Accurate reconstruction in measurement of micro-structures using digital holographic microscopy

Due to the limitation of traditional interferometry, digital holographic microscopy has attracted intensive attention for its capability of measuring complex shapes. However, speckles are inevitable in the recorded interferometric patterns, thereby polluting the reconstructed surface topographies. In this paper, a phase-shifting interferometer is built to realize the in-axis digital holographic microscopy. The anti-aliasing shift-invariant contourlet transform (ASCT) is used for reconstructing the measured surfaces. By avoiding subsampling in the scale and directional filtering schemes, the problems of frequency aliasing and phase distortion can be effectively solved. Practical experiments show that speckles can be recognized and removed straightforwardly. Therefore the proposed method has excellent performance for reconstructing structured surfaces.