Determination of Sensitivity Versus Frequency Characteristics of Miniature Ultrasonic Hydrophones Below 1 MHz Using Planar Scanning Technique

Devaraju, Vadivel; Lewin, Peter A.; Bleeker, H.

doi:10.7863/jum.2002.21.3.261

Cited by 6 publications

(5 citation statements)

References 10 publications

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“…Needle #3 has a peak between 1 and 2 MHz, which is consistent with simulation based on the multilayered structure model [41]. In order to capture the high-pass filter behavior for rigid cylindrical hydrophones with sensitive elements larger than 600 μm, sensitivity should be measured at frequencies below 1 MHz [61]. …”

Section: Resultsmentioning

confidence: 55%

Pressure Pulse Distortion by Needle and Fiber-Optic Hydrophones due to Nonuniform Sensitivity

Wear

Liu

Harris

2018

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Needle and fiber optic hydrophones have frequency-dependent sensitivity, which can result in substantial distortion of nonlinear or broadband pressure pulses. A rigid cylinder model for needle and fiber optic hydrophones was used to predict this distortion. The model was compared with measurements of complex sensitivity for a fiber optic hydrophone and 3 needle hydrophones with sensitive element sizes (d) of 100, 200, 400, and 600 μm. Theoretical and experimental sensitivities agreed to within 12 ± 3% (RMS normalized magnitude ratio) and 8 ± 3 degrees (RMS phase difference) for the four hydrophones over the range from 1 – 10 MHz. The model predicts that distortions in peak positive pressure can exceed 20% when d/λ0 < 0.5 and SI > 7% and can exceed 40% when d/λ0 < 0.5 and SI > 14%, where λ0 is the wavelength of the fundamental component and SI (spectral index) is the fraction of power spectral density contained in harmonics. The model predicts that distortions in peak negative pressure can exceed 15% when d/λ0 < 1. Measurements of pulse distortion using a 2.25 MHz source and needle hydrophones with d = 200, 400 and 600 μm agreed with the model to within a few percent on the average for SI values up to 14%. This work 1) identifies conditions for which needle and fiber optic hydrophones produce substantial distortions in acoustic pressure pulse measurements and 2) offers a practical deconvolution method to suppress these distortions.

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Section: Resultsmentioning

confidence: 55%

Pressure Pulse Distortion by Needle and Fiber-Optic Hydrophones due to Nonuniform Sensitivity

Wear

Liu

Harris

2018

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…As already noted, the planar scanning technique requires absolutely calibrated hydrophone probes, whereas radiation force measurements may require the use of precision microbalances and careful customization of the measurement arrangement. 7,14,16 The preferred method depends mainly on convenience and the experience of the user. The long data acquisition time with the planar scanning technique restricts its use to measurements at lower frequencies.…”

Section: Discussionmentioning

confidence: 99%

Interlaboratory Acoustic Power Measurement

Lewin

Barrie-Smith

Ide

et al. 2003

Journal of Ultrasound in Medicine

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Objective. This article describes an American Institute of Ultrasound in Medicine-sponsored intercomparison of the results of acoustic power measurements performed by several laboratories. Methods. Two primary calibration techniques, namely, planar scanning and radiation force balance, were used in the frequency range typical of that in which sonographic imaging devices operate. The same reference source, the National Institute of Standards and Technology (Gaithersburg, MD) standard ultrasonic power source, capable of producing acoustic fields in the frequency range from approximately 1 to 21 MHz, was circulated to 3 laboratories. Results. The results of the calibrations indicate that the overall uncertainty in acoustic power measurements depends on the target and the measurement method. In the case of radiation force balance measurements with an absorbing target, the largest discrepancy between the available National Institute of Standards and Technology-calibrated results and the reported data was 10.6% at approximately 2.5 MHz. At higher frequencies, beyond 10 MHz, the largest discrepancy reported with an absorbing target was 8.4%. For a reflecting target, the largest discrepancies were 16.2% at approximately 3.7 MHz and 15.4% at about 10 MHz. The largest discrepancy identified for the planar scanning technique below 10 MHz was 7.4% at 3.7 MHz. Conclusions. The results obtained suggest that an absorbing target may be preferable for acoustic power measurements with radiation force balance. In a group that consists of 2 research laboratories and 1 manufacturer, the power measurements agreed within 16%. Key words: planar scanning technique; radiation force balance; ultrasonic hydrophones; ultrasonic transducers.

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“…The sensitivity of the hydrophone to ultrasound emitted from the same distance as the center of the specimen in the experimental setup was calculated in according with a method reported in a literature 29) by measuring the sound field and the total acoustic power of identical sound sources. 24-mm-diameter plane ultrasound transducers at frequencies of 0.30, 0.51, 0.75, and 1.02 MHz were used as sound sources and a force-balance method 29,30) was used for the total acoustic power measurement. The sensitivity was found to be almost flat in the frequency range measured and to be 1:37 AE 0:096 mV/Pa.…”

Section: Index Of Cavitation Generation (Subharmonic Power Spectral E...mentioning

confidence: 99%

Acoustic Response of Microbubbles Derived from Phase-Change Nanodroplet

Kawabata

Asami

Azuma

et al. 2010

Jpn. J. Appl. Phys.

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An in vitro feasibility test for a novel ultrasound therapy using a type of superheated perfluorocarbon droplet, phase-change nanodroplet (PCND), was performed in gel phantoms with the goal of high selectivity and low invasiveness. Measurements of broadband signal emission revealed that a triggering ultrasound pulse (peak negative pressure of 2.4 MPa) reduces the pressure threshold for cavitation induced by a subsequent ultrasound exposure at an order of magnitude from 2.4 to 0.2 MPa. The maximum allowed interval between the two ultrasound exposures for inducing cavitation with 100- and 1,000-cycle triggering ultrasound was about 100 and 500 ms, respectively. The echo signal increases induced by the triggering ultrasound with 100- and 1000-cycles were enhanced and suppressed by the subsequent ultrasound exposure, respectively. This different behavior seemed to be due to the presence of enlarged free bubbles, which should be avoided for the localization of therapeutic effects.

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Determination of Sensitivity Versus Frequency Characteristics of Miniature Ultrasonic Hydrophones Below 1 MHz Using Planar Scanning Technique

Cited by 6 publications

References 10 publications

Pressure Pulse Distortion by Needle and Fiber-Optic Hydrophones due to Nonuniform Sensitivity

Pressure Pulse Distortion by Needle and Fiber-Optic Hydrophones due to Nonuniform Sensitivity

Interlaboratory Acoustic Power Measurement

Acoustic Response of Microbubbles Derived from Phase-Change Nanodroplet

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