Scintillation and multiwavelength coherence effects in a long-path laser absorption spectrometer.
An experimental investigation has been carried out on turbulence-induced noise in a long-path laser absorption spectrometer which measures sequentially the atmospheric transmission at two preselected wavelengths over the same path. A simple analysis shows that performance degradation due to scintillation can be significantly reduced by exploiting the coherence between fluctuations in received signal at the two wavelengths. Auto-correlation and cross-correlation properties for signals at the two wavelengths, recorded experimentally, are compared with results derived from turbulence theory, and implications for choice of spectrometer wavelengths and sampling speed are discussed.
Kjelaas
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AG
Nordal
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PE
Bjerkestrand
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