Microscope Refractive Index Determination via Oblique Incidence
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Solution Overview
Problem
Current methods for determining the refractive index of an optical medium in a microscope, especially the embedding medium, are inaccurate and require complex and costly high-numerical-aperture objectives, making it difficult to correct imaging errors caused by refractive index variations at interfaces.
Innovation Solution
A method involving oblique incidence of a measurement light beam on a cover slip or object carrier to generate spatially separated reflection light beams, which are then detected to determine the refractive index of the optical medium, allowing for precise determination within the microscope without needing to know the intensity of the measurement light beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If total internal reflection microscopy is used to determine refractive index, then refractive index can be determined within the microscope, but it requires an immersion objective with high numerical aperture which is complex and costly
Solution Approach 1:
The patent extracts the refractive index measurement function from the complex high-numerical-aperture objective by using a standard objective combined with a separate measurement beam path that utilizes oblique incidence and total internal reflection at the cover slip interfaces, thereby separating the imaging function from the measurement function
Solution Approach 2:
The patent introduces an intermediary measurement beam path with oblique incidence that mediates between the standard objective and the refractive index determination, using the cover slip interfaces as natural reflection surfaces to enable measurement without requiring specialized high-NA objectives
2Ease of manufacture
If refractive index is measured outside the microscope, then measurement can be performed, but correlation with the actual refractive index in light-microscopy imaging cannot be ensured
Solution Approach 1:
The patent merges the refractive index measurement function with the microscope system itself by integrating the measurement beam path within the existing optical train, allowing simultaneous or sequential measurement and imaging using the same optical path and cover slip configuration, thereby ensuring the measured refractive index directly corresponds to the actual imaging conditions
3Device complexity
If standard objective is used instead of high numerical aperture objective, then device complexity is reduced, but the ability to perform total internal reflection illumination is lost
Solution Approach 1:
The patent segments the illumination and measurement functions by using a separate measurement beam path with oblique incidence that is distinct from the main imaging path, allowing the use of a standard objective for imaging while maintaining total internal reflection capability through the dedicated measurement beam
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
Enables simple and precise determination of the refractive index of the optical medium, facilitating adjustments for embedding media and automation of correction adjustments, and can be used in various microscope types, including inverse and upright transmitted light microscopes.
Implementation Method 1
The optical medium having the refractive index to be determined is one of two optical media, which border two opposing surfaces of a cover slip or object carrier in the sample chamber and thus form two partially reflective interfaces
Data Source
AI summary
A method is useable for determining a refractive index of an optical medium in a microscope, which has an objective facing toward a sample chamber. The optical medium is one of two optical media, which border two opposing surfaces of a cover slip or object carrier in the sample chamber and form two partially reflective interfaces, which are arranged at different distances from the objective. The method includes: deflecting a measurement light beam by the objective with oblique incidence on the cover slip or object carrier; generating two reflection light beams spatially separated from one another by the measurement light beam being partially reflected at each of the interfaces; receiving the two reflection light beams by the objective and conducting them onto a position-sensitive detector; registering intensities by the position-sensitive detector; and determining the refractive index of the optical medium based on the registered intensities.