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laser doppler vibrometer

Lei Chen, Dengwei Zhang, Yilan Zhou, Cheng Liu, Shuangliang Che
A wide dynamic range, high precision, non-contact and large bandwidth angular displacement measurement (ADM) is greatly necessary for the applications such as industrial control and military equipment. This paper proposes a simple and effective ADM method based on Doppler Effect, heterodyne detection and diffuse reflection, which can fulfill these requirements simultaneously. Two beams of parallel light generated by a pair of laser Doppler vibrometers are incident upon the surface of rotational target, then data processing unit acquires the velocity of dual laser incident points on the moving target, and resolves the rotational angular displacement and translation displacement of target through the relationship between dual laser beams dynamically...
June 14, 2018: Scientific Reports
C Y Chang, F G Yuan
Guided wave dispersion curves in isotropic and anisotropic materials are extracted automatically from measured data by Matrix Pencil (MP) method investigating through k-t or x-ω domain with a broadband signal. A piezoelectric wafer emits a broadband excitation, linear chirp signal to generate guided waves in the plate. The propagating waves are measured at discrete locations along the lines for one-dimensional laser Doppler vibrometer (1-D LDV). Measurements are first Fourier transformed into either wavenumber-time k-t domain or space-frequency x-ω domain...
May 16, 2018: Ultrasonics
Liang Wang, Junkao Liu, Yingxiang Liu, Xinqi Tian, Jipeng Yan
A novel single-mode linear piezoelectric ultrasonic motor based on asymmetric structure is proposed. The motor adopts the combination of the first longitudinal vibration and the asymmetric mechanical structure to produce the oblique movement on the driving foot; then, the linear output motion is obtained under the friction coupling between the driving foot and the runner. The motor is designed and its operation principle is illustrated in detail. The transient analysis is developed to verify the formed movement on the driving foot...
May 23, 2018: Ultrasonics
Seppe Sels, Boris Bogaerts, Steve Vanlanduit, Rudi Penne
Currently, galvanometric scanning systems (like the one used in a scanning laser Doppler vibrometer) rely on a planar calibration procedure between a two-dimensional (2D) camera and the laser galvanometric scanning system to automatically aim a laser beam at a particular point on an object. In the case of nonplanar or moving objects, this calibration is not sufficiently accurate anymore. In this work, a three-dimensional (3D) calibration procedure that uses a 3D range sensor is proposed. The 3D calibration is valid for all types of objects and retains its accuracy when objects are moved between subsequent measurement campaigns...
May 8, 2018: Sensors
Habiba Lais, Premesh S Lowe, Tat-Hean Gan, Luiz C Wrobel
Fouling build up is a well-known problem in the offshore industry. Accumulation of fouling occurs in different structures, e.g. offshore pipes, ship hulls, floating production platforms. The type of fouling that accumulates is dependent on environmental conditions surrounding the structure itself. Current methods deployed for fouling removal span across hydraulic, chemical and manual, all sharing the common disadvantage of necessitating halting production for the cleaning process to commence. Conventionally, ultrasound is used in ultrasonic baths to clean a submerged component by the generation and implosion of cavitation bubbles on the fouled surface; this method is particularly used in Reverse Osmosis applications...
July 2018: Ultrasonics Sonochemistry
Shai Chordekar, Ronen Perez, Cahtia Adelman, Haim Sohmer, Liat Kishon-Rabin
Hearing can be elicited in response to bone as well as soft-tissue stimulation. However, the underlying mechanism of soft-tissue stimulation is under debate. It has been hypothesized that if skull vibrations were the underlying mechanism of hearing in response to soft-tissue stimulation, then skull vibrations would be associated with hearing thresholds. However, if skull vibrations were not associated with hearing thresholds, an alternative mechanism is involved. In the present study, both skull vibrations and hearing thresholds were assessed in the same participants in response to bone (mastoid) and soft-tissue (neck) stimulation...
July 2018: Hearing Research
Donato Girolamo, Huan-Yu Chang, Fuh-Gwo Yuan
A fully non-contact laser-based nondestructive inspection (NDI) system is developed to detect and visualize damage in structures. The study focuses on the size quantification and characterization of a barely visible impact damage (BVID) in a honeycomb composite panel. The hardware consists of a Q-switched Nd:YAG pulse laser that probes the panel by generating broadband guided waves via thermo-elastic expansion. The laser, in combination with a set of galvano-mirrors is used to raster scan over a two-dimensional surface covering the damaged region of an impacted quasi-isotropic [60/0/-60]s honeycomb composite panel...
