• Journal of Korean Ophthalmic Optics Society
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• 제20권3호
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• pp.263-276
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• 2015

Purpose: The current study aimed to evaluate the reliability for the combined refractive power when a spherical lens and a cylindrical lens were overlapped in a trial frame. Methods: The refractive powers, central thickness and peripheral thickness of spherical trial lenses and cylindrical lenses with negative power were measured. The combined refractive power of the spherical and cylindrical lenses was measured by auto lens meter. Measurement was repeated by changing the insertion order, and their results were further compared with the calculated combined refractive power. Results: There was no correlation between the variation of central and peripheral thickness in trial lenses and that of the lens power. Among 79 trial lenses, 3 trial lenses wasn't met the international standard. The refractive power calculated by Gullstrand's formula that could compensate vertex distance had smaller difference with the estimated power when compared with that calculated by thin lens formula however, it was significantly different from the estimated power. The refractive powers were generally apparent regardless of the insertion order of a spherical lens and a cylindrical lens: thin lens formula > actual measurements > Gullstrand's formula. The error was only found in cylindrical power calculated by Gullstrand's formula when inserted a spherical lens inside and a cylindrical lens outside however, the error was found in both of cylindrical and spherical powers calculated by Gullstrand's formula when inserted as a opposite order. By comparing actual measurements of equivalent spherical power, the accuracy was higher and the possibility of over-correction was lower when inserted a spherical lens inside and a cylindrical lens outside. Conclusions: From the results, those were revealed that the combined refractive power is influenced by the factors other than the vertex distance and the refractive power varies in accordance with the insertion order of a spherical lens and a cylindrical lens. Thus, it can be suggested that the establishment of standard for these is neccesaty.

• Resources Recycling
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• 제7권5호
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• pp.41-45
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• 1998

A Hew way of contact angle measurement is derived based on simple geometrical calculation. Without using complicated contact angle measurement instrument. Just measuring the diameter and height of liquid lens made it possible to calculate the contact angle value with a reasonable reliability. To validate the contact angle value obtained by this method, contact angle of the same liquid lens is measured using conventional goniometer and it is verified that two values are nearly same within the limit of observational error.

• Journal of Korean Ophthalmic Optics Society
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• 제2권1호
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• pp.55-60
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• 1997

Numerically compares a calculation about a variable process of visual acuity for a artificial myopia with previously the tested result. The calculation is used to the value of Gullstrand's theoretical eyes and a method of geometrical optics. The theoretical eye simplified a entrance pupil and retina. Optical lens and eye changed a equivalent lens. Refractive power of a equivalent lens is converted to focal length within theoretical eyes, and this was calculated about relation of a blur circle on the retina and visual acuity.

• Korean Journal of Optics and Photonics
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• 제5권3호
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• pp.364-371
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• 1994

Real-time MTF measuring system for testing microlens arrays with a linear CCD array is developed. The spread function of slit image that is relayed and magnified by a microscopic object lens can be measured at several times in a second. The signal uniformity and MTF of CCD is also calibrated. The experimental result of micro lens arrays developed for contact image sensor is presented.sented.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.473-476
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• 2015

본 논문에서는 영상의 명암도 분포도를 효과적으로 조정하기 위해 개선된 퍼지 스트레칭 기법을 제안하여 적용한다. 개선된 퍼지 스트레칭이 적용된 영상에서 소벨 마스크를 이용하여 에지를 추출한다. 추출된 에지영상에 퍼지 추론 기법을 적용하여 흠집 크기에 대한 소속도와 중심과 흠집간의 거리에 대한 소속도를 구한 후에 퍼지 추론 기법을 적용하여 흠집이 눈에 미치는 영향 정도를 분석한다. 본 논문에서 제안된 방법의 성능을 평가하기 위해 CHEMI, MID, HL, HM와 같은 시력 보정용 렌즈 영상을 대상으로 실험한 결과, 제안된 방법이 기존 렌즈 흠집 추출 방법보다 흠집 영역이 정확히 추출되고 눈에 미치는 영향을 효과적으로 분석할 수 있는 가능성을 확인하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제19권11호
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• pp.1-7
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• 2018

