Fundus Imaging Optics With Pupil Division to Minimize Flare
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Solution Overview
Problem
Existing ophthalmic apparatuses face issues with image quality degradation due to flare caused by the intersection of illumination and reflected light flux regions in the lens, and existing solutions either require complex configuration modifications or increase the risk of image degradation from eye movement.
Innovation Solution
An ophthalmic apparatus with an illumination optical system that generates slit-shaped illumination light and an imaging optical system that guides returning light through pupil division, setting the overlap region of light flux regions on the fundus side of the lens to minimize flare, using a simple configuration and synchronized light reception with a one-dimensional or two-dimensional array of light receiving elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the illumination light and reflected light flux regions intersect in the lens, then the image can be captured, but flare is generated causing image quality degradation
Solution Approach 1:
The patent applies pupil division to separate the optical paths in the angular dimension. By dividing the pupil into multiple regions with different aperture stop positions, the illumination light and reflected light are directed through different spatial paths, causing their flux regions to intersect only in the image plane rather than in the lens, thereby eliminating flare while maintaining image capture capability
Solution Approach 2:
The patent introduces an aperture stop as an intermediary element positioned at specific locations in the optical path. This aperture stop acts as a mediator that selectively transmits light rays, allowing the illumination and reflected light to be separated in the angular domain while still enabling both to reach the image sensor through different paths
2Object-generated harmful factors
If existing solutions are applied to reduce flare, then flare is suppressed, but the configuration becomes complicated or image degradation from eye movement increases
Solution Approach 1:
The patent makes the aperture stop multi-functional by positioning it to serve both as an illumination light limiter and as a reflected light separator. The same aperture stop structure that controls the illumination beam also facilitates the pupil division effect, eliminating the need for separate components and reducing overall system complexity while suppressing flare
3Object-generated harmful factors
If the overlap region of light flux regions is positioned differently, then flare is reduced, but the imaging accuracy may be affected
Solution Approach 1:
The patent applies different aperture stop positions for different portions of the optical path. By positioning the aperture stop at specific locations, the patent creates different transmission characteristics for illumination light and reflected light, allowing the overlap region to be positioned in the image plane where it does not cause flare while maintaining proper imaging focus and accuracy
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
Achieves high-quality images of the eye with strong contrast by minimizing flare and reducing the impact of eye movement, while maintaining a simple apparatus design.
Implementation Method 1
generate slit-shaped illumination light using light from the light source and guide the illumination light to a fundus of the subject's eye
Implementation Method 2
illumination optical system including a slit in which a slit-shaped aperture is formed and an iris aperture in which two apertures are formed
Implementation Method 3
guide returning light of the illumination light to an image sensor, the returning light being guided from the fundus by pupil division and passing through the aperture formed in the imaging aperture
Implementation Method 4
imaging optical system including an imaging aperture in which an aperture is formed
Implementation Method 5
a width of the slit-shaped aperture, a distance between the two apertures, and a size of the aperture in the imaging aperture are set so that an overlap region of a light flux region of the illumination light and a light flux region of the returning light is located on a side of the fundus from a posterior surface of lens
Data Source
AI summary
An ophthalmic apparatus includes an illumination optical system and an imaging optical system. The illumination optical system includes a slit with a slit-shaped aperture and an iris aperture with two apertures and is configured to generate slit-shaped illumination light and to guide the illumination light to a fundus of a subject's eye. The imaging optical system includes an imaging aperture with an aperture, and is configured to guide returning light of the illumination light to an image sensor. A width of the slit-shaped aperture, a distance between the two apertures, and a size of the aperture in the imaging aperture are set so that an overlap region of a light flux region of the illumination light and a light flux region of the returning light is located on a side of the fundus from a posterior surface of lens of the subject's eye within the eye.