基于光纤式迈克尔逊干涉的大气气溶胶有效吸收测量方法与应用研究

The radiation forcing by aerosol absorption has been restraining the study to climate effect from aerosol radiation. When laser transmits in the atmosphere, the atmospheric refractive index is affected by aerosol absorption, which descends the laser beam quality. At present, the tradional methods for measuring aerosol absorption are not enough accurate and easy to be disturbed by aerosol scattering, and the characters of aerosol absorption are not be inspected completely since the delay process of heating aerosol itself ignored. In this proposal, the sensitive Michelson interferometer is investigated based on modulation and demodulation of light interference. The specification of this approach is that it directly measures the aerosol absorption without interference with aerosol scattering since its signal originates from the thermal dissipation of spectrally absorbed energy. A real-time measuring technique is brought out, primarily attributed to low cost, high precision and easy to operate. By real-time response to time shift and phase shift from interference light, the effective absorption of aerosol, which heats air only, is analyzed. The factors influencing the aerosol effective absorption, such as incident laser characteristics, environmental temperature, humidity and atmospheric pressure etc, are studied. The absorption effects of different aerosol will be studied by using the proposed method. The proposed method will be applied in wide research areas such as the climate radiation forcing of aerosol,the optical characteristics of aerosols and the propagations of laser in atmosphere.

气溶胶吸收引起的辐射强迫已成为气溶胶辐射气候效应研究的主要问题之一。激光在大气中传输时，气溶胶吸收导致大气折射率的变化，恶化了激光的光束质量。目前常用气溶胶吸收特性的测量方法存在精度偏低、易受散射光影响等问题，且忽略了气溶胶由于自身加热而固有的延时过程，不能全面反映气溶胶的吸收特性。本项目通过干涉光束调制解调机理的研究，探讨光纤式迈克尔逊干涉测量气溶胶吸收特性的途径，消除气溶胶粒子散射光的干扰，提供一种成本低、精度高、操作简单的在线测量方法。该方法利用干涉光路上相位变化量和时间变化量的实时测量，考察气溶胶吸收热量中真正用来加热大气的有效吸收，明确入射激光参数、主要环境因素和有效吸收间的关系。本方法所获得的不同类型气溶胶吸收特性的实际应用,能够为气溶胶辐射强迫的计算提供更精确参数，并深化气溶胶光学特性和激光大气传输的研究。

针对常用气溶胶吸收特性测量方法精度偏低、易受散射光影响等问题，本项目以大气气溶胶有效吸收的光纤式迈克尔逊干涉获取方法为研究对象，开展了光热干涉方法的理论模拟与仿真，确定了相位载波的调制解调算法和利用斜率平均获得气溶胶吸收系数的解算方法；完成了光纤式迈克尔逊干涉试验装置的改造与完善，构建了一种全新的高精度大气气溶胶吸收特性的实时测量方法，同时提出了利用赫里奥特池延长作用距离和声共振式全保偏光纤两种全新的光热干涉装置设计思路；通过光纤式迈克尔逊干涉试验装置的标定，获得了典型吸收性物质的有效吸收系数的演化规律，分析了湍流、温度等因素对气溶胶吸收特性计算的影响，结果表明利用频率特性能够较好的提取与吸收相关的相位信息；经外场试验实际测量，初步获得了乡村型和沙漠型气溶胶的吸收特性及其对激光传输性能的影响。本项目所获结果有助于进一步认识激光与大气气溶胶相互作用的机理和过程，加深气候模式和激光大气传输的研究。