Retinal Imager Through-the-Lens Illumination
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Solution Overview
Problem
Conventional retinal imaging systems face challenges with sensitivity to scattering from the eye lens and cornea, limited size and weight, visible ghost images, low resolution, and difficulty in achieving wide-field imaging, especially in pediatric and adult patients with darkly pigmented retinas or aging eyes.
Innovation Solution
A retinal imager with a through-the-lens illumination system that minimizes glare and scatter, utilizing a single objective lens and a field lens to achieve high contrast and resolution, and integrates image-guided OCT for real-time scanning, allowing for hand-held or table-top operation and wide-field imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional illumination systems are used, then the system structure is simple, but visible ghost images and glare appear in the images
Solution Approach 1:
A beamsplitter is introduced as an intermediary optical element to separate the illumination light path from the imaging light path. The beamsplitter directs illumination light toward the retina while allowing reflected imaging light to reach the camera sensor, preventing direct reflection of illumination light into the camera and eliminating ghost images and glare.
Solution Approach 2:
The optical system is segmented into distinct illumination and imaging pathways. The illumination pathway uses a LED source and beamsplitter to deliver light to the retina, while the imaging pathway uses a separate camera sensor to capture reflected light, preventing interference between the two functions.
2Area of stationary object
If the field of view is increased to achieve wide-field imaging, then more retinal area is captured, but image resolution and contrast decrease
Solution Approach 1:
The system uses a adjustable aperture to control the cone angle of illumination light. By optimizing the aperture size and position, the system achieves uniform illumination across a wide field of view (up to 100 degrees) while maintaining sufficient light intensity for high-resolution imaging of the entire retinal surface.
3Illumination intensity
If illumination intensity is increased to improve image quality, then scattering from the eye lens and cornea increases, but if illumination intensity is reduced, then image brightness decreases
Solution Approach 1:
The beamsplitter acts as an intermediary that enables efficient light delivery to the retina while preventing scattered light from the cornea and lens from entering the camera. This allows use of higher illumination intensity for better image quality without the penalty of scattered light degrading the image.
Solution Approach 2:
The system provides localized high-intensity illumination precisely where needed on the retinal surface through controlled light delivery, while the beamsplitter configuration ensures that scattered light from anterior ocular structures (cornea and lens) is directed away from the imaging path, maintaining local image quality.
4Weight of moving object
If a hand-held design is used to improve patient comfort and accessibility, then the device size and weight are reduced, but the complexity of integrating multiple functions increases
Solution Approach 1:
The system merges multiple functions (illumination, imaging, and OCT) into a single hand-held device. The common optical path through the objective lens and beamsplitter allows all three functions to share the same physical platform, achieving compact integration without excessive complexity.
Solution Approach 2:
The objective lens and beamsplitter serve multiple functions simultaneously: they are used for both wide-field imaging and OCT scanning, and the same optical path accommodates both functions. This multi-functionality reduces the number of separate components needed, keeping the hand-held device compact and manageable.
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 system provides high-contrast, high-resolution images with reduced glare and scatter, enabling wide-field imaging of both pediatric and adult patients, including those with darkly pigmented retinas, and offers real-time OCT guidance for precise pathology detection.
Implementation Method 1
an illumination source operable to generate illumination light
Implementation Method 2
a beam splitter operable to receive the illumination light and direct the illumination light along an optical axis
Implementation Method 3
an objective lens disposed along the optical axis and operable to contact a cornea of the eye
Implementation Method 4
a curved aspheric field lens that is free of spherical aberration and coma
Implementation Method 5
reflecting illumination light off of the retina to provide a return signal
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A retinal imager (1000) for imaging a retina of an eye (1010) includes an illumination source (1020) operable to generate illumination light and a beam splitter (520) operable to receive the illumination light and direct the illumination light along an optical axis. The retinal imager also includes a field lens (512, 1120) disposed along the optical axis and an objective lens (510) disposed along the optical axis and operable to contact a cornea of the eye. An aerial image is formed adjacent to the field lens (512, 1120). The retinal imager further includes an image sensor (562) and one or more lenses (540) disposed along the optical axis between the beam splitter (520) and the image sensor (562). The one or more lenses (540) are operable to form a sensor image at the image sensor (562).