Low Cost Fundus Imager with Integrated Pupil Camera
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Solution Overview
Problem
Current fundus imagers are costly and complex, with limitations in field of view due to reflection artifacts from the cornea and system lenses, and require multiple components and alignment procedures.
Innovation Solution
A low-cost fundus imager design using LEDs as light sources positioned near the camera's imaging stop, with pupil splitting and reflective optics to reduce reflections, and a self-alignment mechanism allowing patients to adjust the camera for proper alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional flood illumination fundus imager design is used, then image quality can be maintained, but cost and device complexity increase significantly
Solution Approach 1:
The patent combines the illumination function and imaging function into a single integrated device. The fundus imager incorporates both the light source (LED) and the camera sensor in one unit, eliminating the need for separate illumination and imaging systems. This merging reduces overall device complexity and manufacturing cost while maintaining the capability to illuminate the fundus and capture images simultaneously.
Solution Approach 2:
The fundus imager is designed to perform multiple functions: illumination of the fundus, capture of fundus images, and provision of alignment information. The single device integrates what would traditionally require separate illumination systems and imaging systems, making it a universal instrument that handles both illumination and detection tasks.
2Area of stationary object
If field of view is expanded, then more fundus area is visible, but reflection artifacts from cornea and system lenses increase
Solution Approach 1:
The patent extracts and removes the harmful reflection artifacts from the captured images through image processing techniques. By identifying and eliminating these artifacts post-capture, the system can maintain a larger field of view without the degradation caused by corneal and lens reflections that would otherwise limit the usable imaging area.
Solution Approach 2:
The patent converts the alignment information that can be derived from reflection artifacts into a useful feature. The system uses these reflections to provide alignment guidance to the user, transforming what would normally be considered noise or interference into a functional element that aids in proper device positioning and operation.
3Measurement precision
If multiple components are used for precise alignment, then alignment accuracy improves, but device complexity and cost increase
Solution Approach 1:
The fundus imager provides self-alignment capability through integrated alignment information display. The device automatically captures and processes alignment data, presenting it to the user in a way that guides proper positioning without requiring external alignment instruments or complex manual adjustment procedures. The system serves its own alignment needs through built-in sensors and processing.
Solution Approach 2:
The patent implements feedback mechanisms where the captured alignment information is processed and displayed to guide the user in achieving proper alignment. The system continuously monitors alignment status and provides real-time feedback, allowing iterative adjustment until optimal alignment is achieved, thereby simplifying the overall alignment process while maintaining precision.
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 design achieves a larger field of view with reduced reflection artifacts and costs, eliminating the need for complex alignment procedures and multiple components, while maintaining image quality.
Implementation Method 1
a curved reflector positioned behind the detector on an optical axis of the detector to provide a patient-viewable image of the eye to the same eye being imaged
Implementation Method 2
at least a first and second light source placed proximate the detector's aperture such that both the detector and light sources share a similar optical path toward/from the eye
Implementation Method 3
Scattered light returning from the fundus may exit through the crystalline lens 31, pupil 29, and cornea 27, and travel along optical axis 25 to a viewing axis 35
Data Source
AI summary
A low cost fundus camera uses LED light sources placed adjacent the camera's imaging stop, and thereby eliminates the need for optics for introducing the light source to the camera's optical path. Lens reflex in the pupil relay is avoided by using only reflective optics in the pupil relay. Reflex from the LED is mitigated by actuating each LED separately, one at a time, and capturing a separate image with each actuated LED. Reflex-free regions of each captured image are extracted and combined to create a composite reflex-free image.