• Title/Summary/Keyword: laser measurement

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Transmittance measurement for thickness control of ITO layer (ITO막의 두께 제어를 위한 투과율 측정)

  • 박정규;이무영
    • 제어로봇시스템학회:학술대회논문집
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    • 2000.10a
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    • pp.213-213
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    • 2000
  • A sensor system which can measure the transmittance of ITO(Indium Tin Oxide) layed glass is proposed. The sensor system includes a single wavelength laser beam source, photo diodes and electronic circuit processing sensor signal. The wavelength of laser is 543.5 m, this is most sensitive wavelength to photopic and scotopic vision. We applied the sensor to measure transmittance of ITO layer on general manufacturing environment and verified the effectiveness of sensor through experimental measurement.

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Laser Diagnostic in a Plasma Display Panel Discharge Cell

  • Choi, Young-Wook
    • 한국정보디스플레이학회:학술대회논문집
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    • 2000.01a
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    • pp.21-22
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    • 2000
  • Laser diagnostic method in a plasma display discharge cell was introduced. The information of electric field, potential and electron temperature et al. in the surface of plasma display panel can be measured using laser induced fluorescence spectroscopy. However, because of the very small discharge dimension of ${\sim}$ 100 ${\mu}m$, the measurement attempt has almost not been performed. In this paper, the direct measurement possibility of the parameters and the recent work of electric field measurement are demonstrated in the plasma display panel.

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An Experimental Investigation of Air Fuel Ratio Measurement using Laser Induced Acetone Fluorescence (아세톤 형광을 이용한 공연비 측정 기법 연구)

  • Park Seungjae;Huh Hwanil;Oh Seungmook
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.353-356
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    • 2002
  • Planar laser induced fluorescence(PLIF) has been widely used to obtain two dimensional fuel distribution. Preliminary investigation was performed to measure quantitative air excess ratio distribution in an engine fueled with LPG. It is known that fluorescence signal from acetone as a fluorescent tracer is less sensitive to oxygen quenching than other dopants. Acetone was excited by KrF excimer laser (248nm) and its fluorescence image was acquired by ICCD camera with a cut-of filter to suppress Mie scattering from the laser light. For the purpose of quantifying PLIF signal, an image processing method including the correction of laser sheet beam profile was suggested. Raw images were divided by each intensity of laser energy and profile of laser sheet beam. Inhomogeneous fluorescence images scaled with the reference data, which was taken by a calibration process, were converted to air excess ratio distribution. This investigation showed instantaneous quantitative measurement of planar air excess ratio distribution for gaseous fuel.

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$CO_2$ Laser Absorption Measurement of $CH_3CH_2Br$ using Photoacoustic Method

  • Jang Soo Shin;Kyung Hoon Jung;Cheol Jung Kim
    • Bulletin of the Korean Chemical Society
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    • v.13 no.5
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    • pp.553-556
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    • 1992
  • The ${CO}_2$ laser absorption measurement of ${CH}_3{CH}_2Br$ utilizing photoacoustic (PA) technique was performed using a cw and a pulsed ${CO}_2$ lasers. The absorption profile in the ${CO}_2$ laser wavelength region (9-10 ${\mu}$m) and the macroscopic small signal absorption cross section at 10P(20) (10.59 ${\mu}$m, 944 $cm^{-1}$) laser line were measured using a cw ${CO}_2$ laser. The laser fluence dependence on infrared multiphoton absorption (IRMPA) was also studied with a pulsed TEA ${CO}_2$ laser at 10P(20) laser line. In view of monotonic increase of PA signal with the rise of laser fluence, it was suggested that the anharmonicity in pumped vibration mode did not restrict ir multiphoton absorption in ${CH}_3{CH}_2Br$ system as found in large molecular system.

Depth Measurement Method Robust against Scattering of Line Lasers (라인 레이저의 산란에 강인한 심도 측정 방법)

  • Ko, Kwangjin;Yeon, Sungho;Kim, Jaemin
    • Journal of Korea Multimedia Society
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    • v.21 no.2
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    • pp.181-187
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    • 2018
  • Line-laser beams are used for depth measurement of welding beads along the circumference of a pipe. For this, first we project a line-laser beam on an rotating pipe and take a sequence of images of the beam projected on the pipe using a CCD camera. Second, the projected line laser beam in each image is detected, converted into a thin curve. Finally measure the distance between the thinned curve and an imaginary line. When a line-laser beam is projected to a rough metal surface such as arc welding beads, the beam is severely scattered. This severe scattering makes the thinned curve perturbed. In this paper, we propose a thinning method robust against scattering of line lasers. First, we extract a projected line laser beam region using an adaptive threshold. Second, we model a thinned curve with a spline curve with control points. Next, we adjust the control points to fit the curve to the projected line-laser beam. Finally, we take a weighted mean of thin curves on a sequence of image frames. Experiments shows that the proposed thinning method results in a thinning curve, which is smooth and fit to the projected line-laser beam with small error.

