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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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Journal ArticleDOI
TL;DR: In this article, the authors used a high-speed camera and the single point laser Doppler vibrometer (LDV) to observe the transient cavitating flow patterns and measure the vibration velocities.
Abstract: The objective of this paper is to investigate the unsteady cavitation behaviors and the corresponding cavitating flow-induced vibrations. Results are presented for the modified NACA66 hydrofoils made of stainless steel and POM Polyacetate respectively at Re = 6.0×105 for various cavitation regimes. The high-speed camera and the single point laser Doppler vibrometer (LDV) are used to observe the transient cavitating flow patterns and measure the vibration velocities. The results showed that the vibration amplitude increases dramatically for the cloud cavitation due to the development of large-scale cloud cavity. The main flow-induced frequencies, which are in accordance with the cavity shedding frequency, decrease with the decrease of the cavitation number. As for the effect of the hydroelastic response on the vibration behavior, the lift coefficient for the POM Polyacetate hydrofoil fluctuates more significantly with a larger mean value than that for the stainless steel hydrofoil. Compared with the vaporous cavity along the suction side of the stainless steel hydrofoil, the cavity for POM Polyacetate hydrofoil appears to be fragmentized. The main vibration frequencies for the POM Polyacetate hydrofoil are larger than that for the stainless steel hydrofoil, with the chaotic hydroelastic response with high frequency.

25 citations

Patent
24 Dec 2003
TL;DR: In this paper, a noncontact method and apparatus for continuously monitoring a physiological event in a human or animal, such as blood pressure, which involves utilizing a laser-based interferometer system to produce a waveform that is representative of continuous blood pressure in a subject.
Abstract: A non-contact method and apparatus for continuously monitoring a physiological event in a human or animal, such as blood pressure, which involves utilizing a laser-based interferometer system to produce a waveform that is representative of continuous blood pressure in a subject. The invention may preferably utilize a laser Doppler vibrometer which is oriented to produce a laser beam directed toward the subject substantially perpendicular to a skin surface of the subject wherein the skin surface is moveable in response to blood pressure. The vibrometer is sensitive to motion of the skin surface in a direction parallel to the laser beam and produces a signal representative of this motion. By plotting the velocity of the skin surface movement in the direction parallel to the laser beam with respect to time, a waveform is produced that has been found to be representative of the blood pressure waveform and highly defined to thereby permit accurate timing analysis thereof relating to cardiac cycles.

25 citations

Journal ArticleDOI
TL;DR: In this article, a piezoelectric linear ultrasonic motor with a cylindrical stator and slider structure is proposed, which consists of two PZT tubes connected by a thin film metallic glass (TFMG) pipe.
Abstract: A piezoelectric linear ultrasonic motor is proposed, with a cylindrical stator and slider structure. The length and diameter of the motor are about 10 and 1.5 mm, respectively. The stator consists of two piezoelectric ceramic (PZT) tubes connected by a thin film metallic glass (TFMG) pipe. The stator is designed based on theoretical analyses and finite element method (FEM) simulation. The traveling wave propagation is obtained in the FEM simulation under the proper geometrical sizes, suitable boundary conditions and driving voltage signals. The trajectories of particles on the TFMG pipe are elliptical motion. In the experiment, a 25 µm thick TFMG pipe is fabricated using the rotating magnetron sputtering technique and the vibration characteristics of the stator are measured by a laser Doppler vibrometer (LDV) system. Bidirectional motion of the slider is observed around 600 kHz, the maximum velocity is near to 40 mm s − 1 at 50 Vp–p for the loose slider and the maximum output force is 6 mN at 70 Vp–p for the tight slider.

25 citations

Journal ArticleDOI
TL;DR: In this article, it is shown that arbitrary functions to scan any area can easily be derived from a basic calibration routine, equivalent to the calibration performed in conventional discrete point laser vibrometry.

25 citations

Patent
Ohuchida Shigeru1
07 Aug 2001
TL;DR: In this article, an optical system focuses one of the two laser beams onto a recording surface of an optical recording medium, and receives reflection beams which are reflected from the recording medium to generate detection signals from the received reflection beams.
Abstract: In an optical pickup apparatus of the present invention, either a first laser diode emits a laser beam having a first wavelength or a second laser diode emits a laser beam having a second wavelength. An optical system focuses one of the two laser beams onto a recording surface of an optical recording medium. A photodetector unit receives reflection beams, which are reflected from the recording medium, to generate detection signals from the received reflection beams. A holographic unit has a first hologram suited to the first laser diode and a second hologram suited to the second laser diode, the first hologram provided to diffract a reflection beam of the laser beam of the first laser diode to the photodetector unit, and the second hologram provided to diffract a reflection beam of the laser beam of the second laser diode to the photodetector unit.

25 citations


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