Fig. 2
Two-color photoelectron holography. a Reconstructed photoelectron momentum distribution in log scale measured from argon, using the fundamental laser field only. The interference between the direct and scattered electron trajectories produces a spider-like interference pattern12. b Momentum-resolved two-color oscillation phase, ϕopt(p||, p⊥), extracted from the two-color scan. The black dashed curve traces electrons with a constant absolute value of the momentum (p = 0.5 a.u.) and hence traces electrons with equal kinetic energy. The evolution of the two-color phase along this equal energy curve is used to extract the difference between the ionization times of the direct (reference) and scattered (signal) electron trajectories (see text)
