Optimisation and fabrication of grating beamsplitters

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.