Interferometer-Based Speckle Imaging for Quantitative Blood Flow
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Solution Overview
Problem
Conventional laser speckle contrast imaging (LSCI) systems are limited to relative measurements of cerebral blood flow and require high-power light sources, which are impractical for clinical applications such as intraoperative imaging and ophthalmology.
Innovation Solution
A speckle imaging system utilizing an optical interferometer apparatus with a reference arm and a sample arm, combined with a computer system for processing raw speckle images to determine speckle contrast and visibility, allowing for quantitative measurement of blood flow without the need for high-power light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-power light sources are used in conventional LSCI systems, then measurement precision is improved, but device complexity and impracticality for clinical applications worsen
Solution Approach 1:
The patent introduces an optical interferometer as an intermediary device between the light source and the detector. The interferometer modulates the light field to create heterodyne detection conditions, which amplifies the signal without requiring high-power light sources. This intermediary mechanism enables precise blood flow measurements while reducing the complexity and improving the practicality of the system for clinical applications.
2Measurement precision
If high-power light sources are used in conventional LSCI systems, then measurement precision is improved, but adaptability to clinical applications worsens
Solution Approach 1:
The patent changes the operational parameters of the light detection system by introducing interferometric modulation. Instead of relying on high-power light sources, the system uses parameter changes in the light field (phase modulation) to achieve sensitive detection. This parameter transformation enables the system to adapt to clinical applications where high power is impractical, such as intraoperative imaging and ophthalmology.
3Device complexity
If conventional LSCI is used, then device simplicity is maintained, but measurement precision for absolute blood flow values deteriorates
Solution Approach 1:
The patent segments the optical detection process into distinct functional components within the interferometer: a reference arm, a sample arm, and a detection channel. This segmentation allows the system to maintain relative simplicity while achieving absolute measurement capability through the structured separation of optical paths and the use of heterodyne detection principles.
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 system enables quantitative imaging of absolute blood flow values, overcoming noise limitations and allowing for accurate measurements at lower light intensities, thus being suitable for clinical applications.
Implementation Method 1
an optical interferometer apparatus having a reference arm and a sample arm... The light output includes both the sample light (that has interacted with a target sample in the sample arm) and the reference light
Implementation Method 2
an optical imaging system that contains an optical detector system optically cooperated with the output end... receive from it an electrical signal that represents a raw speckle image formed at the optical detector system
Implementation Method 3
computer system (operably connected with the optical imaging system and configured to receive from it an electrical signal that represents a raw speckle image... determine and/or display a speckle contrast characteristic of said raw speckle image
Data Source
AI summary
A SyntheticMulti-Exposure Speckle Imaging (syMESI) methodology necessarily utilizing an optical interferometer apparatus as part of the speckle imaging system to overcome the optical detector noise that conventionally limits the reliable and accurate determination of a speckle contrast characteristic at low exposure times. The use of such methodology enabled a quantitative determination of absolute value(s) of changes of motion at the target object (such as blood flow changes in tissue) at low photon budget of less than 40 counts of average detection intensity and/or quantitative imaging of the blood flow at the object in interoperative setting with a low-cost camera sensor.