Widefield quantitative phase imaging by second-harmonic dispersion interferometry

Widefield optical characterization of transparent samples is of great importance for gas flow and plasma diagnostics, for example, as well as label-free imaging of biological samples. An optically transparent medium, however, cannot be imaged by techniques based on intensity contrast imaging. Very well-known qualitative phase-contrast imaging methodologies are routinely used to overcome this limitation, and quantitative phase-imaging approaches have also been developed. Here we report the demonstration of, to the best of our knowledge, a novel widefield quantitative phase-imaging technique, based on fully common-path second-harmonic dispersion interferometry that is combined with pixel-by-pixel homodyne dual-channel polarization-dependent phase detection. The device is tested in a harsh environment reaching sub-10 mrad harmonic phase dispersion sensitivity and a spatial resolution of several tens of microns with an optical configuration that is very stable and easy to implement. The time resolution of the demonstrated device is 600 ps, set by the laser-pulse time duration.