Nonperturbing measurements of spatially distributed underwater acoustic fields using a scanning laser Doppler vibrometer.

Localized changes in the density of water induced by the presence of an acoustic field cause perturbations in the localized refractive index. This relationship has given rise to a number of nonperturbing optical metrology techniques for recording measurement parameters from underwater acoustic fields. A method that has been recently developed involves the use of a Laser Doppler Vibrometer (LDV) targeted at a fixed, nonvibrating, plate through an underwater acoustic field. Measurements of the rate of change of optical pathlength along a line section enable the identification of the temporal and frequency characteristics of the acoustic wave front. This approach has been extended through the use of a scanning LDV, which facilitates the measurement of a range of spatially distributed parameters. A mathematical model is presented that relates the distribution of pressure amplitude and phase in a planar wave front with the rate of change of optical pathlength measured by the LDV along a specifically orientated laser line section. Measurements of a 1 MHz acoustic tone burst generated by a focused transducer are described and the results presented. Graphical depictions of the acoustic power and phase distribution recorded by the LDV are shown, together with images representing time history during the acoustic wave propagation.

[1]  August Joseph Ignaz Toepler,et al.  Beobachtungen nach einer neuen optischen Methode : ein Beitrag zur Experimentalphysik , 1906 .

[2]  John R. Tyrer,et al.  Non-invasive measurements of underwater pressure fields using laser doppler velocimetry , 2002 .

[3]  S Schedin,et al.  Tomographic reconstruction of transient acoustic fields recorded by pulsed TV holography. , 1998, Applied optics.

[4]  Piotr Kwiek,et al.  On ultrasound light diffraction , 1993 .

[5]  Ole J. Lo kberg.  Recording of sound emission and propagation in air using TV holography , 1994 .

[6]  B. D. Cook,et al.  Unified Approach to Ultrasonic Light Diffraction , 1967, IEEE Transactions on Sonics and Ultrasonics.

[7]  J. Monchalin.  Optical Detection of Ultrasound , 1986, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[8]  Piotr Kwiek,et al.  Uncertainty considerations of ultrasonic field mapping by light-diffraction tomography , 1997 .

[9]  C. Raman,et al.  The diffraction of light by high frequency sound waves: Part I. , 2012 .

[10]  Piotr Kwiek,et al.  Ultrasound field mapping by light-diffraction tomography: a review , 1995, Acousto-Optics and Applications.

[11]  Hans M. Pedersen,et al.  TV holography measurements of underwater acoustic fields , 1997 .

[12]  R. Rustad.  Acoustic Field of a Medical Ultrasound Probe Operated in Continuous-Wave Mode Investigated by TV Holography. , 1998, Applied optics.

[13]  Erik Blomme,et al.  Diffraction of light by ultrasound - finite analytical expressions for the spectra up to order-3 , 1985 .

[14]  S. P. Robinson,et al.  Application and assessment of laser Doppler velocimetry for underwater acoustic measurements. , 2003 .

[15]  R.C. Preston,et al.  The NPL ultrasound beam calibrator , 1988, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[16]  P. Debye,et al.  On the Scattering of Light by Supersonic Waves. , 1932, Proceedings of the National Academy of Sciences of the United States of America.

[17]  C. V. Raman,et al.  The diffraction of light by high frequency sound waves: Part IV , 1935 .

[18]  O. J. Løkberg,et al.  Sound in flight: measurement of sound fields by use of TV holography. , 1994, Applied optics.

[19]  Bill D. Cook.  Measurement of high frequency sound fields by optical techniques , 1994, Other Conferences.

[20]  C. V. Raman,et al.  The diffraction of light by high frequency sound waves: Part I. , 2012 .

[21]  O. J. Løkberg,et al.  Tomographic reconstruction of sound fields using TV holography. , 1995, Applied optics.

[22]  M. E. Haran,et al.  Visualization and measurement of ultrasonic wavefronts , 1979, Proceedings of the IEEE.

[23]  J. Leendertz,et al.  An image-shearing speckle-pattern interferometer for measuring bending moments , 1973 .

[24]  Rolf Rustad,et al.  Full field tomographic reconstruction of sound fields using TV holography , 1995 .