Imaging cross-correlation FROG: measuring ultrashort, complex, spatiotemporal fields.

We present imaging cross-correlation frequency-resolved optical gating (ImXFROG), a new method for the spatiotemporal phase retrieval of ultrashort pulses. It is demonstrated that ImXFROG can measure phase and intensity of arbitrary, spatiotemporally distorted pulses with femtosecond resolution and up to 10(7) independent variables. ImXFROG is implemented as a plug-in upgrade to an existing correlator and used to demonstrate the reconstruction of highly complex, optical pulses with femtosecond features and massive spatiotemporal distortion.