拉盖尔-高斯光束在凸台周围的气动光学效应

Aero-Optical Effect of Laguerre-Gaussian Beams Around Turret

为研究拉盖尔-高斯(LG)光束在经过凸台周围流场后的气动光学效应,采用二阶紧致差分和四阶龙格库塔积分对抛物型的复振幅方程进行求解,比较了具有不同拓扑荷数的LG光束在同一流场环境下的光强分布、同一光束在同一流场中数值仿真的光程差(OPD)分布与沿光束路径积分的OPD分布,以及不同拓扑荷数的LG光束与高斯光束在不同马赫数、不同攻角、不同海拔下的Strehl比(SR)以及成像偏移。仿真结果表明,在同一流场中,LG光束的拓扑荷数越大,振幅形态保持越好,但光强衰减越大,成像偏移越大。而同一流场下拓扑荷数对LG光束的SR数值几乎无影响,LG光束的相位稳定性均优于高斯光束。在振幅稳定性方面,与高斯光束相比,LG光束受海拔和攻角变化的影响更大。

To study the aero-optical effect of Laguerre-Gaussian （LG） beams passing throtlgh the flow field around a turret, we solve parabolic beam equations of complex amplitude by second-order compact differences and fourth- order Runge-Kutta integration. In the same flow field, light intensity distributions of LG beams with different topological charges, optical path differences （OPD） of the same beam calculated by rumerical simulations and integrated along optical path are both compared. Strehl ratio （SR） and imaging displacement are calculated at different Mach numbers, different angles of attack, and different altitudes, and compared among Gaussian beam and LG beams with different topological charges. The simulation results show that in the s-tme flow field, the larger topological charge the LG beam has, the better the shape of amplitude keeps, but the Jarger the attenuation and imaging displacement are. In the same flow field, the topological charges have nearly no impact on SR of LG beams, and the phase stability of LG beams is always better than Gaussian beam. Changes of altitude and angle of attack have bigger impact on the imaging displacement of LG beams compared with that of Gaussian beams.