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The response of the lead zirconate titanate (PZT) element to an irradiated 20 MeV electron beam was studied. Both the resonant and antiresonant frequencies of the PZT element were measured under irradiation, and then the variation of the electromechanical coupling factor was investigated. It was found that the coupling factor linearly decreased with increasing beam energy absorbed in the PZT element, whereas the surface temperature remained constant. We propose a dosimeter based on piezoelectric PZT.

We have developed a tough hydrophone that was damage-resisted in a high-intensity field. The influence of the tough hydrophone's shape on the spatial distribution of acoustic bubbles in the 22 kHz field was investigated using visualization of acoustic bubbles by using high-speed video camera. Two hydrophones of different shapes with a flat-shape tip and a conical-shape tip were located around an anti-node and a node of sound pressure. In the case of flat-shape tip located at pressure antinode, acoustic bubble clouds were generated on the tip, an amplitude of output signal was changed though the applied voltage to the transducer was same. In contrast, there was no bubble sticking on the conical-shape tip even though the bubbles were readily generated around this region. Furthermore, a similar tendency of less sticking bubble on the conical-shape tip was observed when the tip was located around pressure node that the bubbles were not readily generated. In the case of conical-shape tip, the bubble clouds at the hydrophone tip were significantly reduced because of its shape, although the generation of acoustic bubbles in the high-intensity ultrasound fields cannot be avoided.

The response of a radiation detector fabricated from piezoelectric lead zirconate titanate (PZT) was studied. The response signal due to a single 400 MeV/n xenon (Xe) ion was assumed to have a simple form that was composed of two variables, the amplitude and time constant. These variables were estimated by comparing two output waveforms obtained from a computer simulation and an experiment on Xe beam irradiation. Their values appeared to be dependent on the beam intensity.

We had developed a tough hydrophone using a titanium front plate and hydrothermally synthesized PZT polycrystalline film. Currently, there are two kinds of hydrophones we are developing, one is a tough hydrophone with a cylindrical front plate, and the other is a tough hydrophone with a conical front plate. These two kinds of hydrophones are not decreased their sensitivity even if they are exposed to a sound field with acoustic cavitation in the ultrasound cleaner for a total of 50 hours. However, there are differences in the scratches on the surface of the front plate. In this study, we observed the behavior of acoustic cavitation bubbles around the tip of the hydrophone using a high-speed video camera and a laser light sheet. In the tough hydrophone with a cylindrical front plate, a cavitation bubble cloud has been adhered to the tip of the hydrophone from the beginning of observation. On the other hand, even with a tough hydrophone with a conical front plate, a cavitation bubble cloud was adhered to the tip of the hydrophone at the beginning of observation. However, when the adhered cavitation bubble cloud collided with another cavitation bubble cloud, we were able to observe behavior the adhered cavitation bubble cloud flows along the shape of the tip of the hydrophone.

The variation of the electromechanical coupling factor of lead zirconate titanate (PZT) was studied using a piezoelectric PZT disk exposed to a 400 MeV/n xenon beam. The resonant and antiresonant frequencies were measured in pairs by an impedance analyzer in situ manner. A systematic behavior of the pairs resulted in a decrease of the coupling factor. It was found that the coupling factor linearly decreased with increasing integrated beam energy incident on the PZT disk while its surface temperature was equilibrium at room temperature. We discuss a possible PZT-based radiation detector for practical use in a high-radiation field.

A novel transducer for megasonic cleaning of photomasks presents an approach that differs from previous configurations, and appears to have unique features for cleaning while minimizing damage. As the cleaning and damage processes are determined by the presence of cavitation, a thorough acoustic analysis was performed on the device, by using a calibrated hydrophone scanned at the photomask location, and a quartz photomask with embedded sensors.

Acoustic signals produced by irradiating ethanol with 400 MeV/n Xe ions were experimentally studied. The signals were detected by an array of piezoelectric PZT elements. They were categorized into two types: one was a primary product of the incident fast ions; the other was a secondary product resulting from an energy release to ethanol just before the ions stopped and subsequently diffused in ethanol. A possible mechanism of the secondary signal is discussed in association with the Bragg peak formation.