July 2018: Ultrasonics
Randall P Williams, Donghwan Kim, Kristofer L Gleason, Neal A Hall
In this article, the feasibility of using balloons for the measurement of acoustic particle velocity in air is investigated by exploring the behavior of an elastic balloon in air as it vibrates in response to an incident acoustic wave. This is motivated by the frequent use of neutrally buoyant spheres as underwater inertial particle velocity sensors. The results of experiments performed in an anechoic chamber are presented, in which a pair of laser Doppler vibrometers simultaneously captured the velocities of the front and back surfaces of a Mylar balloon in an acoustic field...
February 2018: Journal of the Acoustical Society of America
Hasan Goktas
Here, we demonstrate the advantages of the laser Doppler vibrometer (LDV) over conventional techniques (the network analyzer), as well as the techniques to create an application-based microelectromechanical systems (MEMS) filter and how to use it efficiently (i.e., tuning the tuning-capability and avoiding both failure and stiction). LDV enables crucial measurements that are impossible with the network analyzer, such as higher mode detection (highly sensitive biosensor application) and resonance measurement for very small devices (fast prototyping)...
February 4, 2018: Journal of Visualized Experiments: JoVE
Guillaume Boivin, Martin Viens, Pierre Belanger
Structural health monitoring is a prominent alternative to the scheduled maintenance of safety-critical components. The nondispersive nature as well as the through-thickness mode shape of the fundamental shear horizontal guided wave mode (SH 0 ) make it a particularly attractive candidate for ultrasonic guided wave structural health monitoring. However, plane wave excitation of SH 0 at a high level of purity remains challenging because of the existence of the fundamental Lamb modes (A 0 and S 0 ) below the cutoff frequency thickness product of high-order modes...
February 10, 2018: Sensors
Cristina Rigato, Sabine Reinfeldt, Bo Håkansson, Karl-Johan Fredén Jansson, Erik Renvall, Måns Eeg-Olofsson
Active transcutaneous bone conduction devices, where the transducer is implanted, are used for rehabilitation of hearing impaired patients by directly stimulating the skull bone. The transducer and the way it is attached to the bone play a central role in the design of such devices. The actual effect of varying the contact to bone has not been addressed yet. The aim of this study is therefore to compare how different attachment methods of the transducer to the bone for direct stimulation affect the ear canal sound pressure and vibration transmission to the ipsilateral cochlea...
April 2018: Hearing Research
T Strenger, M Brandstetter, T Stark, F Böhnke
BACKGROUND: An instrument to measure vibration in the middle ear needs to be sensitive enough to detect displacement on a nanometer scale, yet not affect the vibration itself. Numerous techniques have been described in the literature, but laser Doppler vibrometry (LDV) has nowadays become established as the standard method in hearing research. OBJECTIVE: This article aims to present possible clinical applications of an LDV system in otology. MATERIALS AND METHODS: A commercially available single-point vibrometer was used...
April 2018: HNO
Yasamin Keshmiri Esfandabadi, Luca De Marchi, Nicola Testoni, Alessandro Marzani, Guido Masetti
One of the main challenges faced by the structural health monitoring community is acquiring and processing huge sets of acoustic wavefield data collected from sensors, such as scanning laser Doppler vibrometers or ultrasonic scanners. In fact, extracting information that allows the estimation of the damage condition of a structure can be a time-consuming process. This paper presents a damage detection and localization technique based on a compressive sensing algorithm, which significantly allows us to reduce the acquisition time without losing in detection accuracy...
February 2018: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Xiaofei Zhang, Fengli Gao, Xide Li
Multi-frequency scanning near-field optical microscopy, based on a quartz tuning fork-probe (QTF-p) sensor using the first two orders of in-plane bending symmetrical vibration modes, has recently been developed. This method can simultaneously achieve positional feedback (based on the 1st in-plane mode called the low mode) and detect near-field optically induced forces (based on the 2nd in-plane mode called the high mode). Particularly, the high mode sensing performance of the QTF-p is an important issue for characterizing the tip-sample interactions and achieving higher resolution microscopic imaging but the related researches are insufficient...
