Two-dimensional gas concentration reconstruction method for TDLAS (tunable diode laser absorption spectroscopy)

Abstract

The invention provides a two-dimensional gas concentration reconstruction method for TDLAS (tunable diode laser absorption spectroscopy) based on TDLAS and the matrix theory. The method mainly comprises the following steps: discretization of a measured area, two-dimensional distribution reconstruction and reconstruction accuracy evaluation. The method is implemented by the following steps: constructing a spatial coordinate system of a measured area according to monitoring data of a laser absorption optical path; dividing the measured area into vertexes, edges and central areas and discretizingthe measured area; constructing a weight vector and a gas concentration distribution matrix according to the number of discretized grids; realizing two-dimensional gas concentration reconstruction ofthe measured area with an iterative algorithm; establishing a normalized mean square criterion as the evaluation criterion to accurately evaluate the concentration reconstruction effect of a reconstructed two-dimensional gas concentration map. The method can be widely applied to two-dimensional online monitoring of spatial gas distribution.

Description

technical field [0001] The invention belongs to the field of laser gas measurement, relates to semiconductor laser absorption spectrum technology and matrix theory, and can be used for the two-dimensional reconstruction monitoring map of the concentration of toxic and harmful gas components in space. Background technique [0002] Tunable semiconductor laser absorption spectroscopy (TDLAS) uses wavelength modulation technology and spectral analysis technology to control the drive current of tunable semiconductor diodes to emit a laser beam with the same frequency as the characteristic absorption frequency of the measured gas. According to the Lambert-Beer absorption law , when the laser beam passes through the measurement space and is absorbed by the corresponding component gas, the attenuation of the laser intensity is proportional to the gas concentration. Derived to measure the gas concentration value of the component. This technology measures the measurement optical path...

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Problems solved by technology

[0005] Aiming at the complex problem of processing measurement data in the current gas monitoring space, a two-dimensional reconstruction method of gas concentration with high data processing efficiency and fast two-dimensional reconstruction speed is established to solve the problem of low data processing efficiency in the current two-dimensional reconstruction; In the actual environmental gas monitoring, in order to meet the real-time monitoring of the measurement site and make up for the defect that the measurement site cannot obtain a large amount of projection data, TDLAS technology is based on the measurement of the line of sight effect, and the measurement results can only give the average gas parameter value on the optical path , the internal information of the measurement area on the spatial plane cannot be obtained, so it is necessary to reconstruct the two-dimensional spatial gas concentration distribution map based on part of the measurement optical path data

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