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Decomposition of acoustic fields in quantised Bessel beams
Ultrasonics
|June 1, 2000
Summary
Quantizing Bessel beams on annular arrays creates a sum of limited diffraction fields. This study demonstrates how these fields, including undesired components, affect the desired Bessel beam profile in practical applications.
Area of Science:
- Acoustics
- Wave Physics
- Optics
Background:
- Bessel beams are non-diffracting wave solutions.
- Finite apertures limit Bessel beams to finite diffraction beams.
- Previous theory suggested Bessel beam quantization yields a sum of limited diffraction fields.
Purpose of the Study:
- To experimentally demonstrate the theoretical prediction of Bessel beam quantization.
- To analyze the composition of the quantized Bessel beam field.
- To identify and quantify the components contributing to discrepancies in the actual field.
Main Methods:
- Utilized a five-ring, 20-mm diameter, 2.5-MHz transducer.
- Applied Fourier-Bessel theory for analysis.
- Quantized the Bessel beam profile on an annular array.
Main Results:
- The quantized field is a weighted sum of multiple limited diffraction fields.
- Three major undesired components and 28 lesser components were identified.
- These components have narrower beamwidths and shorter depths of field than the desired beam.
- The major components explain most discrepancies between desired and actual fields.
Conclusions:
- Experimental validation of Bessel beam quantization producing a sum of limited diffraction fields.
- Understanding the contribution of these components is crucial for practical applications.
- Provides a method to estimate and interpret field components based on wavenumber.