We had been developing the anti-cavitation hydrophone by deposition of hydrothermally synthesized lead zirconate titanate poly-crystalline film on the reverse side of the titanium front plate without damage even by measurement in high intensity ultrasound field with inertial acoustic cavitation. In this hydrophone, when exposed to a powerful ultrasonic sound field of an ultrasonic cleaner in which acoustic cavitation occurs, the front plate, the back plate and the outer conductor which had been adhered with the adhesive peeled off and broke. We have to re-design the basic structure of the robust type anti-cavitation hydrophone to solve this problem. In this study, we made a new type of hydrophone with a front plate and an outer conductor set in by changing the structure of the front plate. This new hydrophone showed durability that does not break even when it is exposed to a high intensity ultrasound sound field in a tank of an ultrasonic cleaner in which acoustic cavitation is occurring. Durability test in the water tank of ultrasound cleaner, the new anti-cavitation hydrophone had no significant decrease in sensitivity even after 14 hours of ultrasound exposure.

A novel tough hydrophone was fabricated by depositing hydrothermally synthesized lead zirconate titanate polycrystalline film on the back-side surface of a titanium plate. Our developed tough hydrophone resisted damage in a high-pressure field (15 MPa) at a focal point of a sinusoidal continuous wave driven by a concave high-intensity focused ultrasound (HIFU) transducer with up to 50 W of power input to the sound source. The hydrophone was suitable for the HIFU field, even though the hydrophone has a flat-shape tip of 3.5 mm diameter, which is slightly larger than the wavelength of a few megahertz. In this paper, experiments are performed to assess the effect on the HIFU field of changing the shape of the tough hydrophone, with the aim of developing a tough hydrophone. The spatial distribution of the acoustic bubbles around the focal point was visualized by using ultrasonic diagnostic equipment with the tough hydrophone located at the focal point of the HIFU transducer. From the visualization, the trapped acoustic bubbles were seen to arise from the standing wave, which implies that the acoustic pressure is reduced by this cloud of acoustic bubbles that appeared during hydrophone measurement. Although cavitation and acoustic bubbles may be unavoidable when using high-intensity ultrasound, the estimated result of evaluating acoustic fields without misunderstanding by acoustic bubbles can be obtained by the aid of visualizing bubbles around the tough hydrophone.

A radiation detector fabricated using piezoelectric lead zirconate titanate (PZT) has been studied by irradiating it with a 400 MeV/n xenon (Xe) beam. The beam diameter was controlled to change the irradiation conditions. It was found that the magnitude of the output observed from the PZT detector may be related to the number of Xe ions per unit area per unit time within the limits of the experimental conditions.

Wet photomask cleaning relies on megasonic agitation to enhance the process, but there are many challenges to reliably maximize particle removal efficiency (PRE) and minimize damage. With the shift to pellicle-free EUV masks, photomask processes are more vulnerable to contamination, increasing the urgency to improve the cleaning process. This difficulty is largely due to the unavailability of appropriate measurement of the acoustic field. Typically all that is known about the acoustic output is the driving frequency and the electric power delivered to a transducer, both global parameters that tell little about the field distribution over the substrate, the actual amplitude of the sound at the substrate, or the levels of cavitation (stable and transient) present at the substrate.

Novel tough hydrophones were developed by the depositing hydrothermally synthesized lead zirconate titanate thick film on the back-side surface of titanium plate to protect from acoustic cavitation. This hydrophone was resistant to damage at a high-intensity acoustic field generated by a high-intensity focused ultrasound (HIFU) transducer. Since the generation of acoustic bubbles cannot be avoided at high-intensity ultrasound field, an influence of the tough hydrophone's shape on the spatial distribution of acoustic bubbles around the hydrophone tip was investigated for accurate and precise evaluation of acoustic fields. As the result of the visualization by particle image velocimetry (PIV) system and finite-element method (FEM) simulation, the measurements of sound fields was not affected by the influence of the hydrophone with flat-shape tip with 3.5 mm in diameter lower than a hundred and some dozens of kHz. On the other hand, the influence of the tough hydrophone with flat-shape tip was strongly affected located at focal point of the 1.6 MHz HIFU transducer. Indeed, the trapped acoustic bubbles derived from the standing wave were observed even if the hydrophone has the needle-shape tip.

