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Peculiarities of anisotropic light diffraction in a periodic acoustic field excited by a phased array transducer with the phase shift by π are studied theoretically. Possibilities of this system application for control of unpolarized optical radiation are discussed.
We have previously shown for static abdominal images acquired with a curvilinear array, that image quality can be improved with a model-based beamforming technique, termed ADMIRE. Our goal in this study is to demonstrate that ADMIRE can be extended to small phased arrays apertures, and can improve reliability of GLS in dynamic sequences subject to clutter. In particular, we applied ADMIRE on simulations...
Traditional imaging algorithms within the ultrasonic NDE community typically assume that the material being inspected is homogeneous. Obviously, when the medium is of a heterogeneous or anisotropic nature this assumption can contribute to the poor detection, sizing and characterisation of defects. Knowledge of the internal structure and properties of the material would allow corrective measures to...
Two-dimensional blood speckle tracking has shown promise for measuring the complex flow patterns in neonatal hearts when based on linear array and high-frame-rate plane wave imaging. For phased array pediatric imaging, additional challenges emerge due to the reduced lateral bandwidth and increased imaging depth and field-of-view. In this work, a clinically approved setup with pediatric phased array...
A digital variable sampling high-frequency beamformer implementing real-time grating lobe suppression is described. The system is tested using a semi-kerfed 64 element 45 MHz phased array with 1λ element pitch. The grating lobe suppression is facilitated with the sign coherence factor (SCF) and split-aperture transmit beamforming techniques. A new split-aperture transmit technique called “sub-aperture...
A design of a 4×4 ultrasonic phased array working in flexural mode is presented. The array consists of an elastic metal sheet, a baffle with 16 holes, a back plate and 16 piezoelectric discs. The active area of each flexural array element is defined by the diameter of the holes of the baffle and the back plate provides an additional clamped-edge-like boundary condition through the baffle for each...
The array transducer is a key unit to the phased ultrasound imaging systems. While, size error or element failure of elements are often occurred on the array transducer. Those situations could make serious negative effects on the acoustic field distribution of an array and impact on the quality of ultrasound imaging. In this context, we propose a method to revise those effects of the element failure...
This paper presents an approach to steer the receiving field of view (FOV) of ultrasound imaging by linearly combining the RF signals from adjacent elements of a phased array without applying delay to the elements. The motivation is to reduce the number of measurement channels M (the product of number of transmissions, nT, and the number of receiving channels in each transmission, nR) while retaining...
In this work, we have developed a small, handheld histotripsy transducer where the ablation focus is imaged in real-time using a co-registered 45 MHz 64-element phased array endoscope. The construction of a 2 cm diameter, 40% volume fraction, strongly curved, PZT5A composite transducer capable of generating cavitation within tissue is outlined. The co-registered imaging and ablation tool was able...
It has been shown that row-column-addressed (RCA) 2-D arrays can be an inexpensive alternative to fully addressed 2-D arrays. Generally imaging with an RCA 2-D array is limited to its forward-looking volume region. Constructing a double-curved RCA 2-D array or applying a diverging lens over the flat RCA 2-D array, can extend the imaging field-of-view (FOV) to a curvilinear volume without increasing...
Phased Array (PA) uses a single focus in emission and Dynamic Depth Focusing (DDF) in reception, while Total Focusing Method (TFM) focuses every image pixel in emission and in reception. By contrast, TFM lacks the A-scan information, which is standard in PA and can be very useful for evaluation. Another issue common to both techniques is the difficulty associated with two media propagation and unknown...
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