A new technique to measure phase distribution of ultrasound beams is presented. This method is ba... more A new technique to measure phase distribution of ultrasound beams is presented. This method is based on the phase measurement of the Doppler signal backscat-tered by a moving target traveling at constant velocity, which represents a scanning element exploring the field under examination. It is produced by mechanical equipment consisting of a modified string phantom in which the commonly used cotton thread was substituted by a thin nylon thread with some tight knots over it. The thread diameter was chosen small enough to produce knots smaller than the acoustic field wavelength in order to have " point-like " moving targets. This paper describes how the Doppler signal phase is related to the phase field and the numerical method to extract a phase field distribution from the backscattered signal. Experimental results obtained for two circular transducers, strongly and weakly focused, respectively , are finally shown and commented.
A new processing method for extracting the complex spatial field, in terms of amplitude and phase... more A new processing method for extracting the complex spatial field, in terms of amplitude and phase, from a proper phase-quadrature sampling of the time field behavior at different spatial points, has been presented. The method has been verified only in the case of spherically focused circular transducers employing time signals acquired by a needle type hydrophone connected a digital oscilloscope, providing an appropriate sampling rate, and a precise (low-jitter) triggering between excitation and field data acquisition.
ieee transactions on ultrasonics, ferroelectrics, and …, Jan 1, 1999
A new technique to measure phase distribution of ultrasound beams is presented. This method is ba... more A new technique to measure phase distribution of ultrasound beams is presented. This method is based on the phase measurement of the Doppler signal backscattered by a moving target traveling at constant velocity, which represents a scanning element exploring the held under examination. It is produced by mechanical equipment consisting of a modified string phantom in which the commonly used cotton thread was substituted by a thin nylon thread with some tight knots over it. The thread diameter was chosen small enough to produce knots smaller than the acoustic field wavelength in order to have "pointlike" moving targets. This paper describes how the Doppler signal phase is related to the phase field and the numerical method to extract a phase field distribution from the backscattered signal. Experimental results obtained for two circular transducers, strongly and weakly focused, respectively, are finally shown and commented.
Doppler signals collected with a focused transducer are known to be affected by the so-called int... more Doppler signals collected with a focused transducer are known to be affected by the so-called intrinsic spectral broadening (ISB). This article aims to point out how ISB is, in general, related to both the limited lateral extent of a focused beam (leading to a finite transit time), and the presence of several local insonation angles around the beam axis, due to focusing and diffraction effects (local geometrical broadening). The influence of these two elementary spectral contributions on the whole ISB is shown by considering the Doppler signal as simultaneously modulated in amplitude and frequency, and applying well-known relationships employed in the communication field. Such an analysis reveals that transit time and local geometrical broadening are two different phenomena, whose simultaneous knowledge is necessary for correctly evaluating the overall ISB. Finally, thanks to a novel technique for separately measuring transit time and local geometrical broadening effects on transducers with markedly different focusing properties, more than 1000 experimental acquisitions show how a proper combination of such measured contributions gives an accurate ISB estimation, confirming the theoretical expectations.
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 1999
A new technique to measure phase distribution of ultrasound beams is presented. This method is ba... more A new technique to measure phase distribution of ultrasound beams is presented. This method is based on the phase measurement of the Doppler signal backscattered by a moving target traveling at constant velocity, which represents a scanning element exploring the held under examination. It is produced by mechanical equipment consisting of a modified string phantom in which the commonly used cotton thread was substituted by a thin nylon thread with some tight knots over it. The thread diameter was chosen small enough to produce knots smaller than the acoustic field wavelength in order to have "pointlike" moving targets. This paper describes how the Doppler signal phase is related to the phase field and the numerical method to extract a phase field distribution from the backscattered signal. Experimental results obtained for two circular transducers, strongly and weakly focused, respectively, are finally shown and commented.
A new technique to measure phase distribution of ultrasound beams is presented. This method is ba... more A new technique to measure phase distribution of ultrasound beams is presented. This method is based on the phase measurement of the Doppler signal backscat-tered by a moving target traveling at constant velocity, which represents a scanning element exploring the field under examination. It is produced by mechanical equipment consisting of a modified string phantom in which the commonly used cotton thread was substituted by a thin nylon thread with some tight knots over it. The thread diameter was chosen small enough to produce knots smaller than the acoustic field wavelength in order to have " point-like " moving targets. This paper describes how the Doppler signal phase is related to the phase field and the numerical method to extract a phase field distribution from the backscattered signal. Experimental results obtained for two circular transducers, strongly and weakly focused, respectively , are finally shown and commented.
