| The design of holographic diffusers and birefringent filters by using the genetic algorithm is studied in this thesis.; A holographic diffuser is an optical device that distributes light from a light source with a desired spatial distribution pattern. For diffuse infrared wireless home networking, a holographic diffuser is used to diffuse the laser light to cover a large indoor area such as an office, and at the same time to solve the eye safety problem. In the thesis, a modified genetic algorithm is proposed to design holographic diffuser. The novel algorithm combines the conventional genetic algorithm and the simulated annealing algorithm, in which the simulated annealing algorithm is used to maintain a better diversity of chromosomes for the genetic algorithm. A better performance in locating the global minimum is demonstrated. A 4-level phase-only hologram that is designed by the modified genetic algorithm is fabricated on a quartz substrate. The fabricated hologram is experimentally verified. The results show that diffraction pattern generated by the fabricated hologram agrees well with the theoretically calculated pattern. (Abstract shortened by UMI.)... |
