A set of three dimensionless parameters is proposed to characterize lidar systems. Two of them are based on an asymptotic approximation of the output signal-to-noise ratio as a function of the input optical power reaching the photoreceiver when there is no background radiation. Of these, one is defined as the ratio between the input signal power level coming from a reference range in a reference atmosphere (reference power level) and the input power level that would produce a reference output signal-to-noise ratio if the photoreceiver operated always in signal-shot noise limited regime. The other is defined as the ratio between the reference power level and the input power level for which the signal-induced shot noise power equals the receiver noise power. A third parameter, defined as the ratio between the background optical power at the photoreceiver input and the reference power level, quantifies the effect of background radiation. With these three parameters a good approximation to the output signal-to-noise ratio of the lidar can be calculated as a function of the power reduction with respect to the power reaching the photodetector in the reference situation. These parameters can also be used to compare and rank the performance of different systems.

Peer Reviewed