Optimisation of certain holographic 1 to N and 1 to N*N beamsplitters (Dammann gratings) with the aid of simulated annealing and damped least-squares algorithms is considered. Structures with N=5 to 53 uniform beams have been calculated. A photolithographic technique for fabrication of these elements is also presented, and its accuracy analysed with the aid of numerical simulations and actual test results.
Turunen, J., Vasara, A., Westerholm, J., Jin, G., & Salin, A. (1988). Optimisation and fabrication of grating beamsplitters. Journal of Physics D: Applied Physics, 21(10S), S102-2105. https://doi.org/10.1088/0022-3727/21/10S/029