Ophthalmic Alignment Using Spectral Reflection From Eye Surfaces
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Solution Overview
Problem
Capturing sharp and reflection-free images from the retina of a patient's eye is challenging due to patient movement, eye refractive errors, and eye accommodation, which quickly change alignment and focus, making it difficult to achieve high-quality fundus imaging.
Innovation Solution
An ophthalmic apparatus uses a projection unit to project a spectrally spread light spot on the eye's frontal part, analyzing the spectral reflection to determine the axial position of the cornea and crystalline lens surfaces, employing a spectrograph and data processing to align the apparatus optimally with the eye.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional fundus imaging methods are used, then the apparatus structure is simple, but image quality deteriorates due to patient movement, refractive errors, and accommodation changes
Solution Approach 1:
The imaging system is divided into multiple independent modules: a projection unit that projects test patterns, a separate detection unit that captures reflected light, and a computing unit that processes alignment data. This segmentation allows each module to be optimized independently, improving overall image quality while managing system complexity through modular design
Solution Approach 2:
The system performs preliminary alignment measurements using spectral reflection analysis before actual fundus imaging. By determining the axial position of corneal and lens surfaces in advance, the system pre-adjusts optical parameters to compensate for refractive errors and accommodation, ensuring optimal image quality from the start
2Measurement precision
If spectral reflection analysis is performed to determine axial position, then alignment precision is improved, but measurement complexity increases
Solution Approach 1:
The system introduces spectral reflection analysis as an intermediary measurement process between the illumination source and the final image capture. By analyzing the spectral characteristics of reflected light from known test patterns, the system derives axial position information without requiring direct contact or complex positioning mechanisms, thus improving alignment precision while adding manageable complexity
Solution Approach 2:
The invention replaces mechanical alignment adjustment mechanisms with optical-spectral measurement and computational analysis. Instead of physically moving components to achieve alignment, the system uses spectral reflection analysis to determine axial positions and computationally adjusts imaging parameters, reducing mechanical complexity while enhancing measurement precision
3Stability of the object's composition
If real-time alignment adjustment is implemented, then image stability is improved, but processing time increases
Solution Approach 1:
The system performs alignment measurements and computations in advance before actual image capture. By determining axial positions and calculating necessary adjustments beforehand, the system minimizes real-time processing requirements, maintaining image stability without significant time loss during the critical imaging phase
Solution Approach 2:
The alignment system uses the patient's own eye structures (cornea, lens surfaces) as reference targets for measurement. By analyzing spectral reflections from these naturally present features, the system performs self-alignment without requiring external references or repeated manual adjustments, improving stability while reducing processing time
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 method enables precise alignment and capture of high-quality images by accurately determining the axial position of eye surfaces, improving image clarity and stability during ophthalmic examinations.
Implementation Method 1
project a spectrally spread light spot on the eye's frontal part
Implementation Method 2
analyzing the spectral reflection to determine the axial position of the cornea and crystalline lens surfaces
Implementation Method 3
employing a spectrograph and data processing to align the apparatus optimally with the eye
Data Source
AI summary
An ophthalmic apparatus comprises an illumination channel for illuminating a retina of an eye in response to a distance between the ophthalmic apparatus and the eye being within a working range of the ophthalmic apparatus. An imaging channel collects light reflected from the retina. An image capturing arrangement captures images of the retina through the imaging channel while the distance between the ophthalmic apparatus and the eye is within a working range of the ophthalmic apparatus. A chromatic arrangement causes and/or imitates a longitudinal chromatic aberration of light directed toward an eye while a longitudinal aberration range is at least partially overlapping with a frontal section of an eye between an outer surface of a cornea and a rear surface of a crystalline lens in response to a distance between the ophthalmic apparatus and the eye being within a working range. A collection optics collects light reflected from the frontal section of the eye. An optical spectrum analyzer outputs signals, a single signal of the signals carrying information on intensity of a single wavelength band of the different wavelength bands. A data processing unit measures intensities carried by the signals and determines a distance and/or a need for adjustment of the distance between the ophthalmic apparatus and the eye based on peak(s) of the signals, the peaks being caused by reflections from at least one surface of the eye.