Abstract:
In order to improve the quality of laser micromachining, the focal spot should be shaped. The Fresnel diffraction formula was analyzed, two kinds of axial super-resolved phase plates were designed by using Matlab based on genetic algorithms and design constraints. The normalized radiuses of 0. structure phase plate of four-ring are r1=0.15、r2=0.70、r3=0.81, and the normalized radiuses of non.0. structure phase plate of four-ring are r1=0.25、r2=
0.498、r3=0.652, the phases of each ring from the inside to the outside are 2.879、3.087、0、3.012. The longitudinal spot sizes after using the two phase plates are compressible to 76% and 75% of the Airy pattern , the ratios of the peak energy are respectively 0.39 and 0.42, and sidelobe energy are respectively 0.64 and 0.41.Two phase plates can be applied in femtosecond laser microfabrication.