Laser beam focusing through the atmosphere aerosol

Distortions of the scattered laser beam (λ=0.65μm) were numerically estimated by means of Shack-Hartmann technique and experimentally measured. The ability to focus laser beam, passed through the scattering suspension of polystyrene microspheres in distilled water, using bimorph deformable mirror was investigated both numerically and experimentally. Shack-Hartmann technique was used to measure the local slopes of the Poynting vector, and CCD camera was used to analyze the intensity distribution of the focal spot in the far-field. Bimorph deformable mirror with 14 electrodes was utilized in order to increase the focusing efficiency of the laser beam. The voltages to be applied to the mirror electrodes were calculated using three techniques: LSQ (least squares) fit-error minimization by Shack-Hartmann sensor, Hillclimbing optimization by Shack-Hartmann sensor and Hill-climbing optimization by the far-field CCD camera.