Ophthalmic Gaze Fixation Optics for Artifact-Free UWF Imaging
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Solution Overview
Problem
Ophthalmic imaging scanners face challenges in incorporating a fixation target light source without increasing system complexity and dealing with spurious reflections, which can affect image quality, particularly in widefield and ultra-widefield imaging.
Innovation Solution
An ultra-widefield ophthalmic imaging instrument with a rotatable mirror and ellipsoidal mirror system, where the fixation target light source projects light onto the fundus via the rotatable and ellipsoidal mirrors, and a processor controls the system to fix the gaze direction during imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional optical elements are added to guide fixation light in WF/UWF scanners, then the fixation target can be projected onto the fundus, but the system complexity increases and spurious reflections occur
Solution Approach 1:
The ellipsoidal mirror is designed to perform multiple functions: it serves as a scanning element for the imaging beam and simultaneously acts as a reflection surface for the fixation target light. This multi-functionality eliminates the need for separate optical elements dedicated to fixation light guidance, thereby reducing system complexity while maintaining reliable fixation target projection onto the fundus.
Solution Approach 2:
The patent merges the fixation light path with the existing scanning optics by utilizing the ellipsoidal mirror for both imaging beam scanning and fixation light reflection. This consolidation of functions into a single optical component reduces the total number of elements and minimizes the risk of spurious reflections from additional interfaces.
2Reliability
If additional optical elements are added to guide fixation light, then the fixation target can be projected onto the fundus, but spurious reflections occur causing image artifacts
Solution Approach 1:
By making the ellipsoidal mirror serve dual purposes (imaging beam scanning and fixation light reflection), the patent eliminates additional optical interfaces that would generate spurious reflections. The single-use-of-multiple-functions approach ensures fixation target projection reliability while avoiding harmful artifacts.
3Reliability
If the rotatable mirror is made stationary for fixation, then gaze direction can be fixed, but the fundus imaging requires the mirror to scan
Solution Approach 1:
The rotatable mirror is designed to be dynamically controllable, switching between a stationary position during fixation mode to maintain stable gaze direction and a scanning position during imaging mode to capture fundus images. This dynamic adaptability allows the system to optimize performance for each operational phase.
Solution Approach 2:
The system employs periodic switching between fixation mode (mirror stationary) and imaging mode (mirror scanning). This periodic action allows the mirror to alternate between maintaining gaze stability and performing fundus scanning, ensuring both fixation reliability and imaging productivity are achieved at appropriate times.
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 solution effectively fixes the gaze direction of the eye, reducing the risk of image artifacts and enhancing the quality of ultra-widefield images by integrating the fixation target light source without adding complexity to the system.
Implementation Method 1
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, wherein the rotatable mirror is arranged to scan the beam of light across the ellipsoidal mirror via the first focal point, and a pupil of the eye is positioned at the second focal point during use
Implementation Method 2
a rotatable mirror arranged to scan the beam of light across the fundus
Implementation Method 3
a fixation target light source arranged to project fixation light onto the fundus via the rotatable mirror and the ellipsoidal mirror
Data Source
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AI summary
An ultra-widefield ophthalmic imaging instrument comprising a rotatable mirror which scans a light beam across a fundus of an eye via a focal point of an ellipsoidal mirror to acquire an ultra-widefield image of the fundus of an eye whose pupil is at another focal point of the ellipsoidal mirror, and a light source which projects fixation light for gaze fixation of the eye. The instrument also has a processor which controls the rotatable mirror to be stationary in a predetermined orientation, and the light source to project the fixation light onto the fundus via the stationary mirror and the ellipsoidal mirror to fix the gaze direction of the eye. The processor then controls the ultra-widefield ophthalmic imaging instrument to acquire the ultra-widefield image of the fundus by controlling the rotatable mirror to scan the light beam across the fundus via the ellipsoidal mirror.