Phased Array Transducer Coupling Layer Grating Lobe Suppression
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Solution Overview
Problem
Conventional phased-array ultrasound transducers require a small element-to-element pitch of λ/2 to avoid grating lobes, limiting transducer array element size and increasing energy transmission through the near field, which is costly and inefficient.
Innovation Solution
Incorporation of a coupling layer with a speed of sound exceeding that of the propagation medium, allowing for larger array pitch and element size while suppressing grating lobes by propagating the ultrasound beam through the coupling layer before entering the medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a small element-to-element pitch of λ/2 is used to avoid grating lobes, then grating lobes are suppressed, but the transducer array element size is limited and energy transmission through the near field increases
Solution Approach 1:
A coupling layer is introduced as an intermediary between the transducer array and the propagation medium. This coupling layer has a speed of sound greater than that of the propagation medium, which allows for larger array pitch while suppressing grating lobes. The coupling layer acts as a mediator that transforms the acoustic field characteristics, enabling energy efficiency improvements.
Solution Approach 2:
The invention changes the physical parameter of the coupling layer by selecting a material with a speed of sound greater than that of the propagation medium. This parameter change allows the system to operate with larger array pitch (greater than λ/2) while maintaining grating lobe suppression, thereby reducing energy transmission through the near field.
2Shape
If a larger irregular spacing is employed to obtain a focused beam, then beam focusing is improved, but the element size must be less or equal to λ/2 resulting in increased energy transmission through the near field
Solution Approach 1:
The coupling layer serves as a mediator that enables larger element spacing while maintaining beam focusing capabilities. By having a speed of sound greater than the propagation medium, the coupling layer allows the transducer elements to be spaced more than λ/2 apart without generating grating lobes, thus improving beam focusing while reducing near field energy transmission.
3Area of stationary object
If a fully populated array is used, then coverage is improved, but the number of elements increases due to the short wavelength in the propagation medium
Solution Approach 1:
The invention changes the effective wavelength parameter by introducing a coupling layer with a higher speed of sound. This allows the array to use larger spacing between elements (greater than λ/2 in the propagation medium) while maintaining the same coverage area, thereby reducing the total number of elements required in the array.
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
Enables increased array element size and reduced number of elements, decreasing energy transmission costs and effectively eliminating grating lobes, while maintaining beam focusing capabilities.
Implementation Method 1
said coupling layer having a speed of sound greater than the speed of sound of soft tissue and a thickness sufficient for the generation of a wavefront therein, thereby reducing or suppressing the generation of grating lobes
Data Source
AI summary
An ultrasound phased array transducer is disclosed that achieves suppression of grating lobes through the incorporation of a coupling layer, where the coupling layer is positioned adjacent to the phased array transducer such that an ultrasound beam propagates through the coupling layer prior to encountering a propagation medium. The phased-array elements may be provided such that one or both of the array pitch and a lateral extent of each ultrasound transducer element is larger than half of the ultrasound wavelength in the propagation medium. Grating lobes within the coupling layer and the propagation medium may be reduced or suppressed by selecting a coupling material having a speed of sound that exceeds that of the propagation medium. The coupling layer may have a thickness sufficient for the generation of a wavefront, and the coupling layer may be formed from a viscous or viscoelastic material.