Influence of relative parameters on quality of long distance diffraction-free beam

The influence of relative parameters, such as the focal length of the convergence lens and the distance between the convergence lens and the axicon, on the propagation distance of long distance diffraction-free beam generated by two axicons is analyzed using ray-tracing method. Numerical simulation is carried out with Mathcad. The results show that, while other conditions are invariable, the propagation distance of long distance diffraction-free beam decreases as the focal length of the convergence lens increases, and rises with the increasing of the distance between the convergence lens and the axicon. The theory is verified by experiment, and the experimental results are consistent with theoretical analysis.