• 한국전기전자재료학회논문지
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• 제24권10호
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• pp.817-821
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• 2011

We have proposed an optical thin film and micro lens to improve the luminance of organic light emitting device. The first method, optical thin film was calculated refractive index of dielectric layer material that was modulated refractive index of organic material, ITO (indium tin oxide)and glass. The second method, microlens was applied with lenses on the organic device. Optical thin films were designed with Macleod Simulator and Micro Lenses were calculated by FDTD (finite-difference time-domain) solution. The structure of thin film was designed in organic material/ITO/dielectric layer/glass. The lenses size, height and distance were 5 ${\mu}m$, 1 ${\mu}m$, 1 ${\mu}m$, respectively. The material of micro lenses used silicon dioxide. Result, The highest luminance of OLED which applied with microlens was 11,185 $cd/m^2$, when approval voltage was 14.5 V, applied thin film was 5,857 $cd/m^2$. The device efficiency applying microlens increased 3 times than the device which does not apply microlens.

• 전기전자학회논문지
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• 제26권2호
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• pp.205-210
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• 2022

본 연구에서는 유기 발광 다이오드(OLED)의 광추출 향상을 위한 롤투롤 마이크로컨택(mCP)방식으로 인쇄된 마이크로렌즈 어레이(MLA)를 제시하였다. 상업적으로 사용되는 마이크로렌즈 어레이를 템플레이트로 사용하여서 polydimethylpolysiloxane(PDMS)를 롤스탬프로 제작하였다. 낮은 끓는 점을 가지는 불소화 잉크로부터 PDMS 롤스탬프에 고분자 박막을 형성하고 이를 OLED의 하부면에 고압·고온 처리 없이 인쇄하였다. 최적화된 농도를 찾아서 템플레이트로 사용된 MLA와 거의 동일한 모양의 패턴을 성공적으로 인쇄하였다. 마이크로컨택 방식으로 인쇄된 MLA의 구조와 소재의 낮은 흡수도로 인해서 OLED의 외부양자효율이 18% 향상되었다.

• 한국광학회지
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• 제34권1호
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• pp.13-21
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• 2023

입사하는 빛에 대한 수용각이 큰 인공 겹눈 구조를 제작하기 위해 마이크로 렌즈 어레이의 높이에 따라 곡면형 겹눈 구조체가 갖는 수용각과 이미징 특성을 분석하였다. 마이크로 렌즈의 반지름에 대한 높이인 h/r값을 조절함으로써 보다 큰 입사각을 갖는 빔이 마이크로 렌즈 어레이로 들어올 때도 여전히 빔을 포커싱하고 이미지를 맺을 수 있는 렌즈의 구조를 확인하였다. h/r값이 0.22에서 0.37로 증가할 때 겹눈 구조체의 수용각은 28.70°에서 49.02°로 증가하여 70.8%의 증가폭을 얻어낼 수 있었다. 뿐만 아니라 글자 F를 이미징한 결과, h/r값이 0.37일 때 메인 렌즈의 중심으로부터 23번째에 위치한 마이크로 렌즈에서도 글자가 선명하게 관찰되어 56.35°의 입사각을 갖는 빔에 대해서도 마이크로 렌즈 어레이가 이미지를 맺을 수 있음을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1495_1496
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• 2009

A cylindrical post dipping (CPD) method to fabricate the PDMS microlens arrays is presented in this paper. The proposed CPD method is based on the surface tension effect. 2 mm gap and gapless lenses with 2 mm diameter are fabricated and characterized geometically. Both profiles of the fabricated microlens are well-fitted with ideal lens profile. The surface roughness average of the fabricated lens is measured to be 1.953 nm. The focal length of 2mm gap lenses and the gapless lenses is calculated to be 17.00 mm with 0.65 mm standard deviation and 29.88 mm with 2.58 mm standard deviation, respectively. The proposed CPD method can be applied to wafer level lens fabrication due to its simplicity and versatility.

