• Current Optics and Photonics
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• v.3 no.5
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• pp.365-373
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• 2019

This paper investigates the performance of a hybrid single input multiple output radio frequency/free-space optics (SIMO-RF/FSO) communication system. Each SIMO-RF link is modeled as an independent and identically distributed (i.i.d.) Rayleigh distribution, while the FSO link follows a generalized $M{\acute{a}}laga$ (M) distribution. Considering the fixed gain amplify-and-forward (AF) relay and misalignment errors, novel expressions for the outage probability (OP), average bit error rate (ABER) and average capacity are derived. Numerical results show that atmospheric turbulence and misalignment errors can seriously impair the system performance, and the hybrid RF/FSO communication system using SIMO-RF links can greatly improve system performance. We also analyze system performance under different types of modulation schemes. Numerical results are verified by Monte Carlo simulations.

• Publications of The Korean Astronomical Society
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• v.22 no.3
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• pp.55-61
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• 2007

The KASINICS (Korea Astronomy and Space science Institute Near Infrared Camera System) is a ground-based near-infrared (NIR) imaging instrument. KASINICS has offner relay optics to reduce unwanted infrared light. For the offner optics, we adopted an ultra precision machining process which is installed at KBSI (Korea Basics Science research Institute). Since the offner relay optics is made of aluminum 6061 metal material, we did several tests to reach the specification. We found that a 0.497mm radius nose bite and 220m/min machining speed are best tool and condition to make this offner optics with the precision machine. In this paper, we report the technical method of ultra precision machining and results of the KASINICS offner optics.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.1
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• pp.81-85
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• 2001

The color vision was composed of the wavelength absorption of three R. G. B cone photo-receptors and the r-g, y-b channel of an opponent process. The color vision defects mechanism for the electric circuit made up a photo cell, relay switch and transformer. This mechanism very well applied to the color vision defects mechanism owing to be y-b chromatic valence function in case of a cone R or G defects and to be r-g chromatic valence function in case of a cone B defects.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.3
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• pp.29-35
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• 2009

Purpose: To develop a relay lens type scope with 70 mm eye relief. Methods: By using Sigma 2000 design program, we designed and manufactured a relay lens type scope with 70 mm eye relief, which is integrated after designing an objective part with relay lenses and an eyepiece part, respectively. Results: The characteristics of the relay lens type scope with 70 mm eye relief whch is designed and manufactured by methods, which integrate after respectively designing an object part with relay lenses and an eyepiece part, have the magnification of $+4{\times}$,the length from 1st lens to last lens of about 105 mm, the barrel diameter of 18mm, and the effective diameter of 13 mm. Also we know that the resolution line width is 275 cycles/rad at the 30% MTF value criterion. Conclusions: We could design and manufacture the relay type scope with 70 mm eye relief, the characteristics of which have the magnification of $+4.0{\times}$the MTF above 30% at 275 cycles/rad, and the length from 1st lens to last lens of about 105 mm.

• Journal of the Optical Society of Korea
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• v.12 no.4
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• pp.262-268
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• 2008

A compact imaging spectrometer (COMIS) for use in the STSAT3 microsatellite is currently under development. It is scheduled to be launched into a low Sun-synchronous Earth orbit (${\sim}700km$) by the end of 2010. COMIS was inspired by the success of CHRIS, which is a small hyperspectral imager developed for the ESA microsatellite PROBA. COMIS is designed to achieve nearly equivalent imaging capabilities of CHRIS in a smaller (65 mm diameter and 4.3 kg mass) and mechanically superior (in terms of alignment and robustness) package. Its main operational goal will be the imaging of Earth's surface and atmosphere with ground sampling distances of ${\sim}30m$ at the $18{\sim}62$ spectral bands ($4.0{\sim}1.05{\mu}m$). This imaging will be used for environmental monitoring, such as the in-land water quality monitoring of Paldang Lake, which is located next to Seoul, South Korea. The optics of COMIS consists of two parts: imaging telescope and dispersing relay optics. The imaging telescope, which operates at an f-ratio of 4.6, forms an image (of Earth's surface or atmosphere) onto an intermediate image plane. The dispersion relay optics disperses the image and relay it onto a CCD plane. All COMIS lenses and mirrors are spherical and are made from used silica exclusively. In addition, the optics is designed such that the optical axis of the dispersed image is parallel to the optical axis of the telescope. Previous efforts focused on manufacturing ease, alignment, assembly, testing, and improved robustness in space environments.

