Divall, M.C. Hauri, C.P. Hunziker, S. Romann, A. Trisorio, A. JACoW Geneva, Switzerland 978-3-95450-177-9 10.18429/JACoW-IBIC2016-WEPG52 English 764-767 WEPG52 laser timing gun FEL experiment Contribution to a conference proceedings 2017 2017-02 http://dx.doi.org/10.18429/JACoW-IBIC2016-WEPG52 http://jacow.org/ibic2016/papers/wepg52.pdf SwissFEL will ultimately produce sub-fs X-ray pulses. Both the photo-injector laser and the pump lasers used for the experimental end stations therefore have tight requirements for relative arrival time to the machine and the X-rays. The gun laser oscillator delivers excellent jitter performance at ~20fs integrated from 10Hz-10MHz. The Yb:CaF2 regenerative amplifier, with an over 1km total propagation path, calls for active control of the laser arrival time. This is achieved by balanced cross-correlation against the oscillator pulses and a translation stage before amplification. The experimental laser, based on Ti:sapphire laser technology will use a spectrally resolved cross-correlator to determine relative jitter between the optical reference and the laser, with fs resolution. To be able to perform fs resolution pump-probe measurements the laser has to be timed with the X-rays with <10fs accuracy. These systems will be integrated into the machine timing and complemented by electron bunch and X-ray timing tools. Here we present the overall concept and the first results obtained on the existing laser systems.