Fundus Imaging Slit Layout for Wide-Angle Contrast Control
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Solution Overview
Problem
Existing fundus imaging technologies face challenges in achieving high-quality wide-angle imaging at low cost without requiring advanced optical design, and suffer from issues like contrast reduction, flare, and ghost images due to unnecessary light reception.
Innovation Solution
A fundus imaging apparatus using two or more curved mirrors to scan the fundus with slit-shaped illumination light, where the slit opening is displaced at one end, and an image sensor is positioned at a fundus conjugate point to minimize aberrations and unnecessary light capture, improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a wide-angle fundus imaging is achieved using conventional scanning methods, then the field of view is improved, but contrast reduction and flare occur due to unnecessary light reception
Solution Approach 1:
The patent applies local quality by creating an asymmetric slit opening where one end is displaced in the shorter direction compared to the longitudinal direction. This localized geometric modification at the slit opening enables the optical system to selectively transmit and block specific light paths, thereby reducing unnecessary light reception and flare while maintaining wide-angle coverage. The asymmetric geometry creates distinct optical zones that improve contrast without sacrificing field of view.
Solution Approach 2:
The patent employs asymmetry through the displaced slit opening configuration, where one end of the slit is positioned differently along the shorter direction relative to the longitudinal axis. This asymmetric design disrupts the symmetry of light paths entering the optical system, enabling selective transmission of useful light while blocking stray light that causes flare and contrast reduction. The asymmetric geometry is specifically engineered to optimize the balance between wide field of view and image quality.
2Object-affected harmful factors
If advanced optical design is used to reduce flare and ghost images, then image quality is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies the taking out principle by extracting and modifying only the critical geometric feature (the slit opening) rather than redesigning the entire optical system. By isolating the slit opening as the key element and giving it the asymmetric displaced configuration, the patent eliminates flare and ghost images without requiring complex optical components or multiple optical elements. This approach achieves image quality improvement through a single, simple geometric modification rather than through sophisticated optical design.
Solution Approach 2:
The patent embodies the cheap short-living objects principle by using a simple, easily manufacturable asymmetric slit opening structure instead of expensive, complex optical components. The displaced slit geometry can be implemented through straightforward manufacturing processes such as asymmetric aperture stops or shaped optical elements, avoiding the need for precision-engineered multi-element optical systems. This approach provides effective flare and ghost image reduction at minimal cost and complexity.
3Device complexity
If a simple optical configuration is used, then device complexity is reduced, but manufacturing precision requirements increase for the slit opening
Solution Approach 1:
The patent applies segmentation by dividing the optical system into distinct functional zones created by the asymmetric slit opening. The displaced geometry segments the light paths into useful and useless rays, allowing the simple slit structure to perform multiple functions: defining the field of view, blocking stray light, and preventing flare. This segmentation approach maintains optical simplicity while achieving precise light control through the geometric configuration of the slit rather than through complex optical 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 configuration allows for higher-quality fundus imaging with reduced flare and ghosting, achieving improved contrast without the need for complex optical designs, at a lower cost.
Implementation Method 1
two or more curved mirrors; an illumination optical system including a slit with an opening configured to be disposed at a fundus conjugate position... configured to irradiate slit-shaped illumination light, that is generated by irradiating light from a light source onto the slit, onto the fundus through the two or more curved mirrors
Implementation Method 2
an image sensor configured to be disposed at the fundus conjugate position and to receive returning light from the eye to be examined
Data Source
AI summary
A fundus imaging apparatus includes two or more curved mirrors, an illumination optical system, and an image sensor. The illumination optical system includes a slit with an opening configured to be disposed at a fundus conjugate position. Here, the fundus conjugate position is substantially conjugate optically to a fundus of an eye to be examined. The illumination optical system is configured to irradiate slit-shaped illumination light, that is generated by irradiating light from a light source onto the slit, onto the fundus through the two or more curved mirrors. The image sensor is configured to be disposed at the fundus conjugate position and to receive returning light from the eye to be examined. At least one of both ends of the opening in a longitudinal direction is displaced in a shorter direction of the opening with reference to the longitudinal direction passing through a center of the opening.