The Computation And Research Of Optical Diffraction Field

Diffraction is very important in optics. But the diffractions in near-field and off-axis situations are hardly researched with existing diffraction theory and normal diffraction experiment. This paper solved these problems successfully using the computer simulation experiment. So it has a great meaning. The following works have already been done: Simulating the optical diffraction accurately using the computer and having diffraction patterns in various situations. After that a more deeply computation and research has been done subsequently and that is what was introduced in this paper. The theory based on in this research is Huygens-Fresnel principle and Huygens wavelet conception. A theoretical derivation was made to obtain the intensity distribution formula of the secondary diffraction. Particularly, the formula has more simple form when the aperture is origin-symmetric. And this paper compares the data computed from theoretical formula of the secondary diffraction and the primary diffraction with the same parameters. The same results show that the secondary diffraction is the continuous propagation of the light wave which comes from the primary diffraction patterns. And it also confirms the Huygens wavelet conception through the experiment method. The comparison between the theoretical derivation and the experimental data of the secondary diffraction was given and they show the same results. This paper also analyzes two special cases of the secondary diffraction through the further derivation of the theoretical formula. And the theoretical derivation gives a completely new understanding about diffraction. The research has been done to find the change law of the secondary diffraction patterns vary with the diffraction distance or aperture's size. In addition, this paper puts forward two methods to compute aperture's information while the diffraction pattern is known. These two methods are Fourier method and dichotomy. The former of them bases on the relation between diffraction and Fourier Transform. The latter bases on the dichotomy which can determine the optimal solution in the numerical analysis.