10 February 2005 Maintenance-free principles of FTIR gas analyzers
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Fourier Transform Infrared gas analyzers have been widely used for speedy quantitative analyses of gases, and it is found that in many cases field maintainability determines the instruments’ online applicability instead of the instrument’s accuracy as is desired. To be maintenance-free is both the target of online instruments and the key to their field applications. Analyses show that if a background can be collected simultaneously with the sample spectrum, the transmittance will be only a function of concentration. Gas spectra collected on Nicolet670 of attenuated inputs and adjusted gains are examined via OMNIC software. Collected data exhibit that the absorbance spectra keep constant when input energy increases 8 times and the instrument gains becomes to 2.0 and 4.0 times. On viewing the absorption peaks vary with wavenumber in high “frequency” and that of the spectrometer itself in low frequency, by subtracting its instrumental response function of a transmittance spectrum extracted by wavelet transform, an absorbance spectrum of air is obtained and comparisons demonstrate that it is a summation of absorbance of the sample and that of gases in the optical path of the spectrometer. Calibration-free and background-free principles are thus exhibited and they construct maintenance-free principles of FTIR gas analyzers.
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Xian-yong Liu, Xian-yong Liu, Hong-lei Li, Hong-lei Li, Li-ping Shang, Li-ping Shang, Qiu-hai Zhong, Qiu-hai Zhong, } "Maintenance-free principles of FTIR gas analyzers", Proc. SPIE 5638, Optical Design and Testing II, (10 February 2005); doi: 10.1117/12.581264; https://doi.org/10.1117/12.581264

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