相位恢复与定量相位成像是光学测量与成像技术领域的一个重要课题。传统干涉测量法依赖高度相干光源的干涉叠加，干涉装置复杂，测量环境要求苛刻，引入的散斑噪声极大地限制了传统干涉测量法在显微成像领域的应用。光强传输方程(TIE)作为最具代表性的相位恢复方法之一，为定量相位成像提供了一种新的非干涉手段。近些年来，该方法在国内外得到广泛研究与关注，发展迅速，成果显著，在自适应光学、X射线衍射光学、电子显微学、光学显微成像等领域展现了巨大的应用潜力。从光强传输方程的基本原理、方程求解、光强轴向微分的差分估计、部分相干成像与光场成像等几方面综述了光强传输方程在光学成像领域，特别是定量相位显微成像领域的研究现状与最新进展，并针对现存问题以及今后的研究方向提出了建议。

Phase retrieval and quantitative phase imaging are central subjects in optical measuring and imaging technologies. The most well-established method for obtaining quantitative phase is through interferometry. However, this class of methods relies heavily on the superposition of two beams with a high degree of coherence, and complex interferometric device, stringent requirement on the environmental stability, and associated laser speckle noise greatly limit its applications in the field of microscopic imaging. On a different note, as one of the typical phase retrieval approaches, the transport of intensity equation (TIE) provides a new non-interferometric way to access the quantitative phase information. In recent years, it has been extensively studied and remarkable advancements have been made in the fields of adaptive optics, X-ray diffraction imaging, electron microscopy, and optical microscopy. In this work, we will review the basic principles and some recent advances in TIE phase retrieval, including its solutions, axial intensity derivative estimation, partially coherent imaging and light field imaging, with emphasis on its applications in the field of quantitative phase microscopy. The challenging problems as well as future research directions will also be discussed.