• Title/Summary/Keyword: Pockels

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A possible non-contact measuring technique for the variation of the electric field due to corona discharge by use of Pockels sensor (포켈스센서를 이용한 코로나방전 발생시의 전계변화 측정에 관한 연구)

  • Ma, Ji-Hoon;Kang, Won-Jong;Lim, Yun-Sok;Choi, Jae-Ok;Chang, Yong-Moo;Koo, Ja-Yoon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.05c
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    • pp.189-192
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    • 2001
  • In this paper, an novel optical measuring system based on the electro-optic effect has been proposed and realized using Pockels cell with a view to detecting partial discharge taking place at the needle plane electrode. This system has the following advantages ; nonmetallic probe sensor, immune to external EMI noise and broad band response of the Pockels cell from DC to GHz. This system is constructed by He-Ne laser, Mach-Zehnder interferometer with Pockels sensor, balanced photo receiver, data acquisition board and PC. The response characteristics of the developed proto type sensor are examined for AC and corona discharge.

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A study of the development of a simple driver for the Pockels cell Q-switch and Its characteristics (단순화된 Pockels cell Q-switch용 구동기 개발 및 특성에 관한 연구)

  • Park, K.R.;Joung, J.H.;Hong, J.H.;Kim, B.G.;Moon, D.S.;Kim, W.Y.;Kim, H.J.;Cho, J.S.
    • Proceedings of the KIEE Conference
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    • 2000.07c
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    • pp.2116-2118
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    • 2000
  • In the technique of Q-switching, very fast electronically controlled optical shutters can be made by using the electro-optic effect in crystals or liquids. The driver for the Pockels cell must be a high-speed, high-voltage switch which also must deliver a sizeable current. Common switching techniques include the use of vacuum tubes, cold cathode tubes, thyratrons, SCRs, and avalanche transistors. Semiconductor devices such as SCRs, avalanche transistors, and MOSFETs have been successfully employed to drive Pockels cell Q-switch. In this study, a simple driver for the Pockels cell Q-switch was developed by using SCRs, pulse transformer and TTL ICs. The Pockels cell Q-switch which was operated by this driver was employed in pulsed Nd:YAG laser system to investigate the operating characteristics of this Q-switch. And we have investigated the output characteristics of this Q-switch as a function of the Q-switch delay time to Xe flashlamp current on.

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Optical Voltage Sensor Using $SiO_2$ Pockels Cell ($SiO_2$ 포켈 소자를 이용한 광전압센서)

  • Shin, K.H.;Chun, J.P.;Cho, H.K.;Kim, S.K.;Kim, Y.H.;Kim, Y.S.;Park, H.S.
    • Proceedings of the KIEE Conference
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    • 1991.07a
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    • pp.846-849
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    • 1991
  • This paper reports the principle, system confiquration, test results of optical voltage sensor using quartz pockels cell. The Pockels effect of quartz material is used for designing optical voltage sensor. The quarts material has very high half-wave voltage, so, it can be applied to measure high voltage level. Experimental results show that the optical voltage sensor has excellent linear characteristics within the applied AC voltage of 1200V.

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A possible optical measuring technique for corona discharge by use of Pockets sensor (광계측 시스템을 이용한 코로나 방전 검출)

  • Kang, Won-Jong;Ma, Ji-Hoon;Chang, Yong-Moo;Koo, Ja-Yoon
    • Proceedings of the KIEE Conference
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    • 2001.07c
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    • pp.1561-1563
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    • 2001
  • In this paper, an novel optical measuring system based on the electro-optic effect has been proposed and realized using Pockels cell with a view to detecting partial discharge taking place at the needle plane electrode. This system has the following advantages ; nonmetallic probe sensor, immune to external EMI noise and broad band response of the Pockels cell from DC to GHz. And also it is constructed by He-Ne laser, optical fiber, $LiNbO_3$ Pockels cell, photo detector, grin lens, oscilloscope and PC. The characteristics of the developed prototype sensor are investigated under AC and corona discharges.

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A Possible Application of the Nonuniform Electric Field Measurement Using Laser Interferometer and Pockels Effect (레이저 간섭계와 포켈스 효과를 이용한 불평등 전계 측정)

  • Gang, Won-Jong;Gu, Ja-Yun
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.51 no.6
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    • pp.240-245
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    • 2002
  • In this paper, a novel optical measuring system for the measurement of nonuniform electric field was proposed. The electric field distorted by the discharges was detected through proposed optical measuring system based on the Pockets effect and Mach-Zehnder interferometer. In order to produce distorted electric field, corona discharge was generated from needle-plane electrode in air and detected by optical measuring system. This optical measuring system is constructed by He-Ne laser, single mode optical fiber, $2{\times}2$ 50/50 beam splitter, $LiNbO_3$ Pockets cell, photo detector and PC. In this system, output signal of Pockels sensor is measured by digital oscilloscope and transferred to the PC for recording and statistical processing. Through this paper, a promising possibilities of proto-type optical measuring system were evinced.

