Qu Yufu, Hu Yongbo
Department of Measurement Technology & Instrument, School of Instrumentation Science & Optoelectronics Engineering, Beihang University, Beijing, China.
Microsc Res Tech. 2019 Feb;82(2):101-113. doi: 10.1002/jemt.23113. Epub 2018 Nov 19.
Inserting an electrically tunable lens (ETL), such as liquid lens or tunable acoustic gradient lens, into a microscope can enable fast axial scanning, autofocusing, and extended depth of field. However, placing the ETL at different positions has different influences on image quality. Specially, in a wide-field microscope for measurement, the magnification has to be constant when introducing an ETL, otherwise it will affect measurement accuracy. To determine the best position of ETL, axial scanning range and magnification variation are quantitatively analyzed and discussed in finite and infinite microscopes through theoretical analysis, optical simulation, and experiment for four configurations: when ETL is placed at the back focal plane of objective, at the conjugate plane of objective's back focal plane between two relay lenses, or behind two relay lenses, and at imaging detector plane. The obtained results are as follows. When ETL is placed at the back focal plane, the system has a large scanning range, but the magnification varies because the back focal plane is inside the objective. When ETL is placed between two relay lenses, the magnification stays constant, but the scanning range is small. When ETL is placed behind two relay lenses, the magnification keeps invariant and the scanning range is large, but ETL and two relay lenses are inside the microscope and the system has to be customized. Finally, when ETL is placed at imaging detector plane, the magnification stays constant, but the scanning range is 0, which means the system has no axial scanning capability. RESEARCH HIGHLIGHTS: An electrically tunable lens (ETL) is introduced into a wide-field microscope for measurement. Axial scanning range and magnification variation are analyzed and discussed. Theoretical analysis, ZEMAX optical simulation and experiments are performed.
在显微镜中插入电可调透镜（ETL），如液体透镜或可调谐声梯度透镜，可以实现快速轴向扫描、自动聚焦和扩展景深。然而，将ETL放置在不同位置对图像质量有不同影响。特别地，在用于测量的宽视场显微镜中，引入ETL时放大倍数必须保持恒定，否则会影响测量精度。为了确定ETL的最佳位置，通过理论分析、光学模拟和实验，在有限和无限显微镜中对四种配置定量分析和讨论了轴向扫描范围和放大倍数变化：ETL放置在物镜后焦平面处、两个中继透镜之间物镜后焦平面的共轭平面处、两个中继透镜之后以及成像探测器平面处。得到的结果如下。当ETL放置在物镜后焦平面时，系统具有较大的扫描范围，但放大倍数会变化，因为后焦平面在物镜内部。当ETL放置在两个中继透镜之间时，放大倍数保持恒定，但扫描范围较小。当ETL放置在两个中继透镜之后时，放大倍数保持不变且扫描范围较大，但ETL和两个中继透镜在显微镜内部，系统必须定制。最后，当ETL放置在成像探测器平面时，放大倍数保持恒定，但扫描范围为0，这意味着系统没有轴向扫描能力。研究亮点：将电可调透镜（ETL）引入用于测量的宽视场显微镜中。分析和讨论了轴向扫描范围和放大倍数变化。进行了理论分析、ZEMAX光学模拟和实验。
