scholarly journals Flaw detection with ultrasonic backscatter signal envelopes

2019 ◽  
Vol 145 (2) ◽  
pp. EL142-EL148 ◽  
Author(s):  
Yongfeng Song ◽  
Christopher M. Kube ◽  
Zuoxiang Peng ◽  
Joseph A. Turner ◽  
Xiongbing Li
Keyword(s):  
Flaw Detection ◽  
Backscatter Signal ◽  
Ultrasonic Backscatter

A method to locate spatial distribution of scattering centers from ultrasonic backscatter signal

2019 ◽  
Vol 145 (4) ◽  
pp. 2453-2460
Author(s):  
Fang Chen ◽  
Aijun He ◽  
Sidong Fu ◽  
Xiaozhou Liu ◽  
Yunqing Liu ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Backscatter Signal ◽  
Scattering Centers ◽  
Ultrasonic Backscatter

scholarly journals Variability in Ultrasound Backscatter Induced by Trabecular Microstructure Deterioration in Cancellous Bone

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Xingxing Chou ◽  
Feng Xu ◽  
Ying Li ◽  
Chengcheng Liu ◽  
Dean Ta ◽  
...  
Keyword(s):  
Cancellous Bone ◽  
Fdtd Method ◽  
Bone Microstructure ◽  
Backscatter Coefficient ◽  
Backscatter Signal ◽  
Trabecular Microstructure ◽  
Ultrasound Backscatter ◽  
Ultrasonic Backscatter ◽  
The Relationship ◽  
Difference Time

To determine the relationship between the ultrasonic backscatter parameters and trabecular microstructural variations in cancellous bone, three erosion procedures were performed to simulate various changes in the cancellous bone microstructure. The finite difference time domain (FDTD) method was used to simulate the backscatter signal in cancellous bone. Ultrasonic backscatter properties were derived as functions of the porosity when the ultrasound incident directions were perpendicular and parallel to the major trabeculae direction (MTD), respectively. The variability in the apparent backscatter coefficient (ABC) and apparent integrated backscatter (AIB) due to the trabecular microstructure was revealed. Significant negative correlations between the backscatter parameters (ABC and AIB) and the porosity of the cancellous bone were observed. The simulations showed that the ABC and AIB were influenced by the direction of the trabecular microstructural variations. The linear regressions between the ultrasonic backscatter parameters (ABC and AIB) and the porosity showed significantly different slopes for three erosion procedures when they are ultrasonically perpendicular (for ABC, −1.22 dB, −0.98 dB, and −0.46 dB; for AIB, −0.74 dB, −0.69 dB, and −0.25 dB) and parallel (for ABC, −1.87 dB, −0.69 dB, and −0.51 dB; for AIB, −0.9 dB, −0.5 dB, and −0.34 dB) to the MTD. This paper investigated the relationship between ultrasonic backscatter and cancellous bone microstructure deterioration and indicated that the ultrasonic backscatter could be affected by cancellous bone microstructure deterioration direction.

scholarly journals Measurement and compensation of frequency-dependent attenuation in ultrasonic backscatter signal from cancellous bone

2019 ◽  
Vol 68 (18) ◽  
pp. 184301
Author(s):  
Rui Dong ◽  
Cheng-Cheng Liu ◽  
Xun-Bin Cai ◽  
Liu-Lei Shao ◽  
Bo-Yi Li ◽  
...  
Keyword(s):  
Cancellous Bone ◽  
Backscatter Signal ◽  
Frequency Dependent ◽  
Ultrasonic Backscatter

Low - Voltage Scanning Electron Microscopy Imaging, Secondary and Backscatter, With Microchannel Plate Detector

1990 ◽  
Vol 48 (1) ◽  
pp. 442-442
Author(s):  
Galen Powers ◽  
Ray Cochran
Keyword(s):  
Low Voltage ◽  
Beam Current ◽  
Microchannel Plate ◽  
Normal Operation ◽  
Microscopy Imaging ◽  
Backscatter Signal ◽  
Vacuum Interface ◽  
Width Measurements ◽  
Working Distance ◽  
Beam Currents

The capability to obtain symmetrical images at voltages as low as 200 eV and beam currents less than 9 pico amps is believed to be advantageous for metrology and study of dielectric or biological samples. Symmetrical images should allow more precise and accurate line width measurements than currently achievable by traditional secondary electron detectors. The low voltage and current capability should allow imaging of samples which traditionally have been difficult because of charging or electron beam damage.The detector system consists of a lens mounted dual anode MicroChannel Plate (MCP) detector, vacuum interface, power supplies, and signal conditioning to interface directly to the video card of the SEM. The detector has been miniaturized so that it does not interfere with normal operation of the SEM sample handling and alternate detector operation. Biasing of the detector collection face will either add secondaries to the backscatter signal or reject secondaries yielding only a backscatter image. The dual anode design allows A−B signal processing to provide topological information as well as symmetrical A+B images.Photomicrographs will show some of the system capabilities. Resolution will be documented with gold on carbon. Variation of voltage, beam current, and working distance on dielectric samples such as glass and photoresist will demonstrate effects of common parameter changes.

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