Fast isotropic quantitative differential phase contrast microscopy using radially asymmetric color pupil

Differential phase contrast microscopy based on twelve-axis measurements of half-circle pupil acquires isotropic phase information but suffers with poor imaging speed. We proposed a new method by modulating illumination pattern to realize isotropic PTF within three-axis measurements. Not only provide phase information reconstruction under isotropic phase transfer function in fast imaging speed but also avoid particular imaging issue including motion-blur and low-illumination images. By modulate illumination pattern with programmable thin-fin-transistor(TFT) panel as digital pupil, we design radially asymmetric pupil to achieve isotropic PTF within three-axis measurements. To further improve imaging speed, wavelength-multiplexing approach is implemented by color camera. By pupil engineering, 12-times imaging speed improvement compared with twelve-axis measurements of half-circle pupil is attained. Color-leakage, which is the cross-talk under wavelength-multiplexing, was already calibrated by color-leakage correction as well. Meanwhile, accuracy of phase recover reach 97% by using 10 mu m polystyrene microspheres to guarantee correct result. In our method, color radially asymmetric pupil based on pupil engineering provide lots superiority including high imaging speed, measurement under isotropic phase transfer function, high accuracy of phase recover and immune from imaging issue such as motion-blur and low-illumination images.