Laser Frequency Stabilization with Error Detection

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Solution Overview

Problem

Existing laser apparatuses fail to detect temporary deviations in laser frequency due to external disturbances, leading to instability and unreliable measurement results, as they primarily monitor drive current rather than the frequency itself.

Innovation Solution

A laser apparatus comprising a laser light generator, detector, differential signal generator, frequency locker, and error detector, which adjusts the laser frequency within a predetermined range, detects deviations using a saturated absorption line, and includes a drive status controller to suspend frequency stabilization when errors are detected, ensuring automatic suspension of laser emission when frequency instability occurs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If drive current monitoring is used to detect laser degradation, then long-term degradation can be detected, but temporary frequency deviations due to external disturbances cannot be detected

Engineering Contradiction:
Improvedetection capabilityVSAvoidfrequency deviation information
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

An error detector is introduced as an intermediary component that monitors the output of the frequency locker and generates error signals when frequency deviations occur. This intermediary device bridges the gap between the frequency stabilization system and the external disturbance detection requirement, enabling detection of temporary frequency deviations without interfering with the existing drive current monitoring system.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The error detector is designed to work alongside the existing drive current monitoring system, creating a multi-functional detection mechanism. The system now serves dual purposes: the drive current monitor detects long-term degradation while the error detector captures temporary frequency deviations, together providing comprehensive laser performance monitoring.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Stability of the object's composition

If frequency stabilization is continuously maintained, then frequency stability is improved, but external disturbances cause temporary deviations that go undetected and lead to unreliable measurements

Engineering Contradiction:
Improvefrequency stabilityVSAvoidmeasurement reliability
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The error detector provides feedback about frequency deviations to the system operator or control mechanism. When the error detector generates an error signal indicating a frequency deviation, this feedback enables timely intervention or suspension of measurements, preventing unreliable results while maintaining continuous frequency stabilization effort.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs preliminary detection of frequency deviations before they compromise measurement reliability. By continuously monitoring for error signals from the error detector, the system can identify temporary frequency deviations early and take preventive action, such as suspending measurements, before unreliable data is generated.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If the laser apparatus operates continuously without suspension, then productivity is maintained, but frequency deviations from external disturbances lead to unreliable measurement results

Engineering Contradiction:
Improvecontinuous operation capabilityVSAvoidmeasurement reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system implements periodic checking of frequency stability through the error detector, which continuously monitors for deviations and generates error signals periodically. This allows the laser to operate continuously with periodic verification of frequency stability, suspending operations only when necessary to maintain measurement reliability.

Inventive Principle:
Principle #19Periodic action

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 solution effectively detects and responds to temporary frequency deviations caused by external disturbances, maintaining frequency stability and enabling reliable measurement by automatically suspending laser emission when necessary, thus preventing unreliable results.

Implementation Method 1

The laser light detector bombards an iodine cell with the laser light and photoelectrically converts the laser light that has passed through the iodine cell

Methodology Applied
Scientific EffectPhotoelectric conversion: Photoelectric Effect

Implementation Method 2

detects an amplitude corresponding to a saturated absorption line occurring in the differential signal, and causes the frequency of the laser light to stabilize to a predetermined value

Methodology Applied
Scientific EffectSaturated absorption: Absorption Spectroscopy

Data Source

PatentEP2800213B1Laser-Apparatus
Publication Date: 2017.08.02 MITUTOYO CORP
  • EP2800213B1 patent drawingFigure 1
  • EP2800213B1 patent drawingFigure 2
  • EP2800213B1 patent drawingFigure 3

AI summary

A laser light generator emits laser light, a frequency of which can be adjusted. A laser light detector bombards an iodine cell with the laser light and photoelectrically converts the laser light that has passed through the iodine cell, then outputs a light output signal. A third order differential lock-in amplifier generates a third order differential signal of the light output signal. A frequency locker causes the laser light generator to change the frequency of the laser light within a predetermined range, detects an amplitude corresponding to a saturated absorption line occurring in the third order differential signal, and causes the frequency of the laser light to stabilize to a predetermined value. An error detector outputs an error signal in a case where the amplitude corresponding to the saturated absorption line occurring in the third order differential signal is greater than a predetermined value.