Related Experiment Videos
Limits of time-reversal focusing through multiple scattering: long-range correlation
1Laboratoire Ondes et Acoustique, Universite Denis Diderot-Paris, France. arnaud.derode@espci.fr
The Journal of the Acoustical Society of America
|June 30, 2000
Summary
Time-reversal focusing in complex scattering media achieved high resolution, comparable to the ultrasonic wavelength. Persistent temporal side-lobes emerged in thicker samples due to high-order multiple scattering effects.
Area of Science:
- Physics
- Acoustics
- Wave Propagation
Background:
- High-order multiple scattering complicates wave focusing.
- Time-reversal techniques offer potential for focusing waves in complex media.
Purpose of the Study:
- To experimentally investigate time-reversal focusing in a high-order multiple scattering medium.
- To compare experimental results with theoretical predictions from a statistical model.
Main Methods:
- Utilized an ultrasonic source (3.2 MHz) and an array to transmit and record pulses in a random steel rod medium.
- Implemented time-reversal by sending recorded waves back through the scattering medium.
- Analyzed temporal focusing quality and spatial resolution.
Main Results:
- Temporal focusing quality was accurately predicted by a statistical model.
- Persistent temporal side-lobes appeared in thicker samples, attributed to high-order multiple scattering.
- Spatial focusing resolution was largely independent of array aperture, achieving ~0.5 mm (wavelength scale).
Conclusions:
- A simple statistical model effectively predicts temporal focusing in multiple scattering media.
- High-order multiple scattering leads to temporal side-lobes due to increased path crossings.
- Time-reversal mirrors achieve sub-wavelength spatial resolution in random media.