Dual Wavelength Optical Imaging via Ultrasound Modulation
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Solution Overview
Problem
Current imaging technologies, such as Time-of-Flight (TOF) imaging, face challenges with high costs, bulkiness, and limited resolution due to the need for specialized hardware and high light intensity, especially when imaging human tissue using near-infrared light for Diffuse Optical Tomography.
Innovation Solution
The implementation of a light scattering layer in an imaging system that emits laser light and ultrasound signals, allowing for the generation of composite images by measuring wavelength-shifted light signals, which does not require high-power pulsed lasers and is more sensitive than conventional methods, enabling imaging with continuous wave lasers and reducing the impact of sample motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Time-of-Flight (TOF) imaging is used to image human tissue, then imaging capability is achieved, but cost increases, device size increases, and resolution is limited
Solution Approach 1:
The patent replaces complex mechanical TOF imaging hardware with a combination of continuous wave laser, ultrasound transducer, and photodetector system. Instead of using specialized TOF cameras and high-power pulsed lasers, the invention uses continuous wave optical fields combined with ultrasound modulation to achieve depth-resolved imaging through optical heterodyning, thereby reducing device complexity while maintaining or improving resolution
Solution Approach 2:
The patent introduces ultrasound waves as an intermediary to modulate the optical field. The ultrasound transducer acts as a mediator that imposes acoustic frequency modulation on the continuous wave laser light, creating sidebands that carry depth information. This intermediary approach eliminates the need for complex pulsed laser systems and specialized TOF detectors, reducing hardware complexity while enabling high-resolution imaging
2Measurement precision
If high-power pulsed lasers are used for Diffuse Optical Tomography, then imaging sensitivity is improved, but cost increases and device complexity increases
Solution Approach 1:
The patent uses continuous wave laser illumination instead of high-power pulsed lasers. The continuous optical field is modulated by ultrasound waves to create time-varying optical properties that carry imaging information. This continuous action approach maintains high sensitivity through coherent detection while using lower average laser power compared to pulsed systems
Solution Approach 2:
The patent introduces periodic ultrasound modulation to the continuous wave laser. The ultrasound transducer creates periodic density variations in the medium, which modulate the optical field at acoustic frequencies. This periodic modulation creates detectable sidebands in the optical spectrum, enabling sensitive detection with continuous wave lasers instead of requiring high-power pulsed lasers
3Measurement precision
If conventional optical imaging methods are used, then imaging is achieved, but resolution is limited and sensitivity is reduced
Solution Approach 1:
The patent uses ultrasound vibrations to modulate the optical field. The ultrasound transducer creates mechanical vibrations in the medium that cause periodic changes in refractive index and optical path length. These vibrations create frequency sidebands in the optical spectrum that can be detected with high sensitivity, enabling both high resolution and high sensitivity imaging simultaneously
Solution Approach 2:
The patent changes the temporal frequency parameters of the optical field through ultrasound modulation. By imposing acoustic frequency modulation on the continuous wave laser, the system creates sidebands at frequencies offset from the carrier by the ultrasound frequency. This parameter change in the optical domain enables depth-resolved imaging with high sensitivity through heterodyne detection, overcoming the resolution and sensitivity limits of conventional optical imaging
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
This approach allows for higher sensitivity and cost-effective imaging with improved resolution, capable of generating both optical and mechanical contrast images of diffuse media like human tissue without the limitations of TOF imaging, using a more accessible and compact setup.
Implementation Method 1
a light scattering layer configured to scatter light from the laser
Implementation Method 2
At least a portion of the measurement beam formed between the laser and the light detector is wavelength-shifted by the ultrasound signal
Implementation Method 3
a light detector configured to detect light from the light scattering layer
Data Source
AI summary
A first signal is generated with a first light detector in response to an ultrasound signal encountering a first measurement beam. A second signal is generated with a second light detector in response to the ultrasound signal encountering a second measurement beam. The second measurement beam propagates through the sample and the first measurement beam propagates outside the sample.