Electro-Optic (EO) Based Electron Bunch Length Measurement: Implementation at the Shanghai Soft X-ray FEL and Preliminary Results

Abstract As an online, single-shot, and non-destructive absolute measurement method, an Electro-Optical (EO) system has been installed at the Shanghai Soft X-ray FEL to measure the longitudinal electron bunch profile. This paper presents a detailed description of the experimental setup and preliminary measurement results. The design enables simultaneous time-decoding and spectral-decoding measurements. Additionally, in conjunction with a profiling system and two photodetectors (PDs), it achieves spatial synchronization of the laser and electron beam, with a coarse temporal synchronization resolution better than 250 ps, while only affecting the beam once.