The Research Of Transmittance Algorithm In Oxygen ‘A’ Absorption And Based On The Line-by-line Algorithm

Measurements of spectra have a wide range of value application in the fields ofenvironmental monitoring and control, aviation and space, industrial technology, agricultureand so on. With the breakthrough of spectral technology in recent years, oxygen ‘A’absorption band has been a new type of atmospheric inversion channel. Meanwhile,atmospheric radiation mode also has a growing development and the accuracy becomes moreand more is high. the atmospheric radiation modes have received more attention using thecharacteristics of oxygen ‘A’ absorption band. In this thesis, the basic characteristic of theoxygen ‘A’ and atmospheric radiation transfer mode is in-depth researched. By use ofabsorption spectrum the band average transmittance is calculated adopting the interpolationfitting method.In the process of calculating transmittance in oxygen A band, the choice of radiationmodel is the key. Line-by-line integration algorithm is an accurate transmittance calculationmethods that calculate contribution all gas absorption lines one by one. Due to the highprecision of line-by-line integral integration and extremely high requirement accuracy of thetransmittance calculation, so this thesis uses it as radiation model of oxygen ‘A’ band ofabsorption coefficient calculation.In this article Line-by-line integral algorithm is realized in matlab and the correspondingGUI interface which could show the calculation results of horizontal absorption coefficientunder different conditions is designed. Then, baseline fitting algorithm is simulated in matlabby the above results and the transmittance under different distance is obtained. According tothe simulation on the horizontal path, the approximate calculation of the transmittance onslant path is completed and corresponding simulation is realized in matlab. Through a series of the theoretical calculation and simulation, ABB light source as a radiation, we respectivelymake the corresponding experiments in different distance using Ocean optical fiberspectrometer and Avantes fiber optical spectrometer. The error is within the allowable rangecomparing the inversion distance and given distance. This experiment also validates thefeasibility of the method.In this paper, putting ‘A’ absorption band as a transmission medium. It is proposed thatthe average transmittance is calculated by using oxygen ‘A’ absorption of the radiationspectrum. By a large number of theoretical calculations and simulation and the experiment iscarried out to verify the feasibility. The experimental result is rather desirable. This methodprovides a new way for application of oxygen ‘A’ absorption band.