Measurement of the phase spectra of transparent thin films using white-light interferometry

摘要

Two-beam spectral interference at the output of a slightly dispersive Michelson interferometer is used to measure the phase spectra of transparent thin films over a wide range of wavelengths. First, using a Fourier transform method in processing of the recorded spectral interferograms the ambiguous spectral fringe phase function is obtained. Then, using a simple procedure based on the linear dependence of the optical path difference between beams of the interferometer on the refractive index of material of the interferometer optical element, the ambiguity of the spectral fringe phase function is removed and the thickness of the interferometer optical element and the phase spectrum of the transparent thin films are determined. Knowing both the thickness of the interferometer optical element and the phase spectrum of the transparent thin films for a given configuration, the theoretical spectral interferogram is compared with the recorded one and good agreement between these interferograms is confirmed.