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Updated: Jul 7, 2026
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Published on: March 20, 2017
Focal translation by frequency shift in free space
H C Song1, P Roux, W A Kuperman
1Marine Physical Laboratory, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA92093-0701, USA. hcsong@mpl.ucsd.edu
Summary
This study introduces a new algorithm for acoustic focusing using frequency shifts in transmit arrays. This method enables precise control over the focal spot
Area of Science:
- Acoustic physics
- Waveguide acoustics
- Signal processing
Background:
- Achieving variable focusing in acoustic systems is crucial for applications like medical imaging and non-destructive testing.
- Conventional methods for focal spot manipulation can be complex and require detailed knowledge of the medium.
Purpose of the Study:
- To develop a general algorithm for controlling the focal spot of a linear transmit array in free space.
- To enable both transverse and horizontal movement of the focal spot using frequency shifts.
Main Methods:
- Derivation of a general algorithm for focal spot manipulation via frequency shifts.
- Application of uniform frequency shift for range focusing and element-dependent shifts for transverse focusing.
- Demonstration of the method's suitability for time-reversal mirrors with aberrating layers.
Main Results:
- The proposed algorithm successfully moves the focal spot both transversely and horizontally.
- Variable range focusing is achieved with a uniform frequency shift across all array elements.
- Transverse focal shifts are accomplished by varying the frequency shift with element location.
Conclusions:
- The frequency shift method offers a robust approach for variable focusing in acoustic transmit arrays.
- This technique is particularly advantageous for time-reversal imaging in complex or unknown environments.
- The method eliminates the need for prior knowledge of medium properties for focal spot steering.
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