Detection of spatially nonuniform ultrasonic radiation with phase sensitive (piezoelectric) and phase insensitive (acoustoelectric) receivers

Abstract

An analysis is presented of the responses of a phase sensitive and a phase insensitive ultrasound receiver detecting a spatially nonuniform pressure distribution. The predicted output of each type of receiver is obtained numerically using a model of wave propagation based upon diffraction theory. Experimental verification of these predictions is obtained using a piezoelectric and an acoustoelectric receiver as a phase sensitive and a phase insensitive detector, respectively. Results are illustrated for transmission measurements of the frequency-dependent attenuation of an irregular plastic plate and for scattering measurements of the observed angular and spatial dependence of scattering from a pair of brass rods.

Determining attenuation properties of interfering fast and slow ultrasonic waves in cancellous bone

“…As a result, signals from a relatively large (compared to the wavelength) phase sensitive receiving aperture (real or simulated) will be subject to phase cancellation at its face. 41,42 This phase cancellation represents irretrievable loss of information that will appear as apparent attenuation. Similar examples of phase cancellation appearing as apparent attenuation in bone have been reported previously.…”

Effects of bleeder cloth impressions on the use of polar backscatter to detect porosity

“…The frequency average of the backscatter transfer function, termed the integrated backscatter, provides a useful index of backscatter efficiency over a finite bandwidth [lS,16). Frequency averaging over a broad bandwidth reduces the degrading influence ofphase cancelIation[lS, [17][18][19][20] and otherinterference effects which can compromise the results ofbackscatter measurements. The useful bandwidth chosen for alI ofthe results presented in Section III of this manuscript was over a range from 6 to 12 MHz.…”

Nondestructive Characterization of TMC Materials: A Correlation Between Advanced Ultrasonic Measurements and Internal Material Conditions

“…Using the CdS transducer, an acoustoelectric response signal that is related to the power in an incident ultrasonic field was obtained [2,3,5,9,10]. These acoustoelectric measurements were independent of the instantaneous phase of the impinging ultrasonic wave, in contrast to the measurements obtained with a conventional piezoelectric transducer (2,3,5,6,(8)(9)(10)(11). For the phaseinsensitive measurements, the specimen was placed in the focal region of the transmitting transducer.…”

“…This comparison may illustrate how phase cancellation across the face of a receiving transducer can affect the inspection of the TMC laminate. Phase cancellation across the face of a conventional, piezoelectric receiving transducer may result from phase front distortion occurring from propagation in an inhomogeneous medium and from refraction due to geometrical effects [4,6,7,10]. These effects can create a non-uniform instantaneous pressure field across the receiving transducer face.…”

“…These effects can create a non-uniform instantaneous pressure field across the receiving transducer face. The net instantaneous transducer output is the sum of the resultant local voltages across the transducer and can significantly underestimate the energy contained in the incident field [4,6,7,[9][10][11][12][13][14].…”