差分相衬(Differential phase contrast, DPC)成像是一种基于部分相干照明调控的无标记非干涉相位成像方法, 它为未染色透明样品提供了一种快速、有效且高分辨率的可视化手段。DPC通过多次非对称照明调控或非对称孔径调制使不可见的样品相位信息转换为成像器件可直接探测的强度信号, 从而为定性相衬成像甚至定量相位重建提供了可能。近年来, 随着该领域研究的逐步深入, 成像的相位传递函数得以明确推导, DPC已经逐步从定性观察走向了定量研究。另一方面, 得益于全孔径照明调控和高效相位反卷积算法, DPC定量相位成像的空间分辨率可达到非相干衍射极限, 并能够获得低噪声、高精度的定量相位重构结果。通过与三维光学传递函数理论交融借鉴, DPC最近已被进一步拓展到了三维衍射层析领域, 实现了厚样品三维折射率的定量成像。文中从DPC成像方法的基本原理、成像系统与算法优化等几个方面对其历史发展、研究现状和最新进展进行了详细综述, 并讨论了该方法现存的一些关键问题以及今后可能的研究方向。

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.