Optical Gyroscope Resonator Path Modulation for Bias Error Reduction
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Solution Overview
Problem
Optical gyroscopes face accuracy issues due to bias errors caused by imperfections in the design and manufacture of the resonator, leading to interference and reduced ability to distinguish resonance frequency changes caused by angular velocity from those caused by optical path length variations.
Innovation Solution
The implementation of path length adjustment members, such as microheaters or piezoelectric regions, to modulate the optical path length of the resonator, pushing resonance changes outside the bandwidth used for rate detection, thereby reducing bias errors and allowing for stable average resonant wavelength measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If path length adjustment members are used to modulate optical path length, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent introduces path length adjustment members as intermediary components that modulate the optical path length of the resonator. These members act as mediators between the laser source and the resonator, enabling precise control of the optical path to eliminate bias errors and improve measurement precision without fundamentally redesigning the entire gyroscope system.
Solution Approach 2:
The patent applies parameter changes by modulating the optical path length of the resonator using path length adjustment members. This dynamic adjustment of the optical path length parameter allows the system to push resonance frequency changes outside the detection bandwidth, thereby eliminating bias errors and improving measurement precision.
2Manufacturing precision
If resonator imperfections are present, then manufacturing precision deteriorates, but bias errors increase
Solution Approach 1:
The patent converts the harmful effect of resonator imperfections into a beneficial outcome by using path length adjustment members to actively compensate for these imperfections. The modulation of optical path length transforms the static bias errors caused by manufacturing imperfections into dynamic signals that can be pushed outside the detection bandwidth, thereby eliminating their harmful effects.
Solution Approach 2:
The patent applies preliminary action by pre-modulating the optical path length of the resonator using path length adjustment members before the resonance frequency changes caused by angular velocity occur. This preliminary modulation establishes a baseline that allows the system to distinguish between path length variations due to imperfections and those due to rotation, thereby eliminating bias errors.
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 enhances the accuracy of optical gyroscope measurements by eliminating bias errors and improving the distinction between phase changes caused by angular velocity and optical path length variations, leading to more precise rotation rate determination.
Implementation Method 1
the controller is configured to control the at least one path length adjustment member to modulate the optical path length of the resonator such that a frequency or wavelength corresponding to the optical path length is modulated outside a bandwidth of the optical gyroscope
Implementation Method 2
A common phenomenon exhibited by optical gyroscopes is the change in optical path length due to the Sagnac effect. As the winding circle is rotated in a CW direction about the sense axis, the CW optical beam propagating in the CW direction effectively experiences a longer optical path length
Data Source
AI summary
Techniques for reducing the bias error present in optical gyroscopes is disclosed. Such techniques include at least one path length adjustment member placed in an optical gyroscope resonator, which are configured to modulate the optical path length of the resonator so that bias errors attributable to the optical path length are shifted outside of the bandwidth of the optical gyroscope. In some embodiments, the at least one path length adjustment member includes a plurality of microheaters coupled to the resonator, in which case optical path length modulation is achieved by heating the resonator via the microheaters. Alternatively, a plurality of piezo-electric regions can be placed in the resonator, which enables optical path length modulation through electric field gradients applied to the piezo-electric regions.