同时实现大视场、高分辨率成像是光学显微技术发展至今不断追求的永恒目标。传统光学显微镜由于其光学设计原理限制, 空间带宽积一般总是限制在百万像素量级, 从而无法同时兼顾高分辨率与大视场。另一方面, 复杂的光学系统也使显微镜变得日趋昂贵、笨重、复杂且难以维护, 极大地限制了其推广和应用。无透镜片上显微成像技术是近年来发展出的一种新概念计算成像技术: 其不利用成像透镜聚焦, 而直接将所观测的样本紧贴于成像器件光敏面上方记录图像, 并结合相应的图像恢复算法实现清晰物像的反演与重构。由于具有视野大、分辨率高、无需标记、成本低、便携性好和可实现三维(3D)成像等优点, 无透镜片上显微镜有望拓展传统显微成像技术的疆界, 成为一种新型的快捷、便携的就地检验(POCT)工具。文中从无透镜成像基本原理、实验系统、重构方法及其典型应用进行了综述。最后, 讨论了无透镜显微成像现存的一些关键问题以及今后可能的发展方向。

Wide field-of-view (FOV) and high-resolution is one of the goals of optical microscopy. However, limited by the optical design in traditional optical microscopes, the space bandwidth product (SBP) is generally in the order of megapixels, and thus, high-resolution and wide FOV cannot be achieved at the same time. On the other hand, complex optical systems have also made microscopes increasingly expensive, cumbersome, complex and difficult to maintain, greatly limiting their promotion and application. Lensfree on-chip microscopy is a new computational imaging technology: without the imaging lens to focus, the sample is directly attached to the imaging sensor to record the diffraction patterns and the object information can be achieved with the corresponding reconstructed method. Due to its wide FOV, high-resolution, label-free detection, low-cost, perfect portability and three-dimensional (3D) imaging, the lensfree on-chip microscope is expected to expand the boundaries of traditional microscopic imaging technology and becomes a new type of fast, point-of-care testing (POCT) tool. In this paper, a review was given to introduce the basic principles, experimental systems, reconstruction methods and applications of lens-free imaging. Finally, the changeling problems as well as future research directions were also discussed.