Optically Dithered Atomic Gyro-compass Bias Error Removal
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Solution Overview
Problem
Miniature gyrocompasses require accurate and stable gyroscopes for remote targeting applications, but existing MEMS gyroscopes face challenges with bias error and mechanical dithering introduces moving parts prone to wear and tear.
Innovation Solution
The use of optically dithered atomic gyro-compasses, which employ a vacuum chamber with laser-cooled alkali atoms and coherent laser pulses to modulate the sensing axis, achieving bias error removal without mechanical parts through electrical manipulation of light vectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If MEMS gyroscopes are used to create miniature gyrocompasses, then the device size and power consumption are reduced, but bias error increases and mechanical dithering introduces moving parts prone to wear and failure
Solution Approach 1:
The patent replaces mechanical dithering stages with an optical dithering system using Raman-Nath diffraction gratings. Laser beams are modulated to create virtual dithering motion of the sensing axis without any mechanical moving parts, eliminating wear and tear while maintaining bias error mitigation in miniature atomic gyroscopes
Solution Approach 2:
The patent changes the physical state of atoms from room temperature to laser-cooled ultracold states, and transitions from mechanical to optical dithering mechanisms. This parameter change enables miniature size while maintaining high reliability through optical rather than mechanical means
2Measurement precision
If accurate and stable gyroscopes are used to reduce bias error, then measurement precision improves, but device size, weight, and power consumption increase
Solution Approach 1:
The patent uses optical fields and Raman-Nath diffraction to replace heavy mechanical dithering mechanisms. This substitution achieves high measurement precision for bias error correction while keeping the device lightweight through the use of photonic rather than mechanical components
Solution Approach 2:
The patent introduces laser-cooled atoms as an intermediary medium between the optical dithering system and the sensing mechanism. These ultracold atoms serve as the sensing medium that enables high precision measurements without requiring heavy mechanical structures
3Measurement precision
If mechanical dithering is implemented to remove bias error, then measurement precision improves, but device complexity increases due to rotating stages and moving parts
Solution Approach 1:
The patent replaces complex mechanical dithering stages with a simplified optical system using modulated laser beams and Raman-Nath diffraction gratings. This substitution removes moving parts entirely while maintaining the ability to demodulate signals and eliminate bias error, significantly reducing device complexity
Solution Approach 2:
The patent creates virtual copies of mechanical dithering motion through optical means. By modulating laser beams to simulate the dithering motion that would be produced by mechanical stages, the system achieves the same measurement precision without the complexity of actual mechanical moving parts
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 method provides a miniaturized, accurate, and stable gyroscope solution that enhances signal-to-noise ratio for faster Earth's rotation axis identification, reducing the need for mechanical dithering and its associated failures.
Implementation Method 1
a vacuum chamber containing an atom cloud of laser cooled alkali atoms
Implementation Method 2
coherent laser pulses into the atom cloud that separate a quantum-mechanical wave function of the alkali atoms along trajectories
Implementation Method 3
the first set of laser sources and the second set of laser sources apply a dithering motion to the sensing axis by modulating a relative magnitude of the first set of laser beams with respect to the second set of laser beams
Implementation Method 4
A first optical element in the first optical system and a second optical element in the second optical system may be Raman-Nath diffraction gratings
Implementation Method 5
northfinding gyro-compasses operate by using gyroscopes to measure the Earth's rate of rotation
Implementation Method 6
each will measure a projection of the Earth's rotation onto the sensing axis of that gyroscope
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
Systems and methods for an optically dithered atomic gyro-compass are provided. In one embodiment, an inertial sensor comprises: a vacuum chamber containing a cloud of laser cooled alkali atoms, wherein the atoms are free to fall under the influence of gravity;a first set of laser sources applying a first set of laser beams into the cloud along a first axis;a second set of laser sources applying a second set of laser beams into the cloud along a second axis;wherein the first set and second sets of laser beams apply coherent laser pulses that separate a wave function of the atoms along trajectories defining a plane sensitive to rotation about an axis orthogonal to the plane; and wherein the first and second set of laser sources apply dithering to the axis by modulating a relative magnitude of the first laser beams with respect to the second laser beams.