Design of soil respiration monitoring system based on TDLAS technology

In view of the problems of low detection accuracy, inability to monitor real-time and high cost of measuring instruments in the traditional soil respiratory CO2 concentration detection method, a soil respiratory CO2 concentration online monitoring system is designed by using tunable laser diode absorption spectroscopy technology, which uses the optical path of the three-channel White pool as a CO2 sensor, the DFB laser as the light source, and the real-time inversion processing of the concentration data by the host computer. The host computer software is written by LabViewsoftware, which mainly includes modules such as data acquisition and control, spectral processing, concentration inversion, data and function display, and storage. The system was tested and calibrated in the experimental environment, and the test results showed that the concentration calibration linearity of the three sensors reached more than 0.99. Finally, the actual test verification was carried out in the soil environment of the campus, and the results showed that the change in the relationship between the concentration gradient and the height of the three sensors in the instrument was in line with expectations.