• 한국전기전자재료학회논문지
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• 제20권8호
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• pp.720-725
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• 2007

This study investigated the pressing conditions in the molding of aspheric glass lenses for the mega pixel phone camera module using the DOE method. Tungsten carbide (WC; Japan, Everloy Co., 002K),which contained 0.5 w% cobalt (Co), was used to build the mold. The mold surface was ultra-precision ground and polished, and its form accuracy (PV) was 0.85um in aspheric surface. We selected four factors, pressing temperature, force and time of first step, and force of second step, respectively, as the parameters of the pressing process. in order to reduce the number of experiments, we applied fractional factorial design considering the main effects and two-way interactions. The analysis results indicate that the only two main effects, the pressing temperature and the time of pressing step 1, are available for the form accuracy (PV) of the molded lens. The analysis results indicated that the best combination of the factors for lowering the form accuracy(PV) value of molded lens was to have them at their low levels.

• 세라미스트
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• 제21권4호
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• pp.427-432
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• 2018

In this study, the aspherical lens for optical communications produced not with an one-step pneumatic type of external pressurization system (existed GMP process) but a constant weight of self-loaded mold put up to upper core. So the lens is molding with self-loaded weight molding and it calls Weight Molding process. In self-loaded molding process, we measured changes of center thickness molding lenses with each variable molding temperatures and time to find the effect of center of lens thickness to search key factors. As experimental results, the center thickness reach to targeted lenses step time value was changed drastically and it depends by molding temperature. If the molding temperature gets higher, the targeted lens that is reaching to the center thickness step time value was decreased. To find the effect of life improvement on mold core by imposing the self-loaded molding process we molded with GMP(Glass molding press) method and self-loaded molding method for 9,000 times and measured the lenses shape accuracy and surface roughness to evaluate the core life. As a result the self-loaded molding method core has 2,000 times longer that GMP (Glass molding press) method. If we adopt self-loaded molding method of the optical aspherical lens molding in the future, we expect that it would reduce the expense of changing the molds by molding core life improvements.

• Current Optics and Photonics
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• 제8권3호
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• pp.230-238
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• 2024

The refractive index is a key material-design parameter, especially for high-refractive-index glasses, which are used for precision optics and devices. Increased demand for high-precision optical lenses produced by the glass-mold-press (GMP) process has spurred extensive studies of proper glass materials. B₂O₃, SiO₂, and multiple heavy-metal oxides such as Ta₂O₅, Nb₂O₅, La₂O₃, and Gd₂O₃ mostly compose the high-refractive-index glasses for GMP. However, due to many oxides including up to 10 components, it is hard to predict the refractivity solely from the composition of the glass. In this study, the refractive index of optical glasses based on the B₂O₃-La₂O₃-Ta₂O₅-SiO₂ system is predicted using machine learning (ML) and compared to experimental data. A dataset comprising up to 271 glasses with 10 components is collected and used for training. Various ML algorithms (linear-regression, Bayesian-ridge-regression, nearest-neighbor, and random-forest models) are employed to train the data. Along with composition, the polarizability and density of the glasses are also considered independent parameters to predict the refractive index. After obtaining the best-fitting model by R² value, the trained model is examined alongside the experimentally obtained refractive indices of B₂O₃-La₂O₃-Ta₂O₅-SiO₂ quaternary glasses.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 추계학술대회 논문집
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• pp.307-308
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• 2008

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.469-470
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• 2006

The purpose of this research was to investigate and to find out the optimal annealing condition to mold an aspheric glass to be used for mobile phone module having 2 megapixel and $2.5{\times}$ zoom. Taking annealing rate and re-press temperature after molding as molding variables under the identical molding temperature and pressure, a glass lens was molded. And, Form Accuracy, Lens Thickness, Refractive Index, and Modulation Transfer Function(MTF) were measured in order to observe characteristics of molded lens, and then optimal annealing conditions were determined based on the resulting data. Properties of lens molded under the optimal conditions revealed Form Accuracy[PV] $0.2047\;{\mu}m$ in aspheric surface, and $0.2229\;{\mu}m$ in plane, and MTF value was 30.3 % under 80 lp/mm.

