Implementation of free-space Fourier Ptychography with near maximum system numerical aperture.
Implementation of free-space Fourier Ptychography with near maximum system numerical aperture.
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DOI：
10.1364/oe.459833
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发表时间：
2022-05
期刊：
影响因子：
3.8
通讯作者：
Mingshu Liang;Changhuei Yang
中科院分区：
文献类型：
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作者：
Mingshu Liang;Changhuei Yang
在过去的十年里，傅立叶断层扫描显微镜(FPM)的研究领域取得了许多创新性的进展，大大扩展了它的用途。在这里，我们报告了一种高数值孔径(NA)的FPM实现，它结合了其中的一些创新，以获得1.9的合成NA-接近自由空间FPM系统可能的最大合成NA 2。在这种高合成NA下，我们实验发现，为了获得最佳分辨率，使照明场均匀是至关重要的。我们的FPM实现对于465 nm的光具有266 nm的全音高分辨率，景深为3.6微米。相比之下，对于接近最大可能的NA为0.95的标准透射式显微镜，对于465 nm的光的全音向分辨率为318 nm，景深为0.65微米。虽然通常假设自由空间相干成像系统和自由空间非相干成像系统在各自的最大NA下工作应该具有类似的分辨率，但我们实验发现，FPM系统的分辨率显著高于其非相干标准显微镜对应系统的分辨率20%。再加上FPM的更长的有效景深(5.5倍长)，我们的工作表明，在接近最大NA操作区域，与非相干标准显微镜相比，FPM具有显著的分辨率和景深优势。
Over the past decade, the research field of Fourier Ptychographic Microscopy (FPM) has seen numerous innovative developments that significantly expands its utility. Here, we report a high numerical aperture (NA) FPM implementation that incorporates some of these innovations to achieve a synthetic NA of 1.9 - close to the maximum possible synthetic NA of 2 for a free space FPM system. At this high synthetic NA, we experimentally found that it is vital to homogenize the illumination field in order to achieve the best resolution. Our FPM implementation has a full pitch resolution of 266 nm for 465 nm light, and depth of field of 3.6 µm. In comparison, a standard transmission microscope (incoherent) with close to maximum possible NA of 0.95 has a full pitch resolution of 318 nm for 465 nm light, and depth of field of 0.65 µm. While it is generally assumed that a free-space coherent imaging system and a free-space incoherent imaging system operating at their respective maximum NA should give comparable resolution, we experimentally find that an FPM system significantly outperforms its incoherent standard microscopy counterpart in resolution by a factor of 20%. Coupled with FPM's substantially longer effective depth of field (5.5 times longer), our work indicates that, in the near-maximum NA operation regime, the FPM has significant resolution and depth of field advantages over incoherent standard microscopy.