Reflective Foil Coating for Photoacoustic Transducer Artifact Reduction
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Solution Overview
Problem
Existing photo-acoustic imaging devices face challenges in reducing artifacts due to photo-acoustic conversion at the surface of acoustic-electronic transducers, which affect the Signal-to-Noise Ratio (SNR) and image quality, especially from direct and reflected light interactions.
Innovation Solution
Applying a reflective coating, such as a gold-coated copper foil, onto the sound receiving surface of the transducers, which is easier to install and replace, thereby reducing artifacts by minimizing light absorption and improving smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a reflective coating is applied directly to the transducer surface, then light reflection is improved, but the coating thickness required to overcome surface roughness increases, causing ultrasound attenuation
Solution Approach 1:
A foil substrate is introduced as an intermediary layer between the rough transducer surface and the reflective coating. The foil provides a smooth surface that allows application of a thin reflective coating without shadow effects, while the foil itself acts as an acoustic matching layer to maintain ultrasound transmission.
Solution Approach 2:
The solution uses a composite structure consisting of a foil substrate (e.g., copper or aluminum) combined with a thin reflective coating (e.g., gold). This composite provides both the smooth surface needed for effective light reflection and maintains acoustic properties for ultrasound transmission.
2Illumination intensity
If a thick reflective coating is applied to cover surface roughness, then light reflection is improved, but the coating becomes opaque to ultrasound waves
Solution Approach 1:
The foil substrate serves as a mediator that decouples the requirements for light reflection and ultrasound transmission. It provides a smooth surface for thin coating application, eliminating the need for thick coatings to overcome surface roughness.
Solution Approach 2:
A thin foil film is used as the substrate, allowing the application of a thin reflective coating. The foil's flexibility and smooth surface enable precise coating thickness control while maintaining both optical and acoustic properties.
3Ease of manufacture
If vapor deposition or sputtering is used to deposit gold on a rough surface, then coating application is simplified, but shadow effects occur in crevices and indentations, reducing coating effectiveness
Solution Approach 1:
The foil substrate acts as an intermediary that provides a smooth surface for coating deposition. This eliminates shadow effects in crevices and indentations, ensuring uniform and effective reflective coating coverage while maintaining ease of manufacture.
4Loss of energy
If the gold coating is made very thin to maintain ultrasound transmission, then ultrasound transmission is improved, but the coating becomes insufficient to prevent light absorption at the underlying surface
Solution Approach 1:
The foil substrate serves as a dual-function intermediary: it provides a smooth surface for thin coating application and acts as an acoustic matching layer. This allows the use of thin reflective coatings that maintain ultrasound transmission while the foil itself provides additional light reflection to prevent photo-acoustic conversion at the underlying surface.
Solution Approach 2:
The thin foil film enables the application of a thin reflective coating that is sufficient to prevent light absorption at the underlying surface while maintaining ultrasound transmission. The foil's acoustic properties compensate for the reduced coating thickness.
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
The solution significantly reduces photo-acoustic artifacts, enhancing the SNR and image quality by preventing multiple light reflections and maintaining ultrasound transmission, while being cost-effective and easy to maintain.
Implementation Method 1
a reflective coating provided on the basin side of the foil... Gold has an additional beneficial property that it is inert, especially to oxygen, thereby preserving the reflecting surface. It is known that gold is a very effective reflector for (near-)infrared light.
Implementation Method 2
a foil adhesively connected to the receiving surface... an adhesive layer, which may be provided on the transducer-side surface of the foil before the foil is applied to the sound receiving surface of the transducer
Implementation Method 3
Photo-acoustic imaging involves sending light pulses into tissue and formation of an image (usually a 3 D image) of sound generation due to absorption of the light in the tissue... the light pulses give rise to light absorption, leading to an increase in temperature which causes thermal expansion which in turn leads to pressure transients that give rise to low intensity sound waves
Implementation Method 4
An array of ultrasensitive broadband acoustic to electronic transducers in openings through the wall of the basin detects these waves
Data Source
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AI summary
A photo-acoustic imaging device uses a plurality of acoustic-electronic transducers. The transducers have a sound receiving surface that forms part of the surface of a basin such as a breast cup. The transducers, each have a foil adhesively connected to its sound receiving surface and a reflective coating provided on the basin side of the foil. The reflective coating, for example a gold coating, is used to minimize photo-acoustic sound generation at the surface of the transducer, which can lead to image artifacts when this sound is reflected from within the basin. It has been found that by providing the coating on a smooth foil, such as a copper foil or a polymer foil, adhered to the transducer surface, a reduction of photo-acoustic sound generation at the surface can be achieved that is sufficient for a significant reduction of photo-acoustic image artifacts. The foil may be attached in the form of patches on the transducers after the transducers have been mounted on the basin, and the patches may extend from the transducers to the surrounding surface of the basin to reduce photo-acoustic sound generation in gaps between the transducers and the surface of the basin.