The Lens Design Technique of High Precision Laser Range Finder (고정밀 레이저 거리계용 렌즈 설계 기법)

  • Bae, Young-Chul;Cho, Eui-Joo;Lee, Hyen-Jae;Kim, Sung-Hyen;Kim, Hyeon-Woo
    • Journal of Advanced Navigation Technology
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    • v.13 no.2
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    • pp.187-193
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    • 2009
  • A lens which is one of cores for the high precision laser range finder is utilized to compute the distance by measuring the phase displacement. In order to measure the phase displacement, we transmit the optical signal from the laser diode to a target and receive the reflected laser light from the target. In this paper, we propose new lens design technique to solve the problem due to the inconsistent curvature of the lens, which consistently collects optical signals and performs the transmission and reception of the optical data, and test the implementation of the laser range finder based on the proposed technique. Since the proposed laser range finder has low error rate comparing to the conventional techniques, it may be apply to the high precision distance measurement.

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Study on Optimal Arrangements of Laser Beams in Tunable Diode Laser Absorption Spectroscopy Based Tomography (TDLAST) (레이저흡수분광 토모그래피법에서의 레이저빔의 최적 배치에 관한 연구)

  • KIM, KYUNGWON;YOON, DONGIK;CHOI, DOOWON;CHO, GYEONGRAE;DOH, DEOGHEE
    • Transactions of the Korean hydrogen and new energy society
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    • v.28 no.6
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    • pp.729-737
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    • 2017
  • The measurement accuracy of Tunable Diode Laser Absorption Spectroscopy based Tomography (TDLAST) for the temperature and concentration fields are dependant upon the arrangement method of the used laser beams. This paper reports on the optimization of laser beam arrangements using phantom data. It has been verified that the measurement error of the TDLAST decreased with increase of laser beam numbers. Further, it has been confirmed that perpendicular arrangements between the horizontal and the vertical laser beams without additional diagonal laser beams shows the minimum measurement errors.

Characterization of a Micro-Laser-Plasma Electrostatic-Acceleration Hybrid-Thruster

  • Akira Igari;Masatoshi Kawakami;Hideyuki Horisawa;Kim, Itsuro ura
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2004.03a
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    • pp.271-277
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    • 2004
  • As one of the concepts of the laser/electric hybrid propulsion system, a feasibility study on possibilities of electrostatic acceleration of a laser ablation plasma induced from a solid target was conducted. Energy distributions of accelerated ions were measured by a Faraday cup. A time-of-flight measurement was also conducted for ion velocity measurement. It was found that an average speed of ions from a pure laser ablation in this case was about 20 km/sec for pulse energy of 40 $\mu$J/pulse with pulse width of 250 psec. On the other hand, through an electrostatic field with a + I ,000 V electrode, the speed could be accelerated up to 40 km/sec. It was shown that the electrode with positive potential was more effective than that with negative potential for positive-ion acceleration in laser induced plasma, or pulsed plasma, in which ions were induced with the Coulomb explosion following electrons. In addition, the ion-acceleration or deceleration strongly depended on conditions of pairs of inner diameter and electrodes gap.

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Design of Precision Position Measuring System using Laser Interferometry (광간섭법을 이용한 정밀 위치측정 시스템 설계)

  • 김진상;정성종
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.04a
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    • pp.145-149
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    • 1997
  • A laser mesurement system, a modified Michelson interferometer,which can accurately measure high speed length and position of servomechanisms by detecting a phase shift in the measurement beam using an optical interference was developed. A frequency stabilized laser source and a 20 fold frequency interpolation and digitizing circuit were applied to the system. The refractive index of the ambient air was calibrated through the Edlen's formula. The system achieved a resolution of .lambda./40,16nm, a maximum allowable measurement speed of 600 mm/sec, and a length measurement range of 1500mm. Performance of the system was evaluated on the machining center in short and long length measurements

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Flow Velocity Measurement for Laminar Diffusion Flames Utilizing LII Signal from Soot Particles (매연입자의 LII 신호를 이용한 충류확산화염 유동속도 측정)

  • Lee, Jung-Soo;Nam, Youn-Woo;Lee, Won-Nam
    • 한국연소학회:학술대회논문집
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    • 2006.04a
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    • pp.157-163
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    • 2006
  • A new technique utilizing LII signal for the measurement of flow velocities of laminar diffusion flames has been investigated. Soot particles in ethylene diffusion flames are heated by a modulated Ar-ion laser beam. LII signals and their phase angles are measured using a lock-in amplifier at the different flame heights and the axial flow velocity are obtained from the measured phase angle delay. The measured velocities are similar to those from LDV measurements under the same operating conditions. The effects of laser power, LII signal wavelength, and modulation frequency are not sensitive to the velocity measurement. However, the choice of an optical chopper blade type could affect the measurement result. The use of a 6/5 chopper blade showed the better result that is possibly due to the square shape of modulated laser beam. This study successfully demonstrated that axial flow velocities of laminar diffusion flames can be measured by a new technique utilizing LII signal, which does not need particle seeding unlikely to LDV or PIV techniques.

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