Alexandropoulos Christos, Rodríguez-Suñé Laura, Duocastella Martí
Department of Applied Physics, Universitat de Barcelona, C/Martí i Franquès 1, 08028 Barcelona, Spain.
Institut de Nanociència I Nanotecnologia (IN2UB), Universitat de Barcelona, Av. Diagonal 645, 08028 Barcelona, Spain.
Sensors (Basel). 2025 Jul 20;25(14):4503. doi: 10.3390/s25144503.
The transport of intensity equation enables quantitative phase imaging from only two axially displaced intensity images, facilitating the characterization of low-contrast samples like cells and microorganisms. However, the rapid selection of the correct defocused planes, crucial for real-time phase imaging of dynamic events, remains challenging. Additionally, the different images are normally acquired sequentially, further limiting phase-reconstruction speed. Here, we report on a system that addresses these issues and enables user-tuned defocusing with snapshot phase retrieval. Our approach is based on combining multi-color pulsed illumination with acousto-optic defocusing for microsecond-scale chromatic aberration control. By illuminating each plane with a different color and using a color camera, the information to reconstruct a phase map can be gathered in a single acquisition. We detail the fundamentals of our method, characterize its performance, and demonstrate live phase imaging of a freely moving microorganism at speeds of 150 phase reconstructions per second, limited only by the camera's frame rate.
强度传输方程能够仅从两个轴向位移的强度图像进行定量相位成像，便于对细胞和微生物等低对比度样本进行表征。然而，对于动态事件的实时相位成像至关重要的正确散焦平面的快速选择仍然具有挑战性。此外，不同图像通常是顺序采集的，这进一步限制了相位重建速度。在此，我们报告一种解决这些问题并通过快照相位检索实现用户调谐散焦的系统。我们的方法基于将多色脉冲照明与声光散焦相结合，以实现微秒级色差控制。通过用不同颜色照亮每个平面并使用彩色相机，可以在一次采集中收集重建相位图所需的信息。我们详细介绍了我们方法的基本原理，表征了其性能，并展示了对自由移动微生物的实时相位成像，速度可达每秒150次相位重建，仅受相机帧率限制。
