Compact Acoustic Source Using Resonance-Enhanced Nonlinear Mixing
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Solution Overview
Problem
Conventional low-frequency acoustic sources are large and have wide beam spreads, limiting their use in applications requiring compact, high-lateral-resolution acoustic imaging in highly attenuating media such as the human body, concrete, and drilling mud, due to high acoustic attenuation at higher frequencies.
Innovation Solution
The development of compact acoustic sources that utilize parametric frequency mixing and resonance enhancement in an acoustic nonlinear medium, such as FLUORINERT electronics cooling liquid, to generate a collimated and steerable low-frequency acoustic beam, achieving an order of magnitude increase in acoustic amplitude and improved beam collimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional low-frequency acoustic sources are used, then acoustic penetration depth is improved, but beam collimation deteriorates resulting in wide beam spreads
Solution Approach 1:
The patent changes the operating parameters by using frequency mixing to generate a difference frequency that is resonant with the cavity mode. This resonance condition dramatically enhances the acoustic amplitude and improves beam collimation while maintaining the low frequency needed for deep penetration. The key parameter change is tuning the difference frequency to match the cavity's resonant frequency.
Solution Approach 2:
The patent utilizes acoustic cavity resonance, which is a mechanical vibration phenomenon, to enhance the difference frequency signal. By designing the cavity dimensions to support a resonant mode at the difference frequency, the system achieves significant amplitude enhancement and improved beam collimation without sacrificing penetration depth.
2Volume of moving object
If compact acoustic sources are used, then device size is reduced, but acoustic amplitude deteriorates
Solution Approach 1:
The patent employs resonance enhancement where the cavity dimensions are specifically designed to support a resonant mode at the difference frequency. This resonance phenomenon provides an order of magnitude enhancement in acoustic amplitude, allowing compact source dimensions to achieve high acoustic power output that would otherwise require much larger transducers.
Solution Approach 2:
The system changes the frequency parameters by generating a difference frequency through nonlinear mixing that matches the cavity's resonant frequency. This parameter tuning allows the compact cavity to efficiently convert input acoustic energy into a resonantly enhanced difference frequency signal with high amplitude.
3Shape
If high-frequency acoustic signals are used, then beam collimation is improved, but acoustic attenuation increases
Solution Approach 1:
The patent uses frequency mixing to generate a difference frequency that is much lower than the input frequencies. This parameter transformation allows the system to achieve good beam collimation from the high-frequency input beams while the resulting low-frequency difference frequency experiences minimal attenuation in the propagation medium.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These compact sources provide deeper penetration and higher lateral resolution in attenuating media, enabling effective acoustic imaging in applications where space and size are limited, such as endoscopic imaging and downhole imaging, with enhanced acoustic signal intensity and reduced side lobes.
Implementation Method 1
An acoustic transducer is situated to direct an acoustic signal into the resonator volume, and an electrical signal source is coupled to the acoustic transducer so as to apply an electrical signal at a carrier frequency to the acoustic transducer to produce an acoustic signal at the carrier frequency
Implementation Method 2
frequency mixing in an acoustical nonlinear fluid (or other nonlinear material) in a cavity to generate a difference frequency between two high frequencies, such as around 1 MHz
Implementation Method 3
resonance enhancement of the difference frequency in the cavity. In one example, an order of magnitude enhancement in acoustic amplitude was observed between on-resonance and off-resonance conditions
Data Source
AI summary
Acoustic signal sources include acoustic resonators that include acoustic nonlinear materials. Acoustic signals at higher frequencies are mixed in the nonlinear materials to produce a lower frequency acoustic signal. Resonance provides increased efficiency in producing acoustic signals at difference frequencies corresponding to resonance frequencies. Higher frequency acoustic signals used in nonlinear mixing are preferably at frequencies corresponding to resonance frequencies as well.