Stereo Pupil Alignment in Ultra-Widefield Fundus Imaging
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Solution Overview
Problem
Ophthalmic imaging scanners face challenges in accommodating stereo imaging apparatus within mirror-based widefield or ultra-widefield systems due to complex optical elements that cause spurious reflections and imaging artifacts, making direct visual pathways difficult.
Innovation Solution
An ultra-widefield ophthalmic imaging instrument with a rotatable mirror and ellipsoidal mirror system that includes a stereo imaging apparatus to acquire stereo images of the pupil, using a processor to generate alignment signals and control the instrument for optimal image acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional optical elements are used to guide light from the eye to the stereo cameras within WF/UWF optics, then the stereo imaging capability is improved, but the system complexity increases and spurious reflections occur
Solution Approach 1:
The patent extracts the stereo imaging function from the main WF/UWF optical path by using a separate, dedicated stereo camera system that does not require additional optical elements within the mirror-based optics. The stereo cameras are positioned to directly view the eye through openings in the optical path, eliminating the need for complex light-guiding elements that would cause spurious reflections.
Solution Approach 2:
The optical system is segmented into separate functional paths: the main beam path for fundus imaging through the rotatable and ellipsoidal mirrors, and a separate stereo imaging path using dedicated cameras with direct visual pathways. This segmentation allows each subsystem to be optimized independently without interfering with the other.
2Adaptability or versatility
If additional optical elements are used to guide light from the eye to the stereo cameras, then the stereo imaging capability is improved, but imaging artifacts are generated
Solution Approach 1:
The stereo imaging function is extracted from the main optical path, allowing the stereo cameras to capture images directly without light passing through the WF/UWF optical elements. This eliminates spurious reflections from mirrors and optical surfaces that would otherwise create artifacts in the stereo images.
3Device complexity
If a direct visual pathway is used for stereo cameras, then the system complexity is reduced, but the alignment precision deteriorates in mirror-based systems
Solution Approach 1:
The patent introduces the rotatable mirror as an intermediary element that can be positioned in a specific orientation to reflect light from the eye to the stereo cameras. This allows the stereo cameras to have a direct visual pathway while maintaining precise alignment through the controlled positioning of the mirror, which acts as a mediator between the eye and the imaging system.
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 effective pupil alignment and acquisition of high-quality ultra-widefield fundus images by minimizing optical complexity and reducing artifacts, ensuring accurate stereo imaging within mirror-based systems.
Implementation Method 1
a rotatable mirror arranged to scan the beam of light across the fundus
Implementation Method 2
an ellipsoidal mirror via which the rotatable mirror is arranged to scan the beam of light across the fundus, the ellipsoidal mirror having a first focal point and a second focal point
Implementation Method 3
a stereo imaging apparatus arranged to acquire stereo images of the pupil via the rotatable mirror and the ellipsoidal mirror
Data Source
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AI summary
An ultra-widefield ophthalmic imaging scanner comprising: a rotatable mirror which scans a light beam across an ocular fundus via an ellipsoidal mirror having the rotatable mirror at a first focal point thereof and a pupil of an eye at a second focal point thereof; a stereo imaging apparatus which acquires stereo images of the pupil via the rotatable mirror and the ellipsoidal mirror; and a processor which controls the stereo imaging apparatus to acquire the stereo images via the rotatable mirror and the ellipsoidal mirror while the rotatable mirror remains in a predetermined orientation, and processes the stereo images to generate a signal for aligning the pupil with an imaging position for acquiring an ultra-widefield image of the fundus. The processor then controls the imaging scanner to acquire the ultra-widefield image by rotating the rotatable mirror to scan the beam across the fundus via the ellipsoidal mirror.