A new hybrid algorithm for designing the continuous phase screen used for beam shaping

摘要

A novel hybrid phase-retrieval non-iteration algorithm combining random searching algorithm and simulated annealing algorithm has been proposed for designing the diffractive optical elements (DOE'S) used for producing a uniform focal spot required with top head, steep edge, low side lobe or concentrating high power performance in the main lobe. The continuous phase distribution of diffractive optical elements with a good geometrical structure has been obtained by the new hybrid algorithm. Starting the optimal process with a continuous phase profile and taking the special phase function, this new algorithm can construct fully continuous phase screens for tailoring far-field intensity profiles (beam shaping). The continuous phase distribution using the new algorithm will be fabricated easily , make the elements have high diffractive efficiency, heighten the threshold value resisting the high power laser and get the far-field intensity profile with high uniformity at the main lobe , very small side lobe and steep edge. The computer simulation has shown that the algorithm is robust and maintains the continuous phase distribution throughout the optimal process. The DOE'S with continuous phase have been designed with more than 99% energy efficiency, less than 1% side slobe non-uniformity , and, with more than 90% energy efficiency, less than 2% top non-uniformity, respectively.