Optical Fiber Coil Symmetrical Winding Thermal Stability
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Solution Overview
Problem
Fiber optic gyroscopes face challenges with mechanical and thermal stability due to thermally induced non-reciprocities and inhomogeneous glue distribution in optical fiber coils, leading to temporal stability issues and measurement drifts.
Innovation Solution
A method of manufacturing optical fiber coils with symmetrical winding, where the fiber is wound equidistant from both ends, forming a sectorized arrangement with regular stacking and overlapping zones, allowing for homogeneous glue distribution and infiltration after complete winding, using materials like epoxy or acrylate polymer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the optical fiber coil is wound with symmetrical winding pattern, then thermal stability is improved, but manufacturing complexity increases
Solution Approach 1:
The optical fiber is divided into two halves at the midpoint, with each half forming a separate winding pattern (first pattern and second pattern) that are symmetrical to each other. This segmentation allows thermal compensation while maintaining manageable manufacturing complexity through modular winding approaches.
Solution Approach 2:
The patent employs symmetrical asymmetry by creating two mirror-image winding patterns from the two fiber halves. Each individual pattern may be complex, but their symmetrical relationship ensures thermal stability. The asymmetry in winding direction or layer distribution is deliberately designed to achieve thermal compensation.
2Stability of the object's composition
If glue is applied during winding process, then mechanical stability is improved, but glue distribution homogeneity deteriorates
Solution Approach 1:
The glue application channels and structures are prepared in advance during the winding process, creating predefined pathways for uniform glue distribution before the coating step. This preliminary structuring ensures homogeneous glue application without requiring complex real-time control during coating.
Solution Approach 2:
The patent introduces glue application channels as intermediary structures that mediate between the glue source and the optical fiber coil. These channels ensure uniform glue distribution by controlling the flow and placement, acting as a buffer that simplifies the overall coating process while maintaining precision.
3Measurement precision
If the number of fiber turns is increased, then sensitivity is improved, but thermal drift increases
Solution Approach 1:
Different sections of the optical fiber (first half and second half) are assigned different winding patterns that are symmetrical to each other. This local differentiation ensures that thermal effects experienced by one half are compensated by the other half, allowing high turn counts for sensitivity while maintaining thermal stability through local symmetry.
Solution Approach 2:
The symmetrical winding pattern from the second half of the fiber acts as a thermal counterweight to the first half. When thermal expansion or refractive index changes occur in one half, the symmetrical arrangement ensures corresponding changes in the other half that cancel out the net thermal drift, enabling high sensitivity without proportional thermal drift increase.
4Stability of the object's composition
If symmetrical winding pattern is used, then thermal compensation is improved, but manufacturing time increases
Solution Approach 1:
The winding process follows a periodic pattern where the first half and second half are wound in symmetrical sequences. This periodic symmetry allows for standardized, repeatable manufacturing cycles that reduce overall manufacturing time compared to custom asymmetric patterns, while maintaining thermal compensation benefits.
Solution Approach 2:
The patent optimizes winding parameters such as layer spacing, turn density, and pattern repetition frequency to achieve thermal compensation with minimal manufacturing time. By adjusting these parameters, the symmetrical pattern can be implemented efficiently without excessive manufacturing overhead.
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 method enhances the mechanical and thermal stability of optical fiber coils, reduces thermal drifts, and improves the reproducibility and quality of the manufacturing process, facilitating automation and reducing measurement drifts over time.
Implementation Method 1
A Sagnac ring optical fiber interferometer makes it possible to measure the phase difference between two waves having traveled through the same optical fiber coil in opposite directions. This type of interferometric sensor is implemented in an optical fiber gyroscope where the measured phase shift makes it possible to deduce therefrom a measurement of rotation around the axis of the coil.
Implementation Method 2
A Sagnac ring fiber optic interferometer can also be used as a magnetic field sensor, the phase shift being a function of the magnetic field by magneto-optical Faraday effect
Implementation Method 3
local temperature variations are likely to induce non-reciprocities in a Sagnac ring fiber optic interferometric sensor. In particular, the Shupe effect is due to local differences in thermal drifts at different locations of the coil. Indeed, a local variation in temperature in the optical fiber induces a local variation in the refractive index of the optical fiber which produces an additional phase shift between two counter-propagating waves.
Data Source
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Figure 7~11
AI summary
The invention relates to a method for producing an optical fibre coil (10) comprising the following steps: a. symmetrical winding of an optical fibre around a shaft (11), the winding forming a pattern comprising a same number N of layers of each half of the optical fibre, one layer comprising a set of turns of optical fibre and spaces (19, 29, 39, 49) between adjacent turns, the winding forming a sectored arrangement comprising a regular stacking area (13) comprising at least one continuous sealing surface (14, 24, 34) between two layers of adjacent turns, and an overlap area (12) where portions of optical fibre linking different turns intersect; b. infiltration of a glue (22) through an outer surface of the overlap area (12) in such a way that the glue (12) infiltrates into the spaces (19, 29, 39, 49) located between adjacent turns in the regular stacking area (13).