• Korean Journal of Materials Research
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• v.19 no.12
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• pp.657-660
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• 2009

Optical characteristics and structural changes depending on CuO content in phosphate glasses that are used in near-infrared (near-IR) filters were investigated. With phosphate glasses that contain 1-9 mol% CuO, changes in optical transmittance, optical absorption, and color coordinate were measured with a UV-VIS spectrophotometer. An XPS (X-ray photoelectron spectroscopy) analysis was performed to determine valence of copper ion that influences optical characteristics in near-IR filter glasses. Structural changes in glasses depending on CuO content were also analyzed by FT-IR (Fourier transform infrared) and Raman spectrophotometers. From the UV-VIS spectrophotometer results, strong absorption peaks at 220 & 900 nm were found and transmittance was decreased. The color coordinates of the glasses were shifted to the green color direction with CuO addition for increasing absorption of long wavelength range spectra, in spite of the amount of $Cu^{2+}$, which gives a blue color to glasses, and which was increased in XPS results. Also, structural de-polymerization of glasses with CuO addition were found by FT-IR and Raman results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.337-337
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• 2009

가시광선영역에서 매우 균일한 높은 투과성뿐만 아니라 근적외선영역에서 가파른 홉수성 엣지와 함께 낮은 투과율을 제공하는 산화구리(II)를 함유하는 포스페이트 유리는 컬러 비디오 카메라의 컬러 보정 필터, 발광 컬러 디스플레이용 보호판(sheild), 모노크로메이터의 미광 필터, 플라스틱 복합재 필터의 무기 성분 및 CCD(전하 결합 소자) 및 CMOS(상보성 금속 산화물 반도체) 카메라 및 검출기 분야용 필터 유리로서 사용된다. 용융온도 및 산화구리(II) 첨가량에 따른 투과율을 측정하기 위해 포스페이트 유리 시료를 $1100\sim1500^{\circ}C$ 용융한 후 $400^{\circ}C$에서 2시간 동안 어닐링 공정을 거쳐 제조하였다. 제조된 시료는 두께 0.3mm로 폴리싱하여 자외선-적외선 분광 광도기를 이용하여 광학적 특성을 측정하였다. 본 실험을 통하여 용융온도에 따라 가시광선영역 및 근적외선영역에서의 투과율 거동을 비교한 결과 $1100\sim1200^{\circ}C$에서의 우수한 투과율 특성을 나타냈다. 용융온도가 내려감에 따른 가시광선영역 (400~600nm)에서 높은 투과율 및 근적외선영역 (750~1100nm)에서 낮은 투과율과 가파른 흡수성 엣지를 나타냈다.

• Korean Journal of Optics and Photonics
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• v.17 no.5
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• pp.480-486
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• 2006

Generally, IR cut-off filters for mobile phone is coated on the glass substrate at high temperature(above $300^{\circ}C$). In this work, we prepared IR cut-off filters on the poly(methyl methacrylate)(PMMA) substrates at low temperature(about $70^{\circ}C$ ). using the $CeO_2\;and\;SiO_2$ coatings by physical vapor deposition. The surface energies of coated and uncoated PMMA, and adhesive properties of IR cut-off filters coatings were examined using contact angle measurements. We demonstrate the improve of mobile phone optical system using these results.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.70-77
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• 2010

This study proposed an auto focusing method for a multi-focus image in assembling lens modules in digital camera phones. A camera module in a camera phone is composed of a lens barrel, an IR glass, a lens mount, a PCB board and aspheric lenses. Alignment among the components is one of the important factors in product quality. Auto-focus is essential to adjust image quality of an IR glass in a lens holder, but there are two focal points in the captured image due to thickness of IR glass. So, sharpness, probability and a scale factor are defined to find desired focus from a multi-focus image. The sharpness is defined as clarity of an image. Probability and a scale factors are calculated using pattern matching with a registered image. The presented algorithm was applied to a lens assembly machine which has 5 axes, two vacuum chucks and an inspection system. The desired focus can be determined on the local maximum of the sharpness, the probability and the scale factor in the experiment.

