Free-Form Scan Transfer Element Aberration Correction in Ophthalmoscopes
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Solution Overview
Problem
Ophthalmoscopes, particularly wide-field and ultra-wide-field models, suffer from aberrations introduced by scan elements and transfer elements, leading to defocusing of light and compromised signal-to-noise ratios due to systematic aberrations, resulting in loss of fundus return light and impaired confocal detection.
Innovation Solution
Incorporating a free-form scan transfer element with defined curvature in orthogonal axes, which corrects aberrations in both incident and return light, ensuring uniform divergence and collimation, and utilizing a customized slit aperture to enhance confocal detection by filtering out non-fundus light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If standard scan elements and scan transfer elements are used in wide-field ophthalmoscopes, then the field of view is expanded, but aberrations are introduced causing defocusing and signal loss
Solution Approach 1:
The patent applies local quality by implementing aberration correction specific to different regions of the scan field. The system measures and corrects aberrations at multiple field locations, applying location-specific correction parameters to maintain focus precision across the entire wide field of view rather than using a uniform correction approach
Solution Approach 2:
The patent changes optical parameters dynamically by measuring aberrations at different scan angles and field positions, then adjusting correction parameters accordingly. The system varies correction magnitudes and signs based on the specific aberration characteristics at each field location, enabling maintained focus precision across the expanded field of view
2Device complexity
If standard confocal aperture is used with aberrated light, then the system structure is simple, but fundus return light is lost and signal-to-noise ratio is compromised
Solution Approach 1:
The patent applies preliminary action by correcting aberrations in the incident light path before the light reaches the fundus. By pre-correcting the outgoing wavefront using measured aberration data, the system ensures that light returns from the fundus with minimal aberration, allowing effective confocal detection without requiring complex adaptive correction in the return path
Solution Approach 2:
The patent implements feedback by measuring aberrations at multiple field locations and using this measurement data to adjust correction parameters. The system continuously monitors and adjusts the aberration correction based on actual measured values, creating a closed-loop control system that optimizes focus precision and signal quality
3Productivity
If aberration correction is not applied, then the system is simpler and faster, but systematic aberrations cause defocussing that varies with light position on the fundus
Solution Approach 1:
The patent applies preliminary action by pre-measuring and storing aberration correction parameters for multiple field locations before the actual scanning begins. During scanning, the system simply retrieves and applies the pre-calculated correction parameters based on the current field position, avoiding real-time computation delays while maintaining focus precision
Solution Approach 2:
The patent applies dynamics by implementing adaptive aberration correction that adjusts correction parameters dynamically based on the scan angle and field position. The system modifies correction magnitudes and signs according to the specific aberration characteristics at each location, enabling precise focus maintenance across the entire field of view during active scanning
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
The solution improves aberration correction, leading to enhanced collimation and detection of fundus return light, reducing light loss and improving signal quality by effectively filtering out light from other eye structures.
Implementation Method 1
a free-form scan transfer element with defined curvature in orthogonal axes, which corrects aberrations in both incident and return light
Implementation Method 2
ensuring uniform divergence and collimation
Implementation Method 3
utilizing a customized slit aperture to enhance confocal detection by filtering out non-fundus light sources
Data Source
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AI summary
An ophthalmoscope (10) comprising a light source (12), a first scanner (14), a first scan transfer element (16), a second scanner (18), and a second scan transfer element (20), which provide a two-dimensional scan of incident light from an apparent point source at a pupillary point of an eye (22) onto the fundus of the eye, and which descan a two- dimensional scan of return light from the fundus of the eye to provide return light from an apparent point source at the first scanner,wherein the first scan transfer element comprises a free-form element which has a shape defined to provide aberration correction of the return light from the fundus of the eye.