利用波长慢速扫描和快速调制激光吸收光谱实验数据反演光谱吸收函数的理论和实验研究

Theoretical and experimental study of inversion of spectral absorption function using experimental data of laser absorption spectrum with slow scanning and fast modulation of wavelength

在波长慢速均匀扫描和波长快速周期调制的情况下,基于激光吸收光谱的实验数据,提出了利用激光调制频率和激光扫描范围两个参数以及透射波信号和参考波信号反演谱线吸收函数的矩阵切片方法.当波长调制为单频正弦调制时,利用透射波信号和参考波信号的相除结果得到的矩阵,通过两个相距半个调制周期的切片积分的最小值即可得到准确的谱线吸收函数轮廓,并能反演出调制幅度的大小.当波长的快速调制扭曲为非单频的多频叠加调制时,可以利用多个切片的互补形成谱线吸收函数.上述方法可以用于在扫描波长范围内包含由多条吸收谱线且有重叠的真实吸收函数反演过程.而且,可以利用扫描波长范围内多条谱线的间隔参数来标定激光波长的扫描范围.采用上述的矩阵切片法,通过实验验证,得到了低吸收状况下CO在4300.700 cm^(-1)吸收谱线的吸收函数和较强吸收状况下CO_(2)在6336 cm^(-1)附近2条吸收谱线的吸收函数信息.

Based on the tested data of laser absorption spectra,a matrix slicing method is proposed to invert the absorption function of spectral lines by using the two parameters of laser modulation frequency and laser scanning range as well as transmitted wave signal and reference wave signal under the condition of slow uniform scanning wavelength and fast periodic modulation wavelength.When the modulation is single frequency sinusoidal modulation,an accurate contour of the spectral line absorption function can be obtained by using the matrix data consisting of the values of the transmitted wave signal by the reference wave signal through the minimum value of two slice integrals with the interval of half modulation period,and the amplitude of modulation can be estimated.When the fast modulation of the wavelength is distorted to the multi-frequency superposition modulation,the absorption function is also formed by using the complementarity of multiple slices.The method above is utilized for investigating a real absorption function inversion process involving multiple overlapping absorption lines in the range of the scanning wavelengths.Moreover,the scanning range of laser wavelength can be calibrated by the interval parameters of several spectral lines in the scanning wavelength range.The absorption function of CO at 4300.700 cm^(-1) and CO_(2) at 6336 cm^(-1) are successfully obtained by using this matrix slice method for experimental verification.