Variable-Width Slit Aperture for Wide-Angle Fundus Imaging
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Solution Overview
Problem
Existing ophthalmic apparatuses face challenges in capturing high-quality, wide-angle images of the fundus due to illumination unevenness in peripheral regions, which degrades image quality.
Innovation Solution
The apparatus employs an illumination optical system with a slit-shaped aperture whose width in the shorter direction varies along the longitudinal direction, coupled with a photographic optical system using curved mirrors to receive returning light, thereby eliminating illumination unevenness and enhancing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a conventional slit-shaped aperture is used in the illumination optical system, then the apparatus can achieve wide-angle fundus imaging, but illumination unevenness occurs in peripheral regions degrading image quality
Solution Approach 1:
The aperture is designed with non-uniform width along the longitudinal direction, where the width in the shorter direction varies at different positions. This local variation in aperture geometry compensates for optical aberrations and illumination unevenness in peripheral regions, achieving uniform illumination across the entire field of view while maintaining wide-angle capability
2Area of stationary object
If curved mirrors are used to expand the field of view, then wide-angle imaging is achieved, but optical distortions occur that reduce image quality
Solution Approach 1:
The aperture parameters (width in shorter direction) are varied along the longitudinal direction to compensate for optical distortions introduced by curved mirrors. This parameter change in the aperture geometry counteracts the distortion effects, maintaining image quality while achieving wide-angle imaging
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 the acquisition of high-quality, wide-angle images by correcting optical distortions and suppressing contrast reduction, enabling precise measurement of a wide range of the eye's optical characteristics.
Implementation Method 1
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
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 3
receive returning light from the eye to be examined through the two or more curved mirrors
Implementation Method 4
receive returning light from the eye to be examined through the two or more curved mirrors
Data Source
AI summary
An ophthalmic apparatus includes two or more curved mirrors, an illumination optical system, and a photographic optical system. The illumination optical system includes a slit with an aperture configured to be disposed at a fundus conjugate position, the fundus conjugate position being substantially conjugate optically to a fundus of an eye to be examined, and 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 photographic optical system includes an image sensor configured to be disposed at the fundus conjugate position and to receive returning light from the eye to be examined through the two or more curved mirrors. The aperture is formed so that a width in a shorter direction differs depending on a position in a longitudinal direction.