Gas Analysis System Optical Interference Noise Removal
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Solution Overview
Problem
Gas analysis systems using wavelength-modulation spectroscopy face challenges in improving detection limits due to optical interference noise, which complicates precise measurement of gas concentrations, especially at low concentrations, and existing methods to mitigate this noise are costly and cumbersome.
Innovation Solution
The system calculates and removes the second component of optical interference noise from the detected signal before measuring the gas concentration, using a laser light modulated by a specific frequency and employing a processor to subtract the noise component, thereby improving detection limits without increasing costs or complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wavelength-modulation spectroscopy is used to increase measurement precision, then sensitivity improves, but optical interference noise worsens the detection limit
Solution Approach 1:
The patent segments the 2f component signal into two parts: the gas absorption signal and the optical interference noise. By using a reference cell without target gas, the system separately measures and subtracts the noise component from the total 2f signal, effectively isolating and removing the harmful interference while preserving the measurement precision benefits of wavelength-modulation spectroscopy
Solution Approach 2:
The reference cell acts as an intermediary that captures only the optical interference noise without the gas absorption signal. This intermediary measurement allows the system to calculate and remove the noise component from the main measurement path, resolving the contradiction between maintaining sensitivity and eliminating interference noise
2Measurement precision
If conventional methods are used to remove optical interference noise, then detection limit improves, but device complexity and cost increase
Solution Approach 1:
The reference cell and processing methodology serve multiple functions: it characterizes optical interference noise, provides real-time noise compensation, and works with any wavelength-modulation spectroscopy system. This universal approach improves detection limits without requiring complex system-specific modifications or additional expensive components
Solution Approach 2:
The patent replaces complex mechanical or optical noise filtering systems with a computational approach. By using software-based signal processing to subtract the noise component measured from the reference cell, the system achieves improved detection limits without adding mechanical complexity or expensive optical filtering components
Data Source
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AI summary
A gas analysis system (1) includes: a light-emitting element (13) configured to emit a laser light modulated by a predetermined modulation frequency; and a light-receiving element (17) configured to: receive the laser light that has passed through a measurement target gas; and upon receiving the laser light, output a received signal having an N-frequency that is n times the predetermined modulation frequency, wherein n is an integer no less than 2; and a signal processing device (20) configured to: calculate a third component by removing, from a first component having the N-frequency, a second component, wherein the second component is a component of optical interference noise arising on an optical path of the laser light from the light-emitting element (13) to the light-receiving element (17) and has the same frequency as the first component; and calculate, based on a magnitude of the third component, a concentration of the measurement target gas.