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The laser ultrasonic technique with a pulse-echo mode has been investigated to detect disbonds in a multi-layer bonded structure and a quantitative method has been proposed to evaluate the defect sizes. The simulations were carried out to analyze influences of spot sizes on the characteristics of laser ultrasonic reflected waves, the interaction of laser ultrasonic reflected waves with disbonds, and quantitative characterization on disbonds. A noncontact laser ultrasonic inspection system has been established to perform a series of experiments to verify the theoretical results. Laser ultrasonic C-scans based on reflected shear waves can clearly redraw appearances of disbonds in the adhesive bond. The proposed quantitative method can evaluate the sizes of disbonds within a reasonable error range. Moreover, the experimental data are in good agreement with the simulation results. Therefore, a combination of the laser ultrasonic pulse-echo mode and the proposed quantitative strategy is practical for accurate detection of disbonds in multi-layer bonded structures.

The objective of this study is to explore the feasibility of using ultrasound to detect mastoid effusion (ME). In the past, ultrasound has been used to measure middle ear effusion (MEE) by injecting water into the external ear canal to measure echoes from the tympanic membrane, which is uncomfortable for the patient. It has been shown that air cells in the mastoid of patients with MEE are filled with fluid, which implies that ME could be a useful indicator of MEE. This study suggests using ultrasound to detect ME as a potentially noninvasive approach for MEE detection. In vitro experiments were performed on ten cadaver samples of the human ear. A single-element 1 MHz transducer was used to measure the mastoid of each cadaver before and after injecting water into the mastoid. The experimental results showed that the relative amplitudes of ultrasonic signals differed significantly between before (0.24 ± 0.09, mean ± standard deviation) and after (0.15 ± 0.03) the water injection (p0.05, t-test), demonstrating that the ultrasonic reflection can be used to detect ME. The location of the human mastoid under the skin behind the ear allows external measurements, and hence ultrasound-based ME detection may be an alternative, noninvasive diagnostic approach to detecting MEE in the future, providing an examination that avoids discomfort.

In this paper, a pulse-echo comparison method for measuring ultrasound velocity dispersion in n-tetradecane emulsions is presented. The method was based on an existing device but used a new measurement strategy. Ultrasound velocity in n-tetradecane in water emulsions was measured around the frequency range 1-14 MHz. The results were compared with theoretical prediction. The method is capable of development as an on-line real time method to characterize food emulsions.

Comparison between the local sand and SiO2 with different compositions of CeO2 on the structural properties of glasses was carried out by using ultrasonic technique. The ultrasonic velocities were measured by the pulse echo technique with a frequency of 4 MHz and at room temperature. From these obtained velocities and densities, various elastic moduli, micro-hardness and Poisson’s ratio were calculated. The interesting point of the bulk modulus (SiO2 glass system) decreases at x = 1.25 mol.% initially before it turns to increase between x = 3.75 and x = 5.00 mol.%. While the bulk modulus of the local sand glass system is near constant. FTIR spectra were used to study the structural properties of the prepared glass system. The results supported our discussion of the formation of non-bridging oxygens (NBO) and bridging oxygens (BO).

A new method for the detection of void-disbonds at the interfaces of adhesively bonded joins is considered. Based on a simple plane wave model, the output waveform is presented as a sum of two responses associated with the reflection of the ultrasonic wave at the first metal–adhesive interface and the second metal–adhesive interface, respectively. The strong response produced by the wave reverberating in the first metal sheet is eliminated through comparison between the pulse-echo signal measured at the area under the test and reference waveform recorded for the bare first metal sheet outside of the joint. The developed decomposition algorithm has been applied to the study of steel and aluminum samples having various adhesive layer thicknesses in a range of 0.1–1 mm.

Permanent prostate brachytherapy (PPB) is a common treatment for early stage prostate cancer. While the modern approach using trans-rectal ultrasound guidance has demonstrated excellent outcome, the efficacy of PPB depends on achieving complete radiation dose coverage of the prostate by obtaining a proper radiation source (seed) distribution. Currently, brachytherapy seed placement is guided by trans-rectal ultrasound imaging and fluoroscopy. A significant percentage of seeds are not detected by trans-rectal ultrasound because certain seed orientations are invisible making accurate intra-operative feedback of radiation dosimetry very difficult, if not impossible. Therefore, intra-operative correction of suboptimal seed distributions cannot easily be done with current methods. Vibro-acoustography (VA) is an imaging modality that is capable of imaging solids at any orientation, and the resulting images are speckle free.The purpose of this study is to compare the capabilities of VA and pulse-echo ultrasound in imaging PPB seeds at various angles and show the sensitivity of detection to seed orientation. In the VA experiment, two intersecting ultrasound beams driven at f(1)=3.00 MHz and f(2)=3.020 MHz respectively were focused on the seeds attached to a latex membrane while the amplitude of the acoustic emission produced at the difference frequency 20 kHz was detected by a low frequency hydrophone.Finite element simulations and results of experiments conducted under well-controlled conditions in a water tank on a series of seeds indicate that the seeds can be detected at any orientation with VA, whereas pulse-echo ultrasound is very sensitive to the seed orientation.It is concluded that vibro-acoustography is superior to pulse-echo ultrasound for detection of PPB seeds.

