• Korean Journal of Materials Research
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• v.25 no.10
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• pp.537-542
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• 2015

One-dimensional (1D) silver nanostructures, which possess the highest conductivity among all room-temperature materials, moderate flexibility and high transmittance, are one of the most promising candidate materials to replace conventional indium tin oxide transparent electrodes. However, the short length and large diameter of 1D silver nanostructures cause a substantial decrease in the optical transparency or an increase in the sheet resistance. In this work, ultra-long silver nanofiber networks were synthesized with a low-cost and scalable electrospinning process, and the diameter of the nanofibers were finetuned to achieve a higher aspect ratio. The decrease in the diameter of the nanofibers resulted in a higher optical transparency at a lower sheet resistance: 87 % at $300{\Omega}/sq$, respectively. It is expected that an electrospun silver nanofiber based transparent electrode can be used as a key component in various optoelectronic applications.

• Current Optics and Photonics
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• v.3 no.1
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• pp.8-15
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• 2019

We describe a common optical system that merges a LADAR system, which generates a point cloud, and a more traditional imaging system operating in the LWIR, which generates image data. The optimum diameter of the entrance pupil was determined by analysis of detection ranges of the LADAR sensor, and the result was applied to design a common optical system using LADAR sensors and LWIR sensors; the performance of these sensors was then evaluated. The minimum detectable signal of the $128{\times}128-pixel$ LADAR detector was calculated as 20.5 nW. The detection range of the LADAR optical system was calculated to be 1,000 m, and according to the results, the optimum diameter of the entrance pupil was determined to be 15.7 cm. The modulation transfer function (MTF) in relation to the diffraction limit of the designed common optical system was analyzed and, according to the results, the MTF of the LADAR optical system was 98.8% at the spatial frequency of 5 cycles per millimeter, while that of the LWIR optical system was 92.4% at the spatial frequency of 29 cycles per millimeter. The detection, recognition, and identification distances of the LWIR optical system were determined to be 5.12, 2.82, and 1.96 km, respectively.

• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.13-14
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 2006.02a
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• pp.125-126
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• 2006

• Carbon letters
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• v.8 no.4
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• pp.307-312
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• 2007

A method for evaluating bulk sensitive structural characteristics of unpurified, as-purified, and acid treated single walled carbon nanotubes (SWNTs) was described in the present study. The optical spectra of SWNT solutions were well resolved after prolonged sonication and they were correlated to the diameter and the distribution of nanotubes. The acid-treated SWNTs were similar to as-purified SWNTs in terms of catalyst residue, radial breathing mode (RBM) in the Raman spectra, and the first band gap energy of semiconducting tubes in the optical spectra. The solution phase optical spectra were more sensitive to changes in the small diameter and metallic tubes after the acid treatment than were the RBM spectra.

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.177-181
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• 2005

Although there are many ways to measure the diameter of a cylindrical object, in this study, the diameter of a cylindrical objects were measured by the geometric optical method and interference-diffraction method which are two kinds of tipical non-contact methods. In geometric optical method, the curved laser beam is formed on the cylindrical surface by spreading the inclined laser beam using the cylindrical lens. The curve is captured by CCD camera and the diameter is calculated by geometry. And the interference and diffraction patterns of investigated cylindrical objects are analyzed in interference-diffraction method. In this study, the cylindrical objects, whose diameters are $0.05\;mm\;\~\;100.50\;mm$ were measured by the geometric optical method and interference-diffraction method. The results show that in each method, the relative errors of the measurement are within $2\%$ and $1\%$, respectively and these non-contact methods can be applied in the quick measurement of many objects.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.4
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• pp.28-39
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• 1993

In the international BISDN used satellite, the laser that has large BW has to be used as a carrier for transmitting a lot of visual, vocal, and data information. Interoptical satellite communication has now developed in theoretical and practical aspects. But the optical communication, between satellite and earth station, is hindered by atmospheric absorption, scattering, and turbulence. In this paper, it was supposed that 1Gbps information was transmitted by binary FSK and 50mW AlGaAs semiconductor laser was used as a optical source in the satellite communication link between geosynchronous orbit satellite and earth station. We analyzed the BER and the entire diameter of the noncoherently combined optical heterodyne receiver as el evation angle, and determined the number of the optical heterodyne rece ivers, which is necessary for the BER of the receiver to be less than 10$^{-9}$ by computer simulation under the clear weather condition. It is shown that the BER and the number of the optical heterodyne receivers decrease as the elevation angle increases. In the region used the same number of the optical heterodyne receivers, it is shown that the entire diameter of the receiver increases but the BER decreases as the elevation angle increases.

• Journal of the Optical Society of Korea
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• v.5 no.2
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• pp.33-36
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• 2001

Common methods of determining the spatial resolution of fiber-optic image guides are by measuring the diameter of individual microfibers or by the use of a resolution test target. However these methods cannot provide enough information of spatial resolution in ultrathin fiber-optic image guides. In this study, a simple method to measure the modulation transfer function (MTF) of an mage guide was developed. The MTFs of ultrathin image guides with 3 and 4${\mu}{\textrm}{m}$ Um diameter were measured by examining transmitted sharp edge image. This method should be especially useful for measuring spatial resolution of ultrahigh resolution image guides with less than 5 ${\mu}{\textrm}{m}$ diameter microfibers because their spatial resolution cannot be determined by individual microfiber diameter due to crosstalk and leaky ray phenomena.

• Korean Journal of Optics and Photonics
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• v.18 no.4
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• pp.256-263
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• 2007

High NA objective design by using SELFOC materials was studied, and two kinds of objective for optical pick-up were designed. The SELFOC materials have radial gradient index distribution, and it gives additional degree of freedom in optical design. Therefore, we expect that optical design of high NA objective without aspheric surface will be possible. In this study, the variation of ms spot diameter was investigated as a function of quadratic constant and refractive index on axis for various combinations of axial thickness and entrance pupil diameter. For the survey, Code V was used for optimization and evaluation of the objective lenses. The result suggested that larger quadratic constant and higher refractive index on axis could give us better imaging performance for all combinations of axial thickness and pupil diameter. Based on the survey, we designed high NA objectives for DVR. There were two kinds of design solution consisting two spherical SELFOC lenses. The solution I had positive-positive lens configuration with short over-all-length, but it had poor off-axial performance compared with the solution II. The solution II had negative-positive lens configuration with good off-axial imaging performance. But the solution II had some disadvantages, long over-all-length and large diameter of the second lens.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.4
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• pp.39-44
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• 2009

Purpose: To design a mini optical system photographing the iris, which is used in the iridology. Methods: We designed a mini optical system photographing the iris by using the Sigma 2000 design program. Results: We designed a mini optical system photographing the iris, which is suitable in the CCD using a micro actuator for auto-focusing, of which characteristics have the TCL of 30 mm, a magnification of -0.65, about 8.0 mm distance from the 1st lens to the last lens, the max barrel diameter of 11 mm, and about 1 mm of the effective stop diameter. Also the resolution line width of this system is characterised by 92 lps/mm at the 30% MTF value criterion. Conclusions: By designing an optical system of which characteristics have the TCL of 30 mm, about 8.0 mm distance from the 1st lens to the last lens, the max barrel diameter of 11 mm, and the resolution line width of $5.4{\mu}m$ at the 30% MTF value criterion, we could miniaturize the iris photographing optical system.