A new processing method for extracting the complex spatial field, in terms of amplitude and phase... more A new processing method for extracting the complex spatial field, in terms of amplitude and phase, from a proper phase-quadrature sampling of the time field behavior at different spatial points, has been presented. The method has been verified only in the case of spherically focused circular transducers employing time signals acquired by a needle type hydrophone connected a digital oscilloscope, providing an appropriate sampling rate, and a precise (low-jitter) triggering between excitation and field data acquisition.
ieee transactions on ultrasonics, ferroelectrics, and …, Jan 1, 1999
A new technique to measure phase distribution of ultrasound beams is presented. This method is ba... more A new technique to measure phase distribution of ultrasound beams is presented. This method is based on the phase measurement of the Doppler signal backscattered by a moving target traveling at constant velocity, which represents a scanning element exploring the held under examination. It is produced by mechanical equipment consisting of a modified string phantom in which the commonly used cotton thread was substituted by a thin nylon thread with some tight knots over it. The thread diameter was chosen small enough to produce knots smaller than the acoustic field wavelength in order to have "pointlike" moving targets. This paper describes how the Doppler signal phase is related to the phase field and the numerical method to extract a phase field distribution from the backscattered signal. Experimental results obtained for two circular transducers, strongly and weakly focused, respectively, are finally shown and commented.
Doppler signals collected with a focused transducer are known to be affected by the so-called int... more Doppler signals collected with a focused transducer are known to be affected by the so-called intrinsic spectral broadening (ISB). This article aims to point out how ISB is, in general, related to both the limited lateral extent of a focused beam (leading to a finite transit time), and the presence of several local insonation angles around the beam axis, due to focusing and diffraction effects (local geometrical broadening). The influence of these two elementary spectral contributions on the whole ISB is shown by considering the Doppler signal as simultaneously modulated in amplitude and frequency, and applying well-known relationships employed in the communication field. Such an analysis reveals that transit time and local geometrical broadening are two different phenomena, whose simultaneous knowledge is necessary for correctly evaluating the overall ISB. Finally, thanks to a novel technique for separately measuring transit time and local geometrical broadening effects on transducers with markedly different focusing properties, more than 1000 experimental acquisitions show how a proper combination of such measured contributions gives an accurate ISB estimation, confirming the theoretical expectations.
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 1999
A new technique to measure phase distribution of ultrasound beams is presented. This method is ba... more A new technique to measure phase distribution of ultrasound beams is presented. This method is based on the phase measurement of the Doppler signal backscattered by a moving target traveling at constant velocity, which represents a scanning element exploring the held under examination. It is produced by mechanical equipment consisting of a modified string phantom in which the commonly used cotton thread was substituted by a thin nylon thread with some tight knots over it. The thread diameter was chosen small enough to produce knots smaller than the acoustic field wavelength in order to have "pointlike" moving targets. This paper describes how the Doppler signal phase is related to the phase field and the numerical method to extract a phase field distribution from the backscattered signal. Experimental results obtained for two circular transducers, strongly and weakly focused, respectively, are finally shown and commented.
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these two elementary spectral contributions on the whole ISB is shown by considering the Doppler signal as simultaneously modulated in amplitude and frequency, and applying well-known relationships employed in the communication field. Such an analysis reveals that transit time and local geometrical broadening are two different phenomena, whose simultaneous knowledge is necessary for correctly evaluating the overall ISB.
Finally, thanks to a novel technique for separately measuring transit time and local geometrical broadening effects on transducers with markedly different focusing properties, more than 1000 experimental acquisitions show how a proper combination of such measured contributions gives an accurate ISB estimation, confirming the theoretical expectations.
these two elementary spectral contributions on the whole ISB is shown by considering the Doppler signal as simultaneously modulated in amplitude and frequency, and applying well-known relationships employed in the communication field. Such an analysis reveals that transit time and local geometrical broadening are two different phenomena, whose simultaneous knowledge is necessary for correctly evaluating the overall ISB.
Finally, thanks to a novel technique for separately measuring transit time and local geometrical broadening effects on transducers with markedly different focusing properties, more than 1000 experimental acquisitions show how a proper combination of such measured contributions gives an accurate ISB estimation, confirming the theoretical expectations.