Fundus Imaging Polarization Control
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Solution Overview
Problem
Current fundus imaging technologies using randomly polarized or linearly polarized light struggle to provide high-quality images of the eye's structures, particularly for diagnosing glaucoma and other retinal conditions, as they fail to effectively visualize and differentiate polarized light from various eye structures.
Innovation Solution
A device and method utilizing non-linearly polarized light, including circularly and elliptically polarized light, are employed to improve imaging quality by using a quarter wave plate and linear polarizer to generate desired polarization states, which are directed onto the eye and collected with minimal polarization loss, enhancing visualization of retinal structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linearly polarized light is used for fundus imaging, then the imaging system is simple to operate, but the image quality and visualization of retinal structures is insufficient
Solution Approach 1:
The patent employs dynamic polarization control by rotating a quarter-wave plate to convert linearly polarized light into circularly or elliptically polarized light. This dynamic adjustment allows the system to optimize polarization states for different imaging conditions and retinal structures, thereby improving image quality without requiring a completely complex static polarization system.
Solution Approach 2:
The invention changes the polarization parameter of the illuminating light from linear to circular/elliptical polarization by introducing a quarter-wave plate. This parameter change enhances the differentiation of polarized light from various eye structures, improving the measurement precision and visualization of retinal features while maintaining operational simplicity through automated control.
2Measurement precision
If circularly polarized light is used for fundus imaging, then the visualization of retinal structures is significantly improved, but the device complexity increases due to additional optical elements
Solution Approach 1:
The patent introduces a quarter-wave plate as an intermediary optical element between the light source and the eye. This intermediary component efficiently converts linearly polarized light into circularly or elliptically polarized light, achieving superior visualization of retinal structures. The intermediary approach allows for improved measurement precision without requiring complete redesign of the entire optical system.
Solution Approach 2:
The polarization control system is designed to be multi-functional, capable of generating both circularly and elliptically polarized light depending on the imaging requirements. The same optical elements (linear polarizer and quarter-wave plate) serve multiple purposes: creating different polarization states, adapting to various retinal structures, and maintaining operational flexibility, thereby reducing overall device complexity.
3Measurement precision
If multiple linear polarization states are used for imaging, then some image improvement is achieved, but the signal-to-noise ratio and acutance are still insufficient for accurate diagnosis
Solution Approach 1:
The patent employs periodic rotation of the quarter-wave plate to systematically vary the polarization state of the illuminating light. This periodic action allows the system to capture images at multiple polarization phases, improving the signal-to-noise ratio through temporal averaging and enhancing the acutance of retinal structures. The periodic modulation approach achieves superior diagnostic quality without requiring simultaneous management of multiple complex polarization channels.
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
This approach results in improved visualization and diagnosis of optic nerve head and retinal structures, including blood vessels, by producing higher quality images with better signal-to-noise ratio, acutance, and entropy, effectively addressing the limitations of existing imaging systems.
Implementation Method 1
an optical element configured to generate a desired non-linear polarization state of light in said beam of light passing therethrough, wherein said desired non-linear polarization state of light includes any one of circularly polarized light alone and elliptically polarized light alone
Implementation Method 2
Light coming from structures in fundus images is differentially polarised, leading to clinical applications such as assessment of glaucoma and foveal fixation
Data Source
AI summary
The present invention provides a method and device to image the fundus of the eye using polarized light which includes circular polarization. The invention is most broadly comprised of a device to generate polarization states of light, including circularly polarized light (i.e. potentially combinations of elliptically polarized light and depolarized light combined, elliptically polarized light alone, or circularly polarized light with depolarized light or circularly polarized light alone). This light can be used with any fundus imaging device including but not limited to fundus cameras, scanning laser ophthalmoscopes, confocal scanning laser ophthalmoscopes, optical coherence tomography instruments, with or without some form of wavefront correction. This is a change from common fundus imaging systems which use randomly polarized light or linearly polarized light. The simplest implementation of this is a quarter wave plate (or equivalent retarder) combined with a linear polarizer located after the light source and before the eye. The QWP can be rotated to produce differing circular and elliptical polarizations of light which are ideal for imaging differing structures at the rear of the eye for different people.