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: In this article, the authors developed the operational principle and evaluation of a multi-dimensional vibration transducer that can determine three translational and three rotational displacements of a vibrating structure by sensing the positions of three light beams reflected by a tetrahedral target.
37 citations
TL;DR: A multipoint laser vibrometer that is capable of high spatial and temporal resolution with simultaneous measurement of 256 points along a line at up to 80 kHz is described.
Abstract: Experimental modal analysis of multifrequency vibration requires a measurement system with appropriate temporal and spatial resolution to recover the mode shapes. To fully understand the vibration it is necessary to be able to measure not only the vibration amplitude but also the vibration phase. We describe a multipoint laser vibrometer that is capable of high spatial and temporal resolution with simultaneous measurement of 256 points along a line at up to 80 kHz. The multipoint vibrometer is demonstrated by recovering modal vibration data from a simple test object subject to transient excitation. A practical application is presented in which the vibrometer is used to measure vibration on a squealing rotating disk brake.
37 citations
TL;DR: In this article, the authors present characterization measurements in collaboration with Applied MEMS on two of their devices used in commercial applications, which are used for validating the design of the two-axis micro mirror.
Abstract: The use of Laser Doppler Vibrometry (LDV) technology has been at the forefront of Micro-Electro-Mechanical Systems (MEMS) research since the early 1990’s. By its nature as a sensitive laser optical technique, it is well suited for non-contact dynamic response measurements of microscopic structures. The art of the technology has culminated into the latest micro-scanning vibrometer for automated scan measurement and display of deflection shapes with sub-nanometer resolution. To exemplify the use of this technology, Polytec PI presents characterization measurements in collaboration with Applied MEMS on two of their devices used in commercial applications. LDV characterization measurements are used for validating the design of the Applied MEMS two-axis micro mirror. Scan measurements reveal distinct, isolated rotation modes about x- and y- axes that can be used to promote the mirror motion in either direction. Settling time performance is evaluated from impulse response and optimized using Input Shaping techniques. Scan measurements of a low-noise accelerometer device from Applied MEMS reveals spurious high frequency modes of support spring causing unwanted response effects. Further use of a new time domain animation feature shows ringing response of the accelerometer to step motions.
37 citations
TL;DR: In this paper, a closed-loop control of the vortex-induced vibration of a flexible square cylinder, fixed at both ends, in a cross-flow was presented, where curved piezoceramic actuators were embedded underneath one cylinder surface to generate a controllable motion to perturb the interaction between flow and structure.
37 citations
TL;DR: An absolute frequency measurement of an acetylene stabilized laser is performed utilizing a femtosecond injection locking technique that can select one component among the fiber laser comb modes.
Abstract: We performed an absolute frequency measurement of an acetylene stabilized laser utilizing a femtosecond injection locking technique that can select one component among the fiber laser comb modes. The injection locking scheme has all the fiber configurations. Femtosecond comb lines of 250 MHz spacing based on the fiber femtosecond laser were used for injection locking of a distributed feedback (DFB) laser operating at 1542 nm as a frequency reference. The comb injected DFB laser serves as a selection filter of optical comb modes and an amplifier for amplification of the selected mode. The DFB laser injection locked to the desired comb mode was used to evaluate the frequency stability and absolute frequency measurement of an acetylene stabilized laser. The frequency stability of the acetylene stabilized laser was measured to be 1.1×10-12 for a 1 s averaging time, improving to 6.9×10-14 after 512 s. The absolute frequency of the laser stabilized on the P(16) transition of 13C2H2 was measured to be 194 369 569 385.7 kHz.
36 citations