Results 241 to 250 of about 4,479,393 (285)

Air-coupled flexural electrodynamic acoustic transducers

2014 IEEE International Ultrasonics Symposium, 2014
Flexural transducers use the bending modes in a plate or membrane to produce sound in low acoustic impedance media. Traditionally, piezoelectrically actuated flexural transducers have been used to generate ultrasound with large amplitude for a relatively low excitation voltage.
T.J.R. Eriksson, M. Laws, S.M. Dixon, S.N. Ramadas   +3 more
openaire   +1 more source

Novel Ultrasonic air Coupled Transducers

1999
Airborne ultrasound is currently used for a variety of applications, including distance ranging, level monitoring, broken ply detection and for the limited non-destructive testing of low Z materials (such as green-state ceramics, rubber and carbon fiber composite).
Billson, D., Hutchins, D., Ingleby, P., Robertson, T.   +3 more
openaire   +2 more sources

Non-contact optoacoustic imaging with focused air-coupled transducers

Applied Physics Letters, 2015
Non-contact optoacoustic imaging employing raster-scanning of a spherically focused air-coupled ultrasound transducer is showcased herein. Optoacoustic excitation with laser fluence within the maximal permissible human exposure limits in the visible and near-infrared spectra is applied to objects with characteristic dimensions smaller than 1 mm and ...
X. Luís Deán-Ben, Genny A. Pang, Francisco Montero de Espinosa, Daniel Razansky   +3 more
openaire   +2 more sources

Efficient high voltage pulser for piezoelectric air coupled transducer

Ultrasonics, 2013
The design of high voltage pulser for air coupled ultrasound imaging is presented. It is dedicated for air-coupled ultrasound applications when piezoelectric transducer design is used. Two identical N-channel MOSFETs are used together with 1200V high and low side driver IC.
Linas, Svilainis, Andrius, Chaziachmetovas, Vytautas, Dumbrava   +2 more
openaire   +2 more sources

Air Coupled Ultrasonic Transducers: Design and Applications

2002
In wide sectors of industries there is a growing need of ultrasonic inspection methods which avoid liquid couplants. The excitation of bulk and surface waves by means of air-coupled ultrasonic probes is therefore an attractive tool for nondestructive testing and evaluation. This is in particular true for the rapid scanning of large composite structures
Wolfgang Gebhardt, Martin Spies, Walter Arnold   +2 more
openaire   +1 more source

Development of air-coupled ultrasound transducers for nondestructive evaluation

2008 IEEE 21st International Conference on Micro Electro Mechanical Systems, 2008
We report the development of air-coupled ultrasound transducers for noncontact nondestructive evaluation applications. Air-coupled ultrasound is an attractive inspection technique for materials or structures that are not suitable for contact or immersion ultrasound inspections. However, due to large acoustic impedance mismatch between air and materials
Xuefeng Wang, Ying Fan, Wei-Cheng Tian, Hyon-Jin Kwon, Stacey Kennerly, Glenn Claydon, Andrew May   +6 more
openaire   +1 more source

Metal cap flexural transducers for air-coupled ultrasonics

AIP Conference Proceedings, 2015
Ultrasonic generation and detection in fluids is inefficient due to the large difference in acoustic impedance between the piezoelectric element and the propagation medium, leading to large internal reflections and energy loss. One way of addressing the problem is to use a flexural transducer, which uses the bending modes in a thin plate or membrane ...
T. J. R. Eriksson, S. Dixon, S. N. Ramadas   +2 more
openaire   +1 more source

Modeling and optimization of micromachined air-coupled capacitance transducers

1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118), 2002
A transmission line equivalent circuit network model has been developed to understand and control the high frequency performance of micromachined air-coupled capacitance transducers. The geometric size of the air cavities, the spacing between cavities, diaphragm thickness, air viscosity, bias voltage of the diaphragm and the compressibility of the air ...
L. Sun, M. Sayer, D. Schindel, L. Zou
openaire   +1 more source

A new design of ultrasonic air-coupled ribbon transducer

1997 IEEE Ultrasonics Symposium Proceedings. An International Symposium (Cat. No.97CH36118), 2002
A new design of air-coupled transducer has been developed and tested, based on a metallic ribbon design. The thin ribbon is held under tension within a magnetic field provided by rare-earth magnets and a set of pole pieces. The device can act as a source or receiver at ultrasonic frequencies in air, with reasonable bandwidths.
C.S. McIntyre, D.A. Hutchins
openaire   +1 more source

New type of matching layer for air-coupled ultrasonic transducers

IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2002
This paper presents a new concept in the design of an impedance matching structure for air coupled ultrasonic transducers. A reflective layer structure is inserted between the transducer and propagation medium with a small air space. Adjusting the air space and the reflectivity of the inserted structure causes the transducer impedance to match with the
openaire   +2 more sources