Fundus Line-Scan Tracking Using Sub-Frame Motion Calculation
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Solution Overview
Problem
Existing line scan ophthalmoscope (LSO) imaging systems suffer from time delays in target tracking due to frame-based calculations, leading to decreased precision and reliability in fundus motion estimation, particularly in digital signal processing without optical closed-loop control.
Innovation Solution
Implementing a closed-loop optical tracking system with a second steering mirror and frequency multiplication technology to divide frames into sub-frame elements, using a cross-correlation algorithm and GPU processing for real-time fundus motion calculation, reducing time delays and improving spatial precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frame-based calculation is used to calculate fundus target motion amount, then the control system can process complete image data, but the time delay increases by at least one frame
Solution Approach 1:
The patent divides each complete frame into multiple sub-frames based on the scanning line sequence. By processing sub-frames individually and in temporal order, the system can calculate motion amounts more frequently without waiting for complete frame acquisition, thereby reducing time delay while maintaining measurement precision through cumulative sub-frame processing.
Solution Approach 2:
The patent performs preliminary processing of scan line data as it becomes available during the scanning process, rather than waiting for the complete frame to be acquired. This preliminary action enables earlier motion calculation and reduces the time delay between motion occurrence and control response.
2Productivity
If completely digital signal extraction is used in LSO system, then the system can process image data, but the calculation reliability decreases due to lack of optical closed-loop control
Solution Approach 1:
The patent introduces optical closed-loop control by using the calculated motion amounts to adjust the scanning mirror in real-time. This feedback mechanism ensures that the system not only processes image data but also actively compensates for detected motions, thereby improving the reliability of fundus motion signal calculation while maintaining high processing capability.
Solution Approach 2:
The patent combines digital signal processing with optical mechanical adjustment. Instead of relying solely on digital processing, the system uses optical closed-loop control through scanning mirror adjustment to physically compensate for fundus motions, thereby enhancing the reliability of motion signal calculation.
3Measurement precision
If frequency multiplication technology is applied to divide frames into sub-frame elements, then the spatial precision and time bandwidth of target tracking improve, but the device complexity increases
Solution Approach 1:
The patent segments the frame into sub-frames based on scanning line sequences, which is a logical division that can be implemented through software processing. This segmentation approach improves spatial precision and time bandwidth without requiring complex hardware modifications, as the segmentation is achieved through data processing rather than physical system complexity.
Data Source
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AI summary
Disclosed is a method for calculating the fundus oculi target motion amount of a line scan imaging system, comprising: A. using a line scan fundus oculi camera to obtain a fundus oculi image, and dividing, according to chronological order, each frame image of a reference frame and a target frame into a plurality of equally spaced sub-frame elements according to data reached by the scanning camera; B. using a calculation processing unit to receive the latest sub-frame metadata, and starting a preset algorithm to calculate the position of the current sub-frame element relative to said reference frame, or locate the relative positions of the sub-frame element of the target frame and the sub-frame element of the reference frame; C. using frequency multiplication technology, setting a scan signal and a frame synchronization signal to synchronously trigger the line scan camera to obtain the sub-frame image synchronized with the scan signal; according to the sequence of arrival of each sub-frame element to a host system, calculating in real time the fundus oculi movement information contained in each sub-frame element. Using the present invention, it is possible to effectively improve the instantaneity and precision of target tracking, thereby further improving imaging efficiency.