• Journal of the Optical Society of Korea
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• v.12 no.4
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• pp.298-302
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• 2008

We have developed a 270-W 15-kHz MOPA system based on side-pumped rod-type Nd:YAG gain modules. The master oscillator is a 3-W 15-kHz $TEM_{00}$ $Nd:YVO_4$ laser with a pulse duration of 30 ns. To preserve the high beam quality during the amplification, we use image relay and polarization rotation which can simultaneously compensate for thermal lensing and thermal birefringence generated in the rod-type gain modules. After the amplification to 270 W with six rod-type gain modules, the beam quality factor ($M^2$) of the amplified laser beam is 5-10, and the pulse duration is maintained at 30 ns.

• Korean Journal of Optics and Photonics
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• v.5 no.2
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• pp.212-216
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• 1994

We have designed and constructed a scanner optics for thermal imaging system operating in 8 - 12 /lfll band. The scanner consists of rotating polygon and oscillating mirror for serial-parallel scan using 5 elements SPRITE HgCdTe. A spherical mirror is used for scan relay mirror to minimize size of the scan mirrors and pupil aberration. The scanner has $40^{\circ}\times26.67^{\circ}$ wide scan field of view and the calculated diffraction MTF shows diffraction limited performance. As a result we have obtained high resolution thermal image. image.

• Current Optics and Photonics
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• v.2 no.3
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• pp.241-249
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• 2018

We report a midinfrared dual-field-of-view (FOV) optical system design for an airborne electro-optical targeting system. To achieve miniaturization and weight reduction of the system, it has a common aperture and fore-optics for three different spectral wavelength bands: an electro-optic (EO) band ($0.6{\sim}0.9{\mu}m$), a midinfrared (IR) band ($3.6{\sim}4.9{\mu}m$), and a designation laser wavelength ($1.064{\mu}m$). It is free to steer the line of sight by rotating the pitch and roll axes. Our design co-aligns the roll axis, and the line of sight therefore has a fixed entrance pupil position for all optical paths, unlike previously reported dual-FOV designs, which dispenses with image coregistration that is otherwise required. The fore-optics is essentially an achromatized, collimated beam reducer for all bands. Following the fore-optics, the bands are split into the dual-FOV IR path and the EO/laser path by a beam splitter. The subsequent dual-FOV IR path design consists of a zoom lens group and a relay lens group. The IR path with the fore-optics provides two stepwise FOVs ($1.50^{\circ}{\times}1.20^{\circ}$ to $5.40^{\circ}{\times}4.32^{\circ}$), due to the insertion of two Si lenses into the zoom lens group. The IR optical system is designed in such a way that the location and f-number (f/5.3) of the cold stop internally provided by the IR detector are maintained when changing the zoom. The design also satisfies several important performance requirements, including an on-axis modulation transfer function (MTF) that exceeds 10% at the Nyquist frequency of the IR detector pitch, with distortion of less than 2%.

• Korean Journal of Optics and Photonics
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• v.19 no.2
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• pp.144-149
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• 2008

Thermal distortion of the laser mirrors which are the Coude mirrors of the laser beam director and the wavefront error caused by the thermal distortion are studied. Coude mirrors consist of three relay mirrors and one fast steering mirror. The mirrors have reflectivity of 99.5% with respect to the laser wavelength of $3.8\;{\mu}m$, and absorption of 500 W per second. Thermal distortion and its related wavefront errors are studied with laser beam irradiation for 5 seconds. For the relay mirror, the wavefront error is 334 nm_PV, 98 nm rms and for fast steering mirror, $11.5\;{\mu}m$_PV, $3{\mu}m$ rms.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.221-225
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• 2016

This paper is about vision system that exhibits automatic examination of the conditions of fuses and relay boxes using a camera. Proposed vision system is composed of three parts: image acquisition, vision algorithm, and user interface. The image acquisition part is composed of illumination and optics. The vision algorithmis the examining part, using the grabbed fuse box image. Lastly, user interface is divided into two parts, user interface for registering features of fuse box and user interface for examination operation.