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Laser Doppler vibrometer

About: Laser Doppler vibrometer is a research topic. Over the lifetime, 6319 publications have been published within this topic receiving 76068 citations.


Papers
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Proceedings ArticleDOI
23 Aug 1996
TL;DR: In this paper, the authors investigated experimentally how photodetector size and position relative to the target can lead to noise floor reduction in the laser Doppler Vibrometer output.
Abstract: The range of potential applications of the Laser Doppler Vibrometer is significantly influenced by the behavior of the speckle pattern that is incident on the instrument's photodetector. A speckle pattern is formed when coherent laser light is scattered from an optically rough target. This paper investigates experimentally how photodetector size and position relative to the target can lead to noise floor reduction in the instrument's output. An optimum detector position is specified for the rotating target condition considered. The experimental results are compared with theoretical results in order for the predictive of further noise reduction to be made. For reliable operation and increased reduction it is essential to minimize the speckle noise contribution to the Laser Vibrometer output.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

25 citations

Patent
23 Sep 1986
TL;DR: In this article, an elliptical laser light beam is directed to the target (a bar code symbol) so as to increase the signal to noise ratio of the laser light received by the photodetector.
Abstract: A laser scanner wherein an elliptical laser light beam is directed to the target (a bar code symbol) so as to increase the signal to noise ratio of the laser light received by the photodetector The use of laser light in the shape of an ellipse, instead of the prior spherical shaped laser light, where the long axis of the elliptical laser light is aligned with the bars of the code being read reduces the distortion of the optical signals received by the photodetector Thus the signal to noise ratio is maximized so as to enable the resolution of fine, dense bar codes

25 citations

Journal ArticleDOI
TL;DR: An integrated optoelectronic probe with small dimensions, for direct-contact laser Doppler blood flow monitoring has been realized and it is demonstrated to be less sensitive to subject motion than a commercial fiber-optic device.
Abstract: An integrated optoelectronic probe with small dimensions, for direct-contact laser Doppler blood flow monitoring has been realized. A vertical cavity surface emitting laser (VCSEL), and a chip with photodetectors and all necessary electronics are integrated in a miniature probe head connected to a laptop computer. The computer sound processor is utilized for acquisition and digital signal processing of the incoming Doppler signal. In this paper, the design of the laser Doppler perfusion monitor is described and its performance is evaluated. We demonstrate our perfusion monitor to be less sensitive to subject motion than a commercial fiber-optic device. For medium and high perfusion levels, the performance of our integrated probe is comparable to the fiber-optic flowmeter containing a normal edge-emitting laser diode. For very low perfusion levels, the signal-to-noise ratio of the fiber-optic device is higher. This difference can mainly be attributed to the shorter coherence length of the VCSEL compared with the edge-emitting laser diode

25 citations

Journal ArticleDOI
TL;DR: LDV measurements of the resonance frequency of a bubble suspended in a small tank are presented to illustrate the utility of this measurement technique and are similar to the precision of traditional acoustic techniques.
Abstract: The behavior of bubbles confined in tubes and channels is important in medical and industrial applications. In these small spaces, traditional means of experimentally observing bubble dynamics are often impossible or significantly perturb the system. A laser Doppler vibrometer (LDV) requires a narrow (<1mm diameter) line-of-sight access for the beam and illumination of the bubble does not perturb its dynamics. LDV measurements of the resonance frequency of a bubble suspended in a small tank are presented to illustrate the utility of this measurement technique. The precision of the technique is similar to the precision of traditional acoustic techniques.

25 citations

Journal ArticleDOI
TL;DR: In this article, the effect of unequal spacing of planet gears relative to the rotating carrier plate on various frequency components in the vibration spectra is studied, and the mathematical analysis is validated with experimental data comparing the vibration signature of helicopter transmissions operating either normally or with damage.
Abstract: This paper examines the problem of identifying cracks in planetary gear systems through the use of vibration sensors on the stationary gearbox housing. In particular, the effect of unequal spacing of planet gears relative to the rotating carrier plate on various frequency components in the vibration spectra is studied. The mathematical analysis is validated with experimental data comparing the vibration signature of helicopter transmissions operating either normally or with damage, leading to shifts in the planet gear positions. The theory presented is able to explain certain features and trends in the measured vibration signals of healthy and faulty transmissions. The characterization offered may serve as a means of detecting damage in planetary gear systems.

25 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202381
2022177
2021122
2020142
2019134
2018174