Novel method to design laser beam shaping lenses using PSO techniques

To design beam shaping lenses converting the light from Gaussian intensity distribution into flat-top profile, a new method—particle swarm optimization (PSO) algorithm—was employed. The theoretical values of ray intersections at the output plane are precisely calculated by the energy conservation when a Gaussian beam is converted to a flat-top one, and these values are then used as target values in the optimization process. Real values of ray intersections are obtained from the ray tracing. The absolute values of the differences between real and theoretical values are used to construct the merit function of a shaping lens system, which are also used as the fitness function values for the PSO. By the manipulation of minimizing the fitness function, refractive two-element beam shapers and a refractive single-element beam shaper have been designed. The analyses for the design results demonstrated the feasibility and validity of the PSO method in the design of laser beam shaping lenses.