模拟环境中能见度透射测量与散射测量比对

能见度是气象、环境和交通观测的重要参数,针对不同原理能见度测量设备没有统一的测试环 境和定标标准的问题,设计了能见度环境模拟舱。采用造雾和净化组合实现10 m~50 km能见度模拟。寻找模拟舱内空气均匀度监控方法, 消除由空气不均匀带来的误差。研制了一种新型能见度透射式测量系统。积分球对光源能量 监控和光信号接收起到重要 作用,消除光源不稳定带来的误差。望远镜接收光束减小了光路调节的压力。白色LED光源 受外部高频调制,信号测量端 同步解调,有效消除外界光干扰。准直和扩束透镜组将光源发散角控制在1mrad。反射光路 实现了有限空间光程的增加,缩 短了系统的安装基线。开展了实验室内模拟能见度测量实验,通过积分浊度计传递定标参数, 结果表明两个系统在 1.7 km测试区间相对偏差小于5%.与前向散 射能见度仪对比,测量误差约10%,统一定标后测量误差减小到约5%。模拟舱控制系统结构合理,透射式测量系统 稳定。

Comparison between transmission and scattering measurement for visibility in sim ulation cabin

A simulation cabin has been developed to solve the problem that there is no unif orm test environment an d calibration standard for visibility meters of different principle.Visibility from 10m to 50km is simulated by atomizers and purifiers.A method has been put forward,which can eliminate the error caused by air unevenness.A new transmission system is d eveloped for visibility measurement.Integrating sphere plays an important role in monitoring and receiving light,which can elim inate the error caused by the instability of light source.Adjusting optical path becomes easy by application of telescope.The LED light source in this system is modulated by external high frequency pulse signal and demodulated in receiver,which will eff ectively detach the interference by stray light.The collimation lens and beam expanding lens make divergence angle in 1mrad.The high reflection mirrors increase the optical path in the limited space,which also shorten the baseline of transmission system.Compa rison experiment was made with nephelometer. The result shows that the relative deviation between two systems was less than 5% from the 1.7km to 20km.Compared with the forward scattering visibility meter,the error is about 10%.After a calibration ,the error is reduced to about 5%.The control system of the simulation cabin is reasonable,and the transmission measurement system i s stable.