Temporary "compression" of femtosecond pulses in the focus of truncated microellipsoid

Truncated ellipsoid which all parallel incident rays collects on it’s flat surface is designed. Simulation by $\mathrm{(FD)^2TD}$ method of focusing of femtosecond pulse (duration $1.24$ fs and the carrier wavelength $\lambda = 532 $ nm) by a silica truncated microellipsoid with smaller cross-sectional diameter of $1.16$ mm showed that the ellipsoid gives an elliptical focus spot with a smaller diameter $\mathrm{FWHM}=0,38 \lambda$. At the same time the pulse duration at the focus of a few percent smaller than the duration of the incoming pulse.