Thickness measurement of thin transparent plates with a broad-band wavelength scanning interferometer

A novel broad-band telecom laser source is used to realize a lateral-shear scanning-wavelength interferometer for measuring the thickness of thin plates. We show that the wide tunability range allows to detect samples down to tens of microns with a relative uncertainty of less than 0.5% and a resolution of about 1 nm. A comparable accuracy in the thickness characterization of double-layer structures is also demonstrated. In turn, the wide tunability range needs the dispersion law of the materials to be taken into account in the model for correct thickness evaluation.