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.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this article, the dispersion curves for the propagation mechanism of an ultrasonic guided wave in the evaporator are determined through numerical calculation, and the shear stress and vibration characteristics under ultrasonic excitation are analyzed using finite element method (FEM).
27 citations
TL;DR: Despite the mechanics of the dynamic surface resulting in some out-of-plane motion (which is small in comparison to the in-plane streamwise movement), the positive drag reduction results are encouraging for future investigations at higher Reynolds numbers.
Abstract: The experimental control of turbulent boundary layers using streamwise travelling waves of spanwise wall velocity, produced using a novel active surface, is outlined in this paper. The innovative surface comprises a pneumatically actuated compliant structure based on the kagome lattice geometry, supporting a pre-tensioned membrane skin. Careful design of the structure enables waves of variable length and speed to be produced in the flat surface in a robust and repeatable way, at frequencies and amplitudes known to have a favourable influence on the boundary layer. Two surfaces were developed, a preliminary module extending 152 mm in the streamwise direction, and a longer one with a fetch of 2.9 m so that the boundary layer can adjust to the new surface condition imposed by the forcing. With a shorter, 1.5 m portion of the surface actuated, generating an upstream-travelling wave, a drag reduction of 21.5% was recorded in the boundary layer with Re
τ
= 1125. At the same flow conditions, a downstream-travelling produced a much smaller drag reduction of 2.6%, agreeing with the observed trends in current simulations. The drag reduction was determined with constant temperature hot-wire measurements of the mean velocity gradient in the viscous sublayer, while simultaneous laser Doppler vibrometer measurements of the surface recorded the wall motion. Despite the mechanics of the dynamic surface resulting in some out-of-plane motion (which is small in comparison to the in-plane streamwise movement), the positive drag reduction results are encouraging for future investigations at higher Reynolds numbers.
26 citations
Patent•
19 Sep 1989
TL;DR: In this paper, a laser beam scanning device including a plurality of laser beam sources for emitting laser beams having properties different from each other, respectively such that each of the laser beams is modulated by an image signal, a deflection member for simultaneously deflecting the laser beam emitted by the laser sources, a light detecting member for detecting one of the LBSs such that modulation of the LM beams emitted by LMBSs is started in response to a signal outputted from the light detecting members and an optical member which is disposed on an optical path from the deflection members to
Abstract: A laser beam scanning device including a plurality of laser beam sources for emitting laser beams having properties different from each other, respectively such that each of the laser beams is modulated by an image signal, a deflection member for simultaneously deflecting the laser beams emitted by the laser beam sources, a light detecting member for detecting one of the laser beams such that modulation of the laser beams emitted by the laser beam sources is started in response to a signal outputted from the light detecting member and an optical member which is disposed on an optical path from the deflection member to the light detecting member and optically selects only the one of the laser beams so as to irradiate the one of the laser beams onto the light detecting member.
26 citations
Patent•
30 May 2003
TL;DR: In this paper, the authors present a procedure for maintaining a power of the laser beam (14) applied to the eye at a substantially constant level during at least a portion of the treatment.
Abstract: Systems (10) and methods apply pulsed laser energy to an eye with a pulsed laser system. The laser system (10) includes a pulsed laser (12), a laser beam delivery system (16) and at least one processor (22). The laser (12) makes a beam (14) of an ablative light energy. A dimension across the laser beam (14) varies during a treatment of the eye (E). A firing rate of the laser (12) varies as the dimension across the beam (14) varies during the treatment. The dimension across the beam and the firing rate of the laser (12) can be arranged so as to maintain a power of the beam (14) applied to the eye at a substantially constant level during at least a portion of the treatment. A firing rate of the laser (12) for each pulse may be listed in a treatment table (140).
26 citations
TL;DR: In this paper, a 100J-level Nd:glass laser system in nanosecond-scale pulse width has been constructed to perform as a standard source of high-fluence-laser science experiments.
Abstract: A 100-J-level Nd:glass laser system in nanosecond-scale pulse width has been constructed to perform as a standard source of high-fluence-laser science experiments. The laser system, operating with typical pulse durations of 3–5 ns and beam diameter 60 mm, employs a sequence of successive rod amplifiers to achieve 100-J-level energy at 1053 nm at 3 ns. The frequency conversion can provide energy of 50-J level at 351 nm. In addition to the high stability of the energy output, the most valuable of the laser system is the high spatiotemporal beam quality of the output, which contains the uniform square pulse waveform, the uniform flat-top spatial fluence distribution and the uniform flat-top wavefront.
26 citations