Patent ID: 7649634

Claim:
A method for estimating a surface profile of a sample in an interferometer having a broad bandwidth light source, the method comprising, for each location (x,y) of interest on the sample: detecting interference pattern intensity data over a series of frames of a relative scan between the sample and a reference surface; determining an envelope of the detected intensity data based on amplitudes of the detected intensity data; determining a rough estimate z rough of the surface profile of the sample at the location (x,y) of interest based on the envelope; estimating a phase offset θ of the detected intensity data using a curve fitting optimization process to fit the detected intensity data to a broad bandwidth interference model; and refining the rough estimate z rough , of the surface profile using the phase offset θ to obtain a fine estimate z fine of the surface profile of the sample at the location (x,y) of interest, the fine estimate z fine having improved resolution over the rough estimate z rough .