Laser Wavelength Referencing via Temperature-Compensated Current
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Solution Overview
Problem
Optical measuring systems for gas concentration face challenges in maintaining accurate wavelength distance between target and reference gas absorption lines due to long-term changes in lasers and external temperature fluctuations, leading to measurement errors and the need for frequent recalibration.
Innovation Solution
The method involves maintaining a relative temperature difference between the reference and target gas absorption lines by calculating the required instantaneous base current for the target gas based on the electrical power difference at the peak positions, ensuring precise wavelength determination and reducing measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed current distance is used to reference the target gas absorption line to the reference gas absorption line, then the wavelength distance can be maintained during calibration, but long-term changes in the laser and external temperature fluctuations cause the wavelength distance to deviate, requiring frequent recalibration
Solution Approach 1:
The patent changes the parameter used for referencing from a fixed current distance to a dynamic temperature-compensated current distance. By monitoring the actual temperature of the laser and applying compensation based on pre-determined temperature coefficients, the system maintains accurate wavelength distance despite temperature fluctuations and laser aging, eliminating the need for frequent recalibration
Solution Approach 2:
The patent implements a feedback mechanism where the actual laser temperature is continuously monitored and used to adjust the base current for maintaining accurate wavelength distance. The system measures the temperature, calculates the required compensation based on stored coefficients, and adjusts the current accordingly, creating a closed-loop control that maintains precision over time
2Measurement precision
If the laser base temperature is stabilized, then the wavelength position can be maintained during calibration, but external temperature fluctuations and long-term laser changes still cause wavelength drift, necessitating recalibration
Solution Approach 1:
The patent introduces temperature compensation as a dynamic parameter adjustment mechanism. By storing temperature coefficients determined during calibration and applying real-time temperature compensation to the base current, the system extends the validity period of calibration while maintaining wavelength position accuracy despite external temperature changes and laser aging
Solution Approach 2:
The patent performs preliminary determination of temperature coefficients during the calibration phase. These pre-determined coefficients are stored and later used to calculate compensation values during operation, allowing the system to proactively counteract temperature effects before they cause wavelength drift, thereby extending calibration validity
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 allows for precise and stable measurement of gas concentrations, even when reference and target gas absorption lines are significantly distant, and simplifies calibration, reducing noise and measurement errors caused by temperature changes and laser aging.
Implementation Method 1
optical measuring system for measuring the concentration of a target gas component (ZG) in a measured gas (2) by way of laser absorption spectroscopy (LAS)
Implementation Method 2
wavelength-tunable temperature-stabilized laser light source (3)
Data Source
AI summary
A method for operating an optical measuring system including a wavelength-tunable temperature-stabilized laser light source for measuring the concentration of a target gas in a measured gas, wherein an instantaneous base current IDC_ZG,act corresponding to a wavelength λZG of a target gas absorption line is set so that a wavelength distance ΔλDC defined during calibration between a target gas absorption line for a target gas and a reference gas absorption line for a reference gas is maintained. During operation, a temperature difference in the laser light source, defined in advance during calibration, between the operating points selected at the time of calibration of the reference gas, with a base current IDC_RG,cal, and the target gas, with a base current IDC_ZG,cal, is maintained by determining the required instantaneous base current IDC_ZG,act for the target gas, as a function of an instantaneous base current IDC_RG,act for the reference gas.