Dynamic Path Length Control Modulation for Ring Laser Gyroscope
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Solution Overview
Problem
Ring laser gyroscope (RLG) performance is affected by the controlled magnitude of laser power modulation, which can be too large at the beginning of the life cycle and inadequate at the end, leading to decreased accuracy and efficiency over time.
Innovation Solution
Implementing a dynamic path length control modulation system that adjusts the amplitude of path length control modulation based on the stage in the life cycle and operational phase of the RLG, increasing the amplitude at startup for quick mode acquisition and reducing it during operation to maintain peak laser power tracking, while increasing it as laser power declines to maintain peak detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed large amplitude modulation is used to detect laser power peak at end of life cycle, then peak detection is sufficient for lower laser power, but the modulation amplitude is too large for RLG at beginning of life cycle
Solution Approach 1:
The patent implements dynamic modulation amplitude adjustment where the modulation amplitude varies over time based on the RLG operational phase. During startup and mode acquisition, a larger modulation amplitude is applied. During normal operation, the amplitude is reduced to a smaller value. This dynamic adaptation resolves the contradiction by making the system flexible enough to handle both early-life high-power conditions and end-life low-power conditions with appropriate modulation levels.
Solution Approach 2:
The patent changes the modulation amplitude parameter according to the operational phase and laser power level. The controller monitors laser power and adjusts the modulation amplitude accordingly - using larger amplitudes when laser power is high (beginning of life) and smaller amplitudes when laser power is low (end of life). This parameter adaptation enables optimal peak detection across the entire device lifecycle.
2Measurement precision
If a larger modulation amplitude is used, then laser power peak detection is improved for lower power, but RLG performance is negatively impacted at beginning of life cycle
Solution Approach 1:
The system dynamically adjusts modulation amplitude based on operational phase. During normal operation when RLG performance is critical, a smaller modulation amplitude is used to maintain high reliability and avoid performance degradation. When mode acquisition is needed, the amplitude is temporarily increased to improve peak detection. This temporal separation of modulation amplitudes resolves the contradiction between measurement precision and reliability.
Solution Approach 2:
The patent employs periodic modulation at different amplitude levels depending on the operational phase. During startup and mode acquisition phases, periodic modulation with larger amplitude is applied. During normal operational phases, periodic modulation with smaller amplitude is used to maintain performance. This periodic adaptation allows the system to achieve good peak detection when needed while maintaining reliability during critical operation.
3Device complexity
If fixed modulation amplitude is used, then system complexity is reduced, but the system cannot adapt to changing laser power over life cycle
Solution Approach 1:
The patent implements a feedback control mechanism where the controller monitors the laser power level and uses this information to adjust the modulation amplitude. The photodetector detects laser power, and this detection feeds back to the controller which then adapts the modulation amplitude accordingly. This feedback loop provides adaptability to changing laser power over the life cycle while keeping the control mechanism relatively simple and integrated within the existing RLG structure.
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 approach allows for improved mode acquisition at startup, reduced error effects during operation, and enhanced performance over the life of the RLG by dynamically adjusting modulation amplitudes in response to changing laser power, maintaining peak detection accuracy as the device ages.
Implementation Method 1
a photodetector configured to measure power of the light directed along the path
Implementation Method 2
at least one mirror drive coupled to one of the plurality of mirrors and configured to change a position of the respective mirror
Data Source
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AI summary
Systems and methods for dynamic PLC modulation are provided. In certain embodiments, a gyroscope system includes a block having cavities and passages that define a path; mirrors, each located in one of the cavities, direct light along the path defined by the cavities and the passages; a mirror drive coupled to one of the mirrors to change a position of the mirror, wherein the path's length is changed as the mirror's position changes; a photodetector that measures power of light along the path; and a controller that provides a control signal indicative of an amplitude of PLC modulation and a PLC frequency to the mirror drive; wherein the mirror drive, in response to the control signal, changes the position of the mirror at the frequency, wherein the mirror drive moves based on the amplitude; and wherein the controller changes the amplitude in relation to the measured power of the light.