Miniature NMR Gyroscope Optics Cell Polarization Control

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Solution Overview

Problem

Current optics cells for miniature nuclear magnetic resonance (NMR) gyroscopes face challenges in efficiently splitting and polarizing laser beams to effectively detect noble gas moments, which affects the accuracy of rotation sensing.

Innovation Solution

A compact optics cell design incorporating a polarizing beamsplitter, quarter waveplates, and adjustable polarizers to split incident laser beams into circularly and linearly polarized pump and detection beams, ensuring optimal interaction and detection within a miniature NMR gyroscope.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a compact optics cell design is used to reduce size, then the device fits miniature NMR gyroscope requirements, but beam splitting and polarization efficiency deteriorates

Engineering Contradiction:
Improveoptics cell sizeVSAvoidrotation sensing accuracy
Core Design Contradiction:
Volume of moving objectVSMeasurement precision

Solution Approach 1:

The optics cell is segmented into distinct functional zones: a polarizing beamsplitter separates the laser beam into pump and detection paths, quarter-wave plates create circular polarization for pumping while maintaining linear polarization for detection, and adjustable polarizers fine-tune the polarization states. This segmentation allows each component to optimize its function within the compact volume, maintaining measurement precision despite reduced size.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs three-dimensional beam path folding using multiple mirrors and the beamsplitter to create perpendicular pump and detection beam paths. This dimensional arrangement allows sufficient optical interaction length within a compact footprint, maintaining sensing accuracy while reducing the overall optics cell volume to fit miniature NMR gyroscope requirements.

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

2Manufacturing precision

If adjustable polarizers and variable split ratio beamsplitters are incorporated to improve beam control, then polarization precision improves, but device complexity increases

Engineering Contradiction:
Improvepolarization control precisionVSAvoidoptics cell component count
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent incorporates adjustable polarizers with variable angles and a polarizing beamsplitter with adjustable split ratio to dynamically optimize polarization control. These adjustable elements allow fine-tuning of the pump and detection beam characteristics during operation or calibration, achieving high polarization precision. The adjustability is implemented through mechanical mounting configurations that enable angle adjustment without requiring complex active control systems, thus balancing precision with manageable device complexity.

Inventive Principle:
Principle #15Dynamics

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 enhances the precision of rotation sensing by ensuring circular polarization of the pump beam and linear polarization of the detection beam, allowing for accurate modulation and detection of noble gas moments, thereby improving the overall performance of the NMR gyroscope.

Implementation Method 1

a polarizing beamsplitter, quarter waveplates, and adjustable polarizers to split incident laser beams into circularly and linearly polarized pump and detection beams

Methodology Applied
Scientific EffectPolarization: Polarisation

Implementation Method 2

a polarizing beamsplitter, quarter waveplates, and adjustable polarizers to split incident laser beams into circularly and linearly polarized pump and detection beams

Methodology Applied
Scientific EffectQuarter wave plate effect: Polarisation

Implementation Method 3

detected as modulation of a light beam

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentEP2350564B1Small optics cell for miniature nuclear magnetic resonance gyroscope
Publication Date: 2013.06.05 NORTHROP GRUMMAN GUIDANCE AND ELECTRONICS CO INC
  • EP2350564B1 patent drawingFigure 1~3
  • EP2350564B1 patent drawingFigure 4~5
  • EP2350564B1 patent drawing

AI summary

A beamsplitter (60) is arranged to split an incident laser beam into a pump beam (61) and a detection beam (83). The pump beam (61) passes through the beam splitter (60) and then reflects from a pair of mirrors (66, 78) to a quarter waveplate (74) into an interaction cell (76). After passing through the interaction cell (76), the pump beam (61) reflects from a mirror to a first photodetector. The detection beam (83) reflects from the beam splitter (60) and propagates on a path perpendicular to the path of the pump beam (61) through the interaction cell (76). After passing through the interaction cell (76), the detection beam (83) is incident upon a polarizer (84). The polarized portion of the detection beam (83) then is incident upon a photodetector (86).