Wu Xuejuan, Zhou Ning, Chen Yang, Sun Jiasong, Lu Linpeng, Chen Qian, Zuo Chao
Smart Computational Imaging (SCI) Laboratory, Nanjing University of Science and Technology, No. 200 Xiaolingwei Street, 210094, Nanjing, Jiangsu, China.
Smart Computational Imaging Research Institute (SCIRI) of Nanjing University of Science and Technology, 210094, Nanjing, Jiangsu, China.
Light Sci Appl. 2024 Sep 5;13(1):237. doi: 10.1038/s41377-024-01568-1.
Lens-free on-chip microscopy is a powerful and promising high-throughput computational microscopy technique due to its unique advantage of creating high-resolution images across the full field-of-view (FOV) of the imaging sensor. Nevertheless, most current lens-free microscopy methods have been designed for imaging only two-dimensional thin samples. Lens-free on-chip tomography (LFOCT) with a uniform resolution across the entire FOV and at a subpixel level remains a critical challenge. In this paper, we demonstrated a new LFOCT technique and associated imaging platform based on wavelength scanning Fourier ptychographic diffraction tomography (wsFPDT). Instead of using angularly-variable illuminations, in wsFPDT, the sample is illuminated by on-axis wavelength-variable illuminations, ranging from 430 to 1200 nm. The corresponding under-sampled diffraction patterns are recorded, and then an iterative ptychographic reconstruction procedure is applied to fill the spectrum of the three-dimensional (3D) scattering potential to recover the sample's 3D refractive index (RI) distribution. The wavelength-scanning scheme not only eliminates the need for mechanical motion during image acquisition and precise registration of the raw images but secures a quasi-uniform, pixel-super-resolved imaging resolution across the entire imaging FOV. With wsFPDT, we demonstrate the high-throughput, billion-voxel 3D tomographic imaging results with a half-pitch lateral resolution of 775 nm and an axial resolution of 5.43 μm across a large FOV of 29.85 mm and an imaging depth of >200 μm. The effectiveness of the proposed method was demonstrated by imaging various types of samples, including micro-polystyrene beads, diatoms, and mouse mononuclear macrophage cells. The unique capability to reveal quantitative morphological properties, such as area, volume, and sphericity index of single cell over large cell populations makes wsFPDT a powerful quantitative and label-free tool for high-throughput biological applications.
无透镜片上显微镜是一种强大且有前景的高通量计算显微镜技术，因其在成像传感器的整个视场（FOV）上创建高分辨率图像的独特优势。然而，当前大多数无透镜显微镜方法仅设计用于对二维薄样品进行成像。在整个FOV上以及亚像素水平具有均匀分辨率的无透镜片上断层扫描（LFOCT）仍然是一项关键挑战。在本文中，我们展示了一种基于波长扫描傅里叶叠层衍射断层扫描（wsFPDT）的新型LFOCT技术及相关成像平台。在wsFPDT中，样品由轴上波长可变照明（范围为430至1200nm）照明，而不是使用角度可变照明。记录相应的欠采样衍射图案，然后应用迭代叠层重建程序来填充三维（3D）散射势的频谱，以恢复样品的3D折射率（RI）分布。波长扫描方案不仅消除了图像采集期间的机械运动需求以及原始图像的精确配准需求，而且在整个成像FOV上确保了准均匀、像素超分辨的成像分辨率。借助wsFPDT，我们展示了高通量、十亿体素的3D断层成像结果，在29.85mm的大FOV和大于200μm的成像深度上，横向分辨率为半间距775nm，轴向分辨率为5.43μm。通过对各种类型的样品成像，包括微聚苯乙烯珠、硅藻和小鼠单核巨噬细胞，证明了所提出方法的有效性。wsFPDT独特的揭示单细胞定量形态特性（如大面积细胞群体中的面积、体积和球形指数）的能力，使其成为高通量生物学应用的强大定量且无标记工具。
