Improved 3D imaging of phase shifting digital holographic microscope by compensation for wavefront distortion

This paper is focused on improving the performance of quantitative phase imaging via phase-shifting digital holographic microscope. The development of the interferometric techniques is important for technology and biomedicine, since the surface and structure of samples can be monitored in real-time by non-destructive investigations. The novelty of the optical arrangement is that in the reference beam of the digital holographic microscope a liquid crystal variable retarder is introduced. Thus, it became possible to actively control the polarization state of light for realizing the necessary phase-shifts. In addition, a spatial light modulator is integrated in the optical setup to produce computer-controlled compensation of the spatial distortion. An ad hoc hologram processing technique was developed to execute the numerical correction of the physical phase-shifting errors. Topographical investigations of phase masks recorded on carbazol-based azopolymers provided the experimental testing of the achieved accuracy in phase reconstruction.