• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1091-1096
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• 2007

This paper describes the development of a small lens molding system for manufacturing the small lens like lens of a cellular phone, a small digital camera and so on. In order to manufacture a small lens, firstly, the raw material for lens with spherical shape should be manufactured by processing a glass, secondly, the mold inserted the raw material for lens should be heated till its molding temperature in the electric furnace, finally, the small lens is manufactured by applying the force using pressuring control system. In this paper, the small lens molding system with the function of force control and velocity control was developed. It is composed of a electric furnace and its temperature control system, a pressuring control system, a body, and so on. The temperature characteristic test of the electric furnace, and the force and velocity characteristic test of the pressuring control system were carried out. It was confirmed that the developed system had good functions for manufacturing a small lens.

• 한국정밀공학회지
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• 제25권2호
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• pp.57-64
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• 2008

This paper describes the development of a small lens molding system for manufacturing the small lens like lens of a cellular phone, a small digital camera and so on. In order to manufacture a small lens, firstly, the raw material for lens with spherical shape should be manufactured by processing a glass material, secondly, the mold inserted the raw material for lens should be heated till its molding temperature in the electric furnace, finally, the small lens is manufactured by applying the force using pressuring control system. In this paper, the small lens molding system with the function of force control and velocity control was developed. It is composed of an electric furnace and its temperature control system, a pressuring control system, a body, and so on. The temperature characteristic test of the electric furnace, the force and velocity characteristic test of the pressuring control system were carried out. It was confirmed that the developed system had good functions for manufacturing a small lens.

• 전기전자학회논문지
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• 제22권3호
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• pp.858-861
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• 2018

본 논문에서는 소형 $360^{\circ}$ 구강 스캐너 렌즈 모듈의 개발을 제안한다. 제안하는 소형 $360^{\circ}$ 구강 스캐너 렌즈 모듈은 소형 $360^{\circ}$ 고해상도(4MegaPixel) 렌즈 광학계, 15mm 이미지 센서부, 소형 $360^{\circ}$ 구강 스캐너 렌즈 외형 등으로 구성된다. 소형 $360^{\circ}$ 고해상도 렌즈 광학계는 총 9매의 렌즈로 어린이부터 성년까지 전 연령에 걸쳐 사용이 가능하도록 렌즈 외경을 15mm 이하로 제작한다. 소형 $360^{\circ}$ 고해상도 렌즈 광학계에 의해 입사되는 빛을 $90^{\circ}$ 굴곡을 시켜 이미지 센서에 영상 이미지를 전달하게 한다. 15mm 이미지 센서부는 이미지 센서의 열, 행 주소를 통해 이미지 배열을 거친 후 전압으로 변환된 값을 임베디드 보드의 ISP(Image Signal Processor)에 전송한다. 소형 $360^{\circ}$ 구강 스캐너 렌즈 외형은 개발된 렌즈의 고정을 위하여 경통을 설계하였다. 제안된 소형 $360^{\circ}$ 구강 스캐너 렌즈 모듈의 성능을 평가하기 위하여 공인시험기관에서 실험한 결과, $360^{\circ}$ 렌즈 광학계 분해능은 150cycles/mm에서 30% 이상, $360^{\circ}$ 렌즈 화각은 수평은 $360^{\circ}$, 수직은 $42^{\circ}{\sim}85^{\circ}$, 렌즈 왜곡률은 5% 이하의 세계최고 수준과 동일한 결과를 산출하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.115-118
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• 2002

The purpose of this paper is to design a pick-up for the small form factor optical disk drive and to fabricate a micro-compensatory lens for the pick-up using the micro-compression molding process. At design stage, the optical elements including the objective lens and the compensatory lens are miniaturized. The height of pick-up and free working distance are designed as 2mm and 0.2% respectively. To analyze the fabricated micro-compensatory lens, the system was analyzed using the surface profile of the fabricated micro-compensatory lens and CODE V which is commercial software. The RMS wave front aberration of the system using fabricated micro-compensatory lens is 0.01677λ which is lower than Marechal's criterion, 0.07λ.

• Journal of the Optical Society of Korea
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• 제20권6호
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• pp.739-744
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• 2016

We have designed a new TIR(Total Internal Reflection) structure for generating an LED lens which can produce a rectangular beam with small divergence angle in two perpendicular directions for an optical guidance system. The lens can control the divergence angle in the horizontal direction to be a small value of about $8^{\circ}$ with a $1mm{\times}1mm$ LED source, also in the vertical direction it can be about $7^{\circ}$, with optical collection efficiency higher than 0.83. After the lens is manufactured, the work demonstrates that the lens is suitable for an optical guidance system.

