Experimental setup. A small fraction of the 1030 nm infrared optical beam is converted to 257 nm based on two-stage second harmonic generation. The 257 nm UV pulse is directed onto a gold photocathode generating electron pulses, which are accelerated to 53 keV by the dc electric field. The same infrared laser also drives a multicycle THz generation stage, two single-cycle THz stages, and pump laser for the DLW manipulator, the STEAM streaker, and sample excitation, respectively. The STEAM streaker and the sample are on the same manipulator which can be exchanged for checking the pulse duration at the sample position or performing the ultrafast electron diffraction (UED) experiment.