A frequency-domain interferometer for probing the variations of the dielectric constant of a plasma with sub-100-fs temporal resolution and λ/2000 phase resolution is described. Imaging the plasma on the entrance slit of a spectrograph provides spatial resolution along a diameter of the focal spot. The technique is used to map out the expansion of the critical density surface of a femtosecond laser-produced plasma with subnanometer spatial resolution along the laser axis.
© 1994 Optical Society of America
J. P. Geindre, P. Audebert, A. Rousse, F. Falliès, J. C. Gauthier, A. Mysyrowicz, A. Dos Santos, G. Hamoniaux, and A. Antonetti, "Frequency-domain interferometer for measuring the phase and amplitude of a femtosecond pulse probing a laser-produced plasma," Opt. Lett. 19, 1997-1999 (1994)