Trace Gas Laser Spectrometer Curve Fitting
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Solution Overview
Problem
Current high resolution laser absorption spectrometers face challenges in achieving fast and reliable measurements of trace gases due to long computation times and hardware-related issues like laser instability and current noise, which hinder accurate curve fitting models and prevent zero testing.
Innovation Solution
A system that uses a computer with executable code to apply a curve fitting model, incorporating temperature and pressure values as parameters, and includes a peak tracking function to compensate for current noise and laser instability, enabling rapid and accurate trace gas concentration measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a numeric solution of Voigt line shape profiles is used for curve fitting, then measurement accuracy is improved, but computation time increases significantly
Solution Approach 1:
The patent pre-calculates and stores Voigt profile parameters (such as line strength, broadening coefficients) in lookup tables before actual measurements. During real-time operation, the system retrieves these pre-computed values instead of performing full numeric solutions, dramatically reducing computation time while maintaining accuracy through the use of pre-characterized spectral parameters
Solution Approach 2:
The system focuses curve fitting operations only on specific spectral regions containing absorption lines of interest, rather than processing the entire spectrum. By applying partial action to relevant wavelength ranges and using targeted fitting algorithms, the system achieves sufficient measurement accuracy with reduced computational burden
2Measurement precision
If conventional curve fitting models are used, then trace gas concentration can be measured, but laser instability and current noise cause model failure
Solution Approach 1:
The system continuously monitors laser current and temperature parameters during measurement and feeds this information back to the curve fitting algorithm. By incorporating real-time laser state data as correction factors, the model compensates for laser instability and current noise, maintaining reliability under varying operating conditions
Solution Approach 2:
The patent dynamically adjusts curve fitting parameters based on measured laser conditions. When laser instability or noise is detected, the system modifies fitting parameters such as line width, peak position, and baseline offset to account for these variations, allowing the model to remain robust across different laser states
3Productivity
If the system requires trace target gas to locate peaks for curve fitting, then measurement can proceed, but zero testing becomes impossible
Solution Approach 1:
The system pre-loads spectral database information containing expected absorption line positions and characteristics for target gases. During measurement, it compares observed spectra against these pre-stored reference patterns, allowing peak identification and curve fitting even when target gas concentration is extremely low or zero, thereby enabling zero testing capability
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 system significantly reduces computation time, provides real-time data, and compensates for temperature and pressure variations, achieving accurate trace gas measurements with minimal noise interference and eliminating the need for frequent calibration.
Implementation Method 1
high resolution laser absorption spectrometers have been utilized to measure part per billion (e.g. ppb) and sub ppb level of trace gases
Implementation Method 2
the change in laser intensity caused by the target gas absorption is measured by a detection system
Data Source
AI summary
An embodiment of a system for measuring trace gas concentration is described that comprises a laser absorption spectrometer configured to detect an absorbance measure from a trace gas, as well as a temperature value and a pressure value that correspond to an environment in a gas cell; and a computer having executable code stored thereon configured to perform a method comprising: receiving the absorbance value, the temperature value, and the pressure value; defining a fitting range associated with the trace gas; applying a curve fitting model in the fitting range to the absorbance value using the temperature value and the pressure value as model parameters; and producing a concentration measure of the trace gas.