Adaptive Optics Fundus Imaging Reflection Suppression
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Solution Overview
Problem
Current ophthalmological devices face challenges in achieving shadow-free and uniform illumination while minimizing disturbing reflections, often requiring complex and costly solutions to compensate for image errors and chromatic aberrations, which can lead to image blurring and reduced contrast due to eye movements and limited field of vision.
Innovation Solution
The proposed solution involves an optical arrangement with adaptive optics, including free-form surfaces and wavefront sensors for real-time control of adaptive mirrors, combined with decentered and tilted lenses to compensate for image errors and chromatic aberrations, using LEDs for illumination and synchronized image acquisition to achieve high-resolution, reflection-free fundus images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a black point is used to block the central area of the optical surface to suppress reflections, then disturbing reflections are reduced, but the optical design becomes more complex and expensive due to the need for precise adjustment of the aperture size and position, and shadow effects become visible on the retina
Solution Approach 1:
The patent extracts and removes the problematic central reflection component by using a tilted front lens that deflects the central reflection laterally outside the observation aperture. This eliminates the need for additional blocking elements like black points and their associated complex adjustment mechanisms, while also avoiding shadow effects on the retina.
Solution Approach 2:
The patent introduces asymmetry by tilting the front lens surfaces at specific angles (e.g., 5-15 degrees) relative to the optical axis. This asymmetric configuration causes the central reflection to be deflected laterally, separating it from the observation path. The asymmetric design achieves reflection suppression without requiring additional symmetric blocking components, simplifying the overall optical design.
2Object-affected harmful factors
If front optics are tilted to deflect the central reflection laterally, then disturbing reflections are suppressed, but additional image errors occur that require complex compensation with additional optical components
Solution Approach 1:
The patent merges the reflection suppression function with the existing front lens by tilting its surfaces. The same front lens that focuses light onto the retina also serves to deflect the central reflection laterally. This integration eliminates the need for separate compensation components such as wedges or toric lenses, reducing overall system complexity while maintaining effective reflection suppression.
Solution Approach 2:
The tilted front lens performs multiple functions simultaneously: it focuses light onto the retina, deflects the central reflection laterally outside the observation aperture, and maintains acceptable image quality without requiring additional compensation optics. This multi-functionality reduces the total number of optical components needed in the system.
3Object-affected harmful factors
If multiple optical interfaces and long glass paths are used in the objective, then reflection suppression is achieved, but impurities at the interfaces reduce intensity and cause disruptive scattered light
Solution Approach 1:
The patent converts the potentially harmful central reflection into a beneficial lateral deflection. By tilting the front lens, the reflection is redirected outside the observation aperture, transforming it from a disturbing artifact into a useful indicator of proper optical alignment. This approach eliminates the need for multiple corrective interfaces that would introduce impurities and scattered light.
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 approach simplifies the optical design, reduces costs, and provides high-contrast, sharp images with improved resolution and color accuracy, effectively addressing the limitations of existing technologies by minimizing reflections and chromatic errors, suitable for applications like multi-color laser coagulation and optical coherence tomography.
Implementation Method 1
arrangement for ophthalmological devices for improving fundus images, in particular with regard to freedom from disturbing reflections and ensuring uniform and shadow-free illumination of the images and a true-color representation of the same
Implementation Method 2
If, for example, the image errors and disturbances are known, the wavefront can be corrected in a targeted manner with the aid of an adjustable optical component, for example a mirror consisting of many small, separately adjustable elements
Implementation Method 3
A further possibility of already preventing the formation of the reflection consists in providing front optics with obliquely tilted optical surfaces according to the quantar principle (US Pat. No. 4,730,910). In this case, the central reflex is deflected laterally to such an extent that it can no longer enter the observation aperture
Implementation Method 4
The fundus of the eye is illuminated by a lighting unit located in the device, which creates a ring-shaped pupil at the edge of the pupil of the eye and illuminates the retina evenly. Due to the geometric pupil separation of illumination and observation in the pupil of the eye, it is possible to largely decouple the beam paths on the cornea and to achieve images free of reflections and stray light
Implementation Method 5
The proposed solution involves an optical arrangement with adaptive optics, including free-form surfaces and wavefront sensors for real-time control of adaptive mirrors, combined with decentered and tilted lenses to compensate for image errors and chromatic aberrations
Data Source
Figure 1
AI summary
The invention relates to an optical arrangement for ophthalmological devices for improving fundus images, especially for imaging the retina. Said arrangement comprises, accommodated in a housing, an optical illumination and imaging system with tilted and/or out-of-center, refractive and/or reflecting surfaces or arrangements of non-tilted or non-out-of-center optical surfaces having a black point design in the illumination system. An imaging optical system comprising at least one imaging mirror (11; 12) is provided in an imaging beam path. In order to compensate image defects of the imaging optical system, at least one reflecting, refractive, electronically structurable or adaptive optical element, e.g. a mirror (12) having adjustable, adaptive elements (12a), is provided in the beam path. The arrangement also has means for generating control signals for controlling the adaptive elements (12a) of the at least one optical element (12).