Supicosecond x-ray pulses are routinely produced at ALS, BESSY and SLS with slicing technique and used in pump-probe experiments with controlled delay between laser pump pulses and x-ray probe pulses. New development aiming for a production of a subpicosecond x-ray pulses using rf orbit deflection technique is under way at APS. Both techniques will be reviewed here.

The purpose of a laser heater is to increase the electron beam uncorrelated energy spread as a way to control and ideally suppress the microbunching instability in the linac drive for x-rays FELs. We review the motivations for equipping FERMI with a laser heater and provide a specification for the basics parameters as well as a description of a practical layout including desired diagnostics provisions for both the electron and laser beams. We also outline some useful operational guidelines for commissioning.