Many industrial gases and aerosols have rich spectral characteristics in the long-wave infrared band, which can play an important role in gas detection and chemical protection. In this paper, the principle of Gaussian filtering and the establishment process of Gaussian operator are introduced, and a noise suppression method of long-wave infrared Fourier spectrometer at various piecewise is proposed. The amplitude of interference signal is mapped into noise estimation weight, and then the size and weight of Gaussian filter window are selected to realize adaptive Gaussian filtering of noise estimation weight. Compared with median filtering, mean filtering and single window Gaussian filtering, the experiment shows that the proposed algorithm can protect the spectral energy and suppress the influence of noise on the signal, and the filtering effect is obvious.
KEYWORDS: Spectroscopy, Interferometry, Data modeling, Signal to noise ratio, Interference (communication), Sensors, Data acquisition, Black bodies, Statistical modeling, Fringe analysis
Many sources of spectrometer system noise are introduced, which will be superimposed on the interference data. In this paper, the statistical properties of noise are analyzed, and Gaussian models are established by extracting features from the actual collected interferometric data. For 30-degree and 35-degree target radiation sources, the same sets of interferometric data are collected, and the histogram of noise is established and the curve is fitted to match the corresponding Gaussian model. The ideal interference fringe is simulated for the studied spectrometer object, and the effect of Gaussian noise on the interference fringe is analyzed, and the experiments prove that the effect of the noise-added interference fringe is close to that of the measured interference fringe.
Fourier Transform Infrared(FTIR) spectroscopy has many advantages, such as high light flux, high resolution, high sensitivity and so on, and has been widely used in the field of industrial gas monitoring. Unit detector is used by traditional Fourier transform infrared spectrometer, which needs scanning platform to assist imaging, and the structure of spectrometer is complex. In order to satisfy the application of small area array detector spectrometer, this paper is based on the small area array HgCdTe photoconductive long wave infrared detector and double pendulum interferometer. The working principle and signal characteristics of the spectrometer are analyzed, and a method of multi-channel weak interference signal detection circuit for 4×4 small area array detector is proposed, and the method is simulated and verified by experiments. Using Multisim software to simulate the circuit, the results show that the circuit has good band-pass characteristics and can achieve distortion-free signal amplification. The collected interference data are analyzed by using MATLAB software, and the interference data are subjected to spectral restoration and spectral calibration. The results show that the amplitude consistency and phase consistency of the interference data are good, and the spectral waveforms of each channel are close to each other, which can well distinguish and measure the long wave characteristic peaks in the region.
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