Gas Spectrometer WMS DAS Dual Evaluation
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Solution Overview
Problem
Existing gas concentration determination methods, such as direct absorption spectroscopy (DAS) and wavelength modulation spectroscopy (WMS), face challenges in achieving high functional safety due to non-random errors from external influences like intensity fluctuations and pressure changes, which can lead to errors in gas concentration measurements, especially when using simultaneous or alternating applications of these methods.
Innovation Solution
A method that uses a single measurement with a tunable laser for wavelength modulation spectroscopy (WMS) to generate measurement points, which are then processed to create an artificial measurement curve that can be evaluated using both DAS and WMS methods, allowing for dual evaluation and validation of concentration values to enhance functional safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If DAS and WMS are used simultaneously or alternately to improve measurement accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines DAS and WMS measurement methods into a single spectrometer system that performs both evaluation types on the same measurement data. The control unit processes the detector signal to generate both direct absorption evaluation results and wavelength modulation evaluation results, merging the functionality of what would traditionally require separate measurement systems.
Solution Approach 2:
The spectrometer is designed with multi-functionality to perform both DAS and WMS evaluations using the same hardware components. The control unit can switch between different evaluation algorithms (direct absorption vs. wavelength modulation with harmonics analysis) based on the same detector signal, making the system universal in its measurement capabilities without requiring duplicate equipment.
2Reliability
If DAS and WMS are used alternately to reduce errors, then reliability is improved, but loss of time increases
Solution Approach 1:
The patent implements continuous measurement where the laser wavelength is continuously tuned across the absorption line while the detector signal is simultaneously evaluated using both DAS and WMS methods. This eliminates the need to alternate between separate measurement cycles, maintaining continuous useful action for both evaluation types throughout the tuning process.
Solution Approach 2:
Both DAS and WMS evaluations are performed concurrently on the same continuous detector signal during a single wavelength tuning sequence. The control unit processes the signal to extract both direct absorption information and modulation harmonic information simultaneously, combining the measurement processes to eliminate time loss from alternating measurements.
3Productivity
If a single measurement is used for both DAS and WMS evaluation, then productivity is improved, but measurement precision may worsen due to non-random errors
Solution Approach 1:
The system uses feedback by comparing results from both DAS and WMS evaluations of the same measurement. The control unit can validate concentration values by checking consistency between the two independent evaluation methods, using the agreement or disagreement between them as feedback to assess measurement quality and identify potential non-random errors.
Solution Approach 2:
The patent creates a form of measurement copying where the same detector signal is processed through two different evaluation algorithms (DAS and WMS). This produces parallel concentration determinations from the same data set, allowing validation without requiring a second physical measurement, thus maintaining productivity while improving precision through cross-verification.
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 enables the determination of gas concentrations with increased functional safety by reducing non-random errors, achieving a higher Safety Integrity Level (SIL) through the validation and averaging of concentration values obtained from different evaluation methods.
Implementation Method 1
Light is absorbed by the measurement gas in accordance with the Beer-Lambert law when running through the current ramp when the laser passes through the region of the absorption line.
Implementation Method 2
the wavelength is tuned slowly over an absorption line of the measurement gas and is additionally lightly modulated by a modulation frequency f, typically sinusoidal, with is high in comparison
Implementation Method 3
I=I0*e−α(λ)cL where α(λ) is the absorption dependent on the wavelength; c is the gas concentration; and L is the path over which the gas absorbs.
Data Source
AI summary
The invention relates to a method and to a spectrometer for determining the concentration of a gas component, wherein a light source of the spectrometer is operated as in wavelength modulation spectroscopy (WMS). Thus a determination of the concentration can also take place in accordance with WMS and the measured data can, however, additionally be processed, namely a sorting takes place on the time axis, such that the concentration can be determined using the methods of direct absorption spectroscopy (DAS).