光热低相干干涉法测量大气气溶胶吸收

研究了气溶胶粒子的光热敏效应和热感应光致折射率变化,提出了通过增加光热作用区个数来提高探测灵敏度及用低相干干涉法降低成本的方法。建立了光热低相干干涉法测量大气气溶胶吸收系数的数学模型,分析了干涉仪正交状态测量和干涉条纹细分探测两种方式下的探测灵敏度,讨论了低相干偏振干涉情况下的探测限。结果显示,在典型条纹细分情况下理论探测灵敏度可达1×10-6 m-1;增加光热作用区m个,探测灵敏度理论值可提高m倍。理论和方法研究证明光热低相干干涉法具有可直接测量大气气溶胶吸收系数、在线原位、低成本,易于进行温度修正等优点。

Measurement of aerosol absorption using photothermal low coherence interferometry

The photothermal effect and thermal induced photorefraction change of aerosols in the atmosphere were researched. The method to improve detection sensitivity by increasing the number of photothermal effect zones and to reduce the costs by low coherence interferometry was proposed. A mathematics model to measure the aerosol absorption coefficients by photothermal low coherent interferomtry was established, the detection sensitivities from two ways, interferometric orthogonal measurement and interferometric fringe subdividing detecting, were analyzed, and the detecting limit in low coherent polarized interferometry was discussed. Experiments demonstrate that the detection sensitivity in theory can be 1×10-6 m-1. If a longer interaction length and more number interaction zones are choosen, higher sensitivity can be arrived. The theory and method proposed in this paper can provide references for aerosol measurements.