Analysis of an array of micro lenses using fourier-transform method

The authors present an enhanced Fourier-transform technique to recover the phase profile, and hence the surface topography of an array of micro lenses. The technique combines fringe analysis by the Fourier-transform method, fringe extrapolation to reduce errors at the boundaries and phase unwrapping by the energy minimisation algorithm. The technique is validated by both simulation and experiment and is useful even when the Fourier spectra of the interferograms are not separated completely. The technique is also helpful in the presence of background noise.