Wide Field Fundus Camera With Multi-Beam Haze Reduction
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Solution Overview
Problem
Conventional retinal cameras have limited field of view and struggle with image haze due to less transparent crystalline lenses, particularly in adults, and lack fast auto focus, making them inefficient for wide field retinal imaging.
Innovation Solution
A wide field fundus camera with multiple illumination beam projectors and a consumer image recording device, utilizing auto focus and exposure, captures multiple retinal images at various angles, and processes them into a single composite image while minimizing lens reflections through cross polarization and angled beam projections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If an illumination ring is used to provide uniform illumination over a wide field of view, then the field of view is expanded to 120 degrees, but image haze appears due to Purkinje reflection images from crystalline lens surfaces
Solution Approach 1:
The illumination ring is divided into multiple independently controllable illumination zones or segments. Each segment can be activated selectively to illuminate specific regions of the retina, allowing the system to capture wide field images while minimizing overlapping illumination paths that cause haze through the crystalline lens.
Solution Approach 2:
Different regions of the illumination ring provide different illumination characteristics optimized for their specific viewing angles. The illumination intensity and angular distribution are locally adjusted to reduce Purkinje reflections in critical areas while maintaining wide field coverage, addressing the haze problem without sacrificing field of view.
2Area of stationary object
If multiple illumination beam projectors are used to capture wide field retinal images, then the field of view is expanded and imaging through less transparent lenses is improved, but the device complexity increases
Solution Approach 1:
Multiple illumination beam projectors are integrated into a single handheld fundus camera unit, combining their functions into one cohesive device. This merging approach achieves wide field imaging capability while consolidating the complex components into a manageable portable system rather than requiring multiple separate devices.
Solution Approach 2:
The multiple illumination beam projectors are designed to perform multiple functions: they provide wide field illumination, enable imaging through less transparent crystalline lenses by using angled beam paths, and can be controlled to reduce Purkinje reflections. This multi-functionality justifies the increased device complexity by delivering multiple benefits from a single integrated system.
3Device complexity
If conventional retinal cameras are used, then the optical system is simple, but the auto focus speed is slow and the device lacks fast response
Solution Approach 1:
The fundus camera incorporates an autofocus mechanism that automatically adjusts focus without requiring manual intervention from the operator. The system uses image processing algorithms to detect retinal features and automatically adjusts lens positioning to achieve sharp focus, enabling fast response while maintaining relatively simple optical components.
Solution Approach 2:
The patent replaces complex mechanical focusing mechanisms with a more streamlined optical system combined with digital image processing. By using software-based autofocus algorithms that analyze captured images in real-time, the system achieves fast focus adjustment without requiring complex mechanical lens adjustment mechanisms, thereby improving speed while keeping the optical 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 quick and reliable wide field retinal imaging with reduced haze and improved auto focus, suitable for both infants and adults, facilitating early detection of retinal diseases.
Implementation Method 1
an aspherical lens having a symmetric viewing axis and disposed to form a retinal image
Implementation Method 2
cross polarization optics incorporated between said first and second sources of illumination beams and said image recording device to reject specular reflections of said illumination beams
Implementation Method 3
Image haze may appear due to lens scattering inside a less transparent crystalline lens wherever the illumination beam path overlaps with imaging beam path
Data Source
AI summary
A wide field fundus camera is disclosed to implement multiple illumination beam projectors and to capture multiple retinal images at a various viewing angles to mimic wide field retinal examination with an indirect ophthalmoscope. The wide field fundus camera may incorporate a consumer image recording device with fast auto focusing so as to make the device quick to respond and easy to use. The wide field fundus camera may include narrow and broad slit beam illuminations to enhance autofocusing and imaging through less transparent crystalline lens and through haze due to Purkinje reflections from crystalline lens surfaces. Control of multiple illumination beam projectors in a programmable manner can be used to assess alignment of each illumination beam projector with the eye and to capture said multiple retinal images. Furthermore, a method is disclosed to montage said multiple retinal images into a single montage and to remove haze and reflections.