AN IMAGING FABRY-PEROT SPECTROMETER FOR SITE EVALUATION OF TRACE SPECIES

FIELD-OPERABLE ANALYTICAL SYSTEMS ARE REQUIRED TO EVALUATE POTENTIAL HAZARDOUS CHEMICAL SOURCES AND TO MONITOR REMEDIATION SITES. THIS PROJECT IS DEVELOPING AN IMAGING INFRARED SPECTROMETER THAT CAN RAPIDLY SCREEN FIELD SITES TO DETECT THE PRESENCE OF VOLATILE ORGANIC COMPOUNDS FROM REMOTE LOCATIONS (EITHER IN THE AIR OR ON THE GROUND). THE SYSTEM EMPLOYS A CLOSE MIRROR SPACING TO ENHANCE OPTICAL THROUGHPUT AND ENABLE WIDE SPECTRAL COVERAGE AT MODEST RESOLUTION. THERMAL EMISSION FROM MOLECULES IN THE FINGERPRINT REGION OF THE SPECTRUM (825 TO 1,250 CM-1) IS DETECTED AGAINST A COLD ATMOSPHERIC BACKGROUND USING A MERCURY-CADMIUM-TELLURIUM ARRAY DETECTOR. THE SYSTEM EMPLOYS A WIDE FIELD OF VIEW AND HENCE CAN BE USED TO SCREEN LARGE AREAS FOR EMISSION SOURCES WITH QUANTITATIVE RESULTS. A COMPACT ALL SOLID-STATE DESIGN, COUPLED WITH SIMPLE IMAGE PROCESSING SOFTWARE, ALLOWS FOR THE REAL-TIME AQUISITION AND PROCESSING OF SPECTRAL DATA. THE DATA CAN BE USED TO DETECT AND MONITOR THE CONCENTRATION OF SPECIES SUCH AS 1,1,1-TRICHLOROETHYLENE, PERCHLOROETHLYLENE, CARBON TETRACHLORIDE, AND CHLOROFORM, AS WELL AS GASOLINE AND DIESEL FUEL COMPONENTS. AN EXPERIMENTAL DEMONSTRATION OF THE IMAGING SPECTRORADIOMETER CONCEPT AND A CONCEPTUAL DESIGN OF A COMPACT AND RUGGED VERSION OF THE SYSTEM WILL BE CARRIED OUT IN PHASE I. THIS EFFORT SHOULD DEMONSTRATE THE TECHNICAL FEASIBILITY OF THE CONCEPT AT THE LABORATORY AND FIELD LEVEL.