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Enhanced backscattering and modal echo of reverberant elastic waves
1Department of Theoretical and Applied Mechanics, University of Illinois, Urbana, Illinois 61801, USA.
Physical Review Letters
|September 16, 2000
Summary
Scientists observed coherent backscattering of ultrasonic waves in a 3D elastic body. This phenomenon, known as weak localization, showed enhanced wave energy near the source, independent of material absorption.
Area of Science:
- Physics
- Acoustics
- Materials Science
Background:
- Wave propagation in complex media can exhibit phenomena like scattering and interference.
- Weak localization is a quantum interference effect typically observed in disordered systems.
Purpose of the Study:
- To experimentally investigate coherent backscattering of waves in a three-dimensional elastic body.
- To compare experimental findings with predictions from random matrix theory.
Main Methods:
- Measurement of ultrasonic spectral energy density.
- Time-resolved and distance-dependent measurements from a transient excitation source.
- Analysis of wave energy enhancement near the source.
Main Results:
- Experimental evidence for coherent backscattering of ultrasonic waves was observed.
- A weak localization enhancement factor of 2 at early times and 3 at late times was measured.
- The observed effect was found to be independent of absorption within the elastic body.
Conclusions:
- Coherent backscattering, a form of weak localization, is experimentally demonstrated in a 3D elastic medium.
- The results align with predictions from random matrix theory regarding wave interference in disordered systems.
- The phenomenon's independence from absorption suggests its robustness in elastic wave propagation.
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