Rapid Stokes polarimetry for studying the process of optical tissue clearing

Abstract

Polarization imaging has shown great potentials in biomedical studies, due to its sensitivity to microstructural changes and anisotropic optical effects in biological tissues and contrast between lesion site and normal tissue. However, for total polarization measurement, no matter Muller matrix or Stokes vectors, their imaging processes are both time-consuming and not suitable for dynamic physiological monitoring. In this study, we proposed a method to obtain rapid continuous Stokes images and present it application in tissue characterization with clearing. We use single rotating retarder configuration to attain 2D Stokes vector images, the tissue clearing process and the Stokes measurement are carried synchronously on our vertical experimental device. According to the representation of the Stokes vectors on the Poincare sphere, we extract the linear-retardance and circular-depolarization parameters to characterize the microstructures of biological samples, and valid them by two tissue experiments. We show the dynamic Stokes imaging sequences of two types of in vitro tissue samples with clearing on the resolution board, and evaluate the clearing induced temporal variations quantitatively based on the polarization parameters. These experimental results demonstrate the feasibility of our rapid Stokes imaging based on Stokes measurement, implying a potential application in the tissue administration and physiological process.