Novel anticavitation hydrophones were fabricated by depositing a hydrothermally synthesized lead zirconate titanate polycrystalline film at the back of a titanium front plate. These anticavitation hydrophones were not damaged by the measurement of the acoustic field formed by a high-intensity focused ultrasound (HIFU) device. Their sensitivity was improved by approximately 20 dB over that of the conventional anticavitation hydrophone by modifying their basic structure and materials. The durability of the anticavitation hydrophone that we fabricated was compared by exposing it to a high-intensity acoustic field at the focal point of the HIFU field and in the water tank of an ultrasound cleaner. Therefore, the effect of the surface of the titanium front plate on acoustic cavitation was investigated by exposing such a surface to the high-intensity acoustic field. We found that the fabricated anticavitation hydrophone was robust and was not damaged easily, even in the focused acoustic field where acoustic cavitation occurs.

The responses of a piezoelectric lead zirconate titanate (PZT) element to hypervelocity collisions were experimentally studied. In this study, the particles of masses ranging from 0.3 to 10 fg were made to collide with PZT at velocities between 20 and 96 km/s. The amplitude and the corresponding rise time of the single-pulse output signals that were produced in the piezoelectric PZT element were measured to determine the possible collision states. The results revealed an apparently multimodal output; three classes were assumed to be involved in the pulse formation mechanism. The amplitude and rise time were sensitive to the collision velocity. The multimodal behavior implied that the PZT-based cosmic dust detectors should be calibrated according to the class they belong to.

The characteristics of a detector fabricated using piezoelectric lead zirconate titanate (PZT) were studied by irradiating it with a 400 MeV/n xenon (Xe) beam while changing the beam flux intensity. The largest output signal was observed from the detector when the beam power per unit time was estimated to be largest. It was also found that the sensitivity per Xe ion of the detector seemed to be higher with decreasing the amount of the Xe ion flux within the limits of the experimental conditions.

A cosmic dust monitor for use onboard a spacecraft is currently being developed using a piezoelectric lead zirconate titanate element (PZT). Its characteristics of the PZT sensor is studied by ground-based laboratory impact experiments using hypervelocity particles supplied by a Van de Graaff accelerator. The output signals obtained from the sensor just after the impact appeared to have a waveform that was explicitly related to the particle’s impact velocity. For velocities less than ∼6 km/s, the signal showed an oscillation pattern and the amplitude was proportional to the momentum of the impacting particle. For higher velocities, the signal gradually changed to a single waveform. The rise time of this single waveform was proportional to the particle’s velocity for velocities above ∼6 km/s. The present paper reports on results for the low velocity case and especially discusses the effect of an outer coating of the sensor with a paint, which is used to reduce heating by solar radiation.

A cosmic dust detector is currently being developed using a piezoelectric lead zirconate titanate (PZT) element. The characteristics of the multilayered detector (MD), which was composed of one hundred PZT disks, were investigated by bombarding it with hypervelocity iron particles supplied by a Van de Graaff accelerator. It was confirmed that there was a linear relationship between the signal amplitude observed from MD and the momentum of the particles. As compared with the single-layered detector (SD) that was composed of one PZT disk, it was found that the sensitivity of MD was ∼3 times higher than that of SD within the limits of the experimental conditions.

A cosmic dust detector using piezoelectric lead zirconate titanate (PZT) is currently being developed for use onboard a spacecraft for the BepiColombo mission. The characteristics of the PZT detector were studied by carrying out hypervelocity impact measurements with iron particles supplied by a Van de Graaff accelerator. The measurements with particle velocities of less than 5 km/s showed a linear relationship between the output voltages obtained from the detector and the particle momenta. This linear relationship obtained was almost independent of the impact angle between the particle and the PZT surface.

A piezoelectric ultrasonic sensor has been fabricated using an epitaxial lead zirconate titanate, Pb(Zr x , Ti 1− x )O 3 (PZT) thin film, grown on an epitaxial SrRuO 3 /Pt/γ-Al 2 O 3 /Si substrate. The 3-μm thick PZT film was prepared by the sol–gel method. This sensor structure was very stable during the fabrication process after preparation of the PZT. The fabricated sensor offers a reception sensitivity of up to −243 dB re 1 V/μPa in the frequency range from 1 to 15 MHz, which means that it has higher sensitivity than that of a conventional polyvinylidene fluoride (PVDF) hydrophone. The pressure field of a focused ultrasonic transducer was determined using this ultrasonic sensor. The measured pressure peak was in good agreement with the results derived from calculations. These results suggest that the fabricated ultrasonic sensor can be used as a high sensitivity hydrophone device.