January 24, 2018: Sensors
Nathan Jeger-Madiot, Jérôme Gateau, Mathias Fink, Ros-Kiri Ing
We present a novel non-contact system for monitoring the heart rate on human subjects with clothes. Our approach is based on vibrocardiography, and measures locally skin displacements. Vibrocardiography with a laser Doppler vibrometer already allows monitoring of this vital sign, but can only be used on bare skin and requires an expensive piece of equipment. We propose here to use an airborne pulse-Doppler ultrasound system operating in the 20-60 kHz range, and comprised of an emitter focusing the ultrasound pulses on skin and a microphone recording the reflected waves...
December 2017: Medical Engineering & Physics
A-O Gostian, M S Otte, D Pazen, M Ortmann, D Schwarz, K B Hüttenbrink, D Beutner
HYPOTHESIS: The vibration of the floating mass transducer (FMT) of a single active middle-ear implant (AMEI) is distinctly influenced by the properties of the material coupled to its back side. BACKGROUND: In round window vibroplasty, the FMT needs to be padded against the surrounding bone opposite from the round window membrane. This represents one factor influencing its performance as a round window driver. Therefore, we examined the effects of different materials linked to the back side of an FMT on its vibration range...
April 2018: Clinical Otolaryngology
Ivo Dobrev, Jae Hoon Sim, Stefan Stenfelt, Sebastian Ihrle, Rahel Gerig, Flurin Pfiffner, Albrecht Eiber, Alexander M Huber, Christof Röösli
BACKGROUND: Bone conduction (BC) is an alternative to air conduction to stimulate the inner ear. In general, the stimulation for BC occurs on a specific location directly on the skull bone or through the skin covering the skull bone. The stimulation propagates to the ipsilateral and contralateral cochlea, mainly via the skull bone and possibly via other skull contents. This study aims to investigate the wave propagation on the surface of the skull bone during BC stimulation at the forehead and at ipsilateral mastoid...
November 2017: Hearing Research
Inka Mueller, Claus-Peter Fritzen
The use of piezoelectric wafer active sensors (PWAS) for structural health monitoring (SHM) purposes is state of the art for acousto-ultrasonic-based methods. For system reliability, detailed information about the PWAS itself is necessary. This paper gives an overview on frequent PWAS faults and presents the effects of these faults on the wave propagation, used for active acousto-ultrasonics-based SHM. The analysis of the wave field is based on velocity measurements using a laser Doppler vibrometer (LDV). New and established methods of PWAS inspection are explained in detail, listing advantages and disadvantages...
January 16, 2017: Materials
Yasuomi Kunimoto, Kensaku Hasegawa, Shiro Arii, Hideyuki Kataoka, Hiroaki Yazama, Junko Kuya, Kazunori Fujiwara, Hiromi Takeuchi
OBJECTIVE: In order to help a surgeon make the best decision, a more objective method of measuring ossicular motion is required. METHODS: A laser Doppler vibrometer was mounted on a surgical microscope. To measure ossicular chain vibrations, eight patients with cochlear implants were investigated. To assess the motions of the ossicular chain, velocities at five points were measured with tonal stimuli of 1 and 3 kHz, which yielded reproducible results. The sequential amplitude change at each point was calculated with phase shifting from the tonal stimulus...
July 31, 2017: Acta Oto-laryngologica
Tao Chen, Liu-Jie Ren, Dong-Ming Yin, Jia Li, Lin Yang, Pei-Dong Dai, Tian-Yu Zhang
The Vibrant Soundbridge(©) (VSB) active middle-ear implant provides an effective treatment for mild-to-severe sensorineural hearing loss in the case of normal middle ear anatomy and mixed hearing loss in middle ear malformation. The VSB floating mass transducer (FMT), with proper couplers, can be installed on various structures of the ossicular chain, e.g., the short and long process of the incus, the stapes head, and the stapes footplate. A long process (LP) coupler is most commonly used for FMT attachment to the long process of the incus with intact ossicular chain, while CliP and Bell couplers are two standardized and reliable methods for FMT attachment to the stapes head with missing incus and malleus...
June 23, 2017: Hearing Research
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