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In micro-lidars, because of high sensitivity to the sky background due to a limited energy of laser emitter, there is an obvious need to analyze the micro-lidar limitations in order to formulate requirements and provide conditions for most effective applications. In order to simplify the micro-lidar capabilities prediction when using SiPMs as echo-signal detectors, and to improve its clarity, we use specific ways to generalize optical, energy and excess-noise parameters inherent to remote sensing tasks, taking into account their possible variability. By normalizing all essential sources of noise to the reference signal inherent in a particular lidar in order to simplify the analytical model, we traced the patterns of the signal-to-noise ratio (SNR) degradation, of increasing threshold sensitivity to “optical weather”, and decreasing the lidar operation range. To apply the formalism to UV-, Vis- and NIR limited-energy-lidars and to perform the analysis of SiPMs as promising photodetectors for these spectral regions, we utilized a set of specific characteristics that are built from an envelope of dimensionless optical weather conditions and individual detector parameters. On this basis, the analysis of lidar system performance under intense background conditions is developed, and practical recommendations on detector use are given. The dimensionless formalization and the spectral-noise model of the micro-lidar, used as an actual example, allow this approach to be applied to a wide range of lidar detectors operating in a variety of relations between echo-signals and different sources of noise. |
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