• Current Optics and Photonics
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• v.8 no.5
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• pp.484-492
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• 2024

In response to the difficulty of synchronously obtaining multiwavelength images for fast two-dimensional (2D) temperature measurement, a multispectral framing imaging optical system is designed, based on the segmented-aperture imaging method and asymmetric surface shape. The system adopts a common-aperture four-channel array structure to synchronously collect multiwavelength temperature-field images. To solve the problem of asymmetric aberration caused by being off-axis, a model of the relationship between incident and outgoing rays is established to calculate the asymmetric custom surface. The designed focal length of the optical system is 80 mm, the F-number is 1:3.8, and the operating wavelength range is 0.48-0.65 ㎛. The system is divided into four channels, corresponding to wavelengths of 0.48, 0.55, 0.58, and 0.65 ㎛ respectively. The modulation transfer function value of a single channel lens is higher than 0.6 in the full field of view at 35 lp/mm. The experimental results show that the asymmetric-custom-surface imaging system can capture clear multiwavelength images of a temperature field. The framing imaging system can capture clear images of multiwavelength temperature fields, with high consistency in images of different wavelengths. The designed optical system can provide reliable multiwavelength image data for 2D temperature-field measurement.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.488-491
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• 2003

Biochip-based diagnostic technology is an effective, time- and money- saving way. But, biochip analyzer including CCD imaging system has a complete optical system. It is one of reasons that the cost of biochip analyzer is expensive with CCD imaging system. In this paper, We suggested the simple and effective optical system for biochip analyzer with CCD imaging system. It consists of two parts with the same structure but opposite direction. Each part consists of achromatic doublet and meniscus. Suggested optical system has less lenses than existing system and more efficiently.

• Journal of the Optical Society of Korea
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• v.19 no.5
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• pp.531-536
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• 2015

This paper presents a new graphical method for selecting a pair of optical glass and housing materials to simultaneously achromatize and athermalize a multilens system composed of many elements. To take into account the lens spacing and housing, we quantify the lens power, chromatic power, and thermal power by weighting the ratio of the paraxial ray height at each lens to them. In addition, we introduce the equivalent single lens and the expanded athermal glass map including a housing material. Even though a lens system is composed of many elements, we can simply identify a pair of glass and housing materials that satisfies the athermal and achromatic conditions. Applying this method to design a black box camera lens equipped with a 1/4-inch image sensor having a pixel width of $2{\mu}m$, the chromatic and thermal defocusings are reduced to less than the depth of focus, over the specified ranges in temperature and frequency.

• Current Optics and Photonics
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• v.7 no.3
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• pp.273-282
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• 2023

This paper presents a new method for redistributing effectively the first orders of each lens element to achromatize and athermalize an optical system, by introducing a novel method for adjusting the slope of an achromatic and athermal line. This line is specified by connecting the housing, equivalent single lens, and aberration-corrected point on a glass map composed of available plastic and glass materials for molding. Thus, if a specific lens is replaced with the material characterized by the chromatic and thermal powers of an aberration-corrected point, we obtain an achromatic and athermal system. First, we identify two materials that yield the minimum and maximum slopes of the line from a housing coordinate, which specifies the slope range of the line spanning the available materials on a glass map. Next, redistributing the optical first orders (optical powers and paraxial ray heights) of lens elements by moving the achromatic and athermal line into the available slope range of materials yields a good achromatic and athermal design. Applying this concept to design a mobile-phone camera lens, we efficiently obtain an achromatic and athermal system with cost-effective material selection, over the specified temperature and waveband ranges.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.12-13
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• 2002

The performance improvement of 40Gbit/s soliton transmission system employing nonlinear optical loop mirror (NOLM) as all-optical regenerative repeater is investigated. The switching characteristic of NOLM is optimized using our design strategies. By inserting the optical repeater where the eye-penalty of the transmitted signal becomes 1 ㏈, we achieve the improvement of 0.3㏈ eye-penalty resulting in further 480km transmission distance.

• Korean Journal of Optics and Photonics
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• v.32 no.2
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• pp.68-78
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• 2021

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.

• Korean Journal of Optics and Photonics
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• v.17 no.2
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• pp.113-119
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• 2006

We need a good image of the retina of the human eye in order to inspect or cure it. In this work, an optical system design for a retinal camera is studied and the finite schematic eye model made by Sang Gee Kim and Sung Chan Park is used. The optical system is composed of four lens groups. The rays of the entire object field are collected on the center by the 1st group and the objective is imaged by all the other groups. The image is detected by the CCD array and displayed by a monitor The 1st lens group is employed singlet and other groups are employed triplets. Ray aberrations, spot diagrams, diffraction line spread functions and MTFs are calculated for optical performance assessment. This design may be very useful for the development of a retinal camera with high performance.

• Korean Journal of Optics and Photonics
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• v.28 no.5
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• pp.241-249
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• 2017

This paper presents the design and evaluation of the optical system for an uncooled thermal-imaging camera. The operating wavelength range of this system is from $7.7{\mu}m$ to $12.8{\mu}m$. Through optimization, we have obtained a LWIR (Long Wave Infrared) optical system with a focal length of 5.44 mm, which consists of four aspheric surfaces and two diffractive surfaces. The f-number of the optical system is F/1.2, and its field of view is $90^{\circ}{\times}67.5^{\circ}$. The hybrid lens was used to balance the higher-order aberrations, and its diffraction properties were evaluated by scalar diffraction theory. We calculated the polychromatic integrated diffraction efficiency, and the MTF drop generated by background noise. We have evaluated the thermal compensation of a LWIR fixed optical system, which is optically passively athermalized to maintain MTF performance in the focal depth. In conclusion, these design results are useful for an uncooled thermal-imaging camera.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.308-309
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• 2003

최근 광통신의 발전은 광 통신 소자의 제작시 집적화, 소형화, 경량화 그리고 저가격화를 원하게 되었다. 이러한 문제점을 해결하기 위해, 기판 위에 광소자를 집적하는 미세 광학 벤치 (Micro Optical Bench)에 대한 많은 연구가 진행되고 있는 중이다. MEMS(Micro Electro Mechanical System) 공정기술인 벌크(bulk) 마이크로 머시닝 기술을 이용함으로서 하나의 기판 위에 광소자들을 조립하는 미세 광학 벤치를 구현 할 수 있다. (중략)

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.109-112
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• 2003

Wavelength division multiplexing technology is a promising solution for the next generation optical networks. Optical buffer is a key component for optical packet switching system. It can be used to hold optical packets and to resolve the contention of optical packets. In this paper, we implemented a optical buffer using optical wavelength converters and demonstrated that optical packets are delayed successfully.