• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.119-125
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• 2000

We analyzed to calculate optical capacity after we chose established 2 component zoom copier lens system in this research. As the lens system is zoom lens system of finite object point, it has moving area limited not like to use generally camera zoom lens of infinite object point because it moves between object and image plane. The magnification of optical system can obtain -1.41~-0.64 i.e., extended or shortened image as transverse magnification, and it acquires f/12 and about $20^{\circ}$ field of view. Although this 2 component zoom copier lens system will be down resolution and dark compared with f/2.8 acquired at camera lens, it will be possibile to be able to make large aperture and it can acquire more better correct aberration with the addition of auxiliary group forward or backward.

• Smart Structures and Systems
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• v.21 no.6
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• pp.777-791
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• 2018

This paper discusses the shape control of deformable mirrors for Adaptive Optics in the dynamic range. The phenomenon of control-structure interaction appears when the mirror becomes large, lowering the natural frequencies $f_i$, and the control bandwidth $f_c$ increases to improve the performance, so that the condition $f_c{\ll}f_i$ is no longer satisfied. In this case, the control system tends to amplify the response of the flexible modes and the system may become unstable. The main parameters controlling the phenomenon are the frequency ratio $f_c/f_i$ and the structural damping ${\zeta}$. Robustness tests are developed which allow to evaluate a lower bound of the stability margin. Various passive and active strategies for damping augmentation are proposed and tested in simulation.

• Journal of the Optical Society of Korea
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• v.10 no.1
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• pp.48-54
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• 2006

White-light scanning interferometry (WLI) and phase shifting interferometry (PSI) are increasingly used for surface topography measurements, particularly for areal measurements. In this paper, we compare surface profiling results obtained from above two optical methods with those obtained from stylus instruments. For moderately rough surfaces ($Ra{\approx}500\;nm$), roughness measurements obtained with WLI and the stylus method seem to provide close agreement on the same roughness samples. For surface roughness measurements in the 50 nm to 300 nm range of Ra, discrepancies between WLI and the stylus method are observed. In some cases the discrepancy is as large as 109% of the value obtained with the stylus method. By contrast, the PSI results are in good agreement with those of the stylus technique.

• Journal of the Optical Society of Korea
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• v.16 no.4
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• pp.325-330
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• 2012

Differential absorption LIDAR (DIAL) is frequently used for atmospheric gas monitoring to detect impurities such as nitrogen dioxide, sulfur dioxide, iodine, and ozone. However, large differences in the on- and off-line laser wavelengths can cause serious errors owing to differential aerosol scattering. To resolve this problem, we have developed a new DIAL system for iodine vapor measurements in particular. The suggested DIAL system uses only one laser under seeded and unseeded conditions. To check the detection-sensitivity and error effects, we compared the results from a system using two seeded lasers with those from a system using a seeded and an unseeded laser. We demonstrate that the iodine concentration sensitivity of our system is improved in comparison to the conventional two seeded or two unseeded laser combinations.

• Korean Journal of Optics and Photonics
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• v.20 no.3
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• pp.175-181
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• 2009

Holographic lithography is one of the potential technologies for next generation lithography which can print large areas (6") as well as very fine patterns ($0.35{\mu}m$). Usually, photolithography has been developed with two target purposes. One was for LCD applications which require large areas (over 6") and micro pattern (over $1.5{\mu}m$) exposure. The other was for semiconductor applications which require small areas (1.5") and nano pattern (under $0.2{\mu}m$) exposure. However, holographic lithography can print fine patterns from $0.35{\mu}m$ to $1.5{\mu}m$ keeping the exposure area inside 6". This is one of the great advantages in order to realize high speed fine pattern photolithography. How? It is because holographic lithography is taking holographic optics instead of projection optics. A hologram mask is the key component of holographic optics, which can perform the same function as projection optics. In this paper, Surface-Relief TIR Hologram Mask technology is introduced, and enables more robust hologram masks than those previously reported that were formed in photopolymer recording materials. We describe the important parameters in the fabrication process and their optimization, and we evaluate the patterns printed from the surface-relief TIR hologram masks.

