Adjustable-focus ultracompact endoscopic lens design with ultrahigh optical performance

Yu Shan Chang*, Long Hsu, Kuang Lung Huang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


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 highresolution 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.

Original languageEnglish
Pages (from-to)1091-1099
Number of pages9
JournalApplied Optics
Issue number5
StatePublished - 10 Feb 2018

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