Eye Pupil Alignment Control Using Focus Analysis in Ophthalmic Imaging
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Solution Overview
Problem
Existing ophthalmological imaging devices face challenges in maintaining the alignment of the eye's pupil with the imaging system due to involuntary movements, leading to deficiencies in image formation, and existing alignment systems are either bulky or complex.
Innovation Solution
A method and system that utilize an imaging optical element to form images of elements in the pupil plane on an inclined detection plane, analyzing focus variation to determine lateral and axial positions of the pupil relative to the imaging system's reference frame, allowing for robust and automatic alignment without additional optical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If alignment sources and cameras are added to achieve automatic lateral and axial centering, then alignment precision is improved, but device complexity increases
Solution Approach 1:
The imaging system performs multiple functions: it captures fundus images for diagnosis and simultaneously captures images of the retinal perimeter for alignment assessment. This eliminates the need for separate alignment cameras and sources, as the imaging system itself provides all necessary imaging capabilities for both diagnostic and alignment purposes.
Solution Approach 2:
The patent combines the alignment assessment function with the fundus imaging function by using the same imaging system to capture both the fundus image and the retinal perimeter image. This merging of functions reduces device complexity while maintaining alignment precision through the use of the imaging system's inherent capabilities.
2Measurement precision
If collimators are added to project alignment targets to infinite distance, then axial alignment control is improved, but device bulk increases
Solution Approach 1:
The imaging system is designed to capture images at different focal distances without requiring separate collimators. The same imaging system that captures fundus images can also capture images of the retinal perimeter, providing axial alignment control information through the inherent focal properties of the imaging system.
Solution Approach 2:
The patent extracts the alignment control information from the imaging process itself by analyzing the retinal perimeter image captured during normal fundus imaging. This eliminates the need for separate collimator components, as the alignment information is derived directly from the imaging data without additional optical elements.
3Device complexity
If manual axial centering is used to simplify the system, then device complexity is reduced, but alignment precision deteriorates
Solution Approach 1:
The system provides automatic feedback by capturing the retinal perimeter image and processing it to determine the degree of axial misalignment. This feedback mechanism enables automatic axial centering control, eliminating the need for manual adjustment while maintaining high alignment precision through real-time assessment and correction.
Solution Approach 2:
The imaging system performs self-alignment assessment by automatically capturing and analyzing the retinal perimeter image to determine axial misalignment. This self-service capability allows the system to autonomously evaluate and correct alignment issues without requiring manual intervention, thereby maintaining high precision while keeping the system relatively simple.
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 precise and automatic alignment of the pupil within the imaging system, improving image quality by maintaining the pupil's center in superposition with the imaging system's reference frame despite eye movements, without increasing complexity or bulk.
Implementation Method 1
alignment sources are imaged in reflection from the corneal dioptric interface of the eye
Implementation Method 2
formation, on a two-dimensional detection plane, of at least one image of at least one element located in a plane of the pupil of the eye, by means of an imaging optical element
Data Source
AI summary
A method for controlling alignment of an eye in an ophthalmological imaging device that includes a formation, on a two-dimensional detection plane, of an image of an element located in a plane of the pupil of the eye using an imaging optical element. The method further includes a determination of a lateral position of the pupil of the eye with respect to a point of origin of a reference frame of an imaging system in the eye space based on the position of the image in the detection plane. The method further includes an analysis of a state of focus of the image in two regions of the detection plane. The method further includes a determination of an axial position of the pupil of the eye with respect to the point of origin of the reference frame based on the analysis of the state of focus.