In one of our recent studies, we have shown that a large defocusing distance in the transport of intensity equation (TIE) is required to retrieve the phase information in low-light conditions (OSA Continuum 3 (2020) 236). It has been found that image misalignment issues come into the picture due to translation of the camera for large distances, which creates artifacts in phase recovery. The issue of misalignment can be overcome if, instead of the object, we use the digital hologram of the object for the required defocused intensities and then apply the TIE. In this paper, we demonstrate low-light phase imaging by combining digital holography with the TIE. We reconstruct the required multiple intensity distributions from the captured in-line digital hologram. To implement the low-level light illumination, a variable neutral density filter has been used while recording the in-line digital hologram. Simulation and experimental results with different objects (United States air-force chart and glue drop) are presented. To simulate the low-light conditions, a Poisson distribution based photon-counting imaging technique has been applied.

在我们最近的一项研究中，我们已经表明，在弱光条件下检索相位信息需要强度方程 (TIE) 传输中的较大散焦距离 (OSA Continuum 3 (2020) 236)。已经发现，由于相机的长距离平移，图像未对准问题会出现在图片中，这会在相位恢复中产生伪影。如果我们使用物体的数字全息图而不是物体来达到所需的散焦强度，然后应用 TIE，则可以克服未对准问题。在本文中，我们通过将数字全息与 TIE 相结合来演示低光相位成像。我们从捕获的在线数字全息图中重建所需的多个强度分布。为了实现低级光照，在记录在线数字全息图时使用了可变中性密度滤光片。展示了不同物体（美国空军图表和胶滴）的模拟和实验结果。为了模拟低光照条件，已经应用了基于泊松分布的光子计数成像技术。