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A comparison of hydrophone near-field scans and optical techniques for characterising high frequency sonar transducers

A comparison of hydrophone near-field scans and optical techniques for characterising high frequency sonar transducers
A comparison of hydrophone near-field scans and optical techniques for characterising high frequency sonar transducers
Two potential methods of fully characterising the response of high frequency sonar transducers and arrays operating in the frequency range 100 kHz to 500 kHz are compared. In the first approach two-dimensional planar scans, with a spatial resolution of better than half a wavelength, are performed in the acoustic near-field using a small probe hydrophone. The measured two-dimensional data are propagated numerically using a Fourier Transform method to predict the far-field response. Alternatively the data can be back-propagated to re-construct the pressure distribution at the source, a powerful diagnostic technique which can identify defects in transducers and array elements. The second approach uses a scanning laser vibrometer to measure the velocity of the transducer surface; with the resulting velocity data also being used to predict the far-field response by numerical propagation. The two approaches are compared for a number of devices. Comparison of the propagated hydrophone near-field scan data with direct measurements at these ranges shows very good agreement, indicating the usefulness of the method for deriving far-field transducer responses from near-field measurements in laboratory tanks. The potential limitations introduced to the optical approach by the acousto-optic effect are discussed.
3436-3437
Humphrey, V.F.
23c9bd0c-7870-428f-b0dd-5ff158d22590
Robinson, S.P.
00d341a1-6153-45db-bda4-666928a652e5
Theobald, P.D.
236fc379-85f5-405f-9994-f9b07b14b8fa
Hayman, G.
c767c64a-8eb5-4415-8af3-55d125730818
Cooling, M.P.
caf6c2e0-c385-4f8c-bec6-7dd0473f65af
Humphrey, V.F.
23c9bd0c-7870-428f-b0dd-5ff158d22590
Robinson, S.P.
00d341a1-6153-45db-bda4-666928a652e5
Theobald, P.D.
236fc379-85f5-405f-9994-f9b07b14b8fa
Hayman, G.
c767c64a-8eb5-4415-8af3-55d125730818
Cooling, M.P.
caf6c2e0-c385-4f8c-bec6-7dd0473f65af

Humphrey, V.F., Robinson, S.P., Theobald, P.D., Hayman, G. and Cooling, M.P. (1970) A comparison of hydrophone near-field scans and optical techniques for characterising high frequency sonar transducers. 9th European Conference on Underwater Acoustics ECUA2008, Paris, France. 28 Jun - 03 Jul 2008. pp. 3436-3437 .

Record type: Conference or Workshop Item (Paper)

Abstract

Two potential methods of fully characterising the response of high frequency sonar transducers and arrays operating in the frequency range 100 kHz to 500 kHz are compared. In the first approach two-dimensional planar scans, with a spatial resolution of better than half a wavelength, are performed in the acoustic near-field using a small probe hydrophone. The measured two-dimensional data are propagated numerically using a Fourier Transform method to predict the far-field response. Alternatively the data can be back-propagated to re-construct the pressure distribution at the source, a powerful diagnostic technique which can identify defects in transducers and array elements. The second approach uses a scanning laser vibrometer to measure the velocity of the transducer surface; with the resulting velocity data also being used to predict the far-field response by numerical propagation. The two approaches are compared for a number of devices. Comparison of the propagated hydrophone near-field scan data with direct measurements at these ranges shows very good agreement, indicating the usefulness of the method for deriving far-field transducer responses from near-field measurements in laboratory tanks. The potential limitations introduced to the optical approach by the acousto-optic effect are discussed.

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More information

Published date: 1 January 1970
Additional Information: Paper 1636
Venue - Dates: 9th European Conference on Underwater Acoustics ECUA2008, Paris, France, 2008-06-28 - 2008-07-03

Identifiers

Local EPrints ID: 146715
URI: http://eprints.soton.ac.uk/id/eprint/146715
PURE UUID: 2ea08170-f85f-4959-91b5-15178a5a61c7
ORCID for V.F. Humphrey: ORCID iD orcid.org/0000-0002-3580-5373

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Date deposited: 22 Apr 2010 09:29
Last modified: 16 Jun 2020 00:28

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