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 mm² 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途的高通量计算显微镜技术，因为它具有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，大多数当前的无透镜显微镜方法被设计用于仅对二维薄样品进行成像。在整个视场和亚像素级别具有统一分辨率的无透镜片上断层扫描 (LFOCT) 仍然是一个严峻的挑战。在本文中，我们展示了一种新的 LFOCT 技术和基于波长扫描傅里叶叠层衍射断层扫描 (wsFPDT) 的相关成像平台。在 wsFPDT 中，样品不是使用角度可变照明，而是通过轴上波长可变照明（范围从 430 到 1200 nm）进行照明。记录相应的欠采样衍射图案，然后应用迭代叠图重建程序来填充三维 (3D) 散射势的光谱，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和原始图像精确配准过程中机械运动的需要，而且确保了整个成像视场的准均匀、像素超分辨成像分辨率。借助 wsFPDT，我们展示了高通量、十亿体素 3D 断层成像结果，在 29.85 mm ²的大视场中，半节距横向分辨率为 775 nm，轴向分辨率为 5.43 μm，成像深度为 >200 μm 。通过对各种类型的样品进行成像，包括微聚苯乙烯珠、硅藻和小鼠单核巨噬细胞，证明了该方法的有效性。 wsFPDT 具有揭示定量形态特性（例如大细胞群中单细胞的面积、体积和球形指数）的独特能力，使 wsFPDT 成为高通量生物应用的强大定量和免标记工具。