Review of the development of differential phase contrast microscopy

Differential phase contrast(DPC) is a labeled-free and non-interferometric phase imaging method based on partial coherent illumination control, which provides a fast, effective and high-resolution visualization method for unstained transparent samples. It converts invisible sample phase information into detected intensity signals through multiple asymmetric illumination modulation or asymmetric aperture modulation, thereby providing possibilities for qualitative phase contrast imaging and even quantitative phase reconstruction samples. In recent years, with the gradual deepening of research in this field, the phase transfer function(PTF) of DPC imaging was definitely deduced, and DPC has gradually advanced towards qualitative observation to quantitative research. On the other hand, owning to the full-aperture illumination control and high-efficiency phase deconvolution algorithm,DPC quantitative phase imaging can achieve the incoherent diffraction limit resolution, and obtain a low-noise, high-precision quantitative phase reconstruction result. Furthermore, drawing on the theory of three-dimensional(3D) optical transfer function, DPC has recently been extended to 3D diffraction tomography to achieve quantitative imaging of the 3D refractive index for thick samples. This paper reviews the historical development, research status and latest developments from the basic principles of DPC imaging methods, imaging systems and algorithm optimization, and discusses some key problems existing in this method and possible future research directions.