• 소성∙가공
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• 제16권1호
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• pp.42-47
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• 2007

LCD-BLU is one of kernel parts of LCD and it consists of several optical sheets: LGP, light source and mold frame. The LGP of LCD-BLU is usually manufactured by etching process and forming numerous dots with $50\sim300{\mu}m$ diameter on the surface. But the surface of the etched dots of LGP is very rough due to the characteristics of the etching process during the mold fabrication, so that its light loss is high along with the dispersion of light into the surface. Accordingly, there is a limit in raising the luminance of LCD-BLU. In order to overcome the limit of current etched dot patterned LGP, optical pattern with continuous microlens was designed using optical simulation CAE. Also, a mold with continuous micro-lens was fabricated by UV-LiGA reflow process and applied to 7 inch size of navigator LCD-BLU in the present study.

• Journal of the Optical Society of Korea
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• 제18권1호
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• pp.71-77
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• 2014

We present design and fabrication of a multi-focusing microlens array (MLA) using a thermal reflow method. To obtain multi-focusing properties with different numerical apertures at the elemental lens of the MLA, double-cylinder photoresist (PR) structures with different diameters were made within the guiding pattern with both photolithographic and partial developing processes. Due to the base PR layer supporting the thermal reflow process and the guiding structure, the thermally reflowed PR structure had different radii of curvatures with lens shapes that could be precisely modeled by the initial volume of the double-cylinder PR structures. Using the PR template, the hexagonally packed multi-focusing MLA was made via the replica molding method, which showed four different focal lengths of 0.9 mm, 1.1 mm, 1.6 mm, and 2.5 mm, and four different numerical apertures of 0.1799, 0.2783, 0.3973, and 0.4775.

• Macromolecular Research
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• 제17권3호
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• pp.181-186
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• 2009

We fabricated ordered micro/nano patterns induced by controlled dewetting on the topographically patterned PS/P4VP bilayer thin film. The method is based on utilizing microimprinting lithography to induce a topographically heterogeneous bilayer film that allows the controlled dewetting upon subsequent thermal annealing. The dewetting that was initiated strictly at the boundary of the thicker and thinner regions was guided by the presence of the topographic structure. The dewetting front velocity of the microdomains in the confined regions was linearly proportional to the measurement time, which enabled us to control the size of the dewet domain with annealing time. In particular, the submicron sized dot arrays between lines were generated with ease when the dewetting was confined into geometry with a few microns in size. The kinetically driven, non-lithographical pattern structures accompanied the pattern reduction to 400%. The pattern arrays on a transparent glass substrate were especially useful for non-circular microlens arrays where the focal length of the lens was easily tunable by controlling the thermal annealing.

• Journal of the Optical Society of Korea
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• 제19권3호
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• pp.265-271
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• 2015

We propose a reactive mesogen (RM) lens array to obtain good focusing behavior along with a short focal plane, where the focusing behavior is switchable according to the polarization state of incident light. Polarization-dependent focusing behavior is obtained using a planoconvex RM microlens array on a planoconcave isotropic lens template. Even though the sagitta of our RM lens is high, to obtain the short focal length, the RM layer can be aligned well by introducing a top-down alignment effect, using a nanogrooved template. The optical noise due to the $moir{\acute{e}}$ effect generated by the nanogrooves on the surface of the planoconvex RM layer can be removed simply by overcoating a thin RM layer, which is self-aligned by the geometric surface effect, without an additional alignment process. We demonstrate a hexagonal-packed RM lens array that has a very high fill factor and symmetric phase profile, for an ideal lens.

• 한국산업융합학회 논문집
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• 제26권4_1호
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• pp.517-527
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• 2023

Many techniques have been proposed and investigated for microlens array manufacturing in three-dimensional (3D) structures. We present fabricating a microlens array using selective laser etching and a CO₂ laser. The femtosecond laser was employed to produce multiple micro-cracks that comprise the predesigned 3D structure. Subsequently, the wet etching process with a KOH solution was used to produce the primary microlens array structures. To polish the nonoptical surface to the optical surface, we performed reflow postprocessing using a CO₂ laser. We confirmed that the micro lens array can be manufactured in three primary shapes (cone, pyramid and hemisphere). Compared to our previous study, the processing time required for laser processing was reduced from approximately 1 hour to less than 30 seconds using the proposed processing method. Therefore, micro lens arrays can be manufactured using our processing method and can be applied to mass productionon large surface areas.

• 한국광학회:학술대회논문집
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• 한국광학회 2001년도 하계학술발표회
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• pp.226-227
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• 2001