ABSTRACT
The control of the optical quality of a laser beam requires a complex amplitude measurement able to deal with strong modulus variations and potentially highly perturbed wavefronts. The method proposed here consists in an extension of phase diversity to complex amplitude measurements that is effective for highly perturbed beams. Named camelot for Complex Amplitude MEasurement by a Likelihood Optimization Tool, it relies on the acquisition and processing of few images of the beam section taken along the optical path. The complex amplitude of the beam is retrieved from the images by the minimization of a Maximum a Posteriori error metric between the images and a model of the beam propagation. The analytical formalism of the method and its experimental validation are presented. The modulus of the beam is compared to a measurement of the beam profile, the phase of the beam is compared to a conventional phase diversity estimate. The precision of the experimental measurements is investigated by numerical simulations.
ABSTRACT
Long-range free space optical communications suffer from atmospheric turbulence effects. To mitigate them, a bidirectional full-wave compensation technique seems promising. We present an experimental implementation and characterization of this concept on a laboratory breadboard. Experimental results confirm former numerical results for similar propagation conditions. The effects of measurement and control errors are analyzed by numerical modeling.
