Chang Yu-Shan, Hsu Long, Huang Kuang-Lung
Appl Opt. 2018 Feb 10;57(5):1091-1099. doi: 10.1364/AO.57.001091.
An internally focusing design is developed for a compact endoscopic lens to have optical performance close to the diffraction limit. When changing the working distance from infinity to a predetermined short distance, the overall system length and the field of view remain constant. It is numerically demonstrated that the diffraction-limit-like performance is maintained over a wide range of working distances, showing a novel capability of adjustable focuses. The design concept is numerically proven to be feasible and can enable very high-resolution examination for doctors checking the positions of biological entities through the immediate capture of clear images at different working distances. The corresponding lens configuration, PNN, is shown to be useful in achieving the high-resolution performance once the number of lens elements is four, where P and N are used to denote positive and negative optical power, respectively, for the lens groups. A corresponding tolerance analysis is also presented.
为紧凑型内窥镜镜头开发了一种内聚焦设计，使其光学性能接近衍射极限。当工作距离从无穷远改变到预定的短距离时，整个系统长度和视野保持不变。数值结果表明，在很宽的工作距离范围内都能保持类似衍射极限的性能，展现出一种新型的可调节聚焦能力。数值证明该设计概念是可行的，并且对于医生通过在不同工作距离下即时捕捉清晰图像来检查生物实体位置的操作而言，它能够实现非常高分辨率的检查。一旦透镜元件数量为四个，相应的透镜配置PNN被证明对于实现高分辨率性能很有用，其中P和N分别用于表示透镜组的正光焦度和负光焦度。还给出了相应的公差分析。
