Infrared Multi-Gas Measurement Using Tunable Multi-Band Laser Paths
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Solution Overview
Problem
Existing gas concentration measurement methods lack precision for high-demand environments and cannot simultaneously measure concentrations of multiple harmful gases, limiting their applicability in industries requiring accurate process control and environmental monitoring.
Innovation Solution
A method utilizing a 1.9 μm narrow-linewidth single thulium-doped solid-state laser to generate 2 μm near-infrared laser light, which is adjusted using an electronically controlled rotating mirror and gears to produce 3-5 μm mid-infrared and 6-12 μm far-infrared laser light, allowing simultaneous measurement of methane, ammonia, carbon monoxide, carbon dioxide, acetylene, ethylene, and ethane concentrations through a gas measurement cell and spectrometer analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement methods are used, then device complexity is low, but measurement precision is insufficient for high-demand environments
Solution Approach 1:
The measurement system is segmented into multiple independent laser sources, each operating at specific wavelengths (1.65 μm for methane, 3.3 μm for ammonia, 4.6 μm for carbon monoxide, etc.) that correspond to the absorption peaks of different gases. Each laser source can be independently controlled and optimized for measuring a specific gas type, enabling high-precision simultaneous multi-gas measurement while maintaining manageable system complexity through modular architecture
Solution Approach 2:
The system employs a universal measurement platform that can simultaneously detect multiple gas types (methane, ammonia, carbon monoxide, carbon dioxide, acetylene, ethylene, ethane) using the same basic optical path and detection cell. The multi-functional design allows a single system to perform what would traditionally require multiple separate measurement devices, improving precision across all gas types without proportionally increasing complexity
2Adaptability or versatility
If single-gas measurement methods are used, then device complexity is low, but adaptability for measuring multiple gases is insufficient
Solution Approach 1:
Multiple laser sources operating at different wavelengths are merged into a single optical measurement path that passes through a common gas detection cell. The system combines the output of seven different laser sources (corresponding to seven different gases) into one integrated measurement system, enabling simultaneous multi-gas detection. This merging approach increases adaptability while controlling complexity by sharing common components such as the detection cell, optical path, and data processing system
Solution Approach 2:
The system extends the measurement capability from single-wavelength to multi-wavelength dimension. By introducing laser sources at multiple discrete wavelengths (1.65 μm, 3.3 μm, 4.6 μm, etc.), the system adds a spectral dimension to the measurement process, enabling differentiation and simultaneous detection of multiple gas types based on their unique absorption spectra, thereby dramatically improving adaptability
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
Enables precise simultaneous measurement of multiple gas concentrations across near-infrared, mid-infrared, and far-infrared bands, improving measurement accuracy and capability beyond single-gas detection, thereby enhancing safety and compliance with environmental regulations.
Implementation Method 1
pumping Ho crystal by using a 1.9 μm narrow-linewidth single thulium-doped solid-state laser to obtain a 2 μm narrow-linewidth near-infrared laser output
Implementation Method 2
the 2 μm laser light enters a first four-mirror ring resonator at a second emergent angle, and is coupled to a first nonlinear crystal in the first four-mirror ring resonator to generate 3-5 μm mid-infrared laser light
Implementation Method 3
measuring spectral intensities of incident light and emergent light
Implementation Method 4
method for measuring concentrations of multiple gases by using an infrared band laser light
Data Source
AI summary
A method for measuring concentrations of multiple gases by using an infrared band laser light includes: pumping Ho crystal by using a 1.9 μm single thulium-doped solid-state laser to obtain a 2 μm band near-infrared laser output; controlling a light-emitting angle of 2 μm band laser light; allowing the 2 μm laser light to enter a first measurement cell at a first emergent angle, and measuring a concentration of methane gas in the first measurement cell; generating and introducing the 3-5 μm mid-infrared laser light into a second measurement cell to measure concentrations of ammonia gas and carbon monoxide in the second measurement cell; generating and introducing the 6-12 μm far-infrared laser light into a third measurement cell to measure concentrations of carbon dioxide, acetylene, ethylene and ethane gas in the third measurement cell.