In a microcolumn, a miniaturized electrostatic deflector is often adopted to scan an electron beam. Usually, a double octupole deflector is used because it can avoid excessive spherical aberrations by controlling the electron beam path close to the optical axis of the objective lens and has a wide scan field. Studies on microcolumns have been performed to improve the low throughput of an electron column through multiple column applications. On the other hand, as the number of microcolumns increases, the number of wires connected to the components of the microcolumn increases. This will result in practical problems during the process of connecting the wires to electronic controllers outside of the vacuum chamber. To reduce this problem, modified quadrupole and octupole deflectors were examined through simulation analysis by selecting an ultraminiaturized microcolumn with the Einzel lens eliminated. The modified deflectors were designed changing the size of each electrode of the conventional Si octupole deflector. The variations of the scan field and electric field strength were studied by changing the size of active electrodes to which the deflection voltage was to be applied. The scan field increased linearly with increasing deflection voltage. The scan field of the quadrupole deflector and the electric field strength at the center were calculated to be approximately 1.3 ~ 2.0 times larger than those of the octupole deflector depending on the electrode size.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제39C권12호
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• pp.1318-1322
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• 2014

We develop new sonar system by way of acoustic focusing which is totally different from conventional one in principle. It focuses input wave on the opposite edge of the lens without aberration perfectly. Then, the motion of acoustic source is read by naked eyes. It can be used as an acoustic window deep underwater by converting sound into light. We introduce the sonar in actual size that can be used underwater and report current situation of the development.

• Korean Journal of Optics and Photonics
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• 제13권3호
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• pp.258-265
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• 2002

In this paper, we design single and symmetrical double lenses with DOE. The specifications are the following : Image area is 4.8 mm $\times$ 3.6 mm, F/# is 2.8 and the overall length (from first lens surface to image plane) is 6.8mm. After comparing the optical performance and characteristic values, we determine that symmetrical double lenses are superior to single lenses. Symmetrical double lenses have the merits of fewer zones, weaker flare, and smaller distortion than single lenses.

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.256.1-256.1
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• 2014

21세기 정보화 시대의 도래와 함께 반도체 및 디스플레이 분야는 고부가가치산업으로 급격히 성장하였고, 현재까지도 미래의 지속적인 시장 창출을 위하여 기술개발과 투자로 초미세화, 고효율, 대면적화에 대한 원천기술 확보가 중요시되고 있다. 반도체 및 디스플레이의 대면적화가 진행됨에 따라 플라즈마 공정장비의 대면적화도 활발히 기술개발이 진행되고 있으며, 대면적화에 있어 플라즈마의 공간균일도는 생산수율 및 공정균일화를 위해 기본적으로 평가되어야 하는 중요한 지표가 되었다. 하지만 종래의 진단법들은 대면적 플라즈마 진단에 매우 제한적이기 때문에 본 연구에서는 대면적 플라즈마의 공간균일도 평가를 위해 플라즈마의 방출광 측정을 기초로 하는 진단계를 개발하였다. 플라즈마 방출광을 이용한 진단은 플라즈마에 섭동을 주지 않고 전자온도의 변화 및 공간균일도를 평가할 수 있다. 이 진단법은 두 마주보는 한쪽 면이 평평한 볼록렌즈(plano-convex lens)로 이루어진 수광시스템과 역변환 알고리즘을 통해 선 적분된 방출광으로부터 플라즈마 방출광의 국지적 정보를 측정하는 것이다. 플라즈마와 같이 크기가 큰 광원의 경우 렌즈 광학계에서 필연적으로 수반되는 선적분된(chord-integrated) 방출광을 제거하기 위해 구조에 따른 시스템 함수를 이용한 푸리에 변환 알고리즘을 개발하였고, 이를 통해 렌즈 초점거리의 정확한 방출광 세기만 재구성하였다. 이러한 재구성 방법을 이용하여 렌즈의 거리를 움직이며 대면적 플라즈마의 방출광 분포측정을 수행하였고, 이에 대한 결과를 발표하고자 한다.

• Elastomers and Composites
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• 제44권4호
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• pp.366-372
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• 2009

The present study covers the optimal design for a lens module in a mobile phone camera by using the design of experiments (DOE) and finite element (FE) analysis. FE analyses are performed to investigate the effect of design parameters on the amount of torque required to assemble a barrel and a housing part. The DOE approach is then performed to optimize the design parameters in order to maintain an appropriate torque with less variations.