Ring Laser Gyroscope Thermal Compensation Mechanism
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Solution Overview
Problem
Ring laser gyrosopes (RLGs) experience lock-in due to optical power backscattering from laser mirrors, leading to degraded accuracy and high angular random walk, especially during temperature changes which cause shifts in the incidence spots on the mirrors, affecting the phase of counter-propagating optical beams.
Innovation Solution
The RLG block incorporates a mechanism to laterally shift corners of the mirrors in the lasing plane perpendicular to their normals, maintaining the incidence spots' positions during temperature changes, thereby minimizing backscatter phase changes and preventing lock-in by adjusting the relative positions of the mirrors to compensate for thermal expansion or contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the RLG block is allowed to thermally expand or contract freely with temperature changes, then the device can accommodate thermal variations, but the incidence spots on the mirrors shift causing backscatter phase changes and lock-in
Solution Approach 1:
The patent introduces a temperature compensation mechanism that actively adjusts the lateral position of mirrors in response to temperature changes. The compensation mechanism changes the physical parameter of mirror position to counteract the thermal expansion/contraction effects, maintaining constant incidence spots and preventing backscatter phase changes that would otherwise degrade measurement precision.
Solution Approach 2:
The patent employs a feedback control system where temperature sensors monitor thermal conditions and the compensation mechanism adjusts mirror positions based on this feedback. This closed-loop system ensures that as temperature varies, the incidence spots remain stable by continuously compensating for thermal effects, thereby preventing lock-in and maintaining rotation sensing accuracy.
2Reliability
If dithering is applied to minimize lock-in by keeping the RLG in constant motion, then lock-in time is reduced, but the system complexity and mechanical wear increase
Solution Approach 1:
The patent converts the harmful effect of thermal expansion/contraction into a beneficial compensation mechanism. By using the thermal effects themselves to drive the compensation (through bimetallic strips or similar mechanisms), the system eliminates lock-in without requiring external power or complex control systems, thus improving reliability while avoiding the complexity of active dither mechanisms.
3Stability of the object's composition
If the mirrors are fixed rigidly to the RLG block, then the structure is simple and stable, but thermal expansion causes incidence spot shifts and backscatter
Solution Approach 1:
The patent transitions from a static, rigid mirror mounting to a dynamic compensation mechanism that allows mirrors to adjust their positions in response to thermal changes. This dynamic adjustment maintains optimal incidence conditions despite thermal expansion/contraction, preventing backscatter while preserving overall structural stability through controlled adaptability.
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 solution effectively minimizes backscatter contributions from all mirrors, maintaining constant vector summations of backscattered waves during temperature changes, thus enhancing the RLG's performance and accuracy by preventing lock-in and reducing angular random walk.
Implementation Method 1
when a temperature change of the ring laser gyroscope block causes a contraction of the ring laser gyroscope block. The first portion of the first side shifts the first corner laterally in the lasing plane, in the direction away from the second corner, and perpendicular to the first normal when the temperature change of the ring laser gyroscope block causes an expansion of the ring laser gyroscope block
Data Source
AI summary
A ring laser gyroscope (RLG) block is provided. The RLG block includes a first corner bordered by a first portion of a first side and a first portion of a third side; a second corner bordered by a first portion of a second side and a second portion of the third side; and a third corner bordered by a second portion of the second side and a second portion of the first side. The first portion of the first side shifts the first corner laterally in a lasing plane of the RLG block, toward the second corner, and perpendicular to a first normal of a first mirror when a temperature change contracts the RLG block; and shifts the first corner laterally away from the second corner, and perpendicular to the first normal when the temperature change causes an expansion of the ring laser gyroscope block.