A cosmic dust detector for use onboard a satellite is currently being constructed from piezoelectric lead zirconate titanate (PZT). The characteristics of the PZT detector were studied by bombarding it with hypervelocity iron particles, which were supplied by a Van de Graaff accelerator. There was a linear relationship between the rise time of the signal observed from the detector and the particle's velocity, which was above 10 km/s on impact. It was also found that the rise time was almost independent of the collisional angle between the particles and the PZT surface within the limits of the particle's parameters used in this experiment.

The feasibility of using piezoelectric lead zirconate titanate (PZT) elements as a radiation detector was examined. We tried to observe the pressure wave excited by irradiating liquid ethanol (C 2 H 5 OH) with a 400 MeV/n xenon (Xe) beam using an array of PZT elements, while changing the position of beam irradiation. The elements were designed to obtain two independent electric signals in order to estimate the beam position in one direction on a two-dimensional plane. The time at which the peak of the output signal appeared differed between the two signals obtained from one element under limited experimental conditions. This suggests that the trajectory of the Xe beam may be determined in three-dimensional space with an improved array of the PZT elements.

The propagation of transverse waves generated acoustically in a piezoelectric element by colliding it with hypervelocity microparticles was studied. The propagation times were measured by a set of multiple electrodes on the surface of the element. The coordinates that the particles struck were determined by combining the propagation times and the velocity of the waves. By using the position-sensitive element, significant deviations between the prior indicated and actually measured orbits were observed. The potential of the present element as part of a steering system is discussed.

The detector characteristics of a pentagonal element were studied by colliding it with hypervelocity micro-particles. A charge-sensitive amplifier was developed for the element of its capacitance ∼10 nF. The output amplitudes were expressed as a linear function of the momentum at collision. Empirical formulas obtained from on-ground experiments could be used for the calibration of the detector. The pentagonal element was potential to measure the momentum during collision from the output amplitude. A set of electrodes on the surface was used to confirm the measurement of the coordinates at collision. A possible application of this pentagonal element on a real-time dust detector was discussed.

We have been developing a scanning acoustic microscope (SAM) system for medicine and biology featuring quantitative measurement of ultrasonic parameters of soft tissues. In the present study, we propose a new concept sound speed microscopy that can measure the thickness and speed of sound in the tissue using fast Fourier transform of a single pulsed wave instead of burst waves used in conventional SAM systems. Two coronary arteries were frozen and sectioned approximately 10 mum in thickness. They were mounted on glass slides without cover slips. The scanning time of a frame with 300 X 300 pixels was 90 s and two- dimensional distribution of speed of sound was obtained. The speed of sound was 1680 plusmn 30 m/s in the thickened intima with collagen fiber, 1520 plusmn 8 m/s in the lipid deposition underlying the fibrous cap, and 1810 plusmn 25 m/s in a calcified lesion in the intima. These basic measurements will help in the understanding of echo intensity and pattern in intravascular ultrasound images.

Radiation detectors composed of lead–zirconate–titanate (PZT) were studied by directly irradiating them with a 400 MeV/n xenon beam. Fourier analysis revealed that frequency components of the output signal obtained from the detectors explicitly depended on the beam pulse duration. The sensitivity of the multilayered detector was discussed in comparison with that of a single-layered detector.

A pressure wave excited by irradiating liquid chloroform (CHCl 3 ) with a 400 MeV/n xenon (Xe) beam was observed using a detector composed of piezoelectric lead–zirconate–titanate (PZT) elements. The acoustic signals were examined for various beam pulse durations. The amplitude obtained in the first cycle was inversely proportional to the beam pulse duration. It was also found that the time at which the peak in the first cycle appeared was dependent on the location at which each element was set. This suggests that the position at which the Xe beam stops in CHCl 3 may be precisely determined with the PZT detector.

Novel anti-cavitation hydrophones were fabricated by depositing a hydrothermally synthesized lead zirconate titanate polycrystalline thick film on the back of a titanium plate. We could observe that output waveform from our new type anti-cavitation hydrophone was similar with the output waveform from the commercial anti-high acoustic pressure hydrophone at focal point on focused ultrasound field by the ultrasound diagnostic equipment. A durability test on our fabricated anti-cavitation hydrophone was performed by exposure to the ultrasound acoustic field with the generation of acoustic cavitation in the focal point of the focused ultrasound field and the water tank of an ultrasound cleaner. These hydrophones were not damaged by the measurement of the acoustic field formed by a high-intensity focused ultrasound device.

