Coaxial Illumination Device for Ophthalmic Microscopes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing illumination devices for ophthalmologic operating microscopes, such as those used in cataract surgery, face challenges in achieving a homogeneous, bright 'red reflex' while maintaining good contrasting of phase objects over the entire pupil, especially due to sensitivity to eye movement and variations in pupil size and refraction.
Innovation Solution
The illumination device features a light source with optical elements positioned between the light source and the objective element, where the intermediate image of the light source is located at a distance from the front focal point of the objective element, corresponding to up to 50% of its focal length, allowing for coaxial illumination that ensures a uniform and intense 'red reflex' with enhanced contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If illumination is provided at a small angle (2-4 degrees) for observation, then good contrasting of phase objects is achieved, but the red reflex does not appear uniformly bright over the patient's pupil
Solution Approach 1:
The patent inverts the conventional illumination approach by using coaxial illumination (0° angle) instead of oblique illumination (2-4° angle). This inversion resolves the contradiction by achieving uniform red reflex brightness while maintaining adequate phase object contrast through the specific optical configuration with the intermediate image positioning.
Solution Approach 2:
The patent changes the illumination angle parameter from the conventional 2-4 degrees to 0 degrees (coaxial), and positions the intermediate image of the light source at a specific distance (up to 50% of focal length) from the front focal point of the objective element. These parameter changes enable uniform red reflex illumination while preserving diagnostic contrast.
2Illumination intensity
If coaxial illumination is used to achieve homogeneous red reflex, then uniform brightness is improved, but contrasting of phase objects deteriorates
Solution Approach 1:
The patent applies local quality by creating different illumination conditions for different regions: the central axial region receives coaxial illumination for uniform red reflex, while the peripheral regions maintain oblique illumination angles for phase object contrast. This is achieved through the specific positioning of the intermediate image relative to the objective element's focal point.
3Manufacturing precision
If the intermediate image of the light source is positioned at the front focal point of the objective element, then a precise 0° illumination is achieved, but sensitivity to eye movement and pupil variations increases
Solution Approach 1:
The patent positions the intermediate image of the light source not exactly at the front focal point but at a distance corresponding to up to 50% of the focal length from it. This pre-adjustment creates a tolerance zone that cushions against eye movements and pupil size variations, maintaining illumination stability while preserving coaxial geometry.
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 provides a stable, homogeneous, and contrast-rich 'red reflex' across the pupil, reducing sensitivity to eye movement and improving surgical visibility during cataract operations.
Implementation Method 1
optical elements which are provided between the light source and an objective element, wherein an intermediate image of the light source lies in the front focal point of the objective element
Implementation Method 2
the fraction of illuminating light, which, passing through the transparent media of the eye, finally strikes the retina, which appears red due to good blood perfusion, is reflected therefrom
Data Source
AI summary
Among other items, an illumination device (110) is [provided] for an observation device (100) having one, two or more observation beam paths, each with at least one observation beam bundle, in particular for an operating microscope, having at least one light source (112) for producing at least one illumination beam path with at least one illumination beam bundle (121, 122, 123) for illuminating an object to be observed, in particular, an eye to be observed, in addition having at least one illumination optics unit (11)*, which is constructed according to the Köhler principle of illumination, as well as an objective element (119), wherein the at least one illumination beam path or the at least one illumination beam bundle (121, 122, 123) runs coaxially to an observation beam path or observation beam bundle. In order to produce an optimal solution to the problem of practical requirements relative to homogeneity of the red reflex with a simultaneous good contrasting of the lens pieces or membranes in the lens capsule, it is provided that an intermediate image (125) of the light source (112) lies in the front focal point of the objective element (119), viewed in the direction of the light, or that an intermediate image (125a) of the light source (112) lies at a distance from the front focal point of the objective element (119) corresponding to a maximum of 50% of the focal length of the objective element (119), viewed in the direction of the light. *sic: (111)?—Trans. Note.