The Implementation Of Optical Thin Film Optimal Design

Optical thin film plays an important role in Modern Optics. Without the optical thin film, there are no many complex high performance optical instruments, optoelectronic device and optical system. As the development of Science and Technology, especially in the leading of optical communication and projector display technology, the request on all of kinds optical thin film is much stricter. The design of optical thin films also faces a severe challenge. Not only so many requests on spectrum are brought up, but also the layer number of optical thin film will be larger. That has exceeded the ability of analytical method. The development of computer and its extensive usage have supplied a useful condition for optimal design.The thesis was based on the principles of optimal design and optical thin film,and described four algorithms of optimal design of optical thin film------PowellAlgorithm, Simplex Methods, Genetic Algorithm(GA) and Needle Algorithm. The paper had mainly described the theoretical principle, arithmetic process and implementation of GA. Besides, GA had been programmed in the MATLAB6.5.1 for optimal design of optical thin film. At the same time, the structure of LCD was also studied, which showed that antireflection coating insertion could be used for optimization of LCD, and that the spectrum of the antireflection coating was also concluded. With construction of merit function and fitness function, two antireflection coatings whose wavelength ranges are 400ww ~ 650nm and 450nm ~ 750nm respectively, were designed by the program of GA in the MATLAB successfully. The highest rest reflectivity was below 0.5%. Compared with Needle Algorithm, the result showed that GA was effective.At present, the work of optical thin film optimal design is still in the exploration in our country, and the design of optical thin film is a base for the progress of film technology. So it is worthwhile to work on the design of optical thin film. One of difficulties in the optimal design is that the merit function is rather complex, multi-peak, and nonlinear, so the process of optimization usually doesn't go on if the function reaches local extreme value. GA has the ability of searching for the extreme value in global scope. If it is brought in the optimal design, the design of optical thin film should be make much progress in future.