• Journal of the Optical Society of Korea
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• 제11권3호
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• pp.85-92
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• 2007

In the past, precision optical glass lenses were produced through multiple processes such as grinding and polishing, but mass production of aspheric glass lenses requiring high accuracy and having complex profile was rather difficult. In such a background, the high-precision optical glass molding pressing (GMP) process was developed with an eye to mass production of precision optical glass parts by molding press. In this paper, as a fundamental research to develop the multi-cavity mold for higher productivity of a progressive GMP process used in the fabrication of an aspheric glass lens, an aspheric glass lens forming simulation was carried out.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.567-568
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• 2006

Generally, progressive type GMP process is more efficient than batch type because there are advantages that problems of each stage(heating, press, cooling etc.) are easily grasped and a time of production is shortened. But if single cavity is used in progressive type GMP process, there is disadvantage that productivity is decreased. So, in order to improve productivity of progressive type GMP process, it is essential to secure multi cavity mold technic. In this study, as a fundamental study to develop multi cavity used in glass lens molding, we conducted a compression test for PBK40.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.290-290
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• 2009

Blu-ray Disk, the next generation optical information storing equipment used Blu-ray is the next generation leading storing equipment that has capacity is about from six times to thirty-five times bigger than the existing CDs, DVDs. Especially, we need elaborate optical pick-Up equipment to record and recognize detailed date. Moreover, Blu-ray disk has so narrow track-pitch so it is used high NA(Numerical Aperture) aspheric glass objective lens. In this research, we processed optical pick-up aspheric glass objective lens molding press core by parallel grinding method with ultra precision machining and mold core surface measured form accuracy(PV), surface roughness(Ra).

• 한국산업정보학회논문지
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• 제12권3호
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• pp.124-131
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• 2007

3 Megapixel, 2.5배 Zoom 카메라폰 모듈용 광학계 중 비구면과 평면으로 설계된 평볼록형 비구면 Glass렌즈를 고온압축성형법으로 제작하였다. 제작된 비구면 Glass 성형렌즈의 성능은 성형렌즈의 형상정도(PV) 전사성과 해상도로 평가하였다. Glass렌즈 성형용 몰드의 형상정도(PV)는 비구면의 경우 $0.127\;{\mu}m$, 평면의 경우 $0.168\;{\mu}m$이었고, 성형된 렌즈의 형상정도(PV)는 비구면의 경우 $0.205\;{\mu}m$, 평면의 경우 $0.223\;{\mu}m로 $90{\sim}95%$의 전사정도를 보였다. 성형렌즈의 해상도 평가를 위해 렌즈의 MTF[Contrast]를 측정하였다. 공간주파수 80 lp/mm에서 Contrast가 32.9%을 보였으며, 이 값은 렌즈 광학설계의 전산모사에서 얻어진 Contrast 33%에 근사한 값으로 성형렌즈의 해상도 특성이 우수함을 알 수 있었다.

• 한국산학기술학회논문지
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• 제20권12호
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• pp.27-36
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• 2019

작은 굴절률 및 높은 굴절률을 갖는 저 분산 렌즈에 대한 요구가 증가함에 따라, 높은 내열성 및 내마모성을 갖는 이형성 보호 필름에 대한 필요성이 증가하고 있다. 그러나 광학 산업은 비구면 유리 렌즈 성형에 사용되는 이형보호 필름의 제조 공정 및 품질 표준에 대한 명확한 표준을 아직 확립하지 못했다. 이 기술은 광학 렌즈를 제조하는 각 회사의 노하우로 취급된다. 본 연구에서는 FCVA (Filtered Cathode Vacuum Arc) 기반 ta-C 박막 코팅의 이온에칭, 각 소스 및 필터부의 마그네트론 및 아크 전류, 바이어스 전압의 최적화에 관한 실험을 수행하였다. 그 결과, 코팅성능 측면에서, 이리듐- 레늄 합금 박막 스퍼터링 제품 대비 필름 두께가 약 50% 얇고, 경도는 약 20%, 박막의 접착강도는 약 40 % 개선된 것으로 측정되었다. 본 연구의 박막 코팅 공정 결과는 금형 이형 박막층의 최소 기계적 특성 및 품질 확립을 위한 유리 렌즈의 개발 및 활용에 크게 기여할 것으로 사료된다.