Focusing property of partially coherent flattened Gaussian beam by lens with spherical aberration

Based on the propagation theory of partially coherent beam, the axial light intensity distribution of partially coherent flattened Gaussian beam(PCFGB) focused by a lens with spherical aberration(SA) is studied. Simulation results show that, when SA changes from negative to positive, the best focal point moves towards the geometrical focus and even exceeds it. The larger order of the PCFGB, the smaller the positive SA of causing the best focal point to exceed the geometrical focus. The best focal points corresponding to positive and negative SAs always locate at the two sides of the focus for no-SA cases, respectively. Light intensity the of axial best focus decreases while SA changes from negative to positive. Light intensity of the axial best focal point changes sharply when SA approache