Novel tough hydrophones were developed by the depositing hydrothermally synthesized lead zirconate titanate thick film on the back-side surface of Ti plate to protect from acoustic cavitation. This hydrophone was resistant to damage at a high-intensity acoustic field formed by a high-intensity focused ultrasound (HIFU) transducer. Since the generation of acoustic bubbles cannot be avoided at high-intensity ultrasound field, an influence of the tough hydrophone's shape on the spatial distribution of acoustic bubbles around focal point of HIFU transducer was investigated for accurate and precise evaluation of acoustic fields. As the result of the visualization by sonochemiluminescence in luminol, a stripe pattern derived from the standing wave was observed. Similarly, the trapping acoustic bubbles derived from the standing wave and moving acoustic bubbles derived from acoustic radiation forces were observed using visualization by the ultrasonic diagnostic equipment. By contrast, as the result of the observation using needle type hydrophone, the amount of the trapping acoustic bubbles reduced, while the moving bubbles remained and thinned in shape. The present shape of tough hydrophone tip was good use for low frequency ranges several tens kHz, whereas the influence of existence of the tough hydrophone with round shape tip was reduced as compared to that with flat shaped tip at high frequency.

Novel robust hydrophones were fabricated by depositing hydrothermally synthesized lead zirconate titanate polycrystalline film on the back-side surface of a titanium plate. These hydrophones were resistant to damage during the measurement of the high-intensity acoustic field formed by a high-intensity focused ultrasound transducer driven continuous wave, for driving power of up to 50 W, and to the acoustic field of an ultrasonic cleaner with generation of inertial acoustic cavitation. The sensitivity of the robust hydrophone was linear up to about 8 MPa. We confirmed the linearity of response for the hydrophone at high acoustic pressure. The fabricated robust hydrophone showed receiving sensitivity across a wide frequency range. Furthermore, we observed the output waveforms of the fabricated robust hydrophone with distortion due to non-linear propagation in water. These results indicate that our hydrophone can detect broadband acoustic signals emitted by oscillating and collapsing acoustic cavitation bubbles. However, the flat tip of the hydrophone disturbed the acoustic field, as shown by the results of sonochemiluminescence in luminol solution. This means that the setting position should be considered for measurements at higher acoustic power.

Acoustic signals were observed with a lead–zirconate–titanate (PZT) element that was directly irradiated with a 368 MeV/n xenon beam. Using an array comprising PZT elements, the energy loss in the PZT was studied. These elements are sensitive to an energy deposit of 100 nJ. A series of values of output voltage vs. integrated thickness of PZT was represented along a line similar to the ionization loss calculated by the Bethe–Bloch formula. The induced voltage was attributed to several processes—ionization, thermal, elastic, and piezoelectric processes. This study describes the possible applications of the PZT element as an active medium for calorimeters and a monitor for hypervelocity impact of space dust.

The acoustic signals generated by bombarding 400 MeV/n xenon ions in water were studied using an array of piezoelectric lead–zirconate–titanate elements. The observed signal was reduced to a bipolar form through Fourier analysis. The output voltage corresponded to the amount of energy deposit in water, and it tailed off beyond the range of 400 MeV/n xenon in water. This magnitude was explained qualitatively as cumulative processes. Its behavior was consistent with the calculations based on the Bethe–Bloch formula. Possible applications of this detector to radiology and heavily doped radiation detectors are described.

Dynamic ultrasound three-dimensional (3D) imaging using coded transmission is described. A sequence of 3D images of moving objects is reconstructed for each transmission of pulses modulated by Walsh functions. Then, the dynamic structure of the objects is extracted from the image sequence. In this paper, we discuss the relationship of the system performance to the parameters of the transmitting code such as duration time, repetition period, and total transmission length. A Doppler shift estimation and motion compensated image reconstruction method is described. The computer simulation for the motion compensation image reconstruction was carried out. Ultrasound 3D stroboscopic photography was demonstrated by a preliminary experiment utilizing the evaluation system in a 3D medical diagnostic scanner which has 32 transmitters and 32 receivers.

