Acousto-Optic Imaging Using Unfocused Wave Segmentation
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Solution Overview
Problem
Existing acousto-optic imaging methods are slow due to the need for scanning with a succession of focused ultrasonic waves, limiting their lateral resolution without increasing device complexity or speed.
Innovation Solution
An acousto-optic imaging method using an array of ultrasonic transducers to emit unfocused acoustic waves with periodic spatial amplitude modulations in different directions, combined with simultaneous light emission, to enhance spatial modulation and improve lateral resolution without increasing complexity or speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If focused ultrasonic waves are used to scan the region of observation, then lateral resolution is improved, but imaging speed deteriorates due to the need for many sequential bursts (around 200,000 focused ultrasonic waves)
Solution Approach 1:
The patent segments the ultrasonic wave emission into multiple unfocused waves propagating in different directions, each contributing to different spatial frequencies. This segmentation allows parallel information gathering from multiple directions simultaneously, avoiding the sequential scanning requirement of focused waves while maintaining resolution through the combined spatial frequency data.
Solution Approach 2:
The patent transitions from one-dimensional focused wave scanning to multi-dimensional unfocused wave propagation in different directions. By emitting unfocused waves in multiple directions simultaneously and capturing their respective spatial frequency components, the system achieves comprehensive imaging information without sequential scanning, thereby improving speed while maintaining resolution.
2Productivity
If unfocused ultrasonic waves are emitted in different directions to reduce the number of bursts, then imaging speed is improved, but lateral resolution deteriorates
Solution Approach 1:
The patent makes each unfocused ultrasonic wave serve multiple functions by having waves in different directions contribute to different spatial frequency components of the same image. The measurement signals from multiple directions are not independent but are combined to reconstruct the complete image, allowing a single wave emission to provide information for multiple spatial frequencies simultaneously.
Solution Approach 2:
The patent changes the parameter of wave focusing from focused to unfocused waves, and introduces directional variation as a new parameter. By varying the propagation direction of unfocused waves and capturing their respective spatial frequency components, the system achieves both speed improvement (fewer bursts) and maintains resolution (through multi-directional spatial frequency data combination).
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 method significantly improves lateral resolution by obtaining higher spatial frequencies through acousto-optic signals, allowing for faster image formation with reduced bursts of ultrasonic waves, achieving comparable or improved resolution in fewer steps.
Implementation Method 1
when an ultrasonic wave, with an acoustic frequency fa passes through a scattering medium (for example a biological or other tissue), it causes a periodic displacement of the scattering centers and a periodic modulation of the index of refraction of the medium. If an incident light wave, notably a laser light wave, of incident frequency fi is scattered by the medium, the motion of the scattering centers and the modulation of the index of refraction of the medium generate a tagged light wave comprising, on the one hand, a carrier component at the incident frequency fi and, on the other hand, an acousto-optic component scattered onto one or other of the acoustic sidebands, of frequencies fao=fa±n*fi.
Data Source
AI summary
An acousto-optic imaging method in which light waves and unfocused acoustic waves having various directions of propagation m are emitted in a medium, by spatially modulating the amplitude of the ultrasonic transducers of an array of transducers according to several periodic spatial amplitude modulations j, and the resulting optical signal Smj(t) is captured. For each direction of propagation m, the signals Smj(t) are spatially demodulated in order to determine a signal Sm(t) used to reconstruct the image of the medium.