چكيده به لاتين
Abstract:¬
The purpose of the research is to obtain surface profile with optical methods. In this thesis, interferential methods (Phase-shifting and Fourier transform) has been used. Phase-shifting and Fourier transforms has been simulated using Matlab software. The roughness of the surface is considered in two dimensions. To add noise to the system, the Poisson distribution function is used. In consideration of changes the noise and height of surface roughness, the measurement error of each method has been calculated and compared. By analyzing the change in the amount of noise has been entered in, it was determined that the Phase-shifting method of the Hariharan algorithm has more accuracy than the other algorithms of this method and Fourier transform. The results of the calculations show, in this algorithm, that with amounts of 5% noise, height of surface roughness of 60 nm and a wavelength of 632 nm, the measurement error is 0.06, However the quadruple algorithm is 0.07, the triple algorithm is 0.14 and the Fourier transform is 0.16. Also by investigating the change of the ratio of the height of roughness to wave-length, it was found that the Phase-shifting method of the Hariharan algorithm is more accurate than other methods.The results show, with amounts of 5% noise and the ratio of the height of roughness to wave-length which is 0.09, the measurement error of the Hariharan algorithm is 0.06 and for the quadruple and triple algorithms is equal to 0.07 and 0.14, respectively, also it is 0.16 Fourier transformation. With these comparisons it can be concluded that the Phase-shifting method is more accurate than the Fourier transform method, but the Fourier transform method is faster because of the need for less interference pattern.
keywords: Surface Roughness, Interferometer, Phase-shifting, Fourier transform
