Three-Laser Fiber Optic Gyroscope Resonator Stabilization
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Solution Overview
Problem
Current resonator fiber optic gyroscope (RFOG) designs face challenges due to complex signal spectra from co-propagating laser beams, differential frequency noise between reference and gyroscope resonators, and asymmetric resonance probing, leading to performance degradation and increased complexity, size, and cost.
Innovation Solution
A three-laser RFOG design where a master laser is indirectly locked onto the gyroscope resonator via a feedback loop using two slave lasers, eliminating co-propagating laser beams and achieving symmetric resonance probing by employing a common modulation frequency scheme and optical phase lock loops, thereby reducing signal complexity and eliminating the need for a separate reference resonator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If co-propagating laser beams are used in the resonator, then the gyroscope can perform rotation sensing, but the signal spectrum becomes very complex making it difficult to detect the desired signal
Solution Approach 1:
The patent divides the laser system into separate counter-propagating beams with distinct frequency modulation schemes. Each beam is independently modulated at different frequencies, allowing their signals to be separated in the frequency domain during detection, thus simplifying the overall signal processing while maintaining rotation sensing capability
Solution Approach 2:
The patent introduces frequency domain separation as an additional dimension for signal discrimination. By assigning different modulation frequencies to clockwise and counter-clockwise beams, the system transforms the signal detection problem from spatial overlap to frequency domain separation, enabling clear signal identification despite co-propagation
2Reliability
If an independent reference resonator is used to stabilize the master laser, then the master laser frequency can be stabilized, but the system complexity, size, weight, and cost increase
Solution Approach 1:
The patent merges the reference resonator function with the gyroscope resonator itself. The master laser is stabilized to the gyroscope resonator's resonance frequency, eliminating the need for a separate reference resonator. This integration maintains frequency stability while reducing system complexity, size, weight, and cost
Solution Approach 2:
The gyroscope resonator serves dual functions: as the sensing element for rotation detection and as the reference resonator for master laser frequency stabilization. This multi-functionality eliminates redundant components while maintaining both measurement and stabilization capabilities
3Ease of operation
If resonance probing is performed asymmetrically in clockwise and counter-clockwise directions, then the system can operate, but rotation sensing errors occur
Solution Approach 1:
The patent intentionally introduces controlled asymmetry through different frequency modulation schemes for clockwise and counter-clockwise beams. This asymmetric modulation, combined with symmetric resonance probing, creates distinct frequency signatures that enable accurate signal separation and eliminate rotation sensing errors while maintaining operational simplicity
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 design simplifies signal processing, enhances symmetry in resonance probing, reduces complexity and cost, and improves the flexibility in choosing modulation frequencies, leading to improved performance and reduced errors in rotation sensing.
Implementation Method 1
an optical resonator ring cavity in optical communication with the first slave laser and the second slave laser, with the optical resonator ring cavity configured to receive the CW optical signal and the CCW optical signal
Implementation Method 2
A reflected optical signal from the resonator ring cavity is directed to a feedback laser stabilization loop for the master laser
Implementation Method 3
the first slave laser operatively coupled to the master laser and responsive to the reference optical signal through a CW optical phase lock loop
Data Source
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AI summary
A resonator fiber optic gyroscope comprises a master laser that emits a reference optical signal, a first slave laser that emits a clockwise optical signal, and a second slave laser that emits a counter-clockwise optical signal. A resonator ring cavity in optical communication with the first slave laser and second slave laser is configured to receive the optical signals from the slave lasers without receiving the reference optical signal. A reflected optical signal from the cavity is directed to a feedback laser stabilization loop for the master laser that includes a common modulation frequency scheme. A frequency of the optical signal from the master laser is indirectly locked onto a resonance frequency of the cavity with a fixed frequency offset, which is determined by a relative frequency between the optical signal of the first slave laser or the second slave laser, and the optical signal of the master laser.