Segmented Sawtooth Beam Scanning for Doppler OCT Sensitivity
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Solution Overview
Problem
Current Doppler optical coherence tomography (D-OCT) systems face limitations in comprehensively mapping vascular networks in three dimensions with high speed and flow sensitivity, particularly in achieving rapid and sensitive imaging of microvasculature.
Innovation Solution
The implementation of segmented sawtooth beam scanning, which deviates from conventional ramp scanning, allows for parallelized acquisition of Doppler measurements across the transverse field of view, decoupling the Doppler integration window from the imaging frame rate and enhancing sensitivity without affecting speed, using a combination of galvanometric and acousto-optic deflecting arrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ramp beam scanning is used, then the imaging frame rate is maintained, but the Doppler sensitivity is limited
Solution Approach 1:
The beam scanning pattern is segmented into multiple sawtooth waveforms within a single frame, creating distinct scanning segments that allow parallel Doppler measurements. This segmentation enables the Doppler integration window to be optimized independently for each segment while maintaining the overall frame rate, thereby resolving the contradiction between sensitivity and speed.
Solution Approach 2:
The beam scanning velocity is made dynamic rather than constant, with the sawtooth pattern providing variable velocity profiles that optimize the Doppler integration window. The dynamic scanning allows the system to spend appropriate time at different positions to maximize sensitivity without compromising the overall imaging speed.
2Measurement precision
If the Doppler integration window is increased to improve sensitivity, then the phase noise background increases, but the imaging speed decreases
Solution Approach 1:
By dividing the frame into multiple scanning segments, the system can perform parallel Doppler measurements across segments. This allows the effective Doppler integration window to be increased through multi-segment accumulation without proportionally increasing the total imaging time, as measurements occur in parallel rather than sequentially.
Solution Approach 2:
The sawtooth scanning pattern ensures continuous useful measurement action across all segments of the frame, eliminating idle time and maximizing the utilization of the Doppler integration window throughout the entire imaging sequence, thereby improving sensitivity without sacrificing speed.
3Productivity
If rapid imaging is performed to maintain high frame rate, then the Doppler sensitivity is reduced
Solution Approach 1:
The scanning pattern is divided into multiple segments that can be processed independently and in parallel. This segmentation allows the system to maintain a high frame rate by quickly cycling through segments while still accumulating sufficient Doppler signal across all segments to achieve high sensitivity.
Solution Approach 2:
The invention adds a temporal dimension to the scanning pattern by introducing the sawtooth waveform structure, which creates multiple measurement opportunities within each frame. This transforms the single measurement per frame into multiple parallel measurements, effectively increasing sensitivity without reducing frame rate.
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 highly sensitive Doppler imaging over a large field of view at 24 frames per second, significantly improving the capability to image microvasculature in human skin, with adjustable Doppler sensitivity and maintained phase noise floor, thus advancing the utility of D-OCT systems.
Implementation Method 1
using a combination of galvanometric and acousto-optic deflecting arrangements
Implementation Method 2
using a combination of galvanometric and acousto-optic deflecting arrangements
Implementation Method 3
detection of phase shifts between sequential A-lines (e.g., depth scans) that may result from motion within the sample, e.g., blood flow
Data Source
AI summary
An exemplary apparatus and/or an exemplary method can be provided using which, it is possible (e.g., with at least one first arrangement) to measure an amplitude and/or a phase of at least one electromagnetic radiation provided from a particular portion of a sample. Further, it is possible (e.g., using at least one second arrangement) to scan a location of the particular portion along a path from a first point of the sample to a second point of the sample. In addition, it is possible to control the scan (e.g., with the second arrangement) such that the scan may comprise at least one first segment having a positive velocity and at least one segment having a negative velocity. A first distance of the first segment and/or the second segment can be smaller than a second distance between the first and second points.