LOCALIZED FLUID FLOW MEASUREMENTS WITH AN He–Ne LASER SPECTROMETER

Yeh, Yi‐Cheun; Cummins, H. Z.

doi:10.1063/1.1753925

Cited by 730 publications

(213 citation statements)

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“…This frequency shift scales with the linear velocity and is generally applicable in monitoring the translational motion. 1,2 Since first proposed by Yeh and Cummins 3 in 1964, just a few years after the invention of the laser, the laser linear Doppler technique has become an efficient tool for velocity measurement of surface, 4 fluid, 5 and atmospheric turbulence. 6 In recent years, a rotational analog to linear Doppler effect, namely rotational Doppler effect, has drawn great attention.…”

Section: Introductionmentioning

confidence: 99%

Rotation of an optically trapped vaterite microsphere measured using rotational Doppler effect

et al. 2018

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Abstract. The angular velocity of a vaterite microsphere spinning in the optical trap is measured using rotational Doppler effect. The perfectly spherical vaterite microspheres are synthesized via coprecipitation in the presence of silk fibroin nanospheres. When trapped by a circularly polarized beam, the vaterite microsphere is uniformly rotated in the trap center. The probe beams containing two Laguerre-Gaussian beams of opposite topological charge l ¼ AE7, l ¼ AE8, and l ¼ AE9 are illuminated on the spinning vaterite. By analyzing the backscattered light, a frequency shift is observed scaling with the rotation rate of the vaterite microsphere. The multiplicative enhancement of the frequency shift proportion to the topological charge has greatly improved the measurement precision. The reliability and practicability of this approach are verified through varying the topological charge of the probe beam and the trapping laser power. In consideration of the excellent measurement precision of the rotation frequency, this technique might be generally applicable in studying the torsional properties of micro-objects. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Introductionmentioning

confidence: 99%

Rotation of an optically trapped vaterite microsphere measured using rotational Doppler effect

et al. 2018

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“…The power spectrum of coherent monochromatic light scattered by moving particles is broadened as a result of momentum transfer. The Doppler shift for one scattering event is (18) :…”

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confidence: 99%

Laser Doppler imaging, revisited

Atlan

Gross

2006

Review of Scientific Instruments

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We present a detection scheme designed to perform laser Doppler imaging in a wide-field configuration, aimed at slow flow characterization. The optical field which carries a spectral information about the local scatterers dynamic state that results from momentum transfer at each scattering event is analyzed in the temporal frequencies domain. The setup is based on heterodyne off-axis digital holography.

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“…Doppler ultrasound, the principal clinical tool for examining flow above 10 cm/ s in large vessels, has difficulty detecting flow with speed less than 1 mm/ s. Since the backscattered ultrasound signal from the small amount of red blood cells ͑RBC͒ is much weaker ͑ϳ100 dB͒ than that from the surrounding tissue, 2,3 the Doppler shift from the slowly moving RBC is masked by that from the tissue with slow motion. Laser Doppler flowmetry 4 can measure very low speed flow in microcirculation owing to the short optical wavelength 5 but it suffers from multiple light scattering, which randomizes the optical phase rapidly ͓scattering coefficient in tissue S ϳ 100 cm −1 ͑Ref. 6͔͒.…”

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confidence: 99%

Photoacoustic Doppler flow measurement in optically scattering media

Fang¹,

Maslov²,

Wang³

2007

Applied Physics Letters

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We recently observed the photoacoustic Doppler effect from flowing small light-absorbing particles. Here, we apply the effect to measure blood-mimicking fluid flow in an optically scattering medium. The light scattering in the medium decreases the amplitude of the photoacoustic Doppler signal but does not affect either the magnitude or the directional discrimination of the photoacoustic Doppler shift. This technology may hold promise for a new Doppler method for measuring blood flow in microcirculation with high sensitivity.

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LOCALIZED FLUID FLOW MEASUREMENTS WITH AN He–Ne LASER SPECTROMETER

Cited by 730 publications

References 3 publications

Rotation of an optically trapped vaterite microsphere measured using rotational Doppler effect

Rotation of an optically trapped vaterite microsphere measured using rotational Doppler effect

Laser Doppler imaging, revisited

Photoacoustic Doppler flow measurement in optically scattering media

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