Surface profile measurement using nonlinear optimization approach in diffraction phase microscopy

Abstract

Nanoscale measurement of surface profile has important application in the field of non-destructive surface testing and evaluation. We propose a nonlinear optimization based phase retrieval approach in diffraction phase microscopy for nanoscale surface profile measurement. The proposed approach relies on minimizing an objective function derived from the interferogram signal and the application of total variation regularization. The performance of the method is demonstrated via numerical simulations for processing interferograms affected by sharp phase variations, noise and non-uniform amplitude fluctuations. In addition, the practical application of the method is validated for nanoscale surface topography by processing experimental interferograms obtained in diffraction phase microscopy.