Design And Implementation Of Optical Path For High-precision Toxic And Harmful Gas Sensor

In modern life,the environment issue has become more and more obvious to anyone who cares about living quality,especially air quality.So,it's very important to detect toxic and harmful gasses.In recent years,with the rapid developing manned space engineering,it is increasingly important to detect and control various toxic and harmful gases in the closed environment of spacecraft.High-precision toxic and harmful gas sensors are increasingly used in public health,medical and military applications.Infrared spectroscopy is one of the most rapidly developing high-tech analytical technologies in recent years.Because of many advantages,such as fast response,high efficiency,non-destructiveness and suitable for online analysis,high-precision toxic and harmful gas sensors based on infrared spectroscopy stand out of all gas sensors.And it has been a hot research area among the related fields.Based on the background above,this thesis designs and implements an optical path for high-precision toxic and harmful gas sensor.The main work is as follows:Firstly,it's necessary to understand the basic working principle and classification of existing gas sensors,analyzing the both advantages and disadvantages of various gas sensors,detection limitation conditions.Then,it's also need to clarify the development advantages of gas sensors which based on infrared spectrum analysis technology and research the current situation at home and abroad and analyze the market demand.Based on the Beer-Lambert Law which is the basic principle of gas detection,spectral absorption model and spectral line model,the basic CO and CH₄ gas absorption model can be constructed.The related theoretical formulas are used to analyze the temperature and pressure influence of gas sensors detection accuracy,thus clarifying how to achieve high-precision toxic and harmful gas sensors based on infrared spectrum analysis technology.Then,decomposing the high-precision toxic and harmful gas sensor optical path design into three major modules:infrared light source design,optical absorption cell design and receiver detector design.In each module,the performance indicators,advantages and disadvantages of the existing devices are discussed first,and then the resolution and detection efficiency of the high-precision toxic and harmful gas sensors are improved or redesigned.Among them,for the part of the optical absorption cell design,ZEMAX optical simulation software is specifically used to conduct a series of simulation experiments to verify the feasibility of the design scheme.Finally,the relevant experimental test of the designed high-precision toxic and harmful gas sensor light path is performed,and also the experimental results are processed and analyzed.The deficiencies and future prospects of the entire high-precision toxic and harmful gas sensor optical path design are summarized at the end of the thesis.