• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.6
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• pp.572-580
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• 2015

RF skin tracking of instrumentation RADAR cannot acquire stable track data, because of effect of multipath interference especially elevation direction. In this paper, low altitude target tracking method using laser tracking system is suggested to overcome this restriction. The effect of multipath can be reduced by increasing angle resolution with laser characteristics of very short pulse and narrow beamwidth. RF skin track, beacon track and laser track data for the integrated calibration target on the ground and target ship on the sea are gathered. And they are compared and analyzed to confirm the performance of laser tracking system. As a result, it shows that the suggested laser track method has better performance than RF skin track under multipath conditions.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.1
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• pp.19-26
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• 2006

The ccrf-discharge has in comparison with the hollow-cathode discharge and DC-discharge some advantages: Simple design of the tube and homogeneous plasma. The ccrf-discharge was researched with the goal, to use on the excitation of the gas laser. In this work a rf-exciting system was planned and developed. With it a homogeneous discharge was produced in the cw operation. To supply the rf-power with the frequency 13.56[MHz] effectively in the discharge, laser tube were used with inner diameter of 5[mm] and the specially developed rf-electrodes. A matching circuit was composed also. Thereby the impedance of the discharge tube was adjusted to the 50[$\Omega$] output resistance of the rf-source.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.4
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• pp.101-108
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• 1998

We examine experimentally the dependence of output width on DC bias, RF power, and RF frequency in a gain-switched semiconductor laser. The optimum short pulses are obtained around threshold DC bias. The DC bias to generatoe shorter pulses decreases the RF power increases, whereas it increases to above threshold as the RF freqnecy increases. The pulse width becomes less sensitive to the variations of the DC bias, as the RF bias, or frquency increases.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.214-219
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• 1997

We propose a new scheme of high-resolution heterodyne interferometer that employs the two-axial mode He-Ne laser with an inter-mode beat frequency of 600-1000 MHz. An electronic RF-heterodyne circuit lowers the beat frequency down to 5 MHz, so that the phase change of the interferometer output is precisely measured with a displacement resolution of 0.1 nanometer without significant loss of dynamic bandwidth. A thermal control scheme is adopted to stabilize the cavity length with aims to suppress frequency drifts caused by the phenomena of frequency pulling and polarization anisotropy of the two-axial mode laser to a stability level of 2 parts in $10^9$. The two-axial mode HeNe laser yields a high output power of 2.0 mW, whlch allows us to perform multiple measurements of up to 10 machine axes simultaneously.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.12A
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• pp.1766-1773
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• 2000

이동통신망에서 RF 신호를 송수신하는 기지국(base station)과 이동 통신 신호의 교환 전송을 담당하는 중앙국(central station)을 광섬유로 연결하여 구성하는 SCM (Subcarrier Multiplexing) 전송 시스템은 미래의 음성, 영상, 데이터 서비스 등의 이동통신 시스템에 적용할 수 있기 때문에 최근 관심사가 커지고 있다. 이동통신망을 위한 SCM 광전송 시스템의 유용성에도 불구하고, CDMA RF 신호를 전송하는 과정에서 많은 물리적인 제약이 있다. 특히, 많은 가입자의 CDMA RF 신호가 하나의 레이저 다이오드(LD: Laser Diode)를 구동시킬 때, RF 신호의 합이 레이저 다이오드의 선형영역을 벗어나면 클리핑(clipping)이나 비선형 왜곡이 발생하여 시스템의 성능을 저하시키게 된다. 본 논문에서는 CDMA RF 신호의 SCM 광전송 성능분석을 통해 레이저 다이오드에 의해 발생하는 비선형 왜곡의 영향을 분석하고, 분석 결과로부터 레이저 다이오드에 의한 비선형 효과를 최소화 할 수 있는 비선형 왜곡 보상구조를 제안하였다. 또한 제안된 레이저 다이오드 비선형 보상기의 성능을 시뮬레이션과 실험을 통해 얻어진 BER로부터 측정하였다.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1429-1434
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• 2003

A number of dust particles are intruded into ODD(Optical disk drive) due to the flow caused by disk rotation and are adhered to a lens or disk surface. The space between the disk and the lens is being reduced. Someone indicates the problems of this drive that are relatively small data storing capacity and slow access time. In recent, the problems of this optical disk drive mentioned above are being solved by adding the speed of the disk's revolution, making the actuator high-speed or light, and making the beam spot size smaller than making the space narrow between disk and lens. These particle contamination affects seriously RF Signal, readout signal in an ODD. Especially, the affected parts by a particle contamination in an ODD's readout signal are objective lens and media.

• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.406-412
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• 2003

We have developed a radio frequency excited slab waveguide $CO_2$ laser. The dimension of active volume is 2${\times}$40${\times}$400 mm. One concave and one convex mirror are used to make the unstable resonator of the positive branch. The radio frequency is 123 MHz and RF input power is varied from 100 to 900 W. The laser gas is set to a pressure of 10∼60 torr and the mixing ratio is $CO_2$:$N_2$:He=1:1:3. The laser output power of 70.7 W was obtained which corresponds to laser power to RF power conversion efficiency of 9.2%.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.12
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• pp.586-591
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• 2003

We have developed the radio frequency excited slab waveguide $CO_2$ laser, The dimension of active area is $2{\times}40{\times}400$ mm to get a laser gain. Two pieces of concave mirror are used to make the unstable resonator of negative branch. The radio frequency is 123 MHz and RF input power is from 100 to 900 W. The laser gas is set to a pressure of 10 ∼ 60 torr and the mixing ration is $CO_2$:$N_2$:He=1:1:3. The laser output power of 50.9 W was obtained with laser power to RF power efficiency of 6.5 %.

• Journal of the Korean Vacuum Society
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• v.13 no.1
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• pp.29-33
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• 2004

In this paper, we investigated the ultra-low temperature(<$150^{\circ}C$) polycrystalline silicon film on plastic substrate application using RF-magnetron sputtering and excimer laser annealing. Amorphous silicon films were deposited using Ar/He mixture gas at $120^{\circ}C$ and in-film argon concentration was less than 2%, which was measured to Rutherford Backscattering Spectrometry. At energy density 320mJ/$\textrm{cm}^2$, RMS roughness was 267$\AA$ and UV crystallinity was 62%. The grain size varies from 50nm to 100nm after excimer laser irradiation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.1
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• pp.66-71
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• 2004

Airborne contaminant particles are intruded into optical disk drive(ODD) due to the flow caused by disk rotation and can be adhered to objective lens, which causes read/write errors. Such a phenomenon can be a serious problem for high-density storage devices. The purpose of this paper is to understand the effect of particle contamination of objective lens in a CD-ROM drive on laser diode power and photo diode RF signal. The measurements of laser power and readout RF signal were carried out by using a laser power meter and a time interval analyzer, respectively. The parameters for estimating a readout-signal' distortion were its jitter and amplitude. Alumina(Al$_2$O$_3$) particles were used as test dust particles. The results show that the failure for data access happened as the degree of lens contamination was greater than 20％.