The frequency scanning ultrasonic pulse echo reflectometer (FSUPER) is a device which can be used to measure the ultrasonic velocity, attenuation coefficient and specific acoustic impedance of liquid samples as a function of frequency (0.3–6 MHz).

This work outlines the present theory of attenuation of the ultrasonic waves, particularly the theory of scattering, and describes the measurement of attenuation in metals. Experiments were carried out to measure the attenuation of samples with different grain size taken from materials for railway wheel sets; in these experiments the pulse echo method, with elimination of the effect of the reflexion factor, was applied. The article presents the relation between the overall attenuation coefficient and its scattering component, the grain size and frequency. On the basis of our measurements and an analysis of the obtained results, two methods of evaluation of the structure of railway materials by ultrasonic inspection were derived.

Echo amplitudes, detected by present ultrasonic pulse echo methods, are determined to a great part by the properties of the echo producing interfaces. Quantitative analysis by digital signal processing or sophisticated monitoring, especially by amplitude colour coding, appears to be advantageous only if these unwanted echo amplitude distortions can be avoided or compensated for. A promising way to achieve this aim may be the processing of the spatial echo distributions produced by reflection at the echo producing interfaces. In this paper it is shown by mathematical and experimental examination how interface properties can affect the spatial echo distributions.

Echo patterns obtained by using an ultrasonic pulse-echo system are mainly determined by the structure of an object, but are influenced by many other factors such as the directivity and damping characteristics of the ultrasonic transducer, the dynamic range of the display unit and so on. A simulation model has been developed in which if these factors are specified numerically and fed to the simulator, then an A- or B-mode display pattern is obtained as its output. In this paper the principles of the simulator are presented first and some results of the simulation are given and they are compared with echo patterns obtained experimentally.

This paper presents the design of a high voltage scr pulse generator that is useful for testing highly attenuative materials in the pulse echo mode. Electrical and ultrasonic considerations are discussed in detail followed by an example of a practical circuit design that can operate from a supply voltage of 1000 V at a pulse repetition frequency of 1000 Hz.

Multiple internal reflections within an air-backed transducer lead to a deterioration of pulse shape and consequent errors in pulse echo measurements. This effect is particularly pronounced in low impedance materials. It is demonstrated both by calculations and experimentally that using a quarterwave buffer having a specific acoustic impedance higher than either transducer or sample considerably reduces this echo distortion.

A dedicated general purpose digital computer has been built on the principle of a sampled-data system to run an ultrasonic subsystem under programmed control. A most significant application is the ability to extract a signal from an interfering background. As illustrated in the paper, a 1 mm diameter transducer was used to measure the diameter of a 2.5 mm OD plastics tube with 0.4 mm wall thickness. Echoes from all four surfaces were displayed and the measurements indicated an uncertainty of less than 0.1 mm.

The use of ultrasonic techniques in medicine has been a research field for some years and they are now accepted as having a place, albeit in the future, alongside the X-ray techniques of radiotherapy and diagnosis. The therapeutic use of ultrasound has already promoted the inclusion of a paper in this journal. Its use in ophthalmology for diagnosis of abnormal ocular conditions has been developed over the past eight years; more recently it has been applied to the measurement of the more important optical dimensions of the healthy eye in the investigation of refractive error and its causes. This paper traces the development of these diagnostic and biometric applications of ultrasound to ophthalmology

The accuracy of sound velocity measurements calculated by the pulse echo method is influenced markedly by the transducer used. This influence is the result of multiple internal reflections within the transducer and is dependent both on transducer thickness and the impedance mismatch between transducer and sample. Corrections for this effect have been computed for a wide range of sample acoustic impedances and the results were confirmed by experiment. These corrections improve sound velocity measurements, particularly on low impedance materials.