification of critical plume releases and subsequent mitigation.
The purged gas containment cell is composed of readily available materials. This cell is charged with analyte samples under the conditions of ambient temperature and pressure. The analyte samples are obtained from dilution of commercially available pure material in lecture bottles. This is achieved by injecting pure analyte material into a Tedlar® bags during filling with a known amount of nitrogen diluent. This study demonstrates the utility of the approach using a series of gas samples with concentration-pathlength products spanning the Beer's law range of infrared absorbances. These absorbance values and blackbody radiance levels are within the linearity range of both the active and passive Fourier transform infrared spectrometers that are used in this study. In addition, these conditions are representative of environments that are often encountered in open-air measurements.
KEYWORDS: Absorbance, Spectroscopy, FT-IR spectroscopy, Black bodies, Infrared spectroscopy, Binary data, Temperature metrology, Signal to noise ratio, Liquids, Sensors
Gravimetrically prepared aqueous binary solutions permit the generation of target vapors of methanol and ammonia in a portable vapor cell. A passive Fourier transform infrared (FT-IR) spectrometer monitors a short pathlength optical cell using a calibrated extended-blackbody background source. The temperature of the blackbody ranges from 5°C to 50°C in five degree increments. This temperature range simulates the radiance levels most often encountered for ambient temperature backgrounds in open-air field measurements. The solute liquid mole fractions determine the resultant vapor concentrations. The water component attenuates the target vapor concentration from that of the pure solute component depending on the solute liquid mole fraction. This study demonstrates the utility of a portable vapor cell using a series of binary aqueous solutions per target compound over the Beer’s Law range of infrared absorbances. These Beer’s Law infrared absorbances and blackbody radiance levels are within the linearity range of the passive FT-IR spectrometer and are representative of open-air field conditions.
This paper is a collaborative effort between the US EPA's Technology Applications and Research & Development groups to generate commercial interest in the development of cost effective sensors appropriate for the requirements of organizations in the CIVIL sector chartered with providing emergency first response support. The US EPA Region-7 Technology Applications Group maintains the Airborne Spectral Photometric Environmental Collection Technology (ASPECT) System. This system provides the US EPA with operational 24 hour/seven days a week emergency response remote chemical detection capability. Data collected by the ASPECT system along with the first responder requirements will be encapsulated in a manner suitable for guiding the efforts of commercial sensor system manufactures (e.g., effluents of interest, bounding concentrations/abundances, bounding environmental background parameters, sensor radiometric performance requirements for high-confidence response/action, operational readiness timelines, etc.). This paper is intended to provide the requirements, initiate and guide the synthesis process for sensor(s) and instrument packages providing sufficient area coverage, spectral resolution, and sensitivity to detect, selectivity to identify, image, and map hazardous chemical plumes. It is believed this effort will facilitate cost effective and timely state of the art sensor/system technology development suitable for CIVIL emergency response needs in compact automated packages.
The US Environmental Protection Agency is currently operating an airborne hyperspectral remote infrared spectrometer for the purpose of providing near real-time chemical data to first responders and other response agencies. This system has been designed to fulfill Agency data collection requirements for both traditional chemical emergency response and counter - terrorism activities. The platform consists of a high speed long-wave and mid-wave spectrometer and a multi-spectral infrared line scanner integrated into a mid-sized twin-engine aircraft. Through the use of onboard data processing and short haul data links, chemical information can be relayed to the end user in about ten minutes. An important component of this system is the development of the spectral reference library used to query the incoming data stream. A balance must be reached in providing a library set that is robust enough to provide useful information for the majority of accidents without the overhead of voluminous amounts of rarely used spectral library data. The end goal of the program is to generate a library set which permits a reasonable number of compounds to be automativally processed as data is streamed through the system. This paper will describe the selection technique used to develop the critical list of compounds contained in the library. This paper will likewise describe how this library is integrated into the overall system and the type of data processing and products that are produced.
An airborne infrared (IR) line-scanner and a Fourier transform infrared (FT-IR) spectrometer operating in the 3- 5micrometers and 8-12micrometers spectral regions provide a rapid wide- area surveillance capability. The IR scene containing target vapors is mapped remotely with the wide fields of view (FOV) multi-spectral IR line-scanner using 14 bands. The narrow FOV FT-IR spectrometer permits remote verification of target vapor plume contents within the IR scene. The IR image and FT-IR interferogram analysis supply a near real-time detection that provides visual monitoring of potential downwind vapor hazards. This capability is demonstrated using the target vapor methanol. An active mono-static FT-IR configuration furnishes ground-truth monitoring for methanol released from an industrial stack and a nearby ground-level area. The airborne and ground-truth results demonstrate the usefulness of this approach in alerting first responders to potential downwind vapor hazards from an accidental release.