• International Journal of Precision Engineering and Manufacturing
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• 제4권3호
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• pp.48-54
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• 2003

This paper deals with mirror grinding of a small-sized aspherical lens by a resin bonded diamond spherical wheel. Up to now, a spherical lens has been used for the lens of the optical communication optical part. However, recently, aspherical optical parts are mainly used in order to attempt the improvement in image quality and miniaturization of the optical device. It is possible to manufacture the aspherical lens which is presently being used in optical instrument through ultra-precision machining technology. Also, to realize compactness, efforts are being made to produce a micro aspherical lens, fur which the development of a high-precision, micro molding die is inevitable. Therefore, extensive research is being done on methods of producing a micro aspherical surface by high-precision grinding. In this paper, the spherical wheel was trued by cup-shaped truer and tool path was calculated by the radius of curvature of the wheel after truing and dressing. Then in the aspherical grinding experiment, WC material which is used as a melding die for the small-sized aspherical lens was ground. The results showed that a form accuracy of 0.1918 $\mu\textrm{m}$ P-V and a surface roughness of 0.064 $\mu\textrm{m}$ Rmax could be achieved.

• 한국정밀공학회지
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• 제18권12호
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• pp.82-87
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• 2001

This paper deals with mirror grinding of a small-sized aspherical lens by the resin bonded diamond spherical wheel. Up to now, a spherical lens has been used for the lens of the optical communication optical part. However, recently, the aspherical optical parts are mainly used in order to attempt the improvement in image quality and miniaturization of the optical device. It is possible to manufacture the aspherical lens which is presently being used in optical instrument through ultra-precision machinery technology. Also, to realize compactability, efforts are being made to produce a micro aspherical lens, for which the development of a high-precision, micro molding die is inevitable. Therefore, extensive research is being done on methods of producing an micro aspherical surface by high-precision grinding. In this paper, the spherical wheel was trued by cup-type truer and tool path was calculated by the radius of curvature of wheel after truing and dressing. And then in the aspherical grinding experiment, WC material which is used as a molding die for the small-sized aspherical lens was ground. It results was that a form accuracy of 0.1918${\mu}m$ P-V and a surface roughness of 0.064${\mu}m$ Rmax.

• 정보저장시스템학회논문집
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• 제6권1호
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• pp.37-40
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• 2010

Fresnel lens is a kind of refractive optical lens with various advantages. It has nearly flat shaped optical lens that has small mass. Fresnel lens has number of applications in the compact optical systems. Recently, demands of high quality Fresnel lens for small size optical systems such as illumination units, compact imaging systems, display units, information storage systems, optical detecting units had increased rapidly. Conventional manufacturing process of high quality Fresnel lens is direct machining. However, it is not suitable for mass production because of high cost and long cycle time. Replication method can provide cost effective mass production process. However, there are various issues about replication of Fresnel lens. Fresnel lens has number of sharp blade shape prism. In the replication process, this blade shape causes defects that can affect optical efficiency. In this study, replication processes; injection molding process and UV imprinting process, were developed and evaluated using Fresnel lens that has maximum pattern height of $250\;{\mu}m$ and aspect ratio of 1.5.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.79-82
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• 2005

Fresnel lens has number of applications in the optical systems because of its advantages. It is nearly flat lens that has small weight. It is conventionally used in lighthouse beacons, condensing unit of overhead projector and etc. Recently, demands of small size optical systems such as display units, information storage systems, optical detecting units had increased. Conventional manufacturing process of high quality Fresnel lens is direct machining. But it is not suitable for mass production because of high cost and long cycle time. Replication process is more suitable for mass production. But the Fresnel lens has number of sharp blade shape prism. In the replication process, this blade shape causes defects that can affect optical efficiency. In this study, replication process of blade shape pattern that has maximum height of $280{\mu}m$, aspect ratio 1.4 for Fresnel lens application.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2019년도 학술발표회
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• pp.145-145
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• 2019

Groundwater and rainwater are the only sources of freshwater in small islands as many islands lack surface water sources. Groundwater occurring in the form of freshwater lens floating on denser seawater is highly dependent on natural recharge from rainfall. A sharp interface numerical model for regional and well scale modeling is selected to assess the sustainability of freshwater lens in the island of Tongatapu. In this study, 29 downscaled General Circulation Model(GCM) predictions are input to the recharge model based on water balance modelling. Three GCM predictions which represent wet, dry and medium conditions are selected for use in the groundwater flow model. Total freshwater volume and number of saltwater intruded wells are simulated under various climate scenarios with GCM predicted rainfall pattern, sea level rise and pumping. Simulations indicate that the sustainability of the freshwater lens is threatened by the frequent droughts which are predicted under all scenarios of recharge. The natural depletion of the lens during droughts and increase in water demands, leads to saltwater upconing under the pumping wells. Implementation of drought management measures is of utmost importance to ensure sustainability of freshwater lens in future.