26 September 2007 Signal-to-noise ratios of coherent imaging ladar
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We analyze the signal and noise in coherent active laser imaging systems (LADARs). The principle LADAR noise sources are shot noise in the detection process and target fluctuations in the reflected signal including speckle. The statistical relationships between signal and noise are similar for RADAR and LADAR. Four different metrics of "signal-to- noise" ratio are analyzed. C0 is the average number of detected photoelectrons neglecting speckle variance, C1 and C1' are the clutter-to-noise ratio (with and without bias) of the modulus image including speckle, and C2 is the clutter-to-noise ratio of the intensity image including speckle (always < 1). C1, C1', and C2 are determined by C0. Speckle (and other target fluctuations) affects coherent LADAR imagery similarly to the way it affects RADAR imagery, uses C0 as the principle signal-to-noise metric. C0 also is a valid measure of signal-to-noise ratio for coherent imaging LADAR, and analyses of coherent RADAR imagery noise can be applied to coherent LADAR imagery by replacing thermal noise kT with shot noise .
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Thomas J. Karr, Thomas J. Karr, } "Signal-to-noise ratios of coherent imaging ladar", Proc. SPIE 6712, Unconventional Imaging III, 671203 (26 September 2007); doi: 10.1117/12.729491; https://doi.org/10.1117/12.729491

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