能见度仪探测光束平行度检测方法

Parallelism detection method of visibility meter's probe beam

为实现能见度计算中消光系数的正确测量,论述了光源平行度在能见度测量中的重要作用,设计了探测光束发散角检测方法与测量装置。该装置包括定焦成像系统和移动光源的直线系统,利用成像关系与空间几何关系推导了发散角表达式。以紫外LED作为实验光源,设计完成了测量系统成像装置与控制软件,计算得到水平方向与垂直方向发散角,利用所得发散角分析探测光束。实验结果表明,紫外LED光源的光束发散角水平与垂直方向分别为7.8°和6.9°,经比较得到未加入平行度的能见度与加入后的比值为0.51。该方法测得的能见度值更接近于实际值。

For achieving a correct measurement of the extinction coefficient of visibility, paral lelism importance of the probe beam was discussed, the detection method of probe beam diver gence angle was proposed and the measuring device was designed. The device includes a fixed focus imaging system and a linear motion system. Divergence angle was derived by using the imaging geometry and spatial relationship. With ultraviolet （UV） LED as the light source, measurement systems and control software were completed. According to the imaging results, the horizontal and vertical divergence angles were calculated. The probe beam was analyzed with divergence angle. Experimental results show that the UV LED light horizontal divergence angle is 7.8% and the vertical＇s is 6.9%. By comparison, the visibility ratio of nonparallelism to parallelism is 0.51. Visibility by this method is closer to the actual value.