Novel differential measurement method of atmospheric aerosol absorption coefficient based on coaxial photo-thermal interference

Abstract

The invention discloses a novel double-channel differential measurement method of an atmospheric aerosol absorption coefficient based on coaxial photo-thermal interference. The method comprises the following steps of: forming interference in a to-be-measured aerosol sample region through modulated carrier laser; designing two channel interference light paths, wherein one channel is used to detect baseline phase drift caused by gradual change of environment temperatures and platform vibration, and the other channel is used to detect the total phase change caused by excitation laser absorption of aerosol and the baseline phase drift; performing differential to obtain phase variable caused by aerosol absorption; and detecting the aerosol absorption coefficient on line on the basis of interference amplification factor calibration. The method provided by the invention can be also used for detecting the concentration of specific aerosol ingredients according to fingerprint absorption characteristics. The method provided by the invention overcomes the effect of environmental temperature change and measuring platform vibration, cancels the adjustment of phase inversion difference point, doubles the acting distance of excitation laser and detection laser and has the characteristics of convenience for operation, high detection speed, easiness for miniaturization, high detection sensitivity, and the like.

Description

Technical field: [0001] The invention relates to a new dual-channel differential measurement method using photothermal interference to detect the absorption coefficient of atmospheric aerosol. The interaction between the excitation laser and the interference beam passing through the aerosol area to be measured causes the change of the interference phase, which can be measured in real time according to the phase change The absorption coefficient of the aerosol to be measured, and monitor the evolution of the aerosol absorption coefficient over time. Selecting the excitation laser at a specific "fingerprint" wavelength enables the determination of specific aerosol trace components and their concentrations. Background technique: [0002] The radiative forcing caused by atmospheric aerosol absorption is much more complicated than that of greenhouse gases, and it is one of the most uncertain factors in the calculation of radiative forcing, which greatly affects the accuracy of at...

AI Technical Summary

Problems solved by technology

In order to ensure the linear relationship between the phase change amount and the modulated laser power, the interference beam must be at the point of phase inversion, which is usually realized by a low-frequency piezoelectric ceramic feedback circuit. It is very troublesome when the frequency of the feedback circuit is close to the frequency of the excitation laser.

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