Swept-wavelength null polarimetry for highly sensitive birefringence laser scanning microscopy.

We have recently demonstrated a high-speed null polarimeter [Opt. Express30, 18889 (2022)10.1364/OE.454193OPEXFF1094-4087] based on passive polarization optics and using a fast swept-wavelength laser source. We report here its implementation in a laser-scanning microscope setup, enabling highly sensitive linear retardance imaging with a pixel dwell time of 10 μs. The instrument is also able to measure light depolarization induced by the sample. Images of biological samples, including cancerous tissue and cells, illustrate its performances.