由于取样定理的限制,常规的基于快速傅里叶变换(FFT) 光束传输模拟算法不能进行任意焦距聚焦光束的传输过程的模拟。为此提出了一种新算法:将球面波因子提出,将会聚光束的传输过程转化为非会聚光束的传输,从而间接地求得了聚焦光束的光场分布。利用Fresnel 数对两种传输过程的关系和聚焦光束的传输特性作了分析。

In simulation of focused beam propagation with arbitrary focal length, the traditional beam propagation algorithm based on Fast Fourier Transform will fail to give right results due to the limitation of the sampling theorem. A new algorithm is given, in which the factor of spherical wave front is removing explicitly. Thus the propagation of a focused beam could be evaluated indirectly from propagation of an unfocused beam. The results in two cases are connected inherently by Fresnel number, which plays a key role in focused beam propagation.