• Journal of the Optical Society of Korea
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• 제20권2호
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• pp.283-290
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• 2016

This study presents an 8x four-group inner-focus zoom lens with one-moving group for a compact camera by use of a focus tunable lens (FTL). In the initial design stage, we obtained the powers of lens groups by paraxial design based on thin lens theory, and then set up the zoom system composed of four lens modules. Instead of numerically analytic analysis for the zoom locus, we suggest simple analysis for that using lens modules optimized. After replacing four groups with equivalent thick lens modules, the power of the fourth group, which includes a focus tunable lens, is designed to be changed to fix the image plane at all positions. From this design process, we can realize an 8x four-group zoom system having one moving group by employing a focus tunable lens. The final designed zoom lens has focal lengths of 4 mm to 32 mm and apertures of F/3.5 to F/4.5 at wide and tele positions, respectively.

• 한국안광학회지
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• 제5권1호
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• pp.155-157
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• 2000

A variable process of blur circle is calculated for a artificial hyperopia. The calculation is used to the value of Gullstrand's theoretical eye and a method of geometrical optics. The theoretical eye simplified a entrance pupil and the retina. Ophthalmic lens and eye changed a equivalent lens. Refractive power of a equivalent lens is converted to focal length within theoretical eye, and this is calculated about relation of a blur circle on the retina and ophthalmic lens.

• Journal of the Optical Society of Korea
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• 제17권2호
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• pp.219-223
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• 2013

The purpose of this study was to determine the relationship between the spherical equivalent visual acuity (VA) and uncorrected astigmatism. On 108 emmetropic eyes, the spherical equivalent VA was measured for cross cylindrical lens (CC lens)-induced astigmatic eyes and the VA-astigmatism relation determined. On 158 astigmatic eyes, the spherical equivalent VA and corrected astigmatism were measured and the measured values were compared with the calculated values from the VA-astigmatism relation by correlation coefficient analysis. Subsequent to that, the relationship between spherical equivalent VA and uncorrected astigmatism was made. The relationship was fitted for an exponential equation. Correlation coefficient between calculated values by equation and measured values for astigmatic eyes was 0.991 (p<0.01). The relationship between the spherical equivalent VA and the uncorrected astigmatism was decided as follows (spherical equivalent VA / uncorrected astigmatism): 1.0 / 0.25 D, 0.9 / 0.50 D, 0.8 / 0.75 D, 0.7 / 1.00 D, 0.6 / 1.25 D, 0.5 / 1.50 D, 0.4 / 2.00 D, 0.3 / 2.50 D, 0.2 / 3.00 D, 0.1 / 4.00 D, and 0.05 / 4.75 D. In conclusion, the relationship table devised from this study is a useful reference for predicting uncorrected astigmatism by measurement of decimal VA in spherical equivalent.

• 한국광학회지
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• 제33권6호
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• pp.275-286
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• 2022

광학설계 과정의 첫 단계에서 근축 광선이 만족하는 Gauss 방정식에 대한 해를 구할 수 있는 재귀적 수치 계산법을 도출하였다. 설계 사양으로 렌즈 모듈의 굴절력, 렌즈 제1 주요면으로의 입사각과 제2 주요면으로부터의 출사각이 주어지면 렌즈의 주요면 사이의 거리를 선택한 후, 재귀적 수치 계산법을 적용하여 렌즈의 두께, 렌즈 앞면의 곡률 반경과 뒷면의 곡률 반경을 구할 수 있다. 즉, 설계 사양을 만족하는 두께가 다른 여러 등가렌즈를 얻을 수 있다. 모듈이 2개 이상의 렌즈로 구성되는 경우에도 렌즈의 개수를 하나씩 증가하면서 렌즈의 주요면 사이의 거리를 설계 사양에 맞추어 선택한 후 각 렌즈의 두께와 곡률 반경을 결정할 수 있다.

• 한국안광학회지
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• 제2권1호
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• pp.55-60
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• 1997

인위적인 근시상태에서 시력회복과정을 수치적으로 추적하여 이미 검사된 결과와 비교하였다. 계산은 광학모형안의 수치와 기하 광학적 방법을 사용하였다. 모형안은 입사동과 망막으로 단순화하였고, 렌즈와 눈을 하나의 렌즈로 등가하였다. 또 등가렌즈 굴절력을 모형안 내에서 초점거리로 바꾸고 이것을 다시 망막에서 착란원의 크기로 환산하여 시력과의 관계로 계산하였다.

• Journal of the Optical Society of Korea
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• 제19권5호
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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.

