| Summary: | 碩士 === 國立臺北科技大學 === 光電技術研究所 === 90 === The diffractive optical elements of the optical passive elements just have been gradually used recently for more than ten years. It primarily designed by the optical diffractive theory. Usually, we irradiate the incident rays into the elements by inconsistent thickness to result in different phase shift. And add through the overlap of the waves, we can make into the field of optics of the incident rays redistribute on the screen. Since the special design for the diffractive optical elements , then the outcome can be achieved on the screen.
In this thesis, we use the evolutionary way of the great nature rule: “Survival of the fittest in natural select.” to set on designing the pure phase diffractive elements. This method now is called the Genetic algorithm. And then we compare the principles and the simulated results of the diffractive optical elements designed by the Iterative Fourier transformation algorithm and the Simulated annealing algorithm. Here, we aim at laser beam shaping, the array spots design and the efficiency of wavelength division for comparison. In this research, we improve the Genetic algorithm and the Simulated annealing algorithm for single wavelength design to suit to simulate for multi-wavelength design.
As a result by the values simulation, we obtained that: for the laser beam shaping, the Genetic algorithm has better performance; for the array spots design and the efficiency of wavelength division, the Simulated annealing algorithm has better performance; as to the Iterative Fourier transformation algorithm, its biggest advantage is to greatly reduce the time on calculation. Then we need to aim at the restriction of the environment conditions to select the most suitable algorithm, and design out the most superior diffractive optical elements.
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