Normalized correlated two-electron momentum distributions for laser-induced recollisional (e,2e) process on He⁺ in 45 fs and 800 nm laser pulses at the peak intensity 4.0 × 10¹⁴ W/cm². The momentum components along the polarization direction are shown. The potential change due to the presence of electric field at the recollision time is taken into account, and the focal volume integral is performed. The calculated results are obtained by using the theoretical models (a) 2C, (b) 3C, (c) 4C, (d) DS3C, and (e) DS4C, respectively. The experimental measurements shown in (f) were performed by Staudte et al.^[14] Adapted from Ref. [37].