Coiled Fiber Gas Cell for Stable Optical Wavelengths in Compact Space

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Solution Overview

Problem

Existing gas cells face challenges in providing a stable optical wavelength light beam for long-duration space missions due to physical dimension constraints, weight, gas leak rate, and tolerance to shock and vibration, while also requiring a long service life.

Innovation Solution

A compact gas cell design featuring a glass ring with wound optical fiber, encapsulated in a molding material with slots filled with wavelength reference gas and a gas absorber to maintain stability and replace leaked gas, ensuring a stable optical wavelength light beam.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a traditional elongated gas cell is used to provide wavelength stability, then the optical wavelength stability is achieved, but the physical dimension and weight increase

Engineering Contradiction:
Improveoptical wavelength stabilityVSAvoidphysical dimension
Core Design Contradiction:
Measurement precisionVSLength of moving object

Solution Approach 1:

The patent winds optical fiber around a glass ring to form a compact coiled structure, nesting the fiber path within a small radial space. This allows a long effective optical path length (multiple windings) to be achieved within a compact cylindrical volume, resolving the contradiction between wavelength stability (requiring long path) and physical dimension (requiring compact size).

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

Instead of extending the gas cell in one dimension (elongated cylinder), the patent transforms the optical path into a two-dimensional coiled structure around a ring. The light travels through the gas in a spiral pattern, achieving long effective path length through radial and angular dimensions rather than linear extension, thus maintaining compact overall dimensions.

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

2Length of moving object

If a compact gas cell design is used to reduce physical dimension, then the size is reduced, but the gas leak rate increases

Engineering Contradiction:
Improvephysical dimensionVSAvoidgas leak rate
Core Design Contradiction:
Length of moving objectVSLoss of substance

Solution Approach 1:

The patent incorporates a gas absorber material within the glass ring structure that can absorb and retain reference gas. This creates a gas reservoir that compensates for gas leaks over time, maintaining stable wavelength reference despite increased leak rate from compact design. The absorber acts as a cushion against gas loss, extending the operational life of the compact cell.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Length of moving object

If a compact gas cell design is used to reduce physical dimension, then the size is reduced, but the tolerance to shock and vibration decreases

Engineering Contradiction:
Improvephysical dimensionVSAvoidtolerance to shock and vibration
Core Design Contradiction:
Length of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent uses a glass ring structure that provides mechanical strength and shock tolerance while maintaining compact dimensions. The glass material inherently provides vibration damping and structural integrity. Additionally, the coiled fiber structure within the ring distributes mechanical stresses, enhancing tolerance to shock and vibration despite the compact form factor.

Inventive Principle:
Principle #30Flexible shells and thin films

4Duration of action of stationary object

If traditional gas cell components are used to ensure long service life, then the lifespan is extended, but the weight increases

Engineering Contradiction:
Improveservice lifeVSAvoidweight
Core Design Contradiction:
Duration of action of stationary objectVSWeight of stationary object

Solution Approach 1:

The patent combines multiple functions into integrated components: the glass ring serves as both the structural support and the container for reference gas and absorber material. The optical fiber windings provide both the optical path and structural integrity. This merging of functions eliminates separate heavy components while maintaining long service life through the durable glass and fiber construction.

Inventive Principle:
Principle #5Merging (Combining)

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 compact gas cell design achieves a stable optical wavelength light beam with a long service life, tolerance to shock and vibration, and minimal physical dimensions, while maintaining wavelength stability and precision, even in demanding environments like space missions.

Implementation Method 1

a gas selected to impart a selective frequency characteristic to a coherent light beam passed through the chamber. The selective frequency characteristic of the gas functions as a filter

Methodology Applied
Scientific EffectAbsorption Spectroscopy: Absorption Spectroscopy

Implementation Method 2

a gas absorber to maintain stability and replace leaked gas

Methodology Applied
Scientific EffectAdsorption: Adsorption

Data Source

PatentEP3891542B1Generation of an optical beam with a stable wavelength
Publication Date: 2024.03.13 NORTHROP GRUMMAN SYSTEMS CORP
  • EP3891542B1 patent drawingFigure 1~4
  • EP3891542B1 patent drawingFigure 5~6
  • EP3891542B1 patent drawingFigure 7

AI summary

An exemplary gas cell is adapted to provide wavelength stability to a coherent beam of light. An optic fiber is wound in a plurality winding turns where the optic fiber transports the coherent beam of light from an input fiber end to an output fiber end. An encapsulating material engages and holds the windings in a fixed structure. A plurality of slots define severed portions of the optic fiber windings generally transverse to the windings and portions of the encapsulating material so that the optic fiber is divided into a plurality of end to end segments with open space filling the slots between respective facing ends of the severed optic fibers. A wavelength reference gas is disposed within the open space of the slots so that the beam of light passes from the input fiber end through respective facing ends of the optic fiber segments and wavelength reference gas in the corresponding slots to traverse a path through the plurality of winding turns to the output fiber end.