高功率激光光束经颗粒污染后的近场衍射效应

摘要

The near-field diffraction characteristics when a high-power laser beam traverses contaminant particles are studied by using the designing software of high-power laser drivers-Laser designer.The modulations generated by contaminant particles are sorted.Then the influence of contaminant particles with amplitude or phase modulation on the near-field intensity distribution in vacuum or in fused silica is analyzed in great detail.The results show that in both vacuum and fused silica,the phase modulated contaminant particles have a greater influence on the near-field properties of high-power laser.Moreover,it is found that in fused silica,the small-scale self-focusing hot-image modulation of high-power laser induced by phase modulated hard-edge contaminant particles is momentous. But the lateral shift of high-power laser beam caused by contaminant particles maybe inhibits the small-scale self-focusing effect to some extent,thereby reducing the laser injury risk of optical component.%采用高功率激光驱动器设计软件Laser designer数值研究了激光光束经颗粒污染后的近场衍射特性.对颗粒污染所产生的调制进行了分类,并详细分析了真空和石英玻璃中,振幅调制型和位相调制型颗粒污染对光束近场的影响.研究结果表明,无论在真空或石英玻璃中,位相型颗粒污染对高功率激光光束的近场调制影响较大.且在石英玻璃中,位相型硬边颗粒污染所引起的高功率激光光束小尺度自聚焦热像调制现象相当严重.而由颗粒污染引起光束强区的横向偏移,却在一定程度对小尺度自聚焦有抑制作用.