Spatial and temporal transformation of femtosecond laser pulses by lenses with annular aperture

Abstract Based on a Fourier-optical analysis of the transformation of ultrashort light pulses by lenses it is shown that the drastic increase in pulse duration in the focal plane of a circular lens can be avoided using proper chosen annular apertures. In this case the spatial distribution in the focal plane is the same as it would be expected for monochromatic light.