Time-reversal acoustic focusing system as a virtual random phased array

Area of Science:

• Acoustics
• Wave Physics
• Biomedical Engineering

Background:

• Dynamic focusing of ultrasonic waves is crucial for applications in medical imaging and therapy.
• Conventional 2-D phased arrays (PA) require complex electronics and numerous elements for precise focusing.
• Time-reversed acoustics (TRA) presents an alternative approach for acoustic focusing.

Purpose of the Study:

• To compare the performance of a TRA focusing system (TRA FS) with conventional 2-D PAs for dynamic ultrasonic focusing.
• To evaluate the complexity and steerability of focused fields generated by both systems.
• To assess the feasibility of realizing a TRA FS with simple, cost-effective components.

Main Methods:

• Experimental implementation of a TRA FS using a liquid-filled reverberator with 4 piezotransducers.
• Mathematical simulation of 2-D PAs with varying numbers of elements (tens to hundreds).
• Comparison of focused ultrasonic fields generated by both systems at a center frequency of approximately 600 kHz, using identical apertures.

Main Results:

• The TRA FS, despite using a small number of channels, achieved complex focused patterns.
• Steering efficiency of the TRA FS was comparable to PAs with hundreds of elements.
• A simple TRA FS was successfully realized using a water-filled plastic bottle with few piezotransducers.

Conclusions:

• TRA focusing systems offer a viable and efficient alternative to conventional PAs for dynamic ultrasonic focusing.
• The simplicity and cost-effectiveness of TRA FS make them attractive for various applications.
• Further research can explore advanced configurations of TRA for enhanced ultrasonic focusing capabilities.