Full-Field OCT Imaging of Moving Samples via Motion-Induced Phase Shifts
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Solution Overview
Problem
Conventional optical coherence tomography (OCT) techniques face challenges with motion artifacts due to in vivo tissue movements, limiting their ability to produce clear images, especially in 3D imaging of constantly moving samples like the eye, where full-field OCT is restricted to static samples due to phase shifts caused by sample motion.
Innovation Solution
A method and system for in vivo full-field interference microscopy that utilizes natural sample movements to acquire temporal succession of two-dimensional interferometric signals, determining en face images and cross-sectional images to construct a 3D image by correlating the relative axial position of the reflection surface and sample structures, allowing for precise depth determination and 3D imaging of moving samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional OCT scanning techniques are used to achieve point-by-point imaging, then imaging depth and resolution are improved, but motion artifacts appear due to sequential pixel acquisition
Solution Approach 1:
The imaging process is segmented into multiple low-coherence interferometric measurements taken at different optical path lengths, allowing reconstruction of depth-resolved information from sequential measurements without requiring mechanical scanning of the entire image
Solution Approach 2:
A low-coherence light source acts as an intermediary to enable depth gating through optical coherence tomography principles, isolating signals from specific depth ranges while rejecting out-of-focus light, thereby achieving sectioning without mechanical scanning
2Reliability
If full-field OCT is used to acquire all pixels simultaneously, then immunity to motion artifacts is achieved, but the technique is restricted to static samples due to phase shift requirements
Solution Approach 1:
The system dynamically adapts to sample motion by continuously acquiring interferometric signals and using cross-correlation algorithms to track and compensate for axial displacements between consecutive frames, enabling real-time imaging of moving samples
Solution Approach 2:
The system uses feedback from the interferometric signal analysis to detect sample motion and adjust the reconstruction process accordingly, applying motion compensation algorithms that use the detected phase shifts to correct image artifacts caused by sample movement
3Reliability
If hardware-based motion compensation schemes are implemented, then motion artifacts are reduced, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex hardware-based motion compensation mechanisms with software-based algorithms that process the interferometric signals to detect and correct for sample motion, eliminating the need for additional mechanical components while achieving motion artifact reduction
Solution Approach 2:
The system uses the interferometric signal itself to carry motion information, allowing the signal to serve dual purposes: both imaging and motion detection, thereby eliminating the need for separate motion sensing hardware
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 precise 3D imaging of moving in vivo samples by leveraging natural movements to achieve phase shifts, eliminating the need for hardware-based motion compensation and expanding the applicability of full-field OCT beyond static samples.
Implementation Method 1
producing, at each point of an imaging field, an interference between a reference wave obtained by reflection of incident light waves on an elementary surface of the first reflection surface corresponding to said point of the imaging field and an object wave obtained by backscattering of incident light waves by a voxel of a slice of the sample at a given depth
Data Source
AI summary
According to one aspect, the invention relates to a system (101) for in vivo, full-field interference microscopy imaging of a scattering three-dimensional sample. It comprises a full-field OCT imaging system (130) for providing en face images of the sample, wherein said full-field OCT system comprises an interference device (145) with an object arm (147) intended to receive the sample and a reference arm (146) comprising an optical lens (134) and a first reflection surface (133), and an acquisition device (138) configured to acquire a temporal succession of two-dimensional interferometric signals (I1, I2) resulting from interferences produced at each point of an imaging field; an OCT imaging system (110) for providing at the same times of acquisition of said two-dimensional interferometric signals, cross-sectional images of both the sample and a first reflection surface (133) of said full-field OCT imaging system (130); a processing unit (160) configured to determine a plurality of en face images (X-Y) of a plurality of slices of the sample, each en face image being determined from at least two two-dimensional interferometric signals (I1, I2) having a given phase shift; determine from the cross-sectional images provided by the OCT imaging system (110) at the times of acquisition of each of said two two-dimensional interferometric signals (I1, I2) a depth (z) for each en face image (X-Y) of said plurality of slices; determine a 3D image of the sample from said plurality of en face images of said plurality of slices of the sample and depths.