• 대한기계학회논문집A
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• 제26권11호
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• pp.2450-2456
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• 2002

Microlenses and microlens arrays are fabricated using a novel fabrication technology based on the exposure of a resist (usually PMMA) to deep X-rays and subsequent thermal treatment. The fabrication technology is very simple and produces microlenses and microlens arrays with good surface roughness (less than 1 nm). The molecular weight and glass transition temperature of PMMA is reduced when it is irradiated with deep X-rays. The microlenses is produced through the effects of volume change, surface tension, and reflow during thermal treatment of irradiated PMMA. The geometry of the microlens is determined by parameters such as the X-ray dose applied to the PMMA, the diameter of the microlens, along with the heating temperature, heating time, and cooling rate in the thermal treatment. Microlenses are produced with diameters ranging from 30 to 1500 ${\mu}{\textrm}{m}$. The modified LIGA process is used not only to construct hemispherical microlenses but also structures that are rectangular-shaped, star-shaped, etc.

• 소성∙가공
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• 제13권3호
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• pp.290-295
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• 2004

Mircolens and microlens V-groove are realized using a novel fabrication technology based on the exposure of a resist, usually PMMA, to deep X-rays and subsequent thermal treatment and inclined deep X-ray lithography, respectively. The fabrication technology is very simple and produces microlenses and microlens V-groove with good surface roughness of several nm. The molecular weight and glass transition temperature of PMMA is reduced when it is irradiated with deep X-rays. The microlenses were produced through the effects of volume change, surface tension, and reflow during thermal treatment of irradiated PMMA. Microlenses were produced with diameters ranging from 30 to $1500\mu\textrm{m}$. The surface X-ray mask is also fabricated to realize microlens arrays on PMMA sheet with a large area. The size of the micro V-groove is fabricated in the range of 12~$60\mu\textrm{m}$.

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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• pp.192-193
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• 2000

We studied the characteristics and fabricated the plano-convex refractive microlenses using the thermal reflow method. The exposed resist was resolved in a standard developing process. The remaining resist of circle pattern was melted in an oven 12$0^{\circ}C$ to 15$0^{\circ}C$. The shape of the melted resist microlenses is ruled by surface tension. Diameter and hight of the fabricated microlenses were 250${\mu}{\textrm}{m}$ to 325${\mu}{\textrm}{m}$ and 15${\mu}{\textrm}{m}$ to 22${\mu}{\textrm}{m}$, respectively. The surface profile was calculated using data curve-fitting method with circle equation. The optical characteristics was analysed using optical simulation program.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.965-968
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• 2007

The effect of the modification of the front surfaces of flat fluorescent lamps (FFLs) on the light-output distribution has been investigated by using a ray tracing method and several kinds of microlenses. It was found that microlenses have substantial effects on the light-output distribution, which might be used to reduce the number of optical films in the FFL-backlight unit for LCD applications.

• 한국정밀공학회지
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• 제30권6호
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• pp.644-649
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• 2013

Today, there are lots of progresses in the field of lens researches, especially in the microlens fabrication. Unlike normal lenses, microlens has been widely used as a role of improving the performance of photonic devices which increase the optical precision, and also used in the fields of the display. In this paper, polymer microlenses with $300{\mu}m$ diameter were replicated through hot-embossing from nickel mold which was fabricated by micro-EDM. After hot-embossing process, the polymer microlenses have a rough surface due to the crater formed by micro-EDM process, which is projected onto the surface of the lenses. The surface of polymer microlenses was polished using solvent vapor to improve the surface roughness of the microlenses without changing their shape. In the experiment, the surface roughness was improved with the processing time and vapor temperature. Also, the roughness improvement was greatly affected by the solubility difference between polymer and solvent.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.228-232
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• 2003

Mircolens and microlens arrays are realized using a novel fabrication technology based on the exposure of a resist, usually PMMA, to deep X-rays and subsequent thermal treatment. Hot embossing process is also studied for mass production. The fabrication technology is very simple and produces microlenses and microlens arrays with good surface roughness of several nm. The molecular weight and glass transition temperature of PMMA is reduced when it is irradiated with deep X-rays. The microlenses were produced through the effects of volume change, surface tension. and reflow during thermal treatment of irradiated PMMA. A hot embossing machine is designed and manufactured with a servo motor transfer system. The hot embossing process follows the steps of heating mold to the desired temperature, embossing a mold insert on substrate. cooling mold to the de-embossing temperature. and de-embossing. Microlenses were produced with diameters ranging from 30 to 1500 ${\mu}{\textrm}{m}$. The surface X-ray mask is also fabricated to realize microlens arrays on PMMA sheet with a large area.

• 한국광학회지
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• 제5권2호
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• pp.298-303
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• 1994

두꺼운 Photoresist(PR)로 원기둥 모양을 만들고 이를 용융함으로써 미세렌즈 행렬을 제작하였다. 이 방법으로 직경 $25\mu\textrm{m}$, $50\mu\textrm{m}$, $100\mu\textrm{m}$의 렌즈를 만들고 전자주사현미경과 탐침형 표면측정기를 통해 그 모양을 확인하였다. 그리고 렌즈의 광학적 성능을 측정하기 위해 위상변이 간섭법을 사용하여 평행광의 렌즈 통과 후 파면을 구하였다. 여기서 기준 구면과의 파면오차를 구하여 렌즈 초점거리나 초점광도분포 등을 얻었다. 그 결과 직경 $100\mu\textrm{m}$, 초점거리 $164\mu\textrm{m}$의 미세렌즈는 초점의 spot 직경이 $25\mu\textrm{m}$보다 작은 것으로 측정되었다.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 1999년도 한국우주과학회보 제8권1호
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• pp.28-28
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• 1999

No Abstract, See Full Text

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1682-1683
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• 2011

Through-silicon microlens array has been implemented using glass thermal reflow process. Design, numerical analysis, fabrication, and measurement results are discussed. Microlenses with six different volumetric dimensions were successfully fabricated and characterized. Radius of curvature of each microlenses were measured with less than 1% deviation compared to calculated value. Measured average roughness of the microlens surface was 16.5 nm.

• 소성∙가공
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• 제15권1호
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• pp.34-41
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• 2006

Microlens arrays were fabricated by a modified LIGA process composed of the exposure of a PMMA (Polymethylmethacrylate) sheet to deep x-rays and subsequent thermal treatment. A successful modeling and analyses for microlens formation were presented according to the experimental procedure. A nickel mold insert was fabricated by the nickel electroforming process on the PMMA microlens arrays fabricated by the modified LIGA process. For the replication of microlens arrays having various diameters with different foci on the same substrate, both hot embossing and microinjection molding processes have been successfully utilized with the fabricated mold insert. Replicated microlenses showed very good surface roughness with the order of 1 nm. The focal lengths of the injection molded microlenses were successfully estimated theoretically and also measured experimentally.