Investigation Of Rapid Iodide Vapor Concentration Monitoring Technology

Molecular iodine laser has been widespread concern for its great appliedprospects. At Present, the research of photolysis or electrical excited Alkyl iodideongoing at home and abroad has initially proved that this laser will overcome thehuge volume, low energy conversion efficiency, low repetition rate and othershortcomings of the traditional Molecular iodine laser.But there exits a problem,that is the influence on frequency stability due to the serious loss caused by theAlkyl compound when the laser is running. So, it is necessary for the research of themolecular iodine laser to do some study of the concentration changes of Alkyl andits compounds, and the impact caused from them on the output light power. So,some research have been done for the rapid detection of the concentration changesof Alkyl and its compounds when the laser is running, that is to do some exploratorystudy of the rapid and high-precision detection method and the key technologies forthe situation of low concentration gas in this dissertation. In this system, anintegrated12-bit ADC microcontroller, STM32, has been chosen for dataacquisition and serial communication. The acquired data was taken into thecomputer for post-processing.As the preliminary study of the rapid detection for the concentration changes,the carbon dioxide gas is chosen instead of the Iodide. According to the principle ofinfrared radiation and infrared gas concentration detection, a rapid detection systemhas been designed for the Infrared carbon dioxide gas concentration. In design ofthe system, an incandescent, a pyroelectric detector and a thermistor is chosen asthe infrared light source, the gas concentration sensor and the temperature sensor,respectively, on the hardware. The Light modulation circuit, the concentrationmeasurement circuit, the temperature measuring circuit, the STM32microcontrollerminimum system circuits, digital to analog conversion circuit, the serialcommunication circuit, the power module circuit all have been designed. A method for increasing the reliability of the printing of PCB board has also been proposed.On the software, some programs have been written for the light modulation, dataacquisition and serial communication, respectively. One hertz sinusoidal modulationfor the light source,100Hz data acquisition for the signal from the detector, the datacommunication between the MCU and computer, all of them have been realized. Atlast, the detection system has been calibrated in the experimental conditions.The system showed very good performance when it was running in thelaboratory conditions. It was reflected in the three aspects followed. Firstly, on theside of hardware, the circuit can run stably all the time. Secondly, on the side ofsoftware, the signal data can be acquired by the programs accurately. Finally, thesystem can run stably and continuously. The sensitivity is200ppm, According to thesuccess of the carbon dioxide concentration detection, this system was proved that itcan be used to detect the concentration changes of the Iodide and its compoundssuccessfully in the process of the iodine-molecular laser running. It just needs tochange the pyroelectric detector, calibrate and debug the detection system.