Mirror flatness greatly affects beam quality of output laser in laser system.In order to quantitatively evaluate influence of mirror defects on laser beam quality, parameters τ of describing relevance between mirror surface defects and laser beam, and δ of influence of mirror surface defects on distal light field are proposed.Influence of different mirror defects on laser beam quality is studied by simulation.Variation rules of parameters δ and correlation τ are obtained, ie, intrinsic linear relationship between parameters δ and correlation τ.For any TEM00 mode, TEM01 mode and TEM02 mode, this linear relationship is similar and universal.For example, when transmittance rate of mirror surface defects is 0, slope of linear curve that δ varies with τ is equal to 1.8 approximately, despite of whichever mode laser beam is.%在激光系统中,镜面平整度很大程度上影响了输出激光的光束质量.为了定量地评价镜面瑕疵对激光光束质量的影响程度,提出描述镜面瑕疵与空间光束相关程度的参数τ和镜面瑕疵对远端光场的影响参数δ.经仿真计算,研究了不同镜面瑕疵对激光光束质量的影响程度,得出影响参数δ和相关度τ的变化规律,即影响参数δ和相关度τ的内在线性关系.对于任意TEM00模、TEM01模和TEM02模,此线性关系近似一致,具有普遍性.例如当瑕疵透过率为0时,对于3种模式的光场,δ随τ变化的线性曲线的斜率都近似等于1.8.
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