Wavelength modulation absorption spectrum absorption optical path and gas concentration synchronous inversion method

A technology of wavelength modulation and gas concentration, which is applied in the direction of color/spectral characteristic measurement, can solve inconvenience and other problems, and achieve the effect of high-sensitivity absorption optical path and gas concentration detection

Pending Publication Date: 2020-06-30
HEFEI INSTITUTES OF PHYSICAL SCIENCE - CHINESE ACAD OF SCI
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Problems solved by technology

In open path remote sensing applications, the absorption path length is typically measured with a separate GPS or ranging module, but this is inconvenient in many applications

Method used

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  • Wavelength modulation absorption spectrum absorption optical path and gas concentration synchronous inversion method
  • Wavelength modulation absorption spectrum absorption optical path and gas concentration synchronous inversion method
  • Wavelength modulation absorption spectrum absorption optical path and gas concentration synchronous inversion method

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Embodiment Construction

[0027] The present invention will be further described below in conjunction with accompanying drawing:

[0028] like figure 1 A synchronous inversion method of wavelength modulation absorption spectrum absorption path and gas concentration is shown, the method includes the following steps:

[0029] (1) Obtain the absorption signal I t and background signal I t,0 .

[0030] (2) Using sinusoidal signal sin(2πf m t) respectively with the absorption signal I t , background signal I t,0 Multiply, and perform low-pass filtering on the multiplied results respectively (the cut-off frequency of the low-pass filtering is 5 times of the scanning frequency), to obtain the X-channel demodulation signal X of the first harmonic 1f And X channel background demodulation signal

[0031] (3) Using the cosine signal cos(2πf m t) respectively with the absorption signal I t , background signal I t,0 Multiply, and perform low-pass filtering on the multiplied results, respectively, to obt...

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Abstract

The invention relates to a wavelength modulation absorption spectrum absorption optical path and gas concentration synchronous inversion method. The method comprises the following steps: (1) acquiringan absorption signal It and a background signal It, 0; (2) obtaining a first harmonic phase baseline value and a first harmonic phase angle differential signal delta theta 1f-0 of which background signals are deducted by adopting a quadrature demodulation method; (3) solving an absorption optical path Labs by adopting a formula; and (4) performing least square method linear fitting on the differential phase angle delta theta 1f-0 of which the background is deducted by adopting the following formula so as to obtain the concentration of to-be-detected gas, according to the present invention, with the method, the defects in the prior art can be overcome, the absorption optical path and the gas concentration can be rapidly and synchronously inverted, the high-sensitivity absorption optical path and the gas concentration detection can be achieved, and the method is especially suitable for the gas detection environment with the obvious noise such as remote measurement and the like.

Description

technical field [0001] The invention relates to the technical field of tunable laser gas absorption spectrum detection, in particular to a synchronous inversion method of wavelength modulation absorption spectrum absorption path and gas concentration. Background technique [0002] With the rapid development of infrared diode laser technology, tunable diode laser absorption spectroscopy (TDLAS) has been widely used in greenhouse gas and air pollution monitoring, combustion diagnosis, industrial process control and other fields. In laser absorption spectroscopy, the absorbance is usually proportional to the product of the gas concentration and the absorption path length. Therefore, the measurement error of the absorption path length directly determines the accuracy of the gas concentration inversion. In measurement configurations with single-pass or multi-gas cells, the absorption path is well-defined or can be calibrated with reference measurements of known gas concentration...

Claims

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Application Information

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IPC IPC(8): G01N21/39
CPCG01N21/39
Inventor 陈兵王兴平杨晨光许振宇邓昊阚瑞峰刘建国
Owner HEFEI INSTITUTES OF PHYSICAL SCIENCE - CHINESE ACAD OF SCI
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