Online Wavefront Measurement Algorithm for Real-Time Aberrometry
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Solution Overview
Problem
Current ocular wavefront measurement technologies, such as Hartmann-Shack sensors, are limited by slow centroid detection rates, requiring offline processing and inability to display aberration measurements simultaneously with wavefront measurement, making real-time analysis and evaluation of dynamic eye systems challenging.
Innovation Solution
A fast centroid detection algorithm that compresses images, performs background subtraction, and iteratively refines centroid detection, allowing for simultaneous measurement, analysis, and display of wavefront information at rates up to 25 Hz using an efficient sorting process and Zernike coefficient calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional centroid detection methods are used, then measurement accuracy is maintained, but processing speed is too slow for real-time analysis
Solution Approach 1:
The patent segments the wavefront image into multiple regions of interest (ROIs) and processes each region independently with optimized algorithms. This segmentation allows parallel processing of different image portions, significantly increasing the overall centroid detection rate while maintaining accuracy through region-specific optimization
Solution Approach 2:
The patent dynamically adjusts processing parameters such as threshold values, search window sizes, and algorithm complexity based on image characteristics and desired processing speed. By changing parameters adaptively, the system achieves real-time processing rates while preserving measurement precision through context-appropriate parameter selection
2Loss of time
If wavefront images are recorded and saved for subsequent evaluation, then complete data is preserved, but memory requirements and processing time increase
Solution Approach 1:
The patent extracts only the essential wavefront parameters (centroid positions, Zernike coefficients) directly from the images during acquisition, rather than storing complete high-resolution images. This extraction approach reduces memory requirements by factors of 100 or more while enabling immediate online display and analysis of aberration measurements
Solution Approach 2:
The patent performs preliminary processing and parameter extraction at the time of image acquisition, preparing data for immediate display without requiring subsequent offline evaluation. This preliminary action eliminates the time delay between measurement and analysis while reducing storage needs by maintaining only processed parameters
3Productivity
If multiple wavefront images are processed sequentially, then accurate analysis is possible, but real-time display of aberration measurements cannot be achieved
Solution Approach 1:
The patent implements continuous processing where each incoming wavefront image is immediately analyzed and displayed without waiting for batch processing or sequential evaluation. This continuous action maintains a steady stream of real-time aberration measurements at high repetition rates, enabling dynamic visualization of eye wavefront changes
Solution Approach 2:
The patent employs dynamic processing where the system adapts its processing depth and display updates based on real-time requirements. Fast algorithms provide immediate feedback at high repetition rates, with optional deeper analysis performed selectively, enabling real-time display while maintaining measurement accuracy when needed
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 real-time, online analysis and display of wavefront information, reducing processing time to approximately 13 ms per image and increasing measurement rates, while significantly reducing memory requirements for data storage.
Implementation Method 1
A Hartmann-Shack wavefront sensor typically includes a microlens array that images various portions of a distorted wavefront exiting the eye onto a CCD detector/camera
Implementation Method 2
A further embodiment of the present invention is directed to an image compression algorithm that reduces a wavefront image to a minimal data set while preserving all wavefront information
Data Source
AI summary
A fast algorithm is presented which allows for substantially simultaneous acquisition, analysis, and display of a wavefront centroid image, referred to as online aberrometry. A method embodiment involves determination of an average, or most frequently occurring, wavefront aberration over a selected time interval, e.g., 20 sec. Online pupil diameter measurement allows analysis of wavefront aberration as a function of changing pupil size. A wavefront measuring apparatus is disclosed that supports online aberrometry.