• Journal of Radiation Protection and Research
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• 제47권2호
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• pp.86-92
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• 2022

Background: The present study investigated the radiation dose distribution of balloon kyphoplasty (BKP) among surgeons and medical staff, and this is the first research to observe such exposure in Japan. Materials and Methods: The study subjects were an orthopedic surgeon (n = 1) and surgical staff (n = 9) who intervened in BKP surgery performed at the National Hospital Organization Disaster Medical Center (Tokyo, Japan) between March 2019 and October 2019. Only disposable protective gloves (0.022 mmPb equivalent thickness or less) and trunk protectors were used, and no protective glasses or thyroid drapes were used. Results and Discussion: The surgery time per vertebral body was 36.2 minutes, and the fluoroscopic time was 6.8 minutes. The average exposure dose per vertebral body was 1.46 mSv for the finger (70 ㎛ dose equivalent), 0.24 mSv for the lens of the eye (3 mm dose equivalent), 0.11 mSv for the neck (10 mm dose equivalent), and 0.03 mSv for the chest (10 mm dose equivalent) under the protective suit.The estimated cumulative radiation exposure dose of 23 cases of BKP was calculated to be 50.37 mSv for the fingers, 8.27 mSv for the lens, 3.91 mSv for the neck, and 1.15 mSv for the chest. Conclusion: It is important to know the exposure dose of orthopedic surgeons, implement measures for exposure reduction, and verify the safety of daily use of radiation during surgery and examination.

• 대한안과학회지
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• 제59권12호
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• pp.1129-1136
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• 2018

목적: 백내장수술 후 다초점인공수정체인 BunnyLens $MF^{(R)}$를 삽입한 환자의 수술 전과 수술 후 근거리 및 원거리에서의 시력교정에 관한 임상적 유용성을 알아보고자 하였다. 대상과 방법: 백내장으로 진단을 받고 다초점인공수정체 삽입술을 시행한 환자 중에서 $ReSTOR^{(R)}$를 삽입한 39안을 대조군, BunnyLens $MF^{(R)}$를 삽입한 26안을 실험군으로 분류하여, 총 65안을 분석하였다. 수술 전과 수술 후 1주째, 8주째, 24주째의 원거리 및 근거리 시력과 난시, 구면렌즈대응치, 대비감도를 비교하고, 두 군 간의 수술 후 임상적 유용성을 비교하였다. 결과: 두 군 모두에서 술 전에 비해 술 후 원거리 및 근거리 시력, 구면렌즈대응치가 유의하게 향상되었으나(p<0.05), 두 군 간의 유의한 차이는 없었다(p>0.05). 수술 후 원거리 및 근거리 평균 시력과 난시, 대비감도는 대조군과 실험군은 두 군 간 유의한 차이가 없었다(p>0.05). 구면렌즈대응치의 평균실제오차는 $ReSTOR^{(R)}$와 BunnyLens $MF^{(R)}$는 수술 24주째, 각각 $-0.17{\pm}0.50D$, $-0.34{\pm}0.52D$였고 유의한 차이가 없었다(p>0.05). 결론: 백내장수술 후에 삽입되는 다초점인공수정체인 BunnyLens $MF^{(R)}$는 원거리 및 근거리 시력에서 $ReSTOR^{(R)}$와 유의한 차이가 없었고, 정시안을 기준으로 통계적으로 유의하지는 않으나, $ReSTOR^{(R)}$에 비해 BunnyLens $MF^{(R)}$가 근시의 경향을 보였다.

• Current Optics and Photonics
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• 제7권3호
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• pp.263-272
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• 2023

A collimator refers to an optical system that images a collimated beam at a desired point. A resolution target located at a near distance can be converted into a virtual image located at a long distance. To test the resolution for mobile cameras, a large target is placed at a long distance. If a collimator system is used, the target can be placed at a near distance. The space required for a resolution inspection can thus be drastically reduced. However, to inspect a mobile camera, the exit pupil of the collimator system and the entrance pupil of the mobile camera must match, and the stop of the collimator system must be located on the last surface. Because a collimator system cannot be symmetrical with respect to the stop, the distortion becomes extremely large, which can be corrected by combining the collimator symmetrically with respect to the object plane. A novel system was designed to inspect an optical lens on a mobile phone. After arranging the refractive power, lenses were added using the equivalent lens design method. The distortion was reduced to less than 1%. This optical system satisfies a half-field angle of 45° and an optical performance sufficient for inspection.

• Current Optics and Photonics
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• 제1권4호
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• pp.378-388
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• 2017

We present a graphical method for determining a pair of optical materials and powers to design an achromatic and athermal lens system with corrected Petzval curvature. To graphically obtain the solutions, a three-dimensional (3D) glass chart is proposed. Even if a particular material combination is unavailable, we can select an element suitable for a specific lens and continuously change the element powers of an equivalent single lens for aberrations correction. Thus, we can iteratively identify the materials and powers on a 3D glass chart. By designing a fisheye lens using this method, an achromatic and athermal system with flat Petzval curvature is obtained, over the specified waveband and temperature ranges.