In order to monitor carbon monoxide in industrial production, we developed a passive gas radiation measurement system based on Fourier transform infrared spectroscopy and carried out infrared radiation measurement experiment of carbon monoxide detection in simulated industrial production environment by this system. The principle, condition, device and data processing method of the experiment are introduced in this paper. In order to solve the problem of light path jitter in the actual industrial field, we simulated the noise in the industrial environment. We combine the advantages of MATHEMATICA software in the aspects of graph processing and symbolic computation to data processing to improve the signal noise ratio and noise suppression. Based on the HITRAN database, the nonlinear least square fitting method was used to calculate the concentration of the CO spectra before and after the data processing. By comparing the calculated concentration, the data processed by MATHEMATICA is reliable and necessary in the industrial production environment.
Passive Fourier-transform infrared (Passive-FTIR) spectroscopy allows rapidly identification of the air pollution. However, for the localization of a leak and a complete assessment of the situation in the case of the release of a hazardous chemical gas or biological cloud, information about the position and the spatial distribution of a cloud is very important. In this work, a scanning imaging passive FTIR system, which composed of an interferometer, a data acquisition and processing software, a scanning system, a video system, and a laptop has been developed. The concentration retrieval algorithm for the passive FTIR remote measurement of gas cloud is presented, which involves the infrared radiative transfer model, radiometric calibration and absorption coefficient calculation. The concentration of the object gas is retrieved by using the
nonlinear least squares method. And no background spectra are required. The remote sensing experiment of SF6 was carried out. The measuring result shows that, the column densities of all directions in which a target compound has been identified may be retrieved by a nonlinear least squares fitting algorithm and algorithm of radiation transfer, a false color image is displayed. The results are visualized by a video image, overlaid by false color concentration distribution image. The system has a high selectivity, and it allows visualization and quantification of pollutant clouds. The system allows mobile, real-time and fast measurements of chemical gas and biological clouds.
A method for the measurements of atmospheric transmittance by FTIR spectrometer is proposed. Calibrating special response of system based on two-point temperature with blackbody, transmittance spectra of CO<sub>2</sub> IR absorption band are analyzed and calculated depending on the measurement data. The CO<sub>2</sub> concentration in atmosphere is acquired after fitting the measured spectra with the line parameter in HITRAN employing NLLS algorithm. The results agree with the standard CO<sub>2</sub> concentration considered in the environmental monitoring. It indicates that the method is feasible for measuring atmospheric transmittance and analyzing gases in quantity.