• Journal of Korean Ophthalmic Optics Society
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• v.1 no.1
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• pp.15-22
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• 1996

The fine structure of retinal tissue was studied to investigate on effect of Laser irridation on the ICR mouse with electron microscope. The results obtained were as follows: 1. At the normal groups, the most retinal layers were a complex structure, consisting of several specific cells and nerve fiver. 2. In the increasing time of Laser irridation, each cell layer of retina was not uniform of the structure and band. The visual cells were severely heterochromatin swelling of cytoplasm, irregular shape & heterochromatin of nuclear, and disappear of some cytoplasm. The nucleus and nerve fiber of retinal layer was a very irregular shape, formation of vesicle, not identify of each intercellular boundary. The pigment epithelial cells were not an uniform, a large vesicle formation of cytoplasm, and a condensation & very irregular shape of nucleus.

• Current Photovoltaic Research
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• v.5 no.1
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• pp.25-27
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• 2017

Nanoscale textured black silicon has attracted intensive attention due to its great potential as applications in multicrystalline silicon-based solar cells. It absorbs sunlight over a broad range of wavelengths but introduces large recombination centers, non-uniform doping into cell. In this study, we present a metal-assisted chemical etching technique plus alkaline etching process to fabricate nanoscale pyramid structures with optimized condition. To make the structures, silver nanoparticles-loaded mc-Si wafer was submerged into $H_2O_2/HF$ solution first for nanohole texturing the wafer and textured wafer etched again with KOH solution for making nanoscale pyramid structures. The average reflectivity (350-1050 nm) is about 8.42% with anti-reflection coating.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.26-26
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• 2003

During fabrication process for the large space optical surfaces, the traditional bound abrasive grinding with bronze bond cupped diamond wheel tools leaves the machine marks and the subsurface damage to be removed by subsequent loose abrasive lapping. We explored a new grinding technique for efficient quantitative control of precision CNC grinding for space optics materials such as Zerodur. The facility used is a NANOFORM-600 diamond turning machine with a custom grinding module and a range of resin bond diamond tools. The machining parameters such as grit number, tool rotation speed, work-piece rotation speed, depth of cut and feed rate were altered while grinding the work-piece surfaces of 20-100 mm in diameter. The input grinding variables and the resulting surface quality data were used to build grinding prediction models using empirical and multi-variable regression analysis methods. The effectiveness of the grinding prediction model was then examined by running a series of precision CNC grinding operation with a set of controlled input variables and predicted output surface quality indicators. The experiment details, the results and implications are presented.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.1
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• pp.61-65
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• 2000

${\beta}$-SiC powder and ${\alpha}$-SiC powders of different particle sizes, containing 5.7wt% $Al_2O_3$ and 4.3wt% $Y_2O_3$ as sintering aids, were hot-pressed at $1780^{\circ}C$ and subsequently annealed at $1950^{\circ}C$ to initiate grain growth. All the hot-pressed and annealed materials consisted of large SiC grains and elongated SiC grains. Typical hardness and fracture toughness of materials for spectacle lens cutting were 15.6 GPa and $5.7MPa{\cdot}m^{1/2}$, respectively.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.1
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• pp.55-59
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• 2000

In this study, materials for spectacle lens cutting were fabricated by hot-pressing and annealing SiC powders with $Al_2O_3$ and $Y_2O_3$. A microstructure that consisted of uniformly distributed, large SiC grains and elongated SiC grains was developed by using ${\alpha}$-SiC powders. The microstructure was observed by scanning electron microscope(SEM). By hot-pressing and subsequent annealing, elongated ${\beta}$-SiC grains were grown via ${\beta}{\rightarrow}{\alpha}$ phase. This is caused the crack deflection as toughening mechanism. Typical hardness and fracture toughness of materials for spectacle lens cutting were 13.3 GPa and $4.8MPa{\cdot}m^{1/2}$, respectively.