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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12 Jan 2009TL;DR: In this article, the authors present a sensor module for measuring the distance to a target and/or the velocity of the target (50), the sensor module comprising at least one laser source (100 ), at least detector ( 200 ) being adapted to detect modulated laser light and at least control element the control element ( 400 ) being adaptable to vary the focus point of the laser light.
Abstract: A sensor module ( 1 ) for measuring the distance to a target and/or the velocity of the target ( 50 ), the sensor module ( 1 ) comprising at least one laser source ( 100 ), at least one detector ( 200 ) being adapted to detect modulated laser light and at least one control element the control element ( 400 ) being adapted to vary the focus point of the laser light and/or the intensity of the laser light and/or the direction of the laser light. The control of the laser light emitted by the laser source ( 100 ) either by active optical devices as variable focus lenses or controllable attenuators or passive optical elements in combination with arrays of laser sources ( 100 ) and detectors ( 200 ) enable flexible and robust sensor modules.
31 citations
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TL;DR: In this article, a self-mixing interferometry sensor has been used as a proximity probe to measure possible runout in permanent magnet synchronous motors for fault diagnosis, and a general procedure for the measurement of the 2D trajectory of the motor shaft is described in detail, including procedures for the characterization of the uncertainty due to the shape of the shaft and the management of speckle noise.
Abstract: In this paper, a self-mixing interferometry sensor has been used as a proximity probe to measure possible runout in permanent magnet synchronous motors, for fault diagnosis. A general procedure for the measurement of the 2-D trajectory of the motor shaft is described in detail, including procedures for the characterization of the uncertainty due to the shape of the shaft, and the management of speckle noise. The performance of the proposed sensor has been compared to that of a commercial Polytec laser vibrometer, for validation purposes. Results show inaccuracies in the order of ±6 μm, which agree well with the measured uncertainty introduced by shaft surface imperfections.
31 citations
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14 Oct 2005TL;DR: In this paper, a laser range finder includes a laser and a photosensitive element, which provides a “beat signal to a frequency detection circuit, which is determined and used to calculate distance to the target surface.
Abstract: A laser range finder includes a laser and a photosensitive element. The laser projects a beam onto a target surface. A backscattered portion of the laser beam returns to the laser from the target surface and enters the laser emitting cavity. Variations in laser output power are detected by the photosensitive element, which provides a “beat” signal to a frequency detection circuit. The frequency detection circuit includes a difference frequency analog phase locked loop (DFAPLL) providing a purified form of the beat signal. The frequency of the purified beat signal is determined and used to calculate distance to the target surface.
31 citations
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TL;DR: In this article, a 3D-scanning laser doppler vibrometer (3D-SLDV) is used to measure the 3D displacement of a fan blade, which is then used to calculate the dynamic strain distributions.
31 citations
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16 Aug 2001
TL;DR: In this article, an electromagnetic micro x-y stage was fabricated for probe-based mass data storage (PDS) devices, which consists of Si body containing planar copper coils, glass substrate bonded to the body, and 8 permanent magnets.
Abstract: We fabricated electromagnetic micro x-y stage for application to probe based mass data storage (PDS) devices. The stage consists of Si body containing planar copper coils, glass substrate bonded to the body, and 8 permanent magnets. The dimensions of springs and copper coils were determined so that a current of 100 mA would provide 50 μm motion in x and y. For application to PDS device, electromagnetic stage should have a flat top surface and coils of low resistance. So conducting planar copper coils have been electroplated within silicon trench of high aspect ratio (5 μm in width and 30 μm in depth). As insulating layer, polyimide was used. Silicon flexures with the height of 250 μm were fabricated by using ICP-RIE (Inductively Coupled Plasma Reactive Ion Etching). The characteristics of the fabricated electromagnetic stage were measured by LDV (Laser Doppler Vibrometer) and DSA (Dynamic Signal Analyzer). DC gain was 0.16 μm/mA and the maximum displacement was 42 μm at a current of 180 mA. The natural frequency was 325 Hz.
31 citations