气溶胶散射相函数的精细测量方法研究

Aerosol scattering phase function (ASPF) is a normalized function that represents the energy of scattered light varying with scattered angle, and is a very important optical parameter in aerosol studies. ASPF can be calculated by Mie theory with parameters of aerosol shape, size distribution, complex refractive index, relative humidity, but these parameters change in real-time and in situ. ASPF measurements by aerosol sampling mainly divide into three types in terms of the detector: single detector, multi-detector and detection arrays. Single detector scanning cannot get the ASPF in real-time. Angular resolution of multi-detector is limited by the number of detectors. The aspheric mirror in the last method is difficult and expensive to fabricate. A design based on charge-coupled device and inversion method for ASPF has been proposed in our project. The design increases signal-noise ratio and angular resolution considerably, and works with wide view of angle and in real-time. The project will provide theory and experimental data to the atmospheric modal or apparatus which relies on ASPF, and is favor of understanding the aerosol optical characteristics better.

气溶胶散射相函数是气溶胶粒子散射光能量随散射角变化的归一化函数，是研究气溶胶光学特性的重要参数。米散射等理论算法需要假设气溶胶粒形、粒子谱分布、复折射率和相对湿度等参数，而这些参数在实际环境中随时间地点变化。采样测量法中根据探测器种类不同可分为单探测器、多探测器和阵列探测器，因单探测器需要扫描故不能实时测量，多探测器分布法观测点数有限使角度分辨率不高，阵列探测器中使用的非球面镜加工难度与成本值得考虑。该项目提出了基于电荷耦合器件测气溶胶散射相函数的设计与算法，显著提高了实验观测数据的信噪比和分辨率，测量系统同时具备大视场和实时性的特点。为依赖气溶胶散射相函数的大气模式或探测仪器提供理论和实验数据，有利于深入了解气溶胶的光学特性。

气溶胶是指固体或液体微粒悬浮于大气中形成的分散体系。近年来受工业污染、汽车尾气与沙尘暴等因素的影响，空气中悬浮着过量气溶胶微粒造成了雾霾，已经影响了居民的健康与生活。理论计算气溶胶散射需要预先假设气溶胶粒形、粒子谱分布、复折射率和相对湿度等参数，这些参数随时间地点而变化，因此很有必要通过实验观测得到真实环境中的气溶胶散射相函数。.本项目以连续半导体激光器为发射光源，以电荷耦合器件与鱼眼镜头为探测器，设计了一套大气分子与气溶胶散射光成像的极化浊度计装置。该装置可实时观测大气样品的散射光图像，散射角观测范围14度到162度，极化角观测范围0~360度。实验观测了氮气与水汽的散射图像，观测的氮气散射光与瑞利散射理论吻合，极化角散射光与理论拟合优度0.98。观测的水汽散射光随散射角变化趋势与米散射理论对比一致性较好。实验表明该设计定量化观测气溶胶角散射光有潜在的应用性。