• 한국기계가공학회지
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• 제18권11호
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• pp.18-23
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• 2019

The oil immersion method can be used to create objective lenses with long working distances without sacrificing the focusing resolution for laser processing. In this study, a space in which air or oil can be filled was formed in the middle of a lens for analyzing the optical properties of a liquid-oil immersion lens. As the refractive media, air and oils of different refractive index values (1.2 and 1.5, respectively) were used. A simulation was conducted in the ZEMAX software environment using the ray-tracing technique, and the performance of the oil immersion lens was verified by determining its image distortion and focal length (FL) in each medium. In the case of air, the calculated FL was 0.813 mm, whereas the imaged FLs were 1.594 mm and 8.126 mm when the refraction indices were 1.2 and 1.5, respectively. The FL of an oil immersion lens could be increased considerably. In terms of image distortion, the oil immersion lens exhibited little distortion at the center in all cases, but different degrees of image distortion were observed at different points away from the center depending on the refraction index degree.

• 한국생산제조학회지
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• 제21권5호
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• pp.773-777
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• 2012

Recently UV laser micromachining processes is widely introduced to meet the needs of advanced components of IT, BT and ET industries. Due to the characteristics of non-contact and high-speed laser processing, UV laser micromachining is applied to manufacture very thin substrate such as polymer, metals and composite. These minimum line width obtained by UV laser micromachining is generally determined from laser wavelength, optical lens and its numerical aperture. In this paper we will show the lens effect of water droplet on the surface of workpiece to reduce the line width when UV laser light is irradiated and focused through the water droplet. Because of the refraction effect generated by the semi-spherical or spherical shape of water droplet, we can find smaller line width. And water droplet could not only protect thermal deformation, but also carry away burr around micro dent. Firstly fundamental theory of minimum line width was derived from relationship between the geometry of water droplet and laser light trace, and then experimental and simulation results will be finally compared to verify the effectiveness of water droplet lens effect of UV laser micromachining process.

• Animal cells and systems
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• 제7권4호
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• pp.331-335
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• 2003

Vertebrates with different habitats have different proportions of visual cells, with the rod cells responding to scotopic vision and the cone cells responding to photopic and color vision in their retinas. The present work studied whether the kinds and arrangement patterns of the cone cells and interlocking morphology of the lens were related to the kind of preys and habitats in the genus Zacco. The retinas were observed by a light microscopy using H-E staining method and the interlocking formula of the lens fibers were investigated by a scanning electron microscopy. The interlocking formula of the lens fibers of Z. temmincki is an ' anchor and socket ' connection, and that of Z. platypus is a ' ball and socket ' connection. The cone cells of Z. platypus and Z. temmincki constituted compacted mosaic patterns of row type. Away from the center, the double and single cone cells gradually increased in diameter. Zacco temmincki had identical double cone cells and Z. platypus had non-identical double and single cone cells. The eyes of Z. temminckifeeding on a moving aquatic insects in relative limpid water and swift current of mid and upper stream have better resolution than that of Z. platypus feeding on mainly adhesive algae and some aquatic insects in slightly turbid water of mid stream.

• 한국공작기계학회논문집
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• 제16권3호
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• pp.50-55
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• 2007

The purpose of this research is to enhance the luminance of the LED and to improve the implementation of color by mounting an array lens on the LED without special technology in process. The workmanship of key components considering the economical efficiency and the injection molding technology for high quality of the product are essential to achieve it. In this paper, the mold was computer-aided was designed and manufactured by CAM software (NX4) and high speed machining center. the applied final machining conditions were 3,000-5,000mm/min feed speed, 15,000-25,000rpm and ${\Phi}0.3mm$ ball end-mill. And the Flow analysis was performed using the mold flow software(MPI) in order to get uniformity of resin. Injection conditions acquired by the flow analysis and the injection experiment are as follows. The cylinder temperature is $220-260^{\circ}C$, the mold temperature is $70-80^{\circ}C$, the injection time is about 1.2sec, the injection pressure and velocity is each 7.8-14.7Mpa, and the injection velocity is 0.8-1.2m/sec.

• 한국안광학회지
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• 제19권1호
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• pp.111-120
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• 2014

목적: 콘택트렌즈의 함수율, 재질, 굴절력의 차이에 따른 착용전후의 각막의 형태 변화를 살펴보고자 하였다. 방법: 5가지 유형의 콘택트렌즈를 사용하여 렌즈 착용 전후의 두께차이를 비교하였다. 각막의 중심부와 각막 중심에 떨어진 거리와 방향에 따른 렌즈 착용 전, 후의 각막의 두께, 각막 전, 후면 곡률, 고위수차의 변화를 조사하였다. 측정에 사용된 장비로는 ORB ScanII(Bausch & Lomb Inc, ver 3.14)로 각막 지형도 및 각막 두께를 측정하였으며, 고위수차(high order aberration) 분석을 위하여 Zywave(Bausch & Lomb Inc, ver 5.20)를 사용 하였다. 결과: 산소투과가 낮은 하이드로겔 재질의 소프트 콘택트렌즈(T2 lens)에서 각막의 두께가 증가하는 경향이 두드러지게 나타났다. 각막 중심에서 가장 많은 변화를 보였으며, 중심에 가까울수록 변화정도가 증가하였다. 각막의 방향에 있어서는 코 쪽이 가장 많이 변하였다. 결론: 본 연구에서 사용한 함수율, 재질, 디자인이 다른 5종의 콘택트렌즈 중 Dk가 28이상의 산소투과도를 가진 렌즈에서는 각막의 형태 변화가 적었으며, 산소투과도가 매우 낮은 렌즈에서 가장 많은 각막형태의 변화가 나타났다.

