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http://dx.doi.org/10.3807/KJOP.2021.32.2.068

Optical Design of a Subminiature Catadioptric Omnidirectional Optical System with an LED Illumination System for a Capsule Endoscope  

Moon, Tae Sung (Department of Photonics and Sensors, Graduate School, Hannam University)
Jo, Jae Heung (Department of Photonics and Sensors, Graduate School, Hannam University)
Publication Information
Korean Journal of Optics and Photonics / v.32, no.2, 2021 , pp. 68-78 More about this Journal
Abstract
A subminiature catadioptric omnidirectional optical system (SCOOS) with 2 mirrors, 6 plastic aspherical lenses, and an illumination system of 6 light emitting diodes, to observe the 360° panoramic image of the inner intestine, is optically designed and evaluated for a capsule endoscope. The total length, overall length, half field of view (HFOV), and F-number of the SCOOS are 14.3 mm, 8.93 mm, 51°~120°, and 3.5, respectively. The optical system has a complementary metal-oxide-semiconductor sensor with 0.1 megapixels, and an illumination system of 6 light-emitting diodes (LEDs) with 0.25 lm to illuminate on the 360° side view of the intestine along the optical axis. As a result, the spatial frequency at the modulation transfer function (MTF) of 0.3, the depth of focus, and the cumulative probability of tolerance at the Nyquist frequency of 44 lp/mm and MTF of 0.3 of the optimized optical system are obtained as 130 lp/mm, -0.097 mm to +0.076 mm, and 90.5%, respectively. Additionally, the simulated illuminance of the LED illumination system at the inner surface of the intestine within HFOV, at a distance of 15.0 mm from the optical axis, is from a minimum of 315 lx to a maximum of 725 lx, which is a sufficient illumination and visibility.
Keywords
Lens design; Omnidirectional optical system; Capsule endoscope; Catadioptric omnidirectional optical system; Illumination design;
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Times Cited By KSCI : 1  (Citation Analysis)
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