Resonator Optical Gyroscope Polarization Control for Bias Error
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Solution Overview
Problem
Resonator optical gyroscopes face bias errors due to the existence of parasitic modes (TE and TM) that have different effective indices of refraction and temperature coefficients, which are difficult to compensate for.
Innovation Solution
The use of at least two polarizing beam splitters (PBS) to suppress the energy of parasitic modes more than the desired modes, combined with a travelling wave resonator system that propagates optical signals in one direction, and a beat detector to determine rotation rate by adjusting carrier frequencies to resonate with the resonator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single electromagnetic mode (TE or TM) is used in the resonator optical gyroscope, then the device complexity is reduced, but bias error increases due to the existence of parasitic modes with different effective indices of refraction and temperature coefficients
Solution Approach 1:
The patent extracts and removes the parasitic electromagnetic mode from the system by using a polarizing beam splitter to separate the desired mode from the parasitic mode. This extraction principle eliminates the source of bias error while maintaining system simplicity, resolving the contradiction between device complexity and measurement precision
Solution Approach 2:
The patent introduces a polarizing beam splitter as an intermediary component between the optical source and the resonator. This mediator selectively transmits the desired electromagnetic mode while blocking the parasitic mode, thereby improving measurement precision without significantly increasing device complexity
2Device complexity
If parasitic modes are allowed to exist in the resonator optical gyroscope, then the device complexity remains low, but bias error occurs that is difficult to compensate for due to variations in effective indices of refraction and temperature coefficients
Solution Approach 1:
The polarizing beam splitter extracts the parasitic mode from the optical path before it can enter the resonator. By removing the harmful parasitic mode at the source, the system achieves reliable and stable output without requiring complex compensation mechanisms for temperature and stress variations
Solution Approach 2:
The patent applies preliminary anti-action by using the polarizing beam splitter to prevent the parasitic mode from entering the resonator in the first place. This preventive measure eliminates bias error before it can occur, ensuring output stability without adding complex real-time compensation systems
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
Significantly reduces bias errors in resonator optical gyroscopes by effectively suppressing parasitic modes, enhancing accuracy and reliability.
Implementation Method 1
at least two polarizing beam splitters (PBS) to suppress the energy of parasitic modes more than the desired modes
Implementation Method 2
adjusting a carrier frequency of the CW optical signal emitted from the optical source to equal a resonant frequency of the travelling wave resonator in a CW direction
Implementation Method 3
determining a rate of rotation of the resonator optical gyroscope around a center axis of the travelling wave resonator
Data Source
Figure 1A
Figure 1B
Figure 1C~1D
AI summary
Techniques are provided for diminishing bias error, in a resonator optical gyroscope, due to an undesired, parasitic optical mode which is orthogonal to a desired optical mode. Energy levels of the undesired, parasitic mode can be diminished utilizing polarizing beam splitters each of which suppresses energy of the undesired, parasitic mode of a clockwise or a counterclockwise optical signal more than energy of the desired mode of the CW optical signal. Optionally, one or more components of a travelling wave resonator system are configured to suppress energy of the undesired, parasitic mode of a clockwise and/or a counterclockwise optical signal more than energy of the desired mode of the respective optical signal(s). Optionally, the desired optical mode is either a transverse magnetic (TM) mode or a transverse electric (TE) mode, and the undesired, parasitic optical mode is respectively the TE mode or the TM mode.