Optical Interference And Its Suppression In Semiconductor Laser Spectroscopy Based Gas Detection Systems

My country is a big energy country.The exploitation and use of energy has created a lot of convenience for people’s lives.However,in energy mining,especially coal mining,there will be leakage of coalbed methane or gas,and a gas explosion will occur at a certain concentration,causing casualties.In order to detect the gas concentration in time,the system for detecting methane gas concentration in absorption spectroscopy technology using tunable laser diodes is studied.Gas and natural gas contain a large amount of alkanes,and methane in alkanes accounts for a large proportion.The country now also advocates a green environmental protection policy.Carbon dioxide is a greenhouse gas.In fact,it is not only carbon dioxide.Methane is also a greenhouse gas.The application of tunable semiconductor laser absorption spectroscopy technology in the atmosphere can realize the monitoring and detection of methane gas in the atmosphere.Methane is a kind of gas that has no color and no special smell.Even if there is a leak,it is not easy to be detected by people.In terms of density,the relative atomic mass is 16,which is lighter than air.The gas explosion of industrial and mining enterprises,natural gas pipelines in life Leakage problems are caused by excessively high content of methane,its main component,which will cause casualties and waste of resources.It requires a detection device that can give early warning in time.There are many traditional methods,but they are common and require repeated adjustments.,Slow response time and other issues.The development of spectroscopy technology provides a new method for gas detection.The use of laser absorption spectroscopy for gas detection is more accurate and efficient,especially for measuring methane gas.It is mainly an optical technology that uses semiconductors.The laser is the light source,which can realize the detection of gas with high accuracy.It has the characteristics of high sensitivity,high resolution and timely response.It has been widely studied in major research institutes and universities at home and abroad,and has a high degree of social recognition.The laser methane sensor is easy to maintain,easy to adjust,and simple to use.With the development of semiconductor laser technology in recent decades,methane sensors based on laser technology have achieved rapid development in recent years and have gradually entered the industrial field.The laser methane sensor is a feasibility device,which mainly uses a semiconductor laser as the light source and uses the method of spectroscopy to detect the concentration of methane gas.The core light source of the laser methane sensor is a semiconductor laser.The laser control circuit is used to achieve the purpose of wavelength tuning.The gas absorption cell is filled with the methane gas to be measured.The use of photodetectors and the application of signal processing technology will contain gas.The optical signal that absorbs the signal is converted into an electrical signal for electrical signal processing,and there is no conversion of other physical quantities,which is simple and efficient.The characteristics of the laser methane sensor include: full range,high precision measurement,high degree of intelligence,long adjustment cycle,etc.With the development of semiconductor technology and optical fiber sensing technology,laser sensors based on tunable semiconductor laser spectral absorption are more and more popular.The main content of this article includes the following aspects:(1)A laser made of semiconductor materials is used as the core light source to analyze the absorption characteristic spectrum and realize the detection of methane gas concentration.The basic principles of tunable diode laser absorption spectroscopy technology are explained,including gas molecule absorption theory,Beer-Lambert absorption theorem,absorption line function in gas molecule spectrum absorption theory,absorption line intensity and line width detection technology and detection technology,etc.(2)The composition of the entire laser methane detection system is studied.The entire system is mainly composed of a semiconductor laser,a photodetector,a gas absorption cell,and a circuit part.(3)The optical interference problems encountered in the laser excitation methane detection system experiment were analyzed,and the interference position was obtained by changing the calculation,the gas pool structure was changed,and the lens structure was changed to achieve interference suppression.(4)Perform long-term stability tests on the components and core optical modules used in the laser methane detection system to test whether there will be optical interference problems due to aging in the long-term experiment.(5)For the literature research and experimental research carried out in this article,the work done is summarized,and the direction for future experiments is proposed.