Effect of ultrasonic cavitation on sound pressure at the fundamental, second harmonic, and first ultraharmonic frequencies was investigated from low to high ultrasonic intensities. The driving frequencies were 22, 304, and 488 kHz. Sound pressure was measured using a needle-type hydrophone and ultrasonic cavitation was estimated from the broadband integrated pressure (BIP). With increasing square root of electric power applied to a transducer, the sound pressure at the fundamental frequency linearly increased initially, dropped at approximately the electric power of cavitation inception, and afterward increased again. The sound pressure at the second harmonic frequency was detected just below the electric power of cavitation inception. The first ultraharmonic component appeared at around the electric power of cavitation inception at 304 and 488 kHz. However, at 22 kHz, the first ultraharmonic component appeared at a higher electric power than that of cavitation inception.

We have proposed γ-Al2O3 thin films as an epitaxial buffer layer on Si substrates for obtaining epitaxial Pb(Zr,Ti)O 3 (PZT) thin films and reported a 2-D ultrasonic image sensor and measurement and analysis of ultrasonic transmission using piezoelectric micromachined ultrasonic transducers (pMUTs) on γ-Al 2 O 3 /Si substrates. −6 dB beamwidth and sound pressure at 5 mm from surface of the 4 channel pMUT array were exbited 10 times larger than signle pMUT. These experimental results good agree with analysis results. It will be applied to design miniature 2-D pMUTs array ultrasonic probe.

Novel anti-cavitation hydrophones were fabricated by depositing a hydrothermally synthesized lead zirconate titanate polycrystalline film on the back of a titanium plate. These hydrophones were not damaged by the measurement of the acoustic field formed by a high-intensity focused ultrasound (HIFU) device. The hydrophones were designed using Mason's equivalent circuit and by numerical simulation to improve their receiving characteristics for the measurement of the HIFU device. High receiving sensitivity with flat frequency characteristics was obtained by using a backing material with a specific acoustic impedance of about 20 × 106 kg/(m2 s) [Rayl]. We developed a new type of hydrophone using a tin and titanium rods as backing materials, which have specific acoustic impedances of 24 × 106 and 27 × 106 kg/(m2 s), respectively. The fabricated anti-cavitation hydrophone showed wide frequency characteristics of the receiving sensitivity. Furthermore, we observed the output waveform with distortion due to nonlinear propagation using the fabricated anti-cavitation hydrophone. This hydrophone was not damaged by exposure to a high-intensity acoustic field of an ultrasound cleaner under acoustic cavitation for duration of about ten times longer than the conventional commercial hydrophone.

The characteristics of radiation detector fabricated by stacking some piezoelectric lead zirconate titanate (PZT) elements were studied by irradiating it with a 400 MeV/n xenon (Xe) beam. Comparing between observed results from the detector and calculation results using Bethe–Bloch formula, it was found that the amplitude of the output voltage observed was dependent on the amount of ionization energy loss of Xe ion with PZT.

A cosmic dust detector for installation on a satellite is currently being developed using piezoelectric lead zirconate titanate (PZT), which can possess both functions of the collector and the transducer. The characteristics of the PZT detector have been studied by bombarding it with hypervelocity particles supplied by a Van de Graaff accelerator. The front surface of the detector used in this study was covered with a white paint to reduce any increase in the temperature due to the solar radiation. There was a linear relationship between the rise time of the signal produced by the detector and the particle's velocities, which were above 10 km/s on impact. This implies that individual particle velocities on impact can be inferred through the empirical formula derived from the data obtained from the PZT detector.

The characteristics of piezoelectric lead–zirconate–titanate (PZT) detectors were studied by directly irradiating them with a 400 MeV/n Xe beam. The sensitivity of a multilayered detector was discussed in comparison with that of a monolayered detector. It was found that the sensitivity of the detectors depended on their structure.

