Topic
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.
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TL;DR: Experimental results on spheres of different size, vibrated at various frequencies, confirm the theoretical prediction that the dynamic and static radiation force on a sphere have approximately equal magnitudes.
Abstract: Dynamic radiation force from ultrasound has found increasing applications in elasticity imaging methods such as vibro-acoustography. Radiation force that has both static and dynamic components can be produced by interfering two ultrasound beams of slightly different frequencies. This paper presents a method to measure both static and dynamic components of the radiation force on a sphere suspended by thin threads in water. Due to ultrasound radiation force, the sphere deflects to an equilibrant position and vibrates around it. The static radiation force is estimated from the deflection of the sphere. The dynamic radiation force is estimated from the calculated radiation impedance of the sphere and its vibration speed measured by a laser vibrometer. Experimental results on spheres of different size, vibrated at various frequencies, confirm the theoretical prediction that the dynamic and static radiation force on a sphere have approximately equal magnitudes [G. T. Silva, Phys. Rev. E 71, 056617 (2005)].
29 citations
TL;DR: In this article, a laser Doppler anemometer is described in which an optical fiber is used to transmit the light to and from the measurement zone, and an analysis is made of backscattering into a fibre which shows that the backscattered power is confined to a region extending only a few tens of core diameters from the fibre end.
Abstract: A laser Doppler anemometer is described in which an optical fibre is used to transmit the light to and from the measurement zone. An account is given of the various types of measurement that have been made with the instrument, particularly those involving Brownian motion. An analysis is made of backscattering into a fibre which shows that the back-scattered power is confined to a region extending only a few tens of core diameters from the fibre end.
29 citations
TL;DR: In this paper, the impact of short pulse mercury spallation targets on short pulse proton beam experiments was investigated at LANSCE -WNR in July of 2008, where damage dependence on mercury velocity using geometry more prototypic to the SNS target than previously employed was investigated.
29 citations
Patent•
01 Oct 2008
TL;DR: In this paper, a flip-chip mounting apparatus includes a variable-shape mirror 16 for receiving a laser beam emitted from a laserbeam oscillating source 12, a sensor 18 for sensing a reflected laser beam from the variable shape mirror 16, and a controlling portion 20 for controlling the variable-shaped mirror 16 by comparing a sensed signal input from the sensor 18 with previously input threshold values such that an intensity distribution of the reflected laserbeam corresponds to a distribution of bumps 37 on a semiconductor chip 36.
Abstract: A flip-chip mounting apparatus includes a variable-shape mirror 16 for receiving a laser beam emitted from a laser beam oscillating source 12, a sensor 18 for sensing a reflected laser beam from the variable-shape mirror 16, and a controlling portion 20 for controlling the variable-shape mirror 16 by comparing a sensed signal input from the sensor 18 with previously input threshold values such that an intensity distribution of the reflected laser beam corresponds to a distribution of bumps 37 on a semiconductor chip 36, whereby when the reflected laser beam from the variable-shape mirror 16 is irradiated onto the semiconductor chip 36 through a beam expander 34 and a pushing body 40, a beam shape of the reflected laser beam matches with an outer shape of the semiconductor chip 36 and also joined portions are heated concentratedly.
29 citations
28 Mar 1989
TL;DR: In this article, the authors used finite element analysis to verify the acoustic emission (AE) measurements of the laser Doppler vibrometer and AE (acoustic emission) measurements and determined that the lowest natural frequency of a mini-Winchester slider is around 130 kHz.
Abstract: The natural frequencies of the various transducers and sliders were studied by finite element modeling and experimentation. Finite element analysis shows that the lowest ringing frequency of a 3370 slider is around 310 kHz. This value has been verified by the laser Doppler vibrometer and AE (acoustic emission) measurements. It is determined that the lowest natural frequency of a mini-Winchester slider is around 130 kHz. The 140-kHz frequencies reported in the literature using the two-rail sliders with piezoelectric transducers attached to the slider and the 160-kHz frequencies reported using AE transducers attached to the suspension mount are associated with the natural frequencies of these transducers and not of the sliders. >
29 citations