Interferometric autocorrelation
= Interferometric autocorrelation
{title2=$C_{\rm IAC}(\tau)\propto\int|E(t)+E(t-\tau)|^4dt$}
A two-replica second-harmonic measurement retaining carrier interference fringes. The formula assumes an instantaneous broad-band second-harmonic response and includes the carrier in $E$. The extra interference information does not in general determine an arbitrary complex pulse uniquely.