White-Light Interferometric Sensor for Rough Surface Height Distribution Measurement

A very simple white-light interferometric sensing system for rough surface (RS) height distribution measurement is presented. A simple mathematical analysis is given, where as a final result, the probability density function (PDF) of the RS heights is obtained. The PDF has been found to be proportional to the inverse Fourier transform of the ratio of two optical power spectrums, the “high frequency” part of the channeled spectrum at the interferometer output and the white-light source spectrum, respectively. An experimental setup, based on a very simple fiber-optic interferometeric sensing unit, has been built in order to verify the result of the given mathematical model. A relatively good matching between the surface roughness of the known material and the measurement result is obtained.