• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.31-35
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• 2008

Purpose: This study is to design a triplet optical system for CCTV camera lens. Methods: It was a telescopic lens with $5^{\circ}$ field angle, 56 mm focal length, 20 mm diameter, and 2/3 inches sized CCD array detector. Results: The performance of the subject optical system was evaluated by applying ray fan, spot diagram, and diffraction optical MTF. The wavelength was achromatized at Fraunhofer C, d and F-line, and both MTF and tangential & sagittal MTF shows more than 70% at spatial frequency of 50 linepairs/mm. Conclusions: The marketable triplet optical system for CCTV camera was designed and its utility was considered.

• Current Optics and Photonics
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• v.7 no.3
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• pp.254-262
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• 2023

Novel thermo-optically focus-switchable Fresnel zone plates based on phase-change metafilms are designed and analyzed at a visible wavelength (660 nm). By virtue of the large thermo-optic response of vanadium dioxide (VO₂) thin film, a phase-change material, four different plasmonic phase-change absorbers are numerically designed as actively tunable Gires-Tournois Al-VO₂ metafilms in two and three dimensions. The designed phase-change metafilm unit cells are used as the building blocks of actively focus-switchable Fresnel zone plates with strong focus switching contrast (40%, 83%) and high numerical apertures (1.52, 1.70). The Fresnel zone plates designed in two and three dimensions work as cylindrical and spherical lenses in reflection type, respectively. The coupling between the thermo-optic effect of VO₂ and localized plasmonic resonances in the Al nanostructures offer a large degree of freedom in design and high-contrast focus-switching performance based on largely tunable absorption resonances. The proposed method may have great potential in photothermal and electrothermal active optical devices for nonlinear optics, microscopy, 3D scanning, optical trapping, and holographic displays over a wide spectral range including the visible and infrared regimes.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.1
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• pp.17-25
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• 2005

In modem society, individuality and diversity are emphasized and visual sensation is considered to be very important because of high degree industrialization and development of mass media. And also, the Total Fashion Age opened. In the past, spectacles was a mere means of correcting or protecting sight. It's design was very simple in form and skill. But in 21C, eyewear design is viewed as a vehicle to create fashion and keeps changing to be in line with the contemporary culture and fashion trend beyond the old functions. The purpose of this study was to investigate the conditions of eyewear design in the 21st century by looking into the history of eyewear and analyzing the trend of eyewear design and the color image with fashion, hair, and make-up.

• Journal of electromagnetic engineering and science
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• v.13 no.2
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• pp.73-85
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• 2013

In this paper we present an alternative approach to addressing the problem of designing cloaks for radar targets, which have been dealt with in the past by using the transformation optics (TO) algorithm. The present design utilizes realistic materials, which can be fabricated in the laboratory, and are wideband as well as relatively insensitive to polarization and incident angle of the incoming wave. The design strategy, presented herein, circumvents the need to use metamaterials for cloak designs that are inherently narrowband, dispersive and highly sensitive to polarization and incident angle. A new interpretation of the TO algorithm is presented and is employed for the design of radar cross section-reducing absorbers for arbitrary targets, and not just for canonical shapes, e.g., cylinders. The topic of performance enhancement of the absorbers by using graphene materials and embedded frequency structure surfaces is briefly mentioned. The design procedure for planar absorbing covers is presented and their performance as wrappers of general objects is discussed. A number of test cases are included as examples to illustrate the application of the proposed design methodology, which is a modification of the classical TO paradigm.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.1
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• pp.51-56
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• 2009

Recently, with the increasing lightness and miniaturization of high resolution camera phones, the demand for aspheric glass lens has increased because plastic and spherical lens are unable to satisfy the required performance. An aspheric glass lens is fabricated by the high temperature and pressure molding using a tungsten carbide molding core, so precision grinding and coating technology for the molding core surface are required. This study investigates the effect of diamond-like carbon (DLC) and rhenium-iridium (Re-Ir) coating For aspheric molding core surface. The grinding conditions of the tungsten carbide molding core were obtained by design of experiments (DOE) for application in the ultra precision grinding process of the tungsten carbide molding core of the aspheric glass lens used in 5 megapixel, $4{\times}$ zoom camera phone modules. A tungsten carbide molding core was fabricated under this grinding condition and coated with the DLC and Re-Ir coating. By measurements, the effect of DLC and Re-Ir coating on the form accuracy and surface roughness of molding coer was evaluated.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.74-76
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• 2012

In order to design Transceiver/Receiver antenna with high gain in Ka band, Fresnel zone plate lend(FZPL) antenna is considered and analyzed. Physical optics is applied to demonstrate the FZPL. The FZPL is configured to 11 elements diffraction zones and drived at 20GHz. As a result, calculated received gain using PO method is 33.01dB.

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.2
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• pp.177-183
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• 2003

We tried to design and manufacture an iris photographing optical-system which is used in the Oriental medicine or medical diagnostics. The whole system consists of a light source part, an image focusing part, a CCD transfer part and a diagnosis S/W. We designed the image focusing part to the reduction optical-system with 0.58X magnification of which the chromatic aberration is removed by using materials of FD60 and BACD5. The image focusing part's localization did big contribution in coot reduction of products. The manufactured iris photographing optical-system had superior performance in aspect that has stereoscopic effects of images in comparison with the foreigner's.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.1
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• pp.39-42
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• 2000

It is formed of 3D image stereopsis by the left right retina image's fusion and can be made 3D-Stereogram because of occuring the depth perception of binocular disparity. We made the 3D-stereogram of the object of shape a ball and the eyes by taking a photograph of the light source's position angle contrast of the binocular disparity's field angle. We examined that 3D-stereogram was to be the stereopsis.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.4
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• pp.96-101
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• 2008

Due to improve form accuracy and surface roughness of a aspheric lens core that is made of Ni, the study is carried out on localization about a Subminiature Optics of Proximity and Wide Field of View. The required form accuracy P-V $0.2{\mu}m$ and surface roughness is Ra 10 nm. The design of experiment(DOE) is adopted to find a optimal cutting conditions which are spindle speed, depth of cut, feedrate. Finally, the effects of this study are replacing importation and strengthening competitiveness through the localization of the Subminiature Optics of Proximity and Wide Field of View.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.27-33
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• 2011

HCPV(High Concentrated PV) systems have well known for CPV market all over the world. Low concentration type silicon based modules have been introduced in the market. But low cost of standard flat silicon modules made them useless nowadays. High cost of compound semiconductor solar cell reduced cost effective cpv module production than that of recently silicon solar cell. In order to overcome increasing cost of CPV module, we study middle concentration type fresnel lens simulation using concentrated type silicon based solar cell. Linear type fresnel lens made production of CPV module without secondary optics such as light pipe or light tunnel. This type of fresnel lens design makes more cost effective solution for cpv niche market.