火灾烟颗粒Stokes散射矩阵的实验研究

针对火灾烟颗粒的Stokes散射矩阵,利用电光调制器、1/4波片、偏振片及锁相放大器等设计与搭建了火灾烟颗粒光散射实验平台;并基于该平台测量了棉绳阴燃、正庚烷明火及檀香阴燃生成的3种烟颗粒的Stokes散射矩阵中16个元素的角度分布.实验结果表明,这些烟颗粒在光散射过程中都体现出明显的非球形效应,尤其是阴燃过程生成的灰烟颗粒.这说明基于球形模型的Lorenz-Mie散射理论对于分析烟颗粒光散射特征存在一定的局限性,而为了进一步挖掘火灾烟颗粒光散射过程中的光强与偏振等信息,需要建立合理的非球形模型,从而为光电感烟火灾探测技术的发展提供指导与支撑.

EXPERIMENTAL STUDY ON STOKES SCATTERING MATRIXES OF SMOKE PARTICLES

Aiming at the Stokes scattering matrix of smoke particles,an experimental setup was designed and built with an electro-optic modulation,a quarter waveplate,polarizers and a lock-in amplifier.Through the setup,the angular distributions of the Stokes scattering matrix were measured for the smoke particles generated from smoldering cottons,flaming heptane and smoldering sandals.The results show that the non-sphericity of smoke particles,especially the gray smoke particles,plays an important role on the light scattering.There are some shortcomings for Lorenz-Mie theory,which is based on a spherical model,to analyze the light scattering by smoke particles.In this case,it is suggested that non-spherical models are required to analyze the characteristics,e.g.intensity and polarization etc,of light scattering by smoke particles.