激光波带片衍射性质的数值模拟

根据亥姆霍兹-基尔霍夫积分,对菲涅尔波带片的高斯激光场在轴向、径向强度分布进行了理论分析,研究了高斯激光束照射下波带片的衍射场规律.数值计算表明：沿轴向光场呈系列焦点,各焦点附近光强分布有振荡现象,随焦点级次的增大光强迅速增大；有焦移现象,焦移量随焦点级次的增大而增大；焦深随焦点级次的升高按平方反比律减小,随波带数减小或焦距增大而增大.在焦平面上,光斑大小与最外环宽度成正比,与焦点级次成反比.

Numerical Simulation for the Diffraction Properties of Laser Zone-plate

On the basis of Helmhots-Kirchohoff diffraction integration,Axial and radial intensity distribution and diffraction pattern of Frenel zone plate for Gaussian laser beam were analyzed theoretically.Numerical results showed that it presented a series of focal points on axis,around each of which there is oscillation of intensity distribution,with the increase of order number of focal point,the intensity increasing rapidly.There were phenomena of focal shifts,and focal shifts increased with the rise of the order number of focal point.The focal depth reduced on inverse square law with the rise of the order number of focal point and increasewith the reduction of zone number or the increase of focal length.On focal planes,the size of light spots was proportional to the width of the most external circle and inversely to the order number of focal point.