Wanda Fateley, Robert Hammaker, Martin Spartz, Mark Witkowski, Timothy Marshall, Charles Chaffin, M. Tucker, John Poholarz, V. Makepeace, Billy Fairless, Jody Hudson, Joseph Arello, Mark Thomas
Open-cell long-path Fourier transform infrared (FT-IR) spectroscopy has become a common technique for the monitoring of fugitive emission of VOCs in the atmosphere. Our entry into the study of VOCs in the atmosphere is presented in a historical context. The evolution of our techniques for carrying out field studies is described. Some representative examples of our monitoring activities are given and referenced. Some more recent concerns are presented and future directions are indicated.
KEYWORDS: Infrared radiation, FT-IR spectroscopy, Signal to noise ratio, Nitrous oxide, Absorbance, Calibration, Remote sensing, Agriculture, Spectral calibration, Chemical elements
Structures that exhibit above ambient temperatures are often found on industrial sites. These heated structures are being investigated for use as sources of infrared radiation that can be used to conduct open-path FT-IR monitoring of fugitive plumes from such sites. The use of on-site heated structures as infrared sources in open-path FT-IR monitoring promises many of the advantages of passive open-path FT-IR techniques because the arrangement is single-ended and allows spectra of fugitive plumes to be collected from a position away from the plumes themselves and possibly even outside of the plant's perimeter. The use of the heated on-site structures offers improvements in signal-to-noise ratios over passive techniques, however, similar to traditional `active' open-path techniques that incorporate a heated element (e.g., SiC) as the source of infrared radiation. Open path FT-IR monitoring has been conducted using on-site heated structures as infrared sources at an industrial site that produces agricultural chemicals to provide information about fluctuations in the concentrations of fugitive emissions produced from the site. Signal-to-noise ratios (SNR) and limits of detections (LOD) similar to those associated with traditional active FT-IR monitoring techniques are demonstrated in the spectra collected.
There exists little information concerning the quality of data generated from open-path Fourier transform infrared spectrometer (OP-FTIR) systems as applied to measuring toxic air pollutants. The U.S. Environmental Protection Agency, Region VII conducted a study designed to assess the intercomparability and data quality for several OP-FTIR systems. This paper describes the design of the study, presents the resulting data, and discusses the conclusions reached.
William Fateley, Mark Witkowski, Charles Chaffin, Timothy Marshall, Robert Hammaker, Ray Carter, Dennis Lane, Glen Marotz, Billy Fairless, T. Holloway, Jody Hudson, Joseph Arello, Mark Thomas, D. Gurka
Mark Witkowski, Charles Chaffin, Timothy Marshall, Martin Spartz, Jonathan Fateley, Robert Hammaker, William Fateley, Ray Carter, Dennis Lane, Glen Marotz, Billy Fairless, Jody Hudson, Joseph Arello, Mark Thomas, D. Gurka
The mobile Fourier transform infrared (FT-IR) spectrometer system for the monitoring of volatile organic compounds (VOCs) is now entering its third and final stage of testing. At present, data have been collected in all three stages of testing. From the results obtained during the three stages of testing, modifications have been made to the mobile FT-IR spectrometer system to increase its overall performance in the field.
Martin Spartz, Mark Witkowski, Jonathan Fateley, Robert Hammaker, William Fateley, Ray Carter, Mark Thomas, Dennis Lane, Glen Marotz, Billy Fairless, T. Holloway, Jody Hudson, Joseph Arello, D. Gurka
The field transportable Fourier transform infrared (FT-IR) spectrometer system developed at Kansas State University
is now finishing the testing stage. The testing stage consisted of three parts: the measurements of (1) controlled
releases of volatile organic compounds (VOC), (2) uncontrolled VOC releases at well documented sites, and (3)
uncontrolled VOC releases at complex sites with little or no precharacterization1. Some measurements have been
acquired in all three categories with most of the data acquisition taking place in the first two categories, which are
discussed in these proceedings. These tests were developed to validate the qualitative and quantitative capabilities
while enhancing the versatility and detection limits of the spectrometer system.
The controlled VOC releases, for the most part, took place at the University of Kansas (KU). The KU tests utilized
a co-monitoring technique, evacuated stainless steel canisters followed by GC/FID analysis, during the acquisition of
the infrared data. The ability to monitor the concentrations of the released plume with another technique allowed for
the comparison and examination of how varying parameters can affect the infrared spectrometer technique. The
varying parameters that were addressed were wind, path length, temperature, barometric pressure, water and carbon
dioxide concentration, and air borne particulates.
One set of uncontrolled releases occurred at an active production facility. A list of the possible compounds that might
be observed from the facility directly due to production was obtained. Infrared measurements were acquired at two
different setup geometries down wind and one setup geometry up wind. The three path lengths were 390 meters, 500
meters, and 412 meters respectively. During these measurements two series of canister samples were obtained down
wind and one series of canister samples were obtained up wind. The analyses of these canisters, on-going at this
writing, is being performed by GC/FT-IR (matrix isolation). When the analysis from this method is complete the
results will be compared.
These two different data acquisitions have led to much insight into the capabilities of the spectrometer system and how
varying parameters can affect the FT-IR spectrometer's performance. Preliminary analysis of the spectroscopic data
from both data acquisitions will be discussed.
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