Estimate optimization parameters for incoherent backscatter heterodyne lidar including unknown return signal bandwidth.

The conditions for optimizing the precision of heterodyne atmospheric lidar measurements using extended (deep) targets are investigated. The minimum standard deviation of each unknown (return power, Doppler shift, and signal bandwidth) is approximately twice the optical limit at best and is only weakly dependent on knowledge of the other parameters at optimal power levels. Somewhat stronger signal power levels are needed for bandwidth estimation. Results are displayed as a function of a time-bandwidth product to clarify the trade-off between estimate precision and range weighting. Realization under ideal conditions is confirmed by use of simulations.