Research On The Key Technology Of Three-gas Infrared Optical Sensor

With the development of the social and economic, there are so many occasions that needto use gas concentration testing techniques, such as hazardous gas concentrations test in mine,atmospheric gas composition test. Conventional gas sensor with single parameter detectionmethod has limited application and scope. In many cases, the measured gas is present in theform of mixed gas. With the use of a single gas sensor, toxic gases can not be detected if theyare not the target gas. So the test can not be guaranteed safety. It’s exactly need developing anew miniaturization optical multi-gas monitoring sensor.Based on the above, the multi-gas detecting system is achieved using the infraredabsorption spectrum principle. The design method of infrared optical detection system, theemulation design of light path and gas cell, and system’s hardware design are majorintroduced in this paper. Firstly, according to the infrared optical detection theories, westudied multi-component gas measurement principles and established the spectral absorptionmodel. Then the optical detection system of infrared gas sensor was designed. Focusing onmicro-reflection concentrating structure gas cell design, we calculated and designed aminiature reflection of concentrating cell structure. The zemax optical simulation softwarewas used to simulated the optical path of the gas cell. In order to improve the stability f thesensor and the accuracy of the test, the gas cell walls were plated and the protection of thesensor was designed. The gas cell, the light source and detector was assembled according to acertain order, and we constituted the micro gas-detection system. The detection hardwaresystem of the sensor has been designed. We focused on the weak signal amplifying circuitdesign and the light source modulation circuit design. To improve the measurement accuracy,we corrected the gas detection function model, according to the actual test temperature andhumidity on the test results. The mathematical model of the gas concentration was corrected by temperature and humidity compensation, and finally established a suitable mathematicalmodel. Under the existing experimental conditions, completed assembly the alarm deviceprototype and tested related experiments.All the analysis shows that this paper discussed the design process of infrared opticalthree-gas sensor systematically. All research of infrared three-gas sensors in this paperprovides practical reference value for the future development of other multi-gas sensor.