Turbulence compensation for laser communication, imaging on horizontal path and non-natural turbulence using direct and iterative procedures

We take in consideration three applications which are strongly affected from atmospheric as well as artificial turbulence. Systems in development at the IOSB institute for correcting the turbulence in each application are reported. The set of problems we are interested in are related to the tracking of objects through the atmosphere, the improvement of a laser beam for laser communication or countermeasure and the imaging of objects distorted from turbulent layers. We propose the use of adaptive optics (AO) based on classical Shack-Hartmann sensors (SH) to improve the performances of tracking systems. The SH has the advantage to be sufficiently fast, robust and suited for coherent as well as incoherent point sources correction. In consequence it is also well suited for the purpose of laser beam correction in the atmosphere. The problem of improving a complex image or scene cannot be solved with wavefront sensors in an easy way. A correction of the wavefront based on qua lity metric estimation and the Stochastic Parallel Gradient Descent (SPGD) algorithm is then reported here to cover this aspect. In the final part two modifications of the SPGD algorithm to improve its performances are proposed.