Darkfield Mueller matrix microscope allows the observation of single cells with high contrast

The polarization of light refers to how its electric field oscillates in space and time. This property is highly sensitive to the interaction with matter. Hence, analyzing the changes in polarization is a powerful method for label-free investigation of microscopic samples. In this context, Mueller matrix microscopy utilizes the Stokes-Mueller formalism to describe the anisotropies of the specimens. In this work, we developed a Mueller matrix microscope for observing biological samples, based on a scanning architecture and a photoelastic modulator as a fast and motion-free polarization state generator. A darkfield-like detection scheme is implemented to enhance the contrast of the captured images. This modification enables the acquisition of high signal-to-noise ratio images for the off-diagonal elements of the Mueller matrix. Our attention is primarily focused on m₁₄, which is particularly useful for describing the spatial organization of chiral structures, such as chromatin.