Figure 1: Single-shot pulse duration and arrival time measurements.
From: Single-shot pulse duration monitor for extreme ultraviolet and X-ray free-electron lasers
(a) Schematic of the experimental set-up. The XUV pulse with a beam diameter of ~100 μm FWHM is incident under an angle δ with respect to the sample surface (material: SiO2, Si3N4). Within a single shot, different temporal parts t