Exploring different textures of a nematic liquid crystal for quantitative Fourier phase contrast microscopy

Abstract

Quantitative phase microscopy (QPM) has emerged as a viable technique for investigating biological and biomedical samples in its natural environment. Contrary to well established phase microscopes, QPM provides phase map of the optical path length delays introduced by the specimen. Building on our prior technology of the Fourier phase contrast microscopy (FPCM) technique, we present a low-cost and robust quantitative Fourier phase contrast microscopy system that can easily be attached to most commercial brightfield microscopes. This is derived by merging the FPCM technique with phase shifting interferometry. By applying voltages across a nematic liquid crystal cell with various anchoring properties, Stokes’ parameters are obtained to unwrap the object information quantitatively. Further three different nematic textures were considered to improve the utility of the phase unwrapping: planar, twisted, and hybrid. Our results indicate that the hybrid nematic film presents the best phase contrast filter.