Extended overlap function computation method for atmospheric lidars

Kurzfassung

In this publication, an extended method for calculating the overlap function for atmospheric lidars is introduced. A generic procedure is proposed to compute the overlap function, also referred to as geometrical function, geometric compression, or geometrical form factor. This procedure implements both ray-tracing and physical optics propagation methods to simulate the propagation of the transmitted beam in the atmosphere, and its back-propagation to the receiver telescope, allowing to take into account different factors such as the profile of the transmitted beam, the turbulent atmosphere, the lidar receive system’s optical aberrations, and different lidar configurations. Even though the scope of the publication is for introducing the method without analyzing in detail the dependencies of the overlap function on one of these factors, three applications of the method are described: quantifying the impact on the overlap function of the circular obstruction in a mono-axial lidar, simulating the effects of different focus positions on the lidar signal, and computing the overlap function considering a flat-top transmitted beam.