The effect of three-wave interference in laser Doppler vibrometry

Yarovoi, Leonid K.; Siegmund, Georg

doi:10.1088/0957-0233/15/10/027

Cited by 13 publications

(8 citation statements)

References 4 publications

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“…81 Unwanted light waves can interfere with the desired interaction between the reference and measurement beams-known as threewave interference-but the artifacts of this can be predicted. 82 The vibration of rotating objects and the in-plane motion can likewise be measured, but the setup is relatively complex. 83 Digital holographic (DH) microscopy has been investigated as an alternative to LDV.…”

Section: Acoustic Wave Measurementmentioning

confidence: 99%

Micro/nano acoustofluidics: materials, phenomena, design, devices, and applications

et al. 2018

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Acoustic actuation of fluids at small scales may finally enable a comprehensive lab-on-a-chip revolution in microfluidics, overcoming long-standing difficulties in fluid and particle manipulation on-chip. In this comprehensive review, we examine the fundamentals of piezoelectricity, piezoelectric materials, and transducers; revisit the basics of acoustofluidics; and give the reader a detailed look at recent technological advances and current scientific discussions in the discipline. Recent achievements are placed in the context of classic reports for the actuation of fluid and particles via acoustic waves, both within sessile drops and closed channels. Other aspects of micro/nano acoustofluidics are examined: atomization, translation, mixing, jetting, and particle manipulation in the context of sessile drops and fluid mixing and pumping, particle manipulation, and formation of droplets in the context of closed channels, plus the most recent results at the nanoscale. These achievements will enable applications across the disciplines of chemistry, biology, medicine, energy, manufacturing, and we suspect a number of others yet unimagined. Basic design concepts and illustrative applications are highlighted in each section, with an emphasis on lab-on-a-chip applications.

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Section: Acoustic Wave Measurementmentioning

confidence: 99%

Micro/nano acoustofluidics: materials, phenomena, design, devices, and applications

et al. 2018

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“…Multipath interference may occur if, besides of probe and reference wave, a third wave hits the photo detector [6], [7]. Usually this wave comes from unwanted stationary reflections along the optical path.…”

Section: Multipath Interferencementioning

confidence: 99%

Sources of measurement error in laser Doppler vibrometers and proposal for unified specifications

Siegmund

2008

Eighth International Conference on Vibration Measurements by Laser Techniques: Advances and Applications

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The focus of this paper is to disclose sources of measurement error in laser Doppler vibrometers (LDV) and to suggest specifications, suitable to describe their impact on measurement uncertainty. Measurement errors may be caused by both the optics and electronics sections of an LDV, caused by non-ideal measurement conditions or imperfect technical realisation. While the contribution of the optics part can be neglected in most cases, the subsequent signal processing chain may cause significant errors. Measurement error due to non-ideal behaviour of the interferometer has been observed mainly at very low vibration amplitudes and depending on the optical arrangement. The paper is organized as follows: Electronic signal processing blocks, beginning with the photo detector, are analyzed with respect to their contribution to measurement uncertainty. A set of specifications is suggested, adopting vocabulary and definitions known from traditional vibration measurement equipment. Finally a measurement setup is introduced, suitable for determination of most specifications utilizing standard electronic measurement equipment.

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“…Due to the influence of unintended stray beams, the output of the demodulated signal will be severely distorted. In the field of communication, this phenomenon was first explained as the capture effect in the FM demodulator [4] ; in 1998, the 7th International Conference on Vibration Measurement mentioned for the first time about the parasitic reflection in the LDV system [5] . In 2004, Yarovoi [6] analyzed the phenomenon of three-wave interference in traditional LDV; in the same year, ROchefoucauld analyzed the signal competition problem of reflections from different tissue surface layers in LDV.…”

Section: Introductionmentioning

confidence: 99%

Analysis of multi-beam interference in heterodyne detection system

Tao

Zhen²,

Fang³

et al. 2023

Fourth International Conference on Optoelectronic Science and Materials (ICOSM 2022)

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The Laser Doppler Vibrometry (LDV) system can measure parameters such as amplitude, velocity and acceleration of micro-vibrating objects. However, in the actual measurement process, in addition to the probe beam and the reference beam, as the surface roughness of the measured object increases and the diffuse reflectance decreases, the echo energy of the laser will decrease rapidly. This phenomenon can be extended to heterodyne detection systems. Due to the limitation of optical devices, the third beam (ie stray beam) caused by parasitic reflection is unavoidable. At the same time, the third beam has a certain intensity and phase distribution, which seriously affects signal demodulation of micro-vibrating objects. This paper analyzes the effects of multi-beam interference competition in heterodyne demodulation systems. Mathematical analysis shows that the interference competition depends on the signal amplitude, the interferometric light intensity ratio and the relative phase difference. Through mathematical derivation and simulation verification, the following conclusions can be drawn: when the relative phase difference is π rad, when the ratio of light intensity between the probe light and the stray light is controlled to tend to one, the simple harmonic motion with an amplitude of 1 nm is demodulated, and the amplitude can be observed to be nearly 200 times of the enhancement effect. For micro vibration with different amplitudes, the simulation shows that when the amplitude coefficient is π, the demodulation amplitude does not have amplification effect, and the amplitude coefficient is π can be used as the limit of demodulation amplitude amplification. This method has great application value in the high-sensitivity measurement direction of micro-vibrating objects.

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The effect of three-wave interference in laser Doppler vibrometry

Cited by 13 publications

References 4 publications

Micro/nano acoustofluidics: materials, phenomena, design, devices, and applications

Micro/nano acoustofluidics: materials, phenomena, design, devices, and applications

Sources of measurement error in laser Doppler vibrometers and proposal for unified specifications

Analysis of multi-beam interference in heterodyne detection system

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