Fast Surface Profiling by White-Light Interferometry Using Symmetric Spectral Optical Filter
We propose a surface profiling algorithm by white-light interferometry that extends sampling interval to twice of the widest interval among those used in conventional algorithms. The proposed algorithm uses a novel function called an in-phase component of an interferogram to detect the peak of the interferogram, while conventional algorithms used the squared-envelope function or the envelope function. We show that the in-phase component has the same peak as the corresponding interferogram when an optical filter has a symmetric spectral distribution. We further show that the in-phase component can be reconstructed from sampled values of the interferogram using the so-called quadrature sampling technique. Since reconstruction formulas used in the algorithm are very simple, the proposed algorithm requires low computational costs. Simulation results show the effectiveness of the proposed algorithm.
surface profiling white-light interferometry in-phase component symmetric spectral distribution quadrature sampling