Quadriwave gradient light inteference microscopy for lable-free thick sample imaging

Abstract

Due to the multiple scattering effect, quantitative phase imaging of thick specimens is challenging in biomedicine research. Phase gradient methods with partially coherent illumination in the reflection geometry have significant potential. However, to reconstruct two-dimensional (2D) phase information robustly, these methods cannot avoid changing the shear direction orthogonally. Here we propose a rotation-free method named quadriwave gradient light interference microscopy (qGLIM). qGLIM excludes conventional shear components and uses an amplitude-type spatial light modulator (SLM) to perform lateral shearing and phase shifting. By displaying checkerboard gratings on the SLM, we can reconstruct phase gradient information in orthogonal shear directions simultaneously. We extract the phase quantitatively by applying the phase-shifting technique and deconvolution algorithm. We demonstrate this approach by standard samples, thin samples, and thick multiple scattering samples.