Gas Sensor Calibration Using Nonlinear Function
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Solution Overview
Problem
Existing optical gas analysis methods using a reference light beam to estimate the light beam intensity in the absence of gas absorption are prone to significant uncertainty, affecting the precision of gas concentration measurements.
Innovation Solution
A method for calibrating gas sensors that involves a nonlinear calibration function to estimate the light beam intensity in the measurement spectral band without gas absorption, using measurements from a reference photodetector and varying the supply current to the light source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a reference light beam is used to estimate the light beam intensity in the absence of gas absorption, then the measurement process can be simplified, but significant uncertainty is introduced affecting measurement precision
Solution Approach 1:
The patent changes the parameter being measured from reference light beam intensity to directly measuring the light beam intensity in the measurement spectral band. By using a photodetector to directly measure the intensity parameter I0 in the absorption spectral band, the system eliminates the need for reference light beam measurements and the associated uncertainty, while maintaining operational simplicity through direct measurement
Solution Approach 2:
The patent extracts the essential measurement function by removing the reference light beam estimation step from the measurement process. Instead of using a reference photodetector to estimate I0, the system directly measures I0 using a photodetector configured to detect the light beam in the measurement spectral band, thereby eliminating the source of uncertainty while preserving the core measurement capability
2Reliability
If a reference photodetector is used to measure reference light beam intensity, then the light source intensity can be estimated, but errors in estimation propagate to concentration measurements
Solution Approach 1:
The patent converts the harmful effect of estimation errors by eliminating the estimation process entirely. Instead of using a reference photodetector to estimate light source intensity (which introduces errors), the system directly measures the light beam intensity I0 in the measurement spectral band using a photodetector, thereby transforming the problematic estimation approach into a direct measurement approach that eliminates error propagation
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 significantly improves the precision of gas concentration measurements by reducing errors associated with estimating light beam intensity, as demonstrated by reduced mean squared errors in concentration measurements.
Implementation Method 1
the gaseous species being able to absorb light in an absorption spectral band
Implementation Method 2
the measurement photodetector being designed to measure an intensity, referred to as measurement intensity, of a light beam emitted by the light source, transmitted by the gas contained in the chamber
Implementation Method 3
the reference photodetector being designed to measure a reference intensity of a reference light beam emitted by the light source in a reference spectral band
Implementation Method 4
the light source being configured to have a supply electric current passing through it so as to raise the light source to a temperature value
Data Source
AI summary
In a method for calibrating a gas sensor—for determining a gaseous species concentration in a gas, which species absorbs light in an absorption spectral band—the gas sensor includes a chamber for containing the gas; a light source through which a supply electrical current is passable to raise the light source to a temperature; a measurement photodetector for measuring—in a measurement spectral band comprising the absorption spectral band—a measured intensity of a light beam emitted by the light source and transmitted by the gas in the chamber; and a reference photodetector for measuring a reference intensity of a reference light beam emitted by the light source in a reference spectral band. A non-linear calibration function is determined to estimate an intensity, measured in the measurement spectral band by the measurement photodetector in the absence of gaseous species, from a reference intensity measured in the reference spectral band.