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.

• 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。