In order to study effect of substrates on the focusing laser beam in atom lithograph, the characteristics of Gaussian laser standing wave affected by diffraction of straight edge were simulated based on the scalar optical theory. The results indicate that diffracted by the straight edge, Gaussian laser will show the similar oscillation of intensity to plane wave and the Gaussian incident wave has 1. 18 times of the intensity of the central axis at the first mutation of intensity, while the plane is 1. 37 times. The diffraction of the Gaussian laser by straight edge trends to that of plane wave when the waist becomes larger; the distance between laser axis and substrate will affect the illumination area of the laser outside the straight edge. The optical field superimposed by the diffracted Gaussian laser and its retro-reflective wave is the standing wave with oscillation of intensity outside the shaded area. All the results can make us well understand the essence of the Gaussian laser standing wave with diffraction by straight edge.%为了研究原子光刻实验中基片对汇聚激光场的影响,基于标量光学理论,采用数值计算对直边衍射情况下高斯激光驻波场特性进行了仿真.结果表明,高斯激光的直边衍射效应会呈现与平面光波相似的强度振荡现象,两者直边衍射后的第1个强度突变分别为中轴线强度的1.18倍和1.37倍;随着束腰的增大,高斯激光的衍射越接近平面波;中轴线和基片表面距离会影响高斯激光截面进入直边几何阴影之外的大小;直边衍射后入射波和其经过反射镜作用的反射波相遇叠加在光轴方向上会形成稳定的驻波;这种驻波的强度在垂直光轴截面上呈现一定的衍射特性.该研究有利于理解直边衍射时高斯驻波场形成的实质;并可通过适当的激光参量来调整实验激光驻波场结构.
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