Label-free multimodal polarization-sensitive optical microscope for multiparametric quantitative characterization of collagen.

Collagen is an essential component of biological tissues with a variety of subtypes. To be able to capture these subtypes, fully exploit the polarization-sensitive light-collagen interactions, and provide comprehensive information of collagen, we integrated polarization-sensitive second-harmonic generation (PSHG) microscopy, polarization-sensitive optical coherence microscopy (PSOCM), and two-photon fluorescence lifetime imaging microscopy into a single-source multimodal system in a simultaneous and spatially co-registered configuration. PSOCM information is used in the PSHG numerical model to enable accurate PSHG analysis of unsectioned fresh tissue. This polarization-sensitive multimodal system provides quantitative multiparametric characterization of collagen and facilitates the fundamental understanding of collagen in the unperturbed tissue microenvironment, which can enable future studies into the role of collagen in various diseases.