| 摘要 |
A long-range, wide-area remote sensor system(s) to detect trace levels of atmospheric constituents using bistatic configurations to measure differential absorption (BDIAL) of source beams tuned to the absorption line center and off-peak "wing" in the spectra of species of interest. Potential platforms for the probe beam and detector subsystems include satellites and airborne vehicles, and mapping of large geographical regions is accomplished by tomographic reconstruction of recorded columnar absorption data. The use of bistatic geometries reduces power requirements on the probe beam, as compared to standard backscatter DIAL, and allows detection with platforms at large stand-off ranges, subject to atmospheric conditions. Operation in spectral regions including UV, visible and IR is feasible, provided that there are no overlapping absorption lines when many substances are present. Use of multiple frequency sources and multi-spectral detectors will reduce identification ambiguities. A variant bistatic configuration, using corner cube or gimbaled reflectors will also allow similar stand-off and area coverage to a system with a remote detector, but with much higher source beams and/or lower sensitivities due to return path losses. In excellent atmospheric conditions, detector sensitivities to parts-per-billion (ppb) are possible.
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