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Special gas detection
Laser-based special gas detection technology, as an important component of modern analytical science, focuses on measuring the concentrations of specific gas components (such as methane and carbon monoxide) and is primarily used in industrial safety, environmental monitoring, or the medical field.
1. The basic principle of laser gas detection
The physical basis of laser gas detection technology lies in the science of light-matter interactions, particularly the phenomenon of selective absorption of specific wavelengths of laser light by gas molecules. This phenomenon obeys Beer-Lambert’s law: when a monochromatic laser beam passes through a gaseous medium, the attenuation of its intensity is directly proportional to the gas concentration. Mathematically, this relationship is expressed as I = I0e^(-αCL), where I0 is the incident light intensity, I is the transmitted light intensity, α is the absorption coefficient, C is the gas concentration, and L is the optical path length. This fundamental equation forms the quantitative basis for most laser gas detection techniques; by precisely measuring the degree of light intensity attenuation, one can deduce the gas concentration.
The basic principle of gas detection
2. Classification of Laser Gas Detection Technology
Laser gas detection technology can be classified according to various criteria, including measurement principles, operating modes, and application scenarios. From the perspective of measurement principles, laser gas detection technology is primarily divided into three major categories: absorption spectroscopy, photoacoustic spectroscopy, and Raman spectroscopy. Each category has its own unique advantages and application scenarios.
According to the measurement method and operating mode, laser gas detection technology can be broadly classified into two major categories: in-situ and extractive. In-situ laser gas analyzers are directly installed on the process pipeline being monitored and can perform real-time, online measurements without the need for a sampling system. Extractive analyzers, on the other hand, use a sampling system to draw gas samples into a measurement chamber for analysis; they can also pre-process the samples (such as dust removal and dehumidification) to minimize environmental interference.
From the perspective of application fields, laser gas detection technology can be categorized into four major types: industrial process control, environmental monitoring, laboratory analysis, and portable field detection.
Comparison of Characteristics of Laser Gas Detection Technologies Classified by Application Area
Category | Core requirements | Technical Features | Typical representative | Application Cases |
Industrial Process Control | Real-time performance, stability | In-situ, anti-fouling design, resistant to high temperature and high pressure | In-situ TDLAS | Petrochemical Plant Pipeline Gas Monitoring |
Environmental monitoring | Multi-component, high sensitivity | Pull-type or multi-optical-path, precision temperature control | Photoacoustic Spectrometer | Urban Air Quality Monitoring Station |
Laboratory analysis | High precision, multi-function | Complex optical systems, multi-technology integration | Laser Raman spectrometer | Mixed Gas Composition Analysis |
Portable detection | Miniaturization, rapid response | Low-power design, integrated structure | Portable TDLAS | Natural Gas Pipeline Leak Detection |
3. Application fields of laser gas detection technology
Laser-based gas detection technology, with its advantages of high sensitivity, high selectivity, and non-contact measurement, has been widely applied in various fields such as industry, environment, energy, and healthcare, becoming an indispensable tool for modern gas analysis.
In Industrial Process Control In this field, laser-based gas detection technology has become a critical tool for optimizing production processes and ensuring production safety. The petrochemical industry is one of the largest markets for laser gas analyzers. In refineries, it is essential to monitor various process gases—including cracked gas and synthesis gas—in real time to guarantee the stability and safety of reaction processes. In-situ laser gas analyzers, with their advantages of eliminating the need for sample pretreatment and offering rapid response times, are particularly well-suited for such industrial applications.
The CNI-532nm laser is used in an in-situ laser Raman spectroscopy gas analyzer.
Environmental monitoring It is another important application area of laser gas detection technology. At urban air quality monitoring stations, laser gas analyzers can monitor in real time the concentration changes of pollutants such as sulfur dioxide, nitrogen oxides, and ozone, providing data support for environmental management.
CNI-450nm Laser Differential Photoacoustic Nitrogen Dioxide Gas Detection
Industrial Safety and Leakage Detection represents the third important application area for laser-based gas detection. Once gas leaks occur in facilities such as power plants, chemical plants, refineries, and natural gas transmission and distribution networks, they can lead to serious safety incidents. Laser-based gas detection technology, on the other hand, enables remote, non-contact measurements, making it particularly well-suited for leak detection in hazardous environments.
The CNI-303nm laser is used for SF6 decomposition detection in power systems.
In the ability to Source and Combustion In the field of optimization, laser-based gas detection technology provides critical parameters for the efficient operation of combustion equipment such as thermal power plants and industrial boilers. By continuously measuring the concentrations of components in flue gases—including oxygen, carbon monoxide, methane, and carbon dioxide—operators can precisely control the air-to-fuel ratio during combustion, ensuring complete combustion. This not only enhances energy utilization efficiency but also reduces pollutant emissions.
The CNI-1653/1654nm laser is used for methane detection.
Medical and Life Sciences This constitutes another important application area for laser-based gas detection technology. In respiratory gas analysis, laser spectroscopy can be used to monitor clinical parameters such as anesthetic gas concentrations and end-tidal carbon dioxide partial pressure, thereby ensuring surgical safety and providing support for critical care. Compared with traditional electrochemical sensors, laser detection technology features rapid response times, is unaffected by interference from other gases, and does not require frequent calibration, significantly reducing maintenance costs for medical institutions.
CNI tunable lasers (covering visible and mid-infrared wavelengths) for respiratory gas detection.
4. Laser for typical special gas detection by CNI
Changchun New Industry offers highly stable, narrow-linewidth semiconductor tunable lasers, DFB/DBR/VCSEL/FP narrow-linewidth lasers, quantum cascade lasers, and solid-state lasers, which are widely used in specialized gas detection technologies for gases such as CH4, H2S, NH3, H2O, CO, CO2, C2H4, HF, C2H2, SF6, and SO2.
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Semiconductor tunable laser 390-1074nm | DFB/DBR/FP lasers | quantity Cascade laser for children 3.6–10.5 µm | Solid-state laser 266 nm, 303 nm, 532 nm, etc. |
Welcome to CNI’s website at www.cnilaser.com or via email at sales@cnilaser.com to learn more.
Changchun New Industries Optoelectronics Technology Co., Ltd.
Address: No. 888 Jinhu Road, High-Tech Zone, Changchun, 130103, P.R.China
International Tel:+86-431-85603799
Email: sales@cnilaser.com
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