Circular Resonator Atomic Gyroscope With Evanescent-Wave Trapping

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Solution Overview

Problem

Conventional gyroscopes, including resonant fiber optic and atomic interferometer-based systems, face limitations in sensitivity, size, weight, power, cost, and stability, making them unsuitable for many modern applications that require higher rotation sensitivity and cost-effective mass production.

Innovation Solution

A circular resonator evanescent-wave trapped atomic gyroscope is developed, which generates cold alkali atoms around a circular resonator using continuous wave optical signals to trap and split their wave function, allowing for precise measurement of rotation rates through evanescent fields and optical pulses, enabling smaller, more stable, and cost-effective operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If atomic interferometer-based gyroscopes are used to achieve higher rotation sensitivity, then measurement precision is improved, but device complexity, size, weight, power consumption, and cost increase

Engineering Contradiction:
Improverotation sensitivityVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system is divided into distinct functional modules: a circular resonator for trapping atoms, evanescent wave generation components for splitting wave functions, and detection systems for measuring phase differences. This modular segmentation allows each component to be optimized independently while maintaining overall system performance, reducing total device complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs a circular resonator geometry to trap and guide atoms in a closed loop path. This curved, circular configuration enables continuous atom circulation and repeated measurement cycles, improving sensitivity while compacting the physical footprint of the system, thereby addressing both precision and size/complexity concerns.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Measurement precision

If atomic interferometer-based gyroscopes are used to achieve higher rotation sensitivity, then measurement precision is improved, but size and weight increase

Engineering Contradiction:
Improverotation sensitivityVSAvoidgyroscope weight
Core Design Contradiction:
Measurement precisionVSWeight of moving object

Solution Approach 1:

The system transitions from traditional linear or bulk atomic interferometer geometries to a two-dimensional circular resonator configuration. Atoms are confined to move along a circular path in a plane, reducing the three-dimensional volume and associated mass requirements while maintaining the interferometric measurement capability through the closed-loop geometry.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Measurement precision

If atomic interferometer-based gyroscopes are used to achieve higher rotation sensitivity, then measurement precision is improved, but power consumption increases

Engineering Contradiction:
Improverotation sensitivityVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The circular resonator enables continuous circulation of cold atoms around the loop, allowing the system to maintain measurement capability without repeated heating and cooling cycles. The evanescent wave trapping provides continuous confinement and the closed-loop geometry permits sustained atom circulation, reducing the energy required for atom preparation and maintenance compared to linear configurations.

Inventive Principle:
Principle #20Continuity of useful action

4Measurement precision

If atomic interferometer-based gyroscopes are used to achieve higher rotation sensitivity, then measurement precision is improved, but manufacturing cost and adjustability requirements increase

Engineering Contradiction:
Improverotation sensitivityVSAvoidmass production feasibility
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The system utilizes evanescent waves with specific frequency and intensity parameters to trap and manipulate atoms in the circular resonator. By carefully controlling these optical parameters, the system achieves stable atom confinement and interferometric measurement. The well-defined parameter requirements enable standardized manufacturing processes and reduce the need for complex post-assembly adjustments, improving mass production feasibility.

Inventive Principle:
Principle #35Parameter changes

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

The circular resonator evanescent-wave trapped atomic gyroscope provides enhanced sensitivity, stability, and reduced power consumption, meeting the SWAP-C requirements and enabling cost-effective mass production, while maintaining high rotation sensitivity.

Implementation Method 1

The first and second CW signals, coupled to the circular resonator, have evanescent fields around the circumferential surface of the circular resonator

Methodology Applied
Scientific EffectEvanescent field:

Implementation Method 2

trapping and cooling atoms so that the atoms move along a surface of a waveguide terminated by a waveguide loop

Methodology Applied
Scientific EffectOptical trapping: Optical Tweezers

Implementation Method 3

Each evanescent field splits the atomic wave function of the cold alkali atoms into two portions, where one portion travels around the circular resonator in a first direction and the other portion travels around the circular resonator in a second direction

Methodology Applied
Scientific EffectWave function splitting: Interference

Implementation Method 4

The atomic wave function portions experience a phase difference around the circular resonator based upon a rate of rotation around a center axis of the circular resonator. The phase difference is used to determine the rate of rotation around the center axis of the circular resonator

Methodology Applied
Scientific EffectSagnac effect: Sagnac Effect

Data Source

PatentEP3696505B1Circular resonator evanescent-wave trapped atomic gyroscope
Publication Date: 2021.06.30 HONEYWELL INTERNATIONAL INC
  • EP3696505B1 patent drawingFigure 1A
  • EP3696505B1 patent drawingFigure 1B
  • EP3696505B1 patent drawingFigure 1C

AI summary

Methods and apparatuses are provided for determining rate of rotation around a center axis of circular resonator by trapping cold alkali atoms around the circular resonator and utilizing Raman or Bragg interferometry.