• Tribology and Lubricants
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• v.35 no.2
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• pp.106-113
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• 2019

We investigated the application of tetrahedral amorphous carbon (ta-C) coatings to fabricate a glass lens manufactured using a glass molding process (GMP). In this work, ta-C coatings with different thickness (50, 100, 150 and 200 nm) were deposited on a tungsten carbide (WC-Co) mold using the X-bend filter of a filtered cathode vacuum arc. The effects of thickness on mechanical and tribological properties of the coating were studied. These ta-C coatings were characterized by atomic force microscopy, scanning electron microscopy, nano-indentation measurements, Raman spectrometry, Rockwell-C tests, scratch tests and ball on disc tribometer tests. The nano-indentation measurements showed that hardness increased with an increase in coating thickness. In addition, the G-peak position in the Raman spectra analysis was right shifted from 1520 to $1586cm^{-1}$, indicating that the $sp^3$ content increased with increasing thickness of ta-C coatings. The scratch test showed that, compared to other coatings, the 100-nm-thick ta-C coating displayed excellent adhesion strength without delamination. The friction test was carried out in a nitrogen environment using a ball-on-disk tribometer. The 100-nm-thick ta-C coating showed a low friction coefficient of 0.078. When this coating was applied to a GMP, the life time, i.e., shot counts, dramatically increased up to 2,500 counts, in comparison with Ir-Re coating.

• Journal of Adhesion and Interface
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• v.11 no.4
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• pp.137-143
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• 2010

Glass beads (GBs) were modified via plasma polymerization coatings in order to enhance the adsorption of polycyclic aromatic hydrocarbons (PAHs) in cigarette smoke and activated carbons (ACs) were also utilized for comparative purposes. First, GBs and ACs were subjected to surface modification via plasma polymerization coating of acrylic acid, acrylonitrile, 1,3-diaminopropane, thiophene or dimethylphosphite with a RF plasma (13.56 MHz) generator. Next, their adsorption behavior was evaluated with a home-made 4-port smoking machine by collecting the total particulate matters (TPMs) on a Cambridge filter pad, followed by the separation of PAHs via solid phase extraction and analysis with GC/MS. Finally, the plasma polymerization coatings were analyzed by FT-IR/ATR to elucidate the adsorption mechanism, while the topology of the modified GBs and ACs were studied by FE-SEM.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.27-36
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• 2019

The demand for a low dispersion lens with a small refractive index and a high refractive index is increasing, and accordingly, there is an increasing need for a releasable protective film with high heat resistance and abrasion resistance. On the other hand, the optical industry has not yet established a clear standard for the manufacturing process and quality standards for mold-releasing protective films used in aspheric glass lens molding. Optical lens manufacturers treat this technology as proprietary information. In this study, an experiment was conducted regarding the optimization of ion etching, magnetron, and arc current at each source and filter part, and bias voltage in FCVA (filtered cathode vacuum arc)-based Ta-C thin film coatings. This study found that compared to iridium-rhenium alloy thin film sputtering products, the coating conditions were improved by approximately 50%, 20%, and 40% in terms of thickness, hardness, and adhesive strength of the film, respectively. The thin-film coating process proposed in this study is expected to contribute significantly to the development and utilization of glass lenses, which will help enhance the minimum mechanical properties and quality of the mold-release thin film layer required for glass mold surface forming technology.

• Analytical Science and Technology
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• v.32 no.6
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• pp.243-251
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• 2019

Microplastics (MP) are found in large quantities in the oceans, posing a major threat to the ecosystem. In Korea, MPs have been reported to be detected in sea salts. In order to analyze MPs, information on their composition, size, and shape is required. FT-IR microscopy is used frequently to measure sizes larger than 20 ㎛. Recently, however, Raman microscopy, which can analyze ultrafine plastics below 20 ㎛, has been applied extensively. In this study, 10.0 g samples of commercially available salts were dissolved and filtered through a 45 ㎛ mesh filter with a size of 25.4 mm × 25.4 mm. These filtered samples were then analyzed by both FT-IR microscopy and Raman microscopy. A total of four MPs, including three polyethylene (PE) of size 70-100 ㎛ and a polypropylene (PP) of size 170 ㎛, were detected by FT-IR microscopy, while 10 MPs, including nine PE of size 10-120 ㎛ and one polystyrene (PS) of size 40 ㎛, were detected by Raman microscopy. Approximately, 1,000 MPs/kg was estimated, which was almost two times higher than the previous reported levels (~550-681 particles/kg in sea salts); this is because Raman microscopy can detect much smaller MPs than FT-IR microscopy. A total of 113 particles were found using Raman microscopy: Carbon (35, 31.5 %), minerals (28, 25 %), and glass (16, 14.4 %) were dominant, forming around 70% of the total, but MPs (10, 8.8 %) and cellulose (5, 4.5 %) were also found. Raman microscopy has great potential as an accurate method for measuring MPs, as it can measure smaller size MPs than FT-IR microscopy. It also has a reduced sample preparation time.