Gas Analyzer Doubly Modulated Laser Light High Concentration Accuracy
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Solution Overview
Problem
Existing gas analyzers using singly modulated laser light face challenges in maintaining measurement accuracy at high gas concentrations, as the intensity of the returned light signal decreases, making it difficult to distinguish between high gas concentrations and other factors that may reduce signal intensity.
Innovation Solution
The gas analyzer employs a doubly modulated laser light, which calculates the intensity of concentration signals based on multiple frequency components of the returned light, thereby maintaining measurement accuracy even at high gas concentrations. This approach suppresses the decrease in returned light intensity signal and improves the linearity of the calibration curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If singly modulated laser light is used for gas concentration measurement, then the measurement setup is simple, but the returned light intensity signal decreases significantly at high gas concentrations, making it impossible to distinguish between high concentration and other signal degradation causes
Solution Approach 1:
The patent segments the returned light signal into multiple frequency components through double modulation. By modulating the laser light at two different frequencies and analyzing the resulting spectral components separately, the system can distinguish between signal intensity changes caused by high gas concentration versus other degradation factors, thereby maintaining measurement accuracy without oversimplifying the setup.
Solution Approach 2:
The patent transitions from single-frequency modulation to dual-frequency modulation, adding an additional dimensional parameter (second modulation frequency) to the measurement system. This enables the differentiation of signal characteristics that cannot be distinguished in the single-frequency domain, allowing accurate measurement even when overall signal intensity decreases.
2Ease of manufacture
If singly modulated laser light is used, then the calibration curve is easier to obtain, but the linearity of the calibration curve deteriorates at high gas concentrations, limiting the dynamic range
Solution Approach 1:
The calibration process is segmented into multiple frequency component analyses. By calibrating each frequency component separately and combining the results, the system maintains linear calibration characteristics across a wider dynamic range, including high gas concentrations, while preserving the practical ease of calibration through systematic procedures.
Solution Approach 2:
The patent changes the modulation parameters from single frequency to dual frequencies, which fundamentally alters the calibration curve characteristics. This parameter change enables the calibration curve to maintain linearity over a broader concentration range, expanding the measurable dynamic range while keeping the calibration process manageable through structured approaches.
3Productivity
If singly modulated laser light is used, then the measurement process is faster, but the returned light signal is more susceptible to degradation at high gas concentrations, reducing reliability
Solution Approach 1:
The measurement process segments the signal analysis into multiple frequency components that can be processed in parallel. This segmentation allows the system to maintain fast measurement speeds by utilizing parallel processing of spectral components while simultaneously improving reliability through the robustness of multi-frequency signal characteristics that resist degradation.
Solution Approach 2:
The system incorporates feedback mechanisms where the multi-frequency component analysis provides information about signal quality and gas concentration simultaneously. This feedback enables real-time assessment of signal integrity, allowing the system to maintain reliable measurements even when overall signal intensity decreases at high concentrations.
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 use of doubly modulated laser light in the gas analyzer enhances measurement accuracy across a wide range of gas concentrations, prevents signal degradation at high concentrations, and allows for the selection of concentration signals that avoid specific noise frequencies, thereby improving overall measurement precision.
Implementation Method 1
measuring gas concentration by means of laser light
Implementation Method 2
multiply-modulated measurement light
Implementation Method 3
an intensity of one frequency component of returned light yielded by multiply-modulated measurement light
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A gas analyzer (10) includes a calculator (181). The calculator (181) calculates an intensity of one concentration signal based on an intensity of one frequency component of returned light (102) yielded by multiply-modulated measurement light (101) passing and coming back through a gas to be measured (103), or intensities of a plurality of concentration signals based on respective intensities of a plurality of frequency components of the returned light (102). The calculator (181) calculates a measured value of concentration of the gas to be measured (103), based on the intensity of the one concentration signal or the intensities of the plurality of concentration signals.