Jin Di, Zhou Renjie, Yaqoob Zahid, So Peter T C
Opt Express. 2018 Jan 8;26(1):428-437. doi: 10.1364/OE.26.000428.
Optical diffraction tomography (ODT) is an emerging microscopy technique for three-dimensional (3D) refractive index (RI) mapping of transparent specimens. Recently, the digital micromirror device (DMD) based scheme for angle-controlled plane wave illumination has been proposed to improve the imaging speed and stability of ODT. However, undesired diffraction noise always exists in the reported DMD-based illumination scheme, which leads to a limited contrast ratio of the measurement fringe and hence inaccurate RI mapping. Here we present a novel spatial filtering method, based on a second DMD, to dynamically remove the diffraction noise. The reported results illustrate significantly enhanced image quality of the obtained interferograms and the subsequently derived phase maps. And moreover, with this method, we demonstrate mapping of 3D RI distribution of polystyrene beads as well as biological cells with high accuracy. Importantly, with the proper hardware configuration, our method does not compromise the 3D imaging speed advantage promised by the DMD-based illumination scheme. Specifically, we have been able to successfully obtain interferograms at over 1 kHz speed, which is critical for potential high-throughput label-free 3D image cytometry applications.
光学衍射层析成像（ODT）是一种新兴的显微技术，用于对透明样本进行三维（3D）折射率（RI）映射。最近，为了提高ODT的成像速度和稳定性，人们提出了基于数字微镜器件（DMD）的角度控制平面波照明方案。然而，在已报道的基于DMD的照明方案中，总是存在不期望的衍射噪声，这导致测量条纹的对比度有限，从而导致折射率映射不准确。在此，我们提出一种基于第二个DMD的新型空间滤波方法，以动态去除衍射噪声。所报道的结果表明，所获得的干涉图以及随后导出的相位图的图像质量得到了显著提高。此外，通过这种方法，我们展示了对聚苯乙烯珠以及生物细胞的三维折射率分布进行高精度映射。重要的是，在适当的硬件配置下，我们的方法不会损害基于DMD的照明方案所承诺的三维成像速度优势。具体而言，我们已经能够以超过1 kHz的速度成功获得干涉图，这对于潜在的高通量无标记三维图像细胞术应用至关重要。
