Physical-model-based reconstruction of axisymmetric three-dimensional sound field from optical interferometric measurement

Abstract

Optical interferometric measurement methods for sound fields have garnered considerable attention owing to their contactless nature. The capabilities of non-invasive measurement and reconstruction of three-dimensional sound fields are significant for characterizing acoustic transducers. However, three-dimensional reconstructions are typically time consuming because of the two-dimensional scanning and rotation of the measurement system. This paper presents a scan and rotation-free reconstruction of an axisymmetric sound field in the human hearing range. A physical-model-based algorithm is proposed to reconstruct an axisymmetric sound field from optical interferograms recorded using parallel phase-shifting interferometry and a high-speed polarization camera. We demonstrate that audible sound fields can be reconstructed from data measured in 10 ms. The proposed method is effective for the rapid evaluation of axially symmetric acoustic transducers.

Acousto-optic holography

“…The pressure, particle velocity, and intensity fields are estimated via Eqs. ( 17)- (20). As in conventional planar NAH, a tapered filter was applied in the space domain (cosine filter of length 26 and ratio of 0.3) to transition smoothly toward zero pressure values beyond the plate edges and in the wavenumber domain (exponential filter with decay rate of 0.1) to filter out noisy high-wavenumber components.…”

“…[14][15][16] Acousto-optic sensing based on the retardation of light has gathered significant attention in recent years. [17][18][19][20][21][22] In this case, light is described as an electromagnetic wave with a phase that depends on the pressure variations in the medium. The pressure-induced phase shift of a laser beam can be measured by means of laser interferometry.…”

“…Yatabe et al 19 showed an increased reconstruction accuracy (when compared with classical tomographic methods) when the optical data are expanded using elementary waves. Ishikawa et al 20 proposed expanding the optical measurements in spherical harmonics to reconstruct an axisymmetrical sound field in three dimensions. A recent study by Verburg and Fernandez-Grande 22 showed that an elementary wave representation of the acousto-optic data can lead to a drastic reduction in the number of measurements required.…”

Evaluation of Acoustic Waves in Acousto-Optical Devices by Ultrasonic Imaging

“…In the interferometric [ 11 , 12 ] and holographic [ 13 ] techniques, the spatio-temporal distribution of the probing wide laser beam is recorded by a digital camera. Since the output signal changes at the frequency of the sonic radiator, these techniques are not applicable to high-frequency AO devices.…”

“…In all these methods [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ], the measurement results are in fact averaged over the entire optical path through the sound field. Therefore, in practice, they are effective for the analysisof simple sound fields that have plane or symmetrical wave fronts.…”