Refractive Index Profile Determination for Optical Fiber Preforms
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Solution Overview
Problem
Existing methods for determining the refractive index profile of cylindrical optical objects, such as optical fibers, face inaccuracies due to measurement artifacts at refractive index discontinuities, leading to errors in step profiles and non-measurable regions, requiring complex extrapolation and iterative adaptation techniques.
Innovation Solution
A method involving the preparation of deflection angle distributions through extreme value determination and smoothing, followed by transformation into refractive-index profiles, with iterative fitting of simulated profiles to achieve accurate refractive index profiles, addressing measurement inaccuracies and improving plausibility, accuracy, and reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the Abel transform is used to calculate the refractive index profile from deflection angle distribution, then the calculation can be performed directly, but measurement artifacts at refractive index discontinuities lead to inaccuracies and non-measurable regions
Solution Approach 1:
The patent applies preliminary action by performing extreme value determination and smoothing on the deflection angle distribution before transforming to refractive index profile. This preprocessing step prepares the data to reduce measurement artifacts at discontinuities, thereby improving accuracy before the actual transformation occurs.
Solution Approach 2:
The patent implements feedback through iterative fitting of simulated refractive index profiles to the measured data. The process involves transforming the profile back to deflection angle distribution, comparing with measured values, and adjusting parameters iteratively. This feedback loop continues until convergence, ensuring high accuracy while managing complexity through systematic iteration.
2Measurement precision
If extrapolation techniques are used to handle non-measurable regions, then coverage of the refractive index profile can be improved, but the process becomes more complex and less reproducible
Solution Approach 1:
The iterative fitting process provides continuous feedback that automatically handles non-measurable regions. By comparing simulated and measured deflection angle distributions and adjusting parameters accordingly, the method achieves complete profile coverage without requiring separate extrapolation steps, thus maintaining simplicity while improving completeness.
Solution Approach 2:
The patent merges the handling of non-measurable regions into the main iterative fitting process rather than treating it as a separate extrapolation step. This integration combines profile reconstruction and gap filling into a unified approach, improving completeness while maintaining operational simplicity.
3Measurement precision
If iterative adaptation of parameters is performed to fit simulated profiles to measured data, then accuracy and reproducibility are improved, but computational time and process complexity increase
Solution Approach 1:
The patent performs preliminary action by determining extreme values and smoothing the deflection angle distribution before the iterative fitting process. This preprocessing reduces the complexity of the subsequent iteration and accelerates convergence, thereby improving accuracy while minimizing additional time consumption.
Solution Approach 2:
The iterative fitting process applies partial action by focusing computational effort on adjusting only the necessary parameters (layer radii and refractive indices) rather than reprocessing the entire profile. This targeted approach achieves high accuracy without excessive computational time.
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
The method enhances the accuracy and reproducibility of refractive index profile determination by iteratively adapting simulated profiles to measured data, reducing systematic errors and improving the representation of real refractive index profiles, especially at refractive index discontinuities.
Implementation Method 1
the deflection of a light beam which is transmitted through a volume region of the optical element
Data Source
AI summary
A method for determining the refractive index profile of a preform is provided. The method involves: preparing the measured deflection angle distribution, including an extreme value determination of the deflection angle distribution, to obtain a prepared deflection angle distribution; transforming the prepared deflection angle distribution into a prepared refractive-index profile; evaluating the prepared refractive-index profile for the fixation of orientation values for the layer radius and for the layer refractive index of a hypothetical refractive index profile; generating a simulated deflection angle distribution on the basis of the hypothetical refractive-index profile with the orientation values, and transforming the deflection angle distribution into a simulated refractive-index profile; fitting the simulated refractive index profile to the prepared refractive-index profile by iterative adaptation of parameters to obtain a fitted, simulated refractive-index profile which is defined by adapted parameters, and obtaining the refractive index profile as the hypothetical refractive-index profile with the adapted parameters.