• 한국광학회지
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• 제7권1호
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• pp.9-16
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• 1996

렌티귤러 렌즈를 이용한 2안용 입체영상 시스템에서 렌티큘러 렌즈와 관찰자와의 거리 및 렌티큘러 렌즈의 주기를 변화시키면서 입체영상 시스템의 광학적 특성을 컴퓨터를 이용하여 모의실험을 하였다. 모의실험결과에 의하면 렌즈로부터 관찰자까지의 거리가 가까워짐에 따라서 렌즈의 주기가 주어진 LCD화소의 주기보다 작아져야 한다는 사실을 보여준다. 또한 어떤 일정한 조건하에서 오른쪽 눈에서의 화상과 왼쪽 눈에서의 화상이 공간적으로 비교적 균일하게 분포한다는 것을 알 수 있다. 그러나 이 경우 시스템의 잡음도 공간적으로 균일하게 분포되고 또한 렌즈로부터 관찰자까지의 거리가 멀어질수록 그 잡음의 크기가 커진다는 것을 알 수 있다.

• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.223-228
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• 2005

In oprical disk drives, surface defects on a disk distort tracking error signal and disturb a precision tracking control.. A conventional method against disk defect is held the tracking control signal when a defective portion is detected. However, if the defective portion is getting longer, objective lens will get away from following track. In order to keep the postion of spot from following track, the servo system must predict tracking error and control the object lens in the defective portion. A tracking control system for optical disk drives was proposed recently based on both Coprime Factorization(CF) and Zero Phase Erro. Tracking(ZPET) control. The system was proposed for overcome the limit of previously tracking error. But there were no research about the method against the defective portion. This paper proposes a new and simple ZPET construct. as a new method against the defective portion. From experimental results, we have proved that proposed method improves the performance against the defective portion, decreases the uncertainty of a model, and requires less memory than the previously proposed method.

• 한국광학회지
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• 제18권3호
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• pp.208-215
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• 2007

광섬유 연결 반도체레이저 여기 세라믹 Nd:YAG 레이저의 열렌즈를 보상하기 위한 공진기를 구성하였다. 초점거리 30 mm, 유효직경 22 mm인 보상렌즈를 레이저 매질의 단면으로부터 25 mm 떨어진 곳에 위치시켜 열렌즈 효과를 보상하였다. 보상렌즈가 없는 경우 레이저 출력은 열렌즈 효과에 의해 여기파워 6 W 이상에서 급격히 감소하기 시작하였으며, 12 W에 이르러서는 레이저가 거의 발진되지 않았다. 열렌즈 효과가 보상되었을 경우 레이저 출력은 선형적으로 증가하였으며, 여기파워 12 W에서 $M^{2}$값은 2.4로 좋은 빔질을 나타내었다.

• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1668-1672
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• 2013

We developed a standoff Raman detection system for explosive molecules (EMs). Our system was composed of reflective telescope with 310 mm diameter lens, 532 nm pulse laser, and Intensified Charge-Coupled Device (ICCD) camera. In order to remove huge background noise coming from ambient light, laser pulses with nanosecond time width were fired to target sample and ICCD was gated to open only during the time when the scattered Raman signal from the sample arrived at ICCD camera. We performed standoff experiments with military EMs by putting the detector at 10, 20 and 30 m away from the source. The standoff results were compared with the confocal Raman results. Based on our standoff experiments, we were able to observe the peaks in the range of 1200 and $1600cm^{-1}$, where vibrational modes of nitro groups were appeared. The wave numbers and shapes of these peaks may serve as good references in detecting and identifying various EMs.

• Journal of the Optical Society of Korea
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• 제20권4호
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• pp.481-487
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• 2016

This study presents a new optical system for a combiner-type head-up display (HUD) with a cylindrical lens as an asymmetrical aberration corrector, instead of a freeform mirror. In the initial design process based on off-axial aberration analysis, we obtain an off-axis two-mirror system corrected for linear astigmatism and spherical aberration by adding a conic secondary mirror to an off-axis paraboloidal mirror. Thus, since the starting optical system for an HUD is corrected for dominant aberrations, it enables us to balance the residual asymmetrical aberrations with a simple optical surface such as a cylinder, not a complex freeform surface. From this design process, an optical system for an HUD having good performance is finally obtained. The size of the virtual image is 10 inches at 2 meters away from a combiner, and the area of the eye box is 130×50 mm².