Measurement of High Voltage Pulse using a KDP Pockels Cell (KDP Pockels 소자를 이용한 고전압 펄스 측정)

  • Cho, K.L.;Lee, J.H.;Chang, Y.M.;Koo, J.Y.;Kang, H.B.
    • Proceedings of the KIEE Conference
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    • 1993.07b
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    • pp.566-568
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    • 1993
  • A measuring technique for the fast transient high voltage is under development by use of laser source in order to substitute for the conventional measuring system which could bring about several technical inconveniences. At this moment, this work is aimed to construct a compact measuring system with the use of Pockels cell and specially designed voltage divider. This system is likely to enable us to measure the lightening impulse voltages at the level of 30kV, 50kV and 70kV. Throughout this work, qualified measuring devices are required to be developed for discriminating different kinds of noise from which the system should be protected.

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Investigation on the characteristics of a cavity-dumped Nd:glass laser (Cavity-dumping형 Nd:glass laser의 제작 및 특성 조사)

  • 차용호;강응철;남창희
    • Korean Journal of Optics and Photonics
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    • v.6 no.2
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    • pp.130-134
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    • 1995
  • A small signal gain coefficient of Nd:glass was measured and a cavity-dumped laser was constructed. To measure the small signal gain coefficient, we constructed a resonator consisting of Nd:glass, Pockels cell, polarizing beam splitter. The measured small signal gain coefficient was $0.088 cm_{-1}$ when the input energy was 100 J and the round-trip internal loss of the resonator was 56%. The cavity-dumped laser was constructed using Nd:glass. 2 m radius of curvature HR-mirrors, Pockels cell, polarizinig beam splitter and $\lambda/4$ plate. The output energy of cavity-dumped laser was 0.85 J at 140 J input energy and the laser pulse width was 8 ns.s 8 ns.

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A Possible Application of the PD Detection Technique Using Electro-Optic Pockels Cell With Nonlinear Characteristic Analysis on the PD signals

  • Kang, Won-Jong;Lim, Yun-Sok;Chang, Young-Moo;Koo, Ja-Yoon
    • KIEE International Transactions on Electrophysics and Applications
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    • v.11C no.2
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    • pp.6-11
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    • 2001
  • Abstract- In this paper, a new Partial Discharge (PD) detection using Pockels cell was proposed and considerable apparent chaotic characteristics were discussed. For this purpose, PD was generated from needle-plane electrode in air and detecte by optical measuring system using Pockels cell, based on Mach-Zehner interferometer, consisting of He-Ne laser, single mode optical fiber, 50/50 beam splitter and photo detector. In addition, the presence of chaos of the PD signals has been investigated by examining their means of qualitative and quantitative information. For the former, return map and 3-dimensional strange attractor have been drawn in order to investigate the presence of chaotic characteristics relevant to PD signals, detected through CT and Peckels sensor respectively, in the normalized time series. The presence of strange attractor indicates the existence of fractal structures in it's phase space. For the latter, several dimension values of strange attractor were verified sequentially. Throughout this paper, it is likely that the chaotic characteristics regarding the PD signals under air are verified.

Development of Measuring Techniques for High Voltage Impulse and Small Signals using Pockels Cell (포켈스 소자를 이용한 고전압 임펄스 및 미소신호 측정기술 개발)

  • Hong, J.Y.;Lee, J.B.;Chang, Y.M.;Koo, J.Y.
    • Proceedings of the KIEE Conference
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    • 1994.07b
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    • pp.1571-1573
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    • 1994
  • In order to substitute for the conventional measuring system which could bring about technical inconveiences, measuring techniques for the fast transient high voltage upto 100 kV and small signals less than 1 V are developed by use of Laser Source with Packets cell. for the former, capacitive voltage divider was specially designed for reducing the impulse voltage less than the half-wave voltage of pockets cell. For the tatter, interferometer type was employed as a mean to removing the fluctuation of Laser output intensity. And also the main beam through the Pockels cell and the reference beam from the Laser source are seperated before being detected respectively by photo diodes. And then, these two signals are amplified and compared for detecting only the small signals applied across the Pockels cell. Throughout this work, Laser-based measuring system is likely to enable us, at this moment, to detect correctly lightning impulse voltage upto 100 kV and the small signals less than 1 V upto the 2 MHz. Such a system could be employed as a possible diagnostic measuring system at the substation.

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