Single-Shot Quantitative Polarization Imaging of Complex\nBirefringent Structure Dynamics

Polarization\nlight microscopes are powerful tools for probing molecular\norder and orientation in birefringent materials. While a number of\npolarization microscopy techniques are available to access steady-state\nproperties of birefringent samples, quantitative measurements of the\nmolecular orientation dynamics on the millisecond time scale have\nremained a challenge. We propose polarized shearing interference microscopy\n(PSIM), a single-shot quantitative polarization imaging method, for\nextracting the retardance and orientation angle of the laser beam\ntransmitting through optically anisotropic specimens with complex\nstructures. The measurement accuracy and imaging performance of PSIM\nare validated by imaging a birefringent resolution target and a bovine\ntendon specimen. We demonstrate that PSIM can quantify the dynamics\nof a flowing lyotropic chromonic liquid crystal in a microfluidic\nchannel at an imaging speed of 506 frames per second (only limited\nby the camera frame rate), with a field-of-view of up to 350 ×\n350 μm<sup>2</sup> and a diffraction-limit spatial resolution\nof ∼2 μm. We envision that PSIM will find a broad range\nof applications in quantitative material characterization under dynamical\nconditions.