Direct observation of the ponderomotive force effects in short-scale-length laser plasmas by frequency-domain interferometry

An overview is given on the implementation of a new design for single-shot frequency-domain interferometry that enables to observe, with unprecedented time and space resolution, the effect of the laser ponderomotive force on a fully characterized plasma of varying electron density gradient scale length. The important point is that the measurement gives a direct mapping of the position of the critical density surface.