• Journal of the Korean Society for Precision Engineering
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• v.24 no.6
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• pp.45-50
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• 2007

The aspheric lens has become the most popular optical component used in various optical devices such as digital cameras, pick-up lenses, printers, copiers etc. Using aspheric lenses not only miniaturizes and reduces the weight of products, but also lower prices and higher field angles can be realized. Additionally, plastic lenses are being changed to glass lenses more recently because of low accuracy, low acid-resistance and low thermal-resistance in the plastic lenses. Currently, one fabrication method of glass lenses is using a glass-mold method with a high precision mold core for mass production. In this paper, DOE (Design Of Experiments) and compensation machining were adopted to improve the surface roughness and the form accuracy of the mold core. The DOE has been done in order to discover the optimal grinding conditions which minimize the surface roughness with factors such as work spindle revolution, turbine spindle revolution, federate and cutting depth. And the compensation machining is used to generate high form accuracy of the mold core. From various experiments and analyses, we could obtain the best surface roughness 5 nm in Ra, form accuracy $0.167\;{\mu}m$ in PV.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.11
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• pp.893-898
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• 2016

Plastic array lens are cheap to manufacture; however, plastic is not resistant to high temperatures and moisture. Optical glass represents a better solution but is a more-expensive alternative. Glass array lens can be produced using lithography or precision-molding techniques. The lithography process is commonly used, for instance, in the semiconductor industry; however, the manufacturing costs are high, the processing time is quite long, and spherical aberration is a problem. To obtain high-order aspherical shapes, mold-core manufacturing is conducted through ultra-precision grinding machining. In this paper, a $4{\times}1$ mold core was manufactured using an ultra-precision machine with a jig for the injection molding of an aspherical array lens. The machined mold core was measured using the Form TalySurf PGI 2+ contact-stylus profilometer. The measurement data of the mold core are suitable for the design criterion of below 0.5 um.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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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).

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.3
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• pp.388-393
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• 2010

In recent years the research has been focused on the preparation of special glasses, i.e., chalcogenide and heavy metal oxide ones that can transmit optical radiation above 2 um and also other optical parameters exceed those of silica based glasses. The attention in this paper is focused on chalcogenide glasses, on preparation of high quality base glass, for an application in infrared optical product design and manufacture. The amorphous materials of As-Se and Ge-As-Se chalcogenides were prepared by a standard melt-quenching technique. The compositions were mesaured by ICP-AES and EPMA, and structural and thermal properties were studied through various annealing processes. Several anomalies of glass transition and crystallization were observed in the DSC/DTA/TG results of the chalcogenide glass.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.178-178
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• 2009

High-density optical information storing equipment, which is using Blu-ray, is the next generation information storing equipment that has about form six times to thirty-five times capacities. and high-density optical information storing equipment uses high NA(Numerical Aperture) aspheric glass objective lens as optical pick-up equipment to record and recognize high-density date. Generally this objective lens is developed and produced through a way of GMP(Glass Molding Press) that uses molding core that is performde by Ultra precision grinding, but grinding performing that has high-accuracy is very difficult because objective lens form is high NA. In this research, we preformed Ultra precision turning, using single crystal diamond bite, about WC(Co 0.5%), sintering brittleness material that is used molding core's material for GMP. and we confirmed aspheric glass lens compression of deformities molding core's Ultra precision turning possibility by measuring surface roughness(Ra) and processing surface's condition.

• Transactions of Materials Processing
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• v.18 no.8
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• pp.633-639
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• 2009

Remarkable progress had been made in both technology and production of optical elements including aspheric lens. In the past, precision optical glass lenses were produced through multiple processes such as grinding and polishing, but mass production of aspheric lenses requiring high accuracy and having complex profile was rather difficult. Against such a background, the high-precision optical GMP process was developed with an eye on mass production of precision optical glass pasts by molding press. This GMP process can produce with precision and good repeatability special form lenses such as for cameras, video cameras, aspheric lenses for optical items. In this study, Design Of Experiment(Taguchi method) was adopted to find a tendency of molding conditions that influence formability. Three main factors for molding conditions were selected based on pressure at pressing stage and temperature, pressure at cooling stage. Also, the DOE was carried out and the interference patterns were measured to evaluate the formability of GMP process. From the results, it was found that the cooling pressure is the most sensitive parameter for progressive GMP process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.57-60
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• 2002

The high precision spindle is essential fer mass and low cost production of aspherical glass lens. Especially, in the grinding process of micro glass lens the performance of the spindle determine the machined surface quality. For the aspheric micro glass lens grinding, we design and make a high precision spindle. We use air bearings for high speed and low motion errors of the spindle. And the driving mechanism is an air turbine to remove heat generation. In this study, we make basic performance requirements of the spindle through benchmarking. And we confirm the requirements by basic machining test. We test air consumption, static stiffness, run-out and vibration of the spindle.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.9
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• pp.808-811
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• 2007

Aspheric glass lens have recently been used in camera phone module because they are more effective than spherical ones. In this paper, the grinding condition of the tungsten carbide molding core has been found after applying DOE to the development of the aspheric glass lens for the 3 Megapixel and 2.5x camera-phone module. Also, the ultra precision grinding process was investigated under this condition by experiment. Re-Ir coating was applied on the ground surface of the tungsten carbide molding core. The influence of Re-Ir coating on the form accuracy and surface roughness of molding core was compared and evaluated. The form accuracy and surface roughness of the molding core were improved by application of Re-Ir coating on the surface of the tungsten carbide molding core.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.5
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• pp.69-74
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• 2010

An increasing interest towards the investigations of chalcogenide glasses has been observed in the past years. This interest is due to their specific properties, as well as to the possibilities for their application in different fields of science. The optical devices, working on the basis of photoinduced phase transition between amorphous and crystalline state in the chalcogenide glasses, are a perspective for the micro- and nano-electronics. Here we were analysis basic physical properties for Ge-As-Se and As-Se chalcogenide glasses samples for characteristic for a planning of chalcogenide aspheric lens. From differential DTA/TG results, activation energies of the crystallizations of $Ge_{10}As_{40}Se_{50}$ and $As_{40}Se_{60}$ were approximately 3.6 eV and 3.3 eV, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.441-441
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• 2007

As Rhenium-Iridium{Re-Ir) coating possesses such features as, high hardness, high elasticity, abrasion resistance and chemical stability, there have been exerted continuous efforts in research works in a variety of fields, and this technology has also been applied widely to industrial areas. In this research, the optimal grinding condition was identified using Microlens Process Machine in order to contribute to the development of aspheric glass lens for mobile phone module having 3 mega pixel and 2.5X zoom, and molding core(WC) was manufactured having performed ultra-precision machining. Effects of Re-Ir coating on form accuracy (P-V) of molding core and surface roughness(Ra) were measured and evaluated.