使用离散傅里叶方法分析环缝透镜系统产生无衍射(贝塞尔)光束。将基尔霍夫衍射积分公式与菲涅耳衍射积分公式转换成傅里叶变换的形式，在环缝透镜系统中用傅里叶方法描述观察面的光强分布，对衍射面进行数据抽样，导出观察面光强分布的离散化傅里叶公式；通过设置相关参数并使用MATLAB 软件进行数值模拟，得到不同位置下的贝塞尔光强分布。设计环缝透镜系统进行实验验证，数值模拟和实验结果匹配度较高，表明离散傅里叶方法应用于环缝透镜系统是可行的。

Bessel beam generated by lens-annular slit system is analyzed in discrete Fourier transform method. In the theoretical part, Kirchhoff diffraction integral formula and Fresnel diffraction integral formula are expressed in the form of Fourier transform, the complex amplitude distribution of each surface is described in Fourier method. After collating and sampling, a discrete Fourier formula is derived to describe the intensity distribution of observation surface which has function relation with diffraction surface. After setting related parameters and simulating with MATLAB, the results show the intensity distribution of Bessel beam in different propagation distances. At last, an experimental system is designed to verify the theoretical analysis and numerical simulation. Simulation results and pictures from experiment show a higher match degree, which proves that this discrete Fourier transform method is feasible in lens-annular slit system.