Flange-Bonded Loopback for Fiber-Optic Gyroscope
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Solution Overview
Problem
Fiber-optic gyroscope (FOG) systems face errors in measuring angular rotation rate due to thermally-induced stresses and asymmetrical signal paths caused by the coupling of loopback portions to the optical fiber coil, leading to measurement inaccuracies.
Innovation Solution
A flange-bonded loopback configuration is implemented, where the loopback portion of the optical fiber is secured to the flange rather than the optical fiber coil, ensuring a symmetric signal path and mitigating thermal stresses by using a buffer material with a coefficient of thermal expansion between the optical fiber and the flange, thus stabilizing the optical signal path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the loopback portion is coupled to the optical fiber coil, then the device structure is simplified, but thermal stresses and measurement inaccuracies increase
Solution Approach 1:
The patent segments the mounting structure by providing separate flanges: a first flange for coupling the optical fiber coil and a second flange for coupling the loopback portion. This segmentation isolates the loopback portion from thermal stresses generated by the optical fiber coil, preventing measurement errors while maintaining structural organization.
Solution Approach 2:
The patent introduces a buffer material as an intermediary between the optical fiber coil and the flange. This buffer material has a coefficient of thermal expansion between that of the optical fiber and the flange, acting as a thermal stress mediator that protects the optical fiber from thermal expansion forces while allowing structural integration.
2Ease of manufacture
If the loopback portion is coupled to the optical fiber coil, then assembly is easier, but asymmetrical signal paths cause measurement errors
Solution Approach 1:
The patent provides separate flanges for mounting the optical fiber coil and the loopback portion, segmenting the mounting functions. This segmentation enables independent optimization of each component's positioning, ensuring symmetrical signal paths while maintaining assembly simplicity through modular construction.
Solution Approach 2:
The patent positions the loopback portion on a second flange that is spatially separated from the first flange where the optical fiber coil is mounted. This dimensional separation in space allows the signal path to be configured symmetrically without being constrained by the physical coupling between loopback and coil, thereby improving measurement precision.
3Reliability
If buffer material with intermediate thermal expansion coefficient is used, then thermal stress is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent introduces a buffer material as a thermal intermediary layer between the optical fiber coil and the flange. This buffer material has a coefficient of thermal expansion between that of the optical fiber and the flange, absorbing thermal expansion differential and protecting the optical fiber from stress while maintaining a relatively simple manufacturing process through material selection.
Solution Approach 2:
The patent employs a composite material structure consisting of the buffer material layer combined with the flange and optical fiber assembly. This composite approach allows the system to leverage the beneficial thermal properties of the buffer material while maintaining the structural integrity of the existing components, achieving thermal stress resistance without significant manufacturing complexity.
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 significantly reduces thermal sensitivity and improves the accuracy of angular rotation rate measurement by eliminating operator variability and reducing errors associated with thermal expansion, resulting in consistent and reliable performance.
Implementation Method 1
a fiber optic gyroscope (FOG) can sense a change in orientation using the Sagnac effect, such as based on the interference of light which has passed through a coil of optical fiber
Implementation Method 2
mitigating thermal stresses by using a buffer material with a coefficient of thermal expansion between the optical fiber and the flange
Data Source
AI summary
One example includes fiber optic gyroscope (FOG) assembly. The FOG assembly includes a spool comprising a flange. The FOG assembly also includes an optical fiber comprising an optical fiber coil portion that is counter-wound in a first orientation and a second orientation opposite the first orientation. The optical fiber portion can be coupled to the flange. The optical fiber further includes a loopback portion with respect to the first orientation that is secured to the flange.