Master Slave OCT Axial Tracking via Digital Mask Swapping
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Solution Overview
Problem
Current OCT systems face challenges in accurately tracking and correcting for axial movements of non-stationary objects during imaging, particularly in real-time, due to mechanical latency and limitations in distinguishing between bulk movements and pulsatile blood flow, which affects image quality and interpretation, especially in curved surfaces like the eye or heart.
Innovation Solution
The implementation of a Master Slave (MS) OCT system with a dynamic mask selector and processor that rapidly generates and swaps masks to adapt to axial movements and curvature, allowing for non-mechanical correction and real-time flattening of en-face images, enabling precise axial tracking and segmentation without the need for mechanical translation stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical translation stages are used for axial tracking correction, then axial position compensation is achieved, but mechanical latency and response time are increased
Solution Approach 1:
The patent replaces mechanical translation stages with a digital mask-swapping mechanism. Instead of physically moving components to track axial position changes, the system dynamically selects and swaps digital masks corresponding to different axial positions. This eliminates mechanical inertia and latency, achieving real-time axial tracking through purely electronic operations.
Solution Approach 2:
The patent pre-calculates and stores multiple masks corresponding to different axial positions before imaging begins. When axial movement occurs, the system simply swaps to the pre-prepared mask matching the new position, rather than calculating or mechanically adjusting in real-time. This preliminary preparation enables instantaneous response to axial position changes.
2Ease of operation
If conventional OCT systems are used for imaging curved surfaces, then basic imaging is achieved, but image quality and interpretation are degraded due to curvature effects
Solution Approach 1:
The patent applies different masks to different lateral positions in the image, where each mask is optimized for the local axial position and curvature at that location. Instead of using a single global mask, the system tailors the mask selection to local conditions, enabling accurate tracking and flattening across curved surfaces with varying geometry.
Solution Approach 2:
The patent implements dynamic mask selection that adapts to changing axial positions and curvature during imaging. The mask selector responds in real-time to detected axial movements and curvature variations, swapping masks dynamically throughout the scanning process to maintain optimal image quality across the entire field of view.
3Reliability
If mechanical correction systems are used for axial movement compensation, then axial tracking is achieved, but device complexity is increased
Solution Approach 1:
The patent eliminates mechanical correction systems entirely, replacing them with a digital mask-swapping approach controlled by a processor. This substitution reduces device complexity by removing mechanical components while maintaining or improving axial tracking reliability through purely electronic operations with no moving parts.
Solution Approach 2:
The patent uses digital masks that are copies or representations of the expected axial position information, rather than physically measuring and correcting with mechanical sensors and actuators. This copying approach simplifies the system by using computational models instead of complex mechanical feedback systems.
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 enables faster and more accurate axial tracking and image correction, reducing latency and improving the quality of OCT images by distinguishing between bulk and pulsatile movements, and providing quicker, more reliable en-face images, even in curved or moving tissues.
Implementation Method 1
The light from the object path and from the reference path interferes. Due to interference, the optical spectrum at the interferometer output is channeled (modulated)
Implementation Method 2
a photodetector to produce an electrical signal due to the intensity modulation of the channeled spectrum
Data Source
AI summary
The present specification relates to Master-Slave (MS) interferometry for sensing the axial position of an object subject to optical coherence tomography (OCT) imaging, and to MS-OCT applied to curved and axially moving objects. The methods and apparatuses allow producing OCT signals from selected depths within the object irrespective of its axial position in respect to the imaging system. Images are obtained for curved objects that are flattened along a layer of interest in the object, images that are used to provide OCT angiography images less disturbed by axial movement or lateral scanning.