Acoustic characterization of high intensity therapeutic ultrasound (HITU) field is important for the accurate prediction of ultrasound induced bioeffects in tissue. In this paper, the robust designed needle type hydrophones were fabricated by the titanium front plate to withstand cavitation and by the deposition of a hydrothermally synthesized lead zirconate titanate (PZT) thick film vibrator on the opposite surface of titanium plate. Direct measurements of acoustic distribution profile at a focal region of the HITU probe driven continuous wave (CW) with input power to the sound source up to 50 W were performed. The tough hydrophone sensitivity responding to CW driven power range up to 50 W was measured in a tank of degassed water. The sensitivity was responding linearly up to about 8 MPa and not responding linearly acoustic pressure higher than 8 MPa, while the velocity of the vibration at the HITU probe was responding linearly up to driven power of 50 W. This 8 MPa was estimated in comparison with the standard hydrophone at driven power of 1 W to the sound source. We confirmed the linearity of responsivity of our hydrophone at high acoustic pressure. However, sensitivity of this hydrophone should be calibrated with higher acoustic pressure for higher acoustic power measurements. It is necessary to enable accurate characterization of HITU fields.

Our research group has developed new anti-cavitation hydrophones by depositing a hydrothermally synthesized lead zirconate titanate polycrystalline film with 15 μm thickness on the back surface of a titanium front plate with 50 μm thickness and 3.5 mm diameter. A durability test of the anti-cavitation hydrophone was performed when the anti-cavitation hydrophone under test was placed at the focal point of a concave focused ultrasound transducer with 100 mm diameter and at a resonant frequency of 1.75 MHz. The amplified 80 Vp-p (calculated electric input power: about 40 W) signal was applied to the concave ultrasound transducer at the focal point of the focused ultrasound system and high-intensity ultrasound waves were irradiated in water. The irradiated sound pressure at the focal point was about 4 MPa. Through this research, we will report that the fabricated new anti-cavitation hydrophone was robust and was not damaged easily, even in a high intensity focused ultrasound field with sound pressure of where...

A two-dimensional matrix Pb(ZrxTi1-x)O3 (PZT) ceramics array has been developed to evaluate the principle of an imaging system using a coded wavefront. In this paper, the fabrication process of a PZT 40 ×40 element array for transmitter and receiver is described. Signals modulated by the Walsh functions were used for driving the transmitter array elements. Three-dimensional images were successfully obtained for a standard ultrasonic phantom. It is shown that this method is applicable in medical diagnosis.

It is difficult to measure the high intensity ultrasound field with generation of acoustic cavitaion, since the electrode of hydrophone will be damaged by erosion and acoustic cavitation. Therefore, we developed the original miniature hydrophone by using hydrothermally synthesized lead zirconate titanate poly-crystalline film deposited on a reverse surface of a titanium film front layer as protection layer from damage by acoustic cavitation and erosion. Our hydrophone could be used to measure the high intensity ultrasound field with generation of acoustic cavitation such as focal area of 1.6 MHz HIFU treatment equipment and in a vessel of a 47 kHz ultrasound cleaner without any damage. However, we observed the output waveform of the hydrophone without nonlinear distortion in spite of measurement in high intensity ultrasound field like focal area of 1.6 MHz HIFU treatment equipment. We considered on the cause of above problem and its improving methods by computer simulation with MASON's equivalent circuit ...

It is difficult to use conventional hydrophones for measurement of high power ultrasound with acoustic cavitation by high intensity focused ultrasound (HIFU), because a front electrode of a piezoelectric element in conventional type hydrophone was decorticated by acoustic cavitation and high sound pressure. We fabricated new toughness type hydrophones using titanium membrane acoustic receiving surface and hydrothermally synthesized lead zirconate titanate film for measurement of HIFU. We measured the acoustic field distribution (sound pressure distribution) by HIFU equipment (Frequency: 1.6 MHz). Acoustic power of HIFU is setting from 10 to 250 W. Our new type hydrophone by using for HIFU equipment could receive high intensity focused ultrasound without broken.

A ultrasonic transducer array was fabricated using an epitaxial Pb(Zr,Ti)O 3 (PZT) thin film grown on SrRuO 3 /Pt/γ-Al 2 O 3 /Si structures. The fabricated diaphragm transducer 2-D array with 8 × 8 elements has developed by XeF 2 gas from the topside of Si.

The characteristics of a radiation detector fabricated with stacks of piezoelectric lead zirconate titanate (PZT) elements were studied by irradiating it with a 400 MeV/n xenon (Xe) beam for various beam pulse durations. This detector is referred to as the multilayered detector (MD). To understand the production mechanism behind the output voltage obtained from the MD, measurement of the spatial distribution of the output signals generated in the MD was attempted. It was found that the amplitude observed was dependent on the number of Xe ions per unit time and the amount of ionization loss energy of Xe ions in PZT.