Synthetic Aperture Focusing Techniques in the Near Field of a Focused Transducer

1996 ◽  
pp. 2073-2079
Author(s):  
W. Masri ◽  
M. Mina ◽  
S. S. Udpa ◽  
L. Udpa ◽  
T. Xue ◽  
...  
Keyword(s):  
Near Field ◽  
Synthetic Aperture ◽  
Synthetic Aperture Focusing

scholarly journals REGULARIZATION IMAGING ALGORITHM WITH ACCURATE G MATRIX FOR NEAR-FIELD MMW SYNTHETIC APERTURE IMAGING RADIOMETER

2014 ◽  
Vol 58 ◽  
pp. 193-203 ◽  
Author(s):  
Jianfei Chen ◽  
Yuehua Li ◽  
Jianqiao Wang ◽  
Yuanjiang Li ◽  
Yilong Zhang
Keyword(s):  
Near Field ◽  
Synthetic Aperture ◽  
Synthetic Aperture Imaging ◽  
Imaging Algorithm

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.

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