Image resolution improvement of underwater synthetic aperture ultrasonic holography by virtual aperture augmentation technique

2002 ◽  
Author(s):  
Sheng-Wen Cheng ◽  
Min-Kang Chao
Keyword(s):  
Image Resolution ◽  
Synthetic Aperture ◽  
Resolution Improvement

ULTRASONIC IMAGING SYSTEM USING A 2D ENVELOPE BEAMFORMING TECHNIQUE: IN-HOMOGENEITIES LOCATION

2004 ◽  
Vol 12 (04) ◽  
pp. 571-585
Author(s):  
L. MEDINA ◽  
E. MORENO
Keyword(s):  
Imaging System ◽  
Side Lobe ◽  
Ultrasonic Pulse ◽  
Image Resolution ◽  
Synthetic Aperture ◽  
Water Tank ◽  
Synthetic Aperture Focusing ◽  
Longitudinal Resolution ◽  
Synthetic Aperture Focusing Technique ◽  
Beamforming Technique

An algorithm has been developed to implement synthetic aperture focusing technique for B-scan. This is made at a several transmitter/receiver locations to form a map of ultrasonic reflectivity on the insonified region, considering the path travelled by the ultrasonic pulse from the transducer to the target and back again. To reconstruct the image, a time domain beam-former is applied to the envelope of the detected signals. This method minimizes the side-lobe amplitude and the restriction of λ/2 distance between two adjacent transducer positions can be neglected without loosing image resolution. The present work is focused on the location of the in-homogeneities, caused by the presence of a phantom immersed in a water tank. The results are presented when the distance between two adjacent transducer positions are varied from 0.5λ to 2.5λ showing that the longitudinal resolution is not affected but the lateral resolution becomes poorer when the distance is about 2λ. The error in the longitudinal location of in-homogeneities is within the minimum detectable distance of the system, while the lateral location error is increased when the distance between any two adjacent transducer positions is larger than 1.5λ.

scholarly journals Synthetic aperture-based linear-array photoacoustic tomography considering the aperture orientation effect

2018 ◽  
Vol 11 (04) ◽  
pp. 1850015 ◽  
Author(s):  
Xiangwei Lin ◽  
Jaesok Yu ◽  
Naizhang Feng ◽  
Mingjian Sun
Keyword(s):  
Linear Array ◽  
Great Influence ◽  
Image Resolution ◽  
Synthetic Aperture ◽  
Orientation Effect ◽  
Photoacoustic Tomography ◽  
Optimal Detection ◽  
Phantom Experiment ◽  
Full View ◽  
Array Transducer

The synthetic aperture-based linear-array photoacoustic tomography (PAT) was proposed to address the limited-view shortcomings of the single aperture, but the detection field of view (FOV) determined by the aperture orientation effect was not fully considered yet, leading to the limited-view observation and image resolution degradation. Herein, the aperture orientation effect was proposed from the theoretical model and then it was verified via both the numerical simulation and phantom experiment. Different orientations were enumerated sequentially in the simulation to approximate the ideal full-view case for the optimal detection FOV, considering the detection pattern of the linear-array transducer. As a result, the corresponding optimal aperture orientation was 60[Formula: see text] if the synthetic aperture was seamlessly established by three single linear arrays, where the overlapped detection pattern was optimized from the individual linear-array transducer at the adjacent positions. Therefore, the limited-view artifacts were minimized and the image resolution was enhanced in this aperture orientation. This study showed that the aperture orientation had great influence on the optimal detection FOV in the synthetic aperture configuration, where the full-view imaging quality and enhanced image resolution could be achieved.

scholarly journals Synthetic aperture imaging in acoustic microscopy

2021 ◽  
Author(s):  
Golafsoun Ameri
Keyword(s):  
Image Resolution ◽  
Acoustic Microscopy ◽  
Synthetic Aperture ◽  
Lateral Resolution ◽  
Depth Of Field ◽  
Single Element ◽  
Focal Region ◽  
Array Transducer ◽  
Small Depth ◽  
Better Than

Acoustic microscopy (AM) provides micro-meter resolution using a highly focused single-element transducer. A drawback in AM is a relatively small depth of field, resulting in poor resolution outside the focus. Synthetic aperature focusing technique (SAFT) can be used to improve the image resolution throughout the field of view. SAFT mathematically synthesizes the effect of an array transducer and produces dynamic focusing and depth-independent resolution. SAFT in time domain with and without apodization, TD-SAFT and ATD-SAFT, respectively, and in frequency domain (FD-SAFT) were implemented and tested using simulated and experimental radio-frequency data from an acoustic microscope at 400 MHz. Lateral resolution of all the SAFT reconstructed images were better than those of the conventional B-mode images. While TD-SAFT and FD-SAFT permformed better than ATD-SAFT in improving the lateral resolution, ATD-SAFT provided lower side lobes. In conclusion, SAFT improves resolution in AM outside the focal region.

Blind Deconvolution of SEM Images

2007 ◽  
Author(s):  
William E. Vanderlinde ◽  
James N. Caron
Keyword(s):  
Cross Section ◽  
Integrated Circuit ◽  
Blind Deconvolution ◽  
Signal To Noise Ratio ◽  
Image Resolution ◽  
Reference Standard ◽  
Signal To Noise ◽  
Sem Images ◽  
Resolution Improvement ◽  
Deconvolution Techniques

Abstract Blind deconvolution techniques were used to enhance scanning electron microscope (SEM) images in the range of 200,000x to 500,000x magnification. Typical SEM samples were imaged including a gold island reference standard, a plasma delayered integrated circuit, and an integrated circuit cross section. Image resolution improvement up to 40% was observed. However, it was necessary to use 16-bit TIFF images with greater than 120:1 signal to noise ratio, which required 10 minute frame times.

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