Browsing by Author "Chang, Yu-Shan"

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Adjustable-focus ultracompact endoscopic lens design with ultrahigh optical performance
(2018-02-10)
Chang, Yu-Shan
;
Hsu, Long
;
Huang, Kuang-Lung
;
電子物理學系
;
Department of Electrophysics
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. (c) 2018 Optical Society of America
Hybrid lens design for ultrawide-angle imaging with a high Strehl ratio in a folded system
(2018-07-01)
Chang, Yu-Shan
;
Hsu, Long
;
Huang, Kuang-Lung
;
電子物理學系
;
Department of Electrophysics
When UV-curable material is used with a spherical glass lens, it is classified as a hybrid lens and can provide a new degree of freedom in designing a lens system. This method is used to explore the optical limitation of an ultrawide-angle imaging system of a folded structure, which is utilized to achieve a compact volume. The f-number and field of view of the system are 2.0 and 190 degrees, respectively. Diffraction-limited performance is achieved within a field of view of 80 degrees with Strehl ratios greater than approximately 80%. Even at the maximum field of view of 190 degrees, the Strehl ratio is nearly 75%. The lens configuration is NNPNN, where N and P denote negative and positive optical power, respectively; this configuration uses only two aspherical hybrid lens surfaces. Comparisons of different optimizations are also provided. (C) 2018 Optical Society of America