Application of computer processed video-signal in the optics of thin films

摘要

The interferometric measurement method of a thin film optical thickness is presented in this report. This measurement is realized by Michelson's interferometer. Interferogram of a measured sample with one half of the surface covered by a layer and the other without a layer is digitally recorded from the screen by CCD camera. The video-signals from two rows of the intensity distribution from the part with and without a layer are numerically filtered via fast Fourier transformation (FFT) and the phase change of the two periodical "continuous" functions is evaluated by the first and second derivatives. This phase change allows to determine the path difference and finally the optical thickness of the layer.