Comment on "Heterodyne lidar returns in the turbulent atmosphere: performance evaluation of simulated systems"

The explanation proposed by Belmonte and Rye [Appl. Opt. 39, 2401 (2000)] for the difference between simulation and the zero-order theory for heterodyne lidar returns in a turbulent atmosphere is incorrect. The theoretical expansion the authors considered is not developed under a square-law structure-function approximation (random-wedge atmosphere). Agreement between the simulations and the zero-order term of the theoretical expansion is produced for the limit of statistically independent paths (bistatic operation with large transmitter-receiver separation) when the simulations correctly include the large-scale gradients of the turbulent atmosphere.