Nie Yunfeng, Gross Herbert, Zhong Yi, Duerr Fabian
Appl Opt. 2017 Jul 10;56(20):5630-5638. doi: 10.1364/AO.56.005630.
Most existing techniques that are typically used by specialists to image the cornea are based on point, slit, or annular scanning due to a narrow field of view. The difficulty in achieving a larger field of view comes from the convex shape of the human eyeball. Field curvature for a refractive imaging system with positive power is typically negative and thus a concave image surface. In order to view the full cornea and sclera with snapshot imaging, we calculate qualified two- and three-mirror solutions from Seidel aberration theory. A three-mirror solution is further optimized as a high-resolution off-axis imaging system using freeform surfaces, which can obtain a full-field tailored image shell without scanning. The lateral resolution on the cornea is about 10 μm with good modulation transfer function (MTF) and spot performance. To ease the assembly, a monolithic design is achieved with slightly lower resolution, leading to a potential mass production solution.
由于视野狭窄，大多数现有的由专家用于角膜成像的技术基于点扫描、狭缝扫描或环形扫描。实现更大视野的困难源于人眼球的凸形。具有正光焦度的折射成像系统的场曲通常为负，因此图像表面为凹面。为了通过快照成像观察整个角膜和巩膜，我们根据赛德尔像差理论计算出合格的双镜和三镜解决方案。三镜解决方案进一步优化为使用自由曲面的高分辨率离轴成像系统，该系统无需扫描即可获得全场定制的像壳。角膜上的横向分辨率约为10μm，具有良好的调制传递函数（MTF）和光斑性能。为了便于组装，采用了分辨率略低的整体式设计，从而形成了一种潜在的大规模生产解决方案。
