Atomic Oscillator Buffer Gas Pressure Compensation

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Solution Overview

Problem

Conventional gas-cell type atomic oscillators using alkaline gases experience shifts in resonance frequency due to fluctuations in buffer-gas pressure, leading to instability over time.

Innovation Solution

Incorporating two different alkali-metal atoms within the gas cell, where the resonance frequencies of each atom are measured to estimate buffer-gas pressure fluctuations, allowing for real-time adjustment of the frequency synthesizers to maintain stable oscillation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a gas cell encloses buffer gas to enable CPT resonance, then the atomic oscillator can achieve compact size and low power consumption, but the resonance frequency shifts due to long-term buffer-gas pressure fluctuations caused by gas leakage

Engineering Contradiction:

Improvefrequency stabilityVSAvoidlong-term operation stability

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent implements a feedback mechanism by continuously monitoring the resonance frequency of alkali metal atoms in the gas cell and using this information to adjust and compensate for buffer-gas pressure fluctuations. The system measures the resonance frequency shift caused by pressure changes and applies corrective actions to maintain stable oscillation frequency over long periods

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent utilizes the relationship between resonance frequency and buffer-gas pressure by measuring resonance frequency changes to estimate pressure fluctuations. By monitoring how the resonance frequency parameter changes with pressure, the system can detect and compensate for pressure variations without directly measuring pressure

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the atomic oscillator uses resonance frequency for frequency synthesis, then it achieves high frequency stability, but buffer-gas pressure fluctuations cause shifts in resonance frequency and reduce reliability

Engineering Contradiction:

Improveoscillation frequency reliabilityVSAvoidbuffer-gas pressure fluctuation impact

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system establishes a feedback loop that continuously monitors resonance frequency and uses this information to compensate for pressure-induced frequency shifts. By feeding back the measured frequency deviation and applying corrective adjustments, the system maintains reliable oscillation frequency despite buffer-gas pressure fluctuations

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent converts the harmful effect of buffer-gas pressure fluctuations into a useful measurement signal. By measuring the resonance frequency shift caused by pressure changes, the system gains information about pressure variations and uses this information to compensate for the original harmful effect, turning the frequency shift from a problem into a diagnostic tool

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 ensures high frequency stability over long periods by accurately compensating for pressure fluctuations, enhancing the reliability of the atomic oscillator's frequency output.

Implementation Method 1

an atomic oscillator employing CPT resonance

Methodology Applied

Scientific EffectCPT resonance:

Implementation Method 2

a second semiconductor laser for emitting a second laser light

Methodology Applied

Scientific EffectLaser emission: Laser

Implementation Method 3

the impact of fluctuations of buffer-gas pressure on the resonance frequency depending on the kind of atoms

Methodology Applied

Scientific EffectPressure-induced frequency shift:

Implementation Method 4

measuring resonance frequency of each atoms enclosed in a gas cell

Methodology Applied

Scientific EffectCPT resonance:

Data Source

PatentUS10720745B2Atomic oscillator

Publication Date: 2020.07.21 TOKYO METROPOLITAN PUBLIC UNIVERSITY CORPORATION

AI summary

The present invention provides an atomic oscillator comprising: a first frequency synthesizer for multiplying a reference frequency signal oscillated with a first voltage control oscillator by a first multiplication ratio and synthesizing a first high frequency signal; a first semiconductor laser for emitting a first laser light modulated by the first high frequency signal; a second frequency synthesizer for multiplying an output signal oscillated by a second voltage control oscillator with a second multiplication ratio and synthesizing a second high frequency signal; a second semiconductor laser for emitting a second laser modulated by the second high frequency signal; a gas cell being emitted with the first laser light and the second laser light simultaneously, the gas cell enclosing a first alkali-metal atom gas, a second alkali-metal atom gas, and buffer gas; and a computer for setting the first multiplication ratio in the first frequency synthesizer.