Research On Far Field Beam Shaping Method Based On Fourier Transform

The ultimately achieved purpose of far field beam shaping is to improve the each feature of beam shaping effect to meet the actual demand. Among them, the key point of far field beam shaping technique is how to reasonably design the phase recovery algorithm loaded on the beam shaping components. Therefore, the phase recovery algorithm has becomes the most importantly scientific research issues in the laser beam shaping field. For a long time, the phase retrieval algorithm has attracted the extensive concern for a large number of researchers at home and abroad.At present, there are many kinds of method used in beam shaping including some shaping methods based on the optical device such as aspheric lens group laser shaping method, micro lens array shaping system, reflective lens shaping method, double refraction lens group shaping method, diffraction optical element shaping method and telephoto depth elements shaping method. Currently the most commonly used shaping method is the iterative optimization algorithm and base on Fourier transform, because of the binary devices in beam shaping being pure phase liquid crystal spatial light modulator. However, the theoretical defect existed in the currently iterative optimization algorithm results in that the actual shaping effect can not meet the application requirements. Finally, the optimized GAA algorithm is presented in this paper, which based on GS algorithm and GAA algorithm.The optimized GAA algorithm proposed in this paper is an improved and more universal algorithm based on the GAA algorithm. The optimized GAA algorithm has a well fast convergence and design flexibility. Since the different values of the factorξin the GAA algorithm is ignored for most researchers, which is directly related to the effect of beam shaping. Therefore, the value ofξdirectly gave in the GAA algorithm has certain blindness, so it is possible to improve.So we put forward by optimizing the factor ofξand finally realize the improvement of GAA algorithm.To other iterative optimization algorithm, the optimized GAA algorithm not only take into account the diffraction efficiency, but also better improve the output beam at the top of poor uniformity defects. In addition, the most prominent advantage of the optimized GAA algorithm is that it not only can achieve flattened beam shaping but also can achieve non-flattened beam shaping. The instance simulation is conducted by the optimization GAA algorithm in this thesis。...