Demonstration of tolerance to dispersion of master/slave interferometry.

A theoretical model is developed for the Master/Slave interferometry (MSI) that is used to demonstrate its tolerance to dispersion left uncompensated in the interferometer when evaluating distances and thicknesses. In order to prove experimentally its tolerance to dispersion, different lengths of optical fiber are inserted into the interferometer to introduce dispersion. It is demonstrated that the sensitivity profile versus optical path difference is not affected by the length of fiber left uncompensated. It is also demonstrated that the axial resolution is constant within the axial range, close to the expected theoretical resolution determined by the optical source bandwidth. Then the thickness of a glass plate is measured several times in the presence of dispersion and errors in measurements are evaluated using the MSI method and the conventional Fourier transformation (FT) based method using linearized/calibrated data. The standard deviation for thickness results obtained with the MSI is more than 5 times smaller than the standard deviation for results delivered by the conventional, FT based method.