脉冲激光入射下介质薄膜双频互相关散射截面及功率展宽
Double frequency scattering section and power broadening of laser pulse scattering from dielectric film
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摘要: 结合特殊的镀金聚酯薄膜表面的粗糙度和半球反射率，依据基尔霍夫近似及粗糙面脉冲散射互相关函数，数值计算了脉冲激光（1.06 μm）在不同入射角照射下该材料薄膜双频互相关散射截面随相干带宽频差和散射角的变化情况。并给出δ脉冲和高斯脉冲波入射下，其散射功率随时间和散射角的波形分布。计算结果表明：该薄膜材料激光双频互相关散射截面在镜反射方向有最大的散射峰值，在非镜反射方向上，其散射值随相干带宽频差的增大迅速减小，当窄脉冲垂直入射时，粗糙面散射功率展宽现象明显。Abstract: According to the mean roughness and semisphere reflectivity of the gold plated polyester film surfaces, and based on the Kirchhoff’s approximation along with the pulse scattering mutual coherence function(MCF), we computed the double frequency scattering section(DFSS) changing with coherence bandwidth frequency difference and scattering angle for different incident angles of a laser (1.06 μm). For δ and Gaussion pulses incidence, scattering power patterns have been obtained with different scattering angle and time by two frequency MCF. The numerical results show that there exists a maximal DFSS in the mirror reflection direction. While the DFSS will decrease rapidly in the diffusing scattering direction with the increase of coherence bandwidth frequency difference. As to vertical inci
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