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Proceedings Paper

Detection of vibrating sound fields using speckle shearography
Author(s): E. A. Abd El-Ghafar; Hatem El-Ghandoor
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Paper Abstract

A loudspeaker at certain frequencies, producing vibrating sound wave causes periodic pressure variations in air. This pressure variation can be displayed in the form of a corresponding variations in the refractive index of air. The induced variation of the refractive index of air lead to a deflection of light rays traveling through the disturbed area of air by the vibrating sound waves. Speckle photography technique has been sued in this work to measure the light deflection along a certain cross-section of the integrated sound fields. The deflection angle of light rays can be measured as a speckle shift in the image plane leads to the formation of interference fringes similar to Young's fringes pattern. In the present work, a fringe pattern displaying the speckle shift due to the refractive index variation has been obtained using the electronic speckle pattern shearing interferometry. This fringe pattern in a measure of the speckle displacement due to light deflection caused by a vibrating sound source making a periodic pressure and refractive index variations of air.

Paper Details

Date Published: 28 September 1999
PDF: 8 pages
Proc. SPIE 3786, Optomechanical Engineering and Vibration Control, (28 September 1999); doi: 10.1117/12.363789
Show Author Affiliations
E. A. Abd El-Ghafar, Ain Shams Univ. (Egypt)
Hatem El-Ghandoor, Ain Shams Univ. (Egypt)

Published in SPIE Proceedings Vol. 3786:
Optomechanical Engineering and Vibration Control
Eddy A. Derby; Eddy A. Derby; Colin G. Gordon; Colin G. Gordon; Daniel Vukobratovich; Carl H. Zweben; Daniel Vukobratovich; Paul R. Yoder Jr.; Carl H. Zweben, Editor(s)

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