Airborne and laboratory remote sensing applications of the CSIRO CO2 laser spectrometer MIRACO2LAS

摘要

Abstract: The mid-infrared airborne CO$-2$/ laser spectrometer(MIRACO$- 2$/LAS) was developed by CSIRO Division ofExploration and Mining to investigate the potentialrole of high spectral resolution thermal infrared (TIR)remote sensing for improved remote sensing of minerals,especially those silicate minerals that do not havediagnostic features at shorter wavelengths, such asquartz, feldspars, pyroxenes and garnets. Otherobjectives include testing and validating methods usedto separate the mineralogically significant emissivityfrom temperature effects in passive TIR systems, asMIRACO$-2$/LAS reflectance data are unaffected bysurface temperature effects. MIRACO$-2$/LAS uses aCO$-2$/ laser, which scans through 100 wavelengthsbetween 9.1 and 11.2 micrometers, as a light source for'active' remote sensing. The laser system issufficiently rapidly tuned to allow the airborne systemto operate in a line profile mode, producing contiguousground reflectance spectra for a footprint (or pixel)diameter of 2 meters. Typical airborne data arepresented, demonstrating successful identification of anumber of minerals. A laboratory carbon-dioxide laserspectrometer system has also been developed to validatethe MIRACO$-2$/LAS spectral signatures and to constructreference spectral libraries of pure minerals and othermaterials. Besides the compositional influence on thereflectance spectra, physical parameters, such as grainsize and grain shape, are shown to affect thereflectance spectra. Plant materials, many of whichdepart significantly from blackbody behavior fordifferent leaf orientations and arrangements, are alsoinvestigated. !10