沙尘暴多重散射对激光脉冲传输的影响

根据光脉冲在离散随机介质中的传输理论,应用米氏理论和蒙特卡罗方法,研究了不同能见度情况下1.06μm脉冲激光在沙尘暴中的传输特性。得到了双频互相关函数的幅度和相位随相干带宽、脉冲时域展宽和延时随能见度的关系。结果表明,脉冲的展宽和时延随沙尘暴能见度的变化非常显著。当能见度为3~5 km时,多重散射对脉冲双频互相关函数、脉冲展宽和延时的影响已较明显。当能见度小于1 km时,对于1 ns的输入脉冲,其展宽大于10 ns,延时大于15 ns。因此,当沙尘暴的能见度较低时,必须考虑多重散射对激光脉冲频域及时域特性的影响。

Influence of Multiple Scattering on Laser Pulse Propagation through Sand and Dust Storm

Based on optics pulse propagation theory in discrete random media, by means of Mie theory and Monte Carlo method, the characteristics of 1.06 μm pulsed laser propagating in sand and dust storm are studied under various visibility conditions. The relations of the amplitude and phase of the two-frequency mutual coherence function with coherence bandwidth, pulse width extension in time domain and time delay with visibility are obtained. These results show that the width extension and time delay of laser pulse increase apparently with visibility increase. When the visibility is about 3～5 km, the influences of the multiple scattering of sand and dust storm on the two-frequency mutual coherence function, pulse width extension and time delay become apparent. Under visibility less than 1 km, for a 1 ns input pulse, the width extension is more than 10 ns, and the time delay is more than 15 ns. Therefore, when the visibility of sand and dust storm is low, the effects of the multiple scattering on the pulse characteristics of frequency and time domains should be taken into account for laser propagation in sand and dust storm.