High resolution measurement of multilayer structures.

It is possible to measure the thickness of a single layer by the fringes-of-equal-chromatic-order interferometric system with nanometer resolution. This method uses Müller fringes which represent the Fourier transformed autocorrelation (i.e., power spectrum) of the surfaces. We show how this method can be expanded to multilayer structures with a maximum total thickness of some millimeters and a resolution of better than the diameter of an atomic layer. It is possible to evaluate the real multilayer sequence by holographically measuring two power spectra.