Scanning Near-Field Ultrasound Holography
Published Online: 15 DEC 2010
Copyright © 2000 John Wiley & Sons, Ltd. All rights reserved.
Encyclopedia of Analytical Chemistry
How to Cite
Avasthy, S., Shekhawat, G. and Dravid, V. P. 2010. Scanning Near-Field Ultrasound Holography. Encyclopedia of Analytical Chemistry. .
- Published Online: 15 DEC 2010
Nondestructive metrology of nanoscale structures, embedded defects, and buried patterns in microelectronic devices is a daunting challenge. Similarly, noninvasive nanoscale imaging of subcellular components, spatiotemporal transfection of pathogens, and environmental pollutants in a biological cell is an equally formidable problem. Various traditional imaging methods using optics, acoustics, electron beams, X-rays and the like are either invasive or are incapable of achieving nanoscale lateral resolution. We have developed an innovative scanning near-field ultrasound holography (SNFUH) approach as a promising solution to this challenge. SNFUH exploits viscoelastic contrast between subsurface structures and matrix for imaging the “phase” component of ultrasound scattering. The experimental setup is a modified scanning probe microscopy (SPM) platform, wherein ultrasonic waves are excited at the probe tip and in the sample bulk, using transducers. Ultrasonic plane waves launched from the bottom of the specimen experience perturbations due to changes in viscoelastic properties and/or geometry of the embedded structures. These perturbations are detected and imaged via SNFUH's optoelectronic feedback system. The SNFUH system has already been used to image nanoscale structures in microelectronic and biological specimens, and further development and understanding will considerably aid in the development of nanoscale noninvasive metrology fields.
- Nondestructive testing;
- subsurface imaging;
- nanoscale imaging;
- near field;
- defect detection;
- scanning probe microscopy