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This paper investigates the consistency in phased array element performance by extracting information from the Full Matrix Capture (FMC) of a reflection from a planar interface. The purpose of this work is to generate a robust methodology for tracking phased array performance over time, therefore, ensuring the reliability of measured data. To achieve this, a calibration method has been developed that...
Synthetic aperture sonar has the characteristics of high resolution imaging which is not limited by the detection range. It can be used for imaging and mapping of the seafloor. However, the product value of detection range and speed of navigation is limited by the physical length of the array in the traditional synthetic aperture sonar. When the speed of navigation is improved on condition that the...
Sequent data acquisition and imaging in traditional active millimeter-wave imaging system in market results in serious time delay, cost, and system complexity. A point-by-point imaging approach is proposed in this paper to address the issue. Imaging starts shortly after data acquisition begins and virtually simultaneously with data acquisition. Partially known image and new data are used to image...
An active millimeter wave imaging system with sparse antenna array for security inspection is introduced in this review. Several key parts and related techniques of the imaging system are explained and numerical results are provided.
Terahertz (THz) radar has developed a lot in recent years. Its ability for near field security inspection becomes a popular research topic. However, the phase errors caused by THz radar's motion are difficult to compensate due to the submillimeter wavelength, which means a tiny motion error will bring a huge phase deviation. In this paper, we report a crossed array radar imaging method, which employs...
This paper presents our study on a sparse antenna array for 0.22 THz imaging. Based on the effective aperture concept for the design of sparse antenna array, two schemes for high performance THz imaging of a target at distance of 1 m have been achieved in simulation. Then, different schemes of larger array element spacing and mechanical scanning spacing have been investigated to build the relationship...
Ultrasound is a widely used imaging modality, both for diagnosis and guidance of interventional procedures such as biopsies. Ultrasound imaging commonly provides 2D data, which can be a limitation for further data processing, since information like out-of-plane motion is inaccessible. In this study, a specific multi-row array transducer — developed for the elastography application — is presented....
Lateral resolution and therefore image quality in ultrasound is tied to aperture size. While this relationship is understood in ideal imaging conditions, the utility of a large aperture in the presence of clutter is unknown. This problem is particularly relevant to abdominal imaging where thick tissue layers and deep targets create a challenging imaging environment. Previous studies have focused on...
The backbone of modern infrastructure is concrete, yet modern ultrasonic characterization techniques often fail to be accurate and repeatable. Recent advances in low frequency ultrasonic array hardware have generated a new potential for improved material and structural characterization of concrete. However, the analysis and interpretation associated with the new array based hardware is more difficult...
Data acquisition from 2-D transducer arrays has become one of the main challenges for the development of endoscopic and catheter-based 3-D ultrasound imaging devices. Front-end ASICs with sub-array pre-beamforming have been reported that reduce the cable number by an order of magnitude. Further channel reduction requires digitization in the front-end ASIC to facilitate more in-probe data processing...
Bio-medical ultrasound imaging has recently gained considerable attention. A two-dimensional (2-D) array is essential for three-dimensional (3-D) volumetric imaging. Fully populated 2-D dense array requires thousands of active elements and their interconnections. We present a 2-D CMUT sparse array with 128 elements for 3-D volumetric imaging. This CMUT sparse array with a die size of 6.3 mm × 6.3...
As medical ultrasound (MU) signals are not stationary, the radiation pattern of the corresponding input data does not have a specific shape; thus, their reconstruction using Adaptive Beamformers (BF) becomes indispensable in order to improve the quality of the imaging system. Generalized Sidelobe Canceller (GSC) is a robust realization against clutter and interference, resulting from an elegant representation...
Today, 3-D vector flow imaging (VFI) in a full volume requires a fully populated NxN 2-D matrix array if a sufficient frame rate should be maintained. Such arrays require an expensive ultrasound system, which can handle the enormous data stream created by the N2 channels. As an alternative to the matrix array, N+N 2-D row-column addressed (RCA) arrays were introduced, which reduce the channel count...
Ultrasonic perfusion imaging requires high sensitivity to slow disorganized blood-flow patterns while simultaneously rejecting clutter and noise. We achieve high sensitivity to both vascular flow and perfusion without contrast enhancement by adopting the following sampling pattern. Doppler pulses sampled at 1 kHz were acquired to form a Doppler frame. Frames were recorded at 10 Hz over 10 seconds...
Electromechanical wave imaging (EWI) is an ultrasound-based methodology that can map the electromechanical activation of the heart at high temporal resolution. Previous reports have shown strong correlation between EWI-based and electrical activation times. However, EWI has been performed only with 2D echocardiography, which cannot map the full cardiac volume in a single heartbeat. Our objective in...
A novel ultrasound (US) platform with high channels density that offers flexibility, precision and open access is a pre-requisite to open new frontiers in diagnostic and/or therapy by experimental implementation of new enabled advanced techniques: dual-mode US imaging/therapies in the heart, new approaches to study the myocardial tissue (structure/characterization), fast sparse array strategies, multi-line...
In this letter, a three-dimensional (3D) image reconstruction approach is proposed for terahertz (THz) holographic by a sharply reduced amount of antennas and frequency samples, without reducing the quality of the image reconstruction results. With the obtained 3D sparse random sampling data, a sparse recovery procedure combined by two-dimensional fast Gaussian gridding based non-uniform Fourier transform...
Sparse multistatic array designs that are based on the effective aperture concept enable real-time and cost-effective 3D CW terahertz imaging solutions. However, reduced system costs or challenging imaging scenarios eventually require a violation of the Nyquist sampling criterion, which leads to the appearance of grating lobes in the terahertz image. We propose a method to suppress grating lobes by...
Ground-based SAR has become an important remote sensing technology means for deformation monitoring in recent years. However, in order to achieve higher efficiency data acquisition and wider observation, arc antenna array technology is applied to ground-based SAR. In this paper, a polar format imaging algorithm for arc antenna array ground-based SAR is proposed. Firstly, a brief background on ground-based...
At present, APD (Avalanche Photo Diode) arrays LIDAR (Light Detection and Ranging) has been broadly accepted as an important means to obtain 3D (Three Dimensional) data. A new method of a scalable adaptive N × N channel communication system is introduced in the paper, which is aimed at improving the transmission rate of APD array LIDAR data. This paper presents the research on multi-channel communication...
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