• Title/Summary/Keyword: Laser doppler velocimeter

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Stabilizing circuit of doppler beat signal obtained by coherence-dependent fiber-optic laser doppler velocimeter

  • Shinohara, shigenobu;Michiwaki, Motohiko;Ikeda, Hiroaki;Yoshida, Hirofumi;Sawaki, Toshiko;Sumi, Masao
    • 제어로봇시스템학회:학술대회논문집
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    • 1993.10b
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    • pp.434-439
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    • 1993
  • Described is a stabilizing circuit of the Doppler beat signal obtained by the coherence-dependent fiber-optic laser Doppler velocimeter (LDV), which employs both a self-mixing laser diode (SM-LD) and a 10m-100m long optical fiber. The stabilizing circuit maintains the SM-LD drive current at an optimum value, which gives a maximum Doppler signal during long hours.

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Laser doppler velocimeter using the self-mixing effect of a $CO_2$ laser (산란광의 되먹임을 이용한 $CO_2$ 레이저 도플러 속도 측정)

  • 최종운;김용평;김윤명
    • Korean Journal of Optics and Photonics
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    • v.7 no.2
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    • pp.157-161
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    • 1996
  • A simple laser Doppler velocimeter(LDV) using a $CO_2$ laser with its self-mixing effect has been developed. We measured the laser power which was modulated by Doppler frequency, when monochromatic laser light was focused to a moving target. The Doppler-shifted frequency was controlled by changing rotating speed of the turntable or the cosine of the angle between the direction of the laser beam and that of the rotating velocity.

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Laser Doppler Velocimetry Using the Photoacoustic Effect of $CO_2$ Laser (광음향 효과를 이용한 $CO_2$ 레이저 도플러 속도 측정기)

  • 최종운;유문종
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.53 no.1
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    • pp.36-40
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    • 2004
  • A new laser Doppler velocimeter employing a $CO_2$ laser has been developed by using its photoacoustic effect. A change in the pressure of a discharge, induced by mixing of a returned wave with an originally existing wave inside the cavity, is employed to detect the Doppler frequency shift. We found that a Doppler frequency shift as much as 34 KHz was detected, and also a good linear relationship between the velocity and the Doppler frequency shift was obtained.

Design and Evaluation of Blood flow Measurement Using Self-mixing type Semiconductor Laser (자기혼합형 반도체 레이저를 이용한 혈류측정 시스템 설계 및 평가)

  • Kim, Duck-Young;Lee, Jin;Kim, Se-Dong;Ko, Han-Woo;Kim, Sung-Hwan
    • Journal of Biomedical Engineering Research
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    • v.17 no.4
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    • pp.499-506
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    • 1996
  • Blood flow velocimeter is an essential device to measure the blood flow in skin tissue. In this study, we developed a high-speed LDV(laser Doppler Velocimeter) that has real time processing capability using a DSP(digital signal processing) chip and is able to continuously measure information about blood-flow based on a noninvasive method using self-mixing type laser diode. This LDV system has a simpler structure than any other typical blood flow velocimeter and is composed of new self-mixing probe, stabilizer circuits DSP board, and interf'ace boule We measured velocity of speaker-unit by operational frequencies to identify Doppler effect of this system, performed clinical experiment on bare finger tip and compared it with a commercial euipment BPM403A(USA).

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Measurement of Velocity Profiles in the Laminar Free Convection Boundary Layer on A Uniformly Heated Vertical Flat Plate by A Laser- Doppler Velocimeter (수직평판의 자연대류 경계층에서의 유속의 Laser-Doppler 유속계에 의한 측정)

  • ;;Lee, Jeong Bae
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.3 no.1
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    • pp.27-34
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    • 1979
  • The velocity profiles in the laminar free convection boundary layer on a uniformly heated vertical plate are measured by a Laser Doppler Velocimeter for air in the range of modified Grashof number G $r_{\chi}$*=1.172x10$^{9}$ . The fringe mode, forward scatter type of the LDV system is used and the small magnesium oxide particles are used for the scattering pafticles. The analytical non-dimensionalized velocity profiles are obtained by use of an analog computer for the comparison with the experimental results. The experimental reults are in good agreement with the analytical solution obtained with an aid of the analog computer.er.

Determination of Flow Direction by Using an Acousto-Optic Effect (광음향 변조효과를 이용한 유체의 방향 결정)

  • 김규욱
    • Proceedings of the Optical Society of Korea Conference
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    • 1990.02a
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    • pp.34-36
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    • 1990
  • The flow direction in a glass tube is measured by using a forward scatering dual beam laser Doppler velocimeter with an acousto-optic modulator. We can determine the flow direction by measuring the shifted Doppler frequency which is dependent on the order of modulation of the laser frequency shifting moves only the Doppler signal, enabling complete separation of the Pedestal and Doppler singal.

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Laser doppler velocimetry using the optogalvanic effect of $Co_2$ laser (광전류 효과를 이용한 $Co_2$ 레이저 도플러 속도 측정기)

  • 최종운;김용평;김윤명
    • Korean Journal of Optics and Photonics
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    • v.8 no.6
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    • pp.482-485
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    • 1997
  • A new laser Doppler velocimeter employing a $CO_2$laser has been developed by using its optogalvanic effect. A change in the electric impedance of a discharge, induced by mixing of a returned wave with an originally existing wave inside the cavity, was employed to detect the Doppler frequency shift. A Doppler frequency shift as much as 60 KHz was detected, and also a good linear relationship between the velocity and the Doppler frequency shift was obtained.

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Photoacoustic Laser Doppler Velocimetrv Using the Self - mixing Effect of RF - excited CO2 Laser

  • Choi, Jong-Woon;You, Moon-Jong;Choi, Sung-Woong;Woo, Sam-Young
    • Journal of the Optical Society of Korea
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    • v.8 no.4
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    • pp.188-191
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    • 2004
  • A new laser Doppler velocimeter employing a $CO_2$ laser has been developed by using its photoacoustic effect. A change in the pressure of a discharge, induced by mixing of a returned wave with an originally existing wave inside the cavity, is employed to detect the Doppler frequency shift. We found that a Doppler frequency shift as small as 50 kHz was detected, and also a good linear relationship between the velocity and the Doppler frequency shift was obtained.

A Study on the Flow Characteristics of Developing Transitional Steady Flows in a Curved Duct by Using Laser Doppler Velocimeter (I) (곡관덕트에서 LDV를 이용한 천이정상유동의 유동특성에 관한 연구(I))

  • 봉태근;박길문
    • Journal of Advanced Marine Engineering and Technology
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    • v.24 no.6
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    • pp.96-101
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    • 2000
  • In this paper, an experimental investigation of characteristics of developing transitional steady flows in a square-sectional 180 urved duct is presented. The experimental study is carried out to measure axial velocity profiles by using Laser Doppler Velocimeter (LDV) system. The flow development is found to depend upon Dean number and curvature ratio. For transitional steady flows, the maximum velocity position of axial velocity profiles begins to incline toward the outer wall from $\phi$=$30^{\circ}$bended angle, velocity profiles in center of the duct have lower value than those of the inner and outer walls because of the centrifugal forces.

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