  We present a new variant of dispersion scan (d-scan) based on surface
third-harmonic generation (STHG) and a ptychographic algorithm taylored for
full retrieval (amplitude and phase) of broadband laser pulses. We demonstrate
the technique by temporally measuring and compressing few-cycle pulses with 7
fs and 2.5 nJ from a Ti:Sapphire oscillator, using a sapphire window as the
nonlinear medium. The results are in very good agreement with standard
second-harmonic d-scan measurements based on a nonlinear crystal. The
intrinsically broadband and phase-matching-independent nature of STHG make this
technique very suitable for the characterization of ultrashort laser pulses
over a broad wavelength range extending into the mid-infrared.
