Tilted Fundus Imaging Optics for Ghost Reflection Suppression
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Solution Overview
Problem
Existing fundus imaging systems suffer from ghost reflections due to light being reflected at the surface of the objective lens, cornea, and eye's lens, which reduce image quality, necessitating complex optical arrangements that increase cost and complexity, making them less portable and accessible for remote areas.
Innovation Solution
The system aligns the illumination path coaxially with the imaging axis and tilts the optical axis relative to the imaging axis, eliminating the need for complex optical elements like holed coupling mirrors and black dot masks, using a tilted objective lens and beam splitter to deflect reflections off-axis, and incorporates achromatic lenses to minimize chromatic aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a masked light source is used to eliminate ghost reflections, then image quality is improved, but device complexity increases
Solution Approach 1:
The patent applies asymmetry by tilting the optical axis relative to the imaging axis, creating an asymmetric optical path that deflects ghost reflections away from the sensor. This asymmetric configuration eliminates the need for symmetric masking elements while maintaining image quality.
Solution Approach 2:
The patent extracts the problematic ghost reflections from the optical path by tilting the objective lens, separating the reflection path from the imaging path. This extraction eliminates the need for additional masking elements that would otherwise be required to block these reflections.
2Measurement precision
If complex optical elements are used to eliminate ghost reflections, then image quality is improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the orientation parameter of the objective lens by tilting it at a specific angle relative to the imaging axis. This parameter change fundamentally alters the optical path geometry, eliminating ghost reflections without requiring additional optical elements, thereby reducing manufacturing complexity and cost.
3Measurement precision
If complex optical arrangements are used to eliminate ghost reflections, then image quality is improved, but portability decreases
Solution Approach 1:
The patent merges the illumination and imaging functions through the tilted objective lens, allowing a single optical element to serve multiple purposes. This consolidation eliminates the need for separate masking elements and complex optical arrangements, reducing overall system weight and improving portability.
4Measurement precision
If complex optical arrangements are used to eliminate ghost reflections, then image quality is improved, but system complexity increases
Solution Approach 1:
Instead of adding elements to block reflections (the conventional approach), the patent inverts the approach by tilting the objective lens to redirect reflections away from the sensor. This inversion simplifies the optical system by eliminating the need for masks, beam splitters, and other complex elements.
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
This simplifies the optical design, reducing mechanical complexity, size, and cost, enhancing portability while improving image quality by eliminating ghost reflections and allowing for clearer, focused images suitable for medical diagnosis.
Implementation Method 1
incident light is reflected at the surface of the objective lens, cornea, front and back of the eye's lens; this reflected light is often described as 'ghost reflections'
Implementation Method 2
The beam splitter may be, for example, a half-silvered mirror, regular glass, or a mirror with other optical coatings. The beam splitter may be used to redirect light emitted from the light source
Implementation Method 3
at least one objective lens aligned with the optical axis
Data Source
AI summary
The invention provides an imaging system (102) for imaging a fundus (104) of an eye (106), which has an optical axis (116). The imaging system (102) has a light source (108), an illumination path (118) along which light travels from the light source (108) to the eye (106), a light sensor (10) and imaging optics (44) defining an imaging axis (114), and at least one objective lens (112) aligned with the optical axis (116). At least a part of the illumination path (118) is substantially coaxial with the imaging axis (114), and the optical axis (116) is tilted with respect to the imaging axis (114).