Difference-frequency generation in vibro-acoustography

Silva, Glauber T.; Mitri, F.G.

doi:10.1088/0031-9155/56/18/013

Cited by 21 publications

(16 citation statements)

References 35 publications

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“…For rigid movable objects, S2 is decomposed into D2 and R2. The D2 component p D2 is given by Equation (25) with boundary condition (36). The R2 component p R2 is given by Equation (25) with boundary condition (37), where the centroidal motion is determined from the wave-exciting force by Equation (39).…”

Section: Discussionmentioning

confidence: 99%

“…Greenleaf et al, proposed measuring an object's difference frequency response from primary wave insonification for applications in medical ultrasound where significant interest in this exists [4,5]. Without a complete theoretical formulation for the second order field in the presence of a movable object, it was noted that the interaction of primary scattered waves may dominate the second order field [36,43,44] and mask information about the object's difference frequency response contained in weaker field components. Such a complete theory, as presented here, is necessary to investigate the conditions under which an object's difference frequency response may be detectable and when each of the various second order mechanisms may dominate.…”

Section: Discussionmentioning

confidence: 99%

“…For nonlinear medical ultrasound sensing applications [28,36,37], which are portable to fine-scale high frequency underwater sensing, a transition between nonlinear mechanisms can be seen for rigid (Figures 3-5) and vacuous objects ( Figure 6) sensed at the difference frequency in a watery environment. The SS mechanism is dominant (top right point of Figures 3b and 4b) for a 0.5 mm rigid object in a water environment sensed at a range of 1 m in backscatter for 1 MHz primary and 10 kHz difference frequency, and stands above noise with typical incident and received levels.…”

Section: Medical and Fine-scale Underwater Sensingmentioning

confidence: 99%

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Active Nonlinear Acoustic Sensing of an Object with Sum or Difference Frequency Fields

et al. 2017

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A number of nonlinear acoustic sensing methods exist or are being developed for diverse areas ranging from oceanic sensing of ecosystems, gas bubbles, and submerged objects to medical sensing of the human body. Our approach is to use primary frequency incident waves to generate second order nonlinear sum or difference frequency fields that carry information about an object to be sensed. Here we show that in general nonlinear sensing of an object, many complicated and potentially unexpected mechanisms can lead to sum or difference frequency fields. Some may contain desired information about the object, others may not, even when the intention is simply to probe an object by linear scattering of sum and difference frequency incident waves generated by a parametric array. Practical examples illustrating this in ocean, medical, air and solid earth sensing are given. To demonstrate this, a general and complete second-order theory of nonlinear acoustics in the presence of an object is derived and shown to be consistent with experimental measurements. The total second-order field occurs at sum or difference frequencies of the primary fields and naturally breaks into (A) nonlinear waves generated by wave-wave interactions, and (B) second order waves from scattering of incident wave-wave fields, boundary advection, and wave-force-induced centroidal motion. Wave-wave interactions are analytically shown to always dominate the total second-order field at sufficiently large range and carry only primary frequency response information about the object. As range decreases, the dominant mechanism is shown to vary with object size, object composition, and frequencies making it possible for sum or difference frequency response information about the object to be measured from second-order fields in many practical scenarios. It is also shown by analytic proof that there is no scattering of sound by sound outside the region of compact support intersection of finite-duration plane waves at sum or difference frequencies, to second-order. Analytic expressions for second-order fields due to combinations of planar and far-field wave-wave interactions are also derived as are conditions for when wave-wave interactions will dominate the second order field.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Medical and Fine-scale Underwater Sensingmentioning

confidence: 99%

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Active Nonlinear Acoustic Sensing of an Object with Sum or Difference Frequency Fields

et al. 2017

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“…Greenleaf and colleagues developed this original idea (Fatemi and Greenleaf, 1999), generating interesting images of arterial plaque, defects in industrially derived materials and other relevant examples where variations in stiffness can be expected. One may fi nd a detailed study of the physics of vibroacoustography in Silva and Mitri (2011).…”

Section: Acoustic Radiation Pressurementioning

confidence: 99%

Therapeutic ultrasound with an emphasis on applications to the brain

Mourad

2012

Ultrasonic Transducers

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“…With the DF transmission, not only the second harmonic signal at 2f 0 band but also the inter-modulation harmonic signal at f 0 band will be generated within the pass band of the transducer during the nonlinear propagation of the acoustic waveform. Note that the intermodulation between DF acoustic beams is also utilized to monitor the tissue stiffness in the vibro-acoustography by vibration the tissue at the difference frequency [6,7]. By spectral compounding, the simultaneous DF harmonic imaging has the advantage of high contrast-to-noise ratio and high axial resolution [8].…”

Section: Introductionmentioning

confidence: 99%