Fundus Imaging Objective Optical System Mirror Design
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Solution Overview
Problem
Existing fundus imaging devices face challenges in capturing high-quality wide-range images due to aberrations and noise issues, particularly when trying to scan a wide angle, which affects image quality and makes it difficult to obtain both front and tomographic images effectively.
Innovation Solution
The implementation of a fundus imaging device with an objective optical system that includes a mirror system without lens elements, utilizing a first mirror with a quadric surface and a second spheroidal mirror to reduce noise and aberrations, allowing for a wider scanning range while maintaining image quality by adjusting the pivot points and optical path coupling to minimize incidence angle dependence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a lens system is used to widen the scanning angle, then the scanning range is improved, but reflection noise from lens surfaces and aberrations increase
Solution Approach 1:
The patent removes lens elements from the optical system and replaces them with a mirror system. Specifically, the objective optical system uses only mirrors (first mirror with quadric surface and second spheroidal mirror) without any lens elements, thereby eliminating reflection noise from lens surfaces while maintaining the ability to scan wide ranges of the fundus
Solution Approach 2:
The patent substitutes the lens-based optical system with a mirror-based optical system. The objective optical system is configured to direct light from the scanning optical system to the fundus using mirrors instead of lenses, which eliminates chromatic aberrations and reduces reflection noise while preserving the scanning functionality
2Area of stationary object
If the scanning angle is widened to capture more fundus area, then the imaging coverage is improved, but image quality deteriorates due to increased aberrations
Solution Approach 1:
The patent employs mirrors with specific curved surfaces to maintain image quality across wide scanning angles. The first mirror has a quadric surface and the second mirror is spheroidal, with carefully designed curvatures that compensate for aberrations introduced by wide-angle scanning, thereby maintaining sharp focus and image quality throughout the expanded field of view
Solution Approach 2:
The patent optimizes specific optical parameters including the curvature radii and positions of the mirrors. The first mirror has a curvature radius R1 and the second mirror has a curvature radius R2, with their positions and shapes carefully adjusted to minimize spherical aberration and coma across the wide scanning range, ensuring consistent image quality
3Device complexity
If lens elements are used in the objective optical system, then the optical path is simpler, but noise and aberrations increase
Solution Approach 1:
The patent extracts and removes all lens elements from the objective optical system, retaining only mirror components. This elimination of refractive elements removes the sources of chromatic aberration and reflection noise while the mirror system maintains the necessary optical functionality for wide-angle fundus 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 enables the capture of clear, wide-range fundus images with reduced noise and aberrations, allowing for both front and tomographic images to be obtained effectively, improving image quality and reducing the impact of incidence angle dependence on the optical path coupling.
Implementation Method 1
an objective optical system that includes a mirror system without lens elements, utilizing a first mirror with a quadric surface and a second spheroidal mirror
Data Source
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AI summary
A fundus imaging device 100 includes a scanning optical system 1 that includes optical scanners 15 and 27 which change the travelling direction of light from light sources 11 and 21 so as to scan a fundus Er with the light; and an objective optical system 2 that is disposed between the optical scanners 15 and 27 and a subject's eye E, and guides light from the optical scanners 15 and 27 to the fundus Er. The fundus imaging device 100 forms an image of the fundus Er based on fundus reflected light. The objective optical system 2 includes a first mirror 50 that reflects light from the optical scanners 15 and 27, and thus forms a first pivot point r1 around which light turns in correspondence with the operation of the optical scanners 15 and 27, and a second mirror 60 that further reflects light reflected by the first mirror 50, and thus forms a second pivot point r2 around which light emitted to the subject's eye E turns. The swing angle of light incident to the first mirror 50 is smaller compared to the swing angle of light with respect to the second pivot point r2.