Mid-Infrared Remote Sensing Systems and Their Application to Lithologic Mapping |
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Authors: | Eberhardt JE Green AA Haub JG Lyon RJP Pryor AW |
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Affiliation: | Division of Mineral Engineering, Commonwealth Scientific and Industrial Research Organization, Lucas Heights Research Laboratories, Lucas Heights, N. S. W., 2232 Australia; |
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Abstract: | Mid-infrared remote lithologic mapping by emittance and by reflectance are assessed in laboratory experiments. The emittance spectra of various rocks and minerals, measured in the 8-13, ?m atmospheric transmission window, are compared with reflectance data measured in the range of 9.2-11.2 Am using a line-tuned CO2 laser. We conclude that the reflectance data are more useful for lithologic discrimination than the passive emittance data. An experimental laser suitable for terrain mapping from a low-flying aircraft is described. The low-pressure longitudinal discharge CO2 laser has a rotating mirror to scan the diffraction grating and generates 90 bursts of pulses per second. Each 1-ms burst contains 92 pulses at 92 CO2 laser wavelengths. The mean output power is 12 W and the average pulse power is 370 W. With that power, and using incoherent detection, a signal-to-noise ratio of better than 100: 1 should be obtained from terrain with an albedo of 0.01 at a height of 500 m. |
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