Fast retrieval of temporal characteristics of FEL pulses using streaking by THz field.

A simple and very fast method for reconstruction of temporal structure of linearly polarized FEL pulses from the THz streaking spectra of photoelectrons is suggested. The method is based on a quantum mechanical approach within the strong-field approximation. The method is suitable for online retrieval of the temporal characteristics of the FEL pulses. It can be applied for any photon frequency in a broad range of FEL pulse duration with a proper selection of the streaking field. To enhance its accuracy, it is suggested to simultaneously analyze the streaking spectra for several emission angles. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement