Resonator Optical Gyroscope Phase Modulation Optimization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Resonator fiber optic gyros face bias errors and reduced signal-to-noise sensitivity due to polarization cross-coupling-induced intensity modulation, which complicates and costs more to mitigate with high-performance phase modulators.
Innovation Solution
Optimizing phase modulation amplitudes and frequencies to null polarization cross-coupling induced intensity modulation, specifically setting amplitudes near values like 3.832 or 7.016 radians to minimize bias errors while maximizing signal-to-noise sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high performance phase modulators with high polarization extinction ratio are used to reduce polarization cross-coupling induced intensity modulation, then bias errors are reduced, but device complexity and cost increase
Solution Approach 1:
The patent changes the operating parameters of the phase modulator by selecting specific modulation amplitudes (zeros of Bessel functions J1 and J2) rather than changing the modulator hardware itself. This parameter optimization reduces polarization cross-coupling effects while using standard, lower-cost modulators.
Solution Approach 2:
The patent uses software/mathematical modeling to predict and optimize modulator performance before physical implementation. A computer model simulates the gyro system to identify optimal modulation amplitudes, avoiding the need for expensive trial-and-error hardware iterations.
2Measurement precision
If phase modulation amplitude is adjusted to reduce polarization cross-coupling induced intensity modulation, then bias errors are reduced, but signal-to-noise sensitivity decreases
Solution Approach 1:
The patent identifies specific parameter values (modulation amplitudes at Bessel function zeros) that simultaneously minimize both bias error and maintain signal-to-noise ratio. The computer model evaluates multiple parameter combinations to find the optimal operating point that satisfies both requirements.
Solution Approach 2:
The patent employs a feedback loop where the computer model predicts the effects of different modulation amplitudes on both bias error and signal-to-noise ratio, allowing iterative optimization to find the amplitude that best balances both performance metrics.
3Object-generated harmful factors
If production complexity is increased to reduce polarization cross-couplings in the gyro optical path, then intensity modulation is reduced, but manufacturing cost increases
Solution Approach 1:
Instead of modifying the physical optical path or improving component quality (which会增加 manufacturing complexity), the patent changes the operational parameter (modulation amplitude) to compensate for polarization cross-coupling effects. This maintains manufacturing simplicity while achieving the desired performance.
Solution Approach 2:
The patent replaces physical/mechanical solutions (improving modulator quality, reducing polarization cross-couplings through better alignment or higher PER components) with a mathematical/software-based solution (optimizing modulation amplitude parameters through computer modeling).
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 reduces bias errors and enhances signal-to-noise sensitivity, allowing for lower-cost modulators without sacrificing performance, and stabilizes gyro measurements by selecting optimal modulation frequencies for CW and CCW input lightwaves.
Implementation Method 1
monochromatic light waves are typically sinusoidally phase/frequency modulated and coupled into the RFOG resonator
Implementation Method 2
The resonant cavity supports light waves propagating in opposite directions... leading to a resonant frequency difference between them
Implementation Method 3
Fractions of light circulating inside the resonator are coupled out of the resonator and converted to electronic signals at photodetectors
Data Source
AI summary
Systems and methods for optimizing input beam modulation for high gyro sensitivity and low bias errors. The present invention is a resonator optical gyroscope having an optimized phase-modulation amplitude (frequency) for a selected modulation frequency (amplitude) that maximizes the gyro signal-to-noise (S/N) sensitivity. For selected values of the phase modulation amplitude, the polarization cross-coupling induced intensity modulation can be nulled. By setting the phase modulation amplitudes substantially close to these nulling points (e.g. M=3.832 or 7.016 radians, which causes the first order Bessel function to be zero J1(M)=0) and then optimizing the modulation frequency, the intensity modulation induced bias is reduced to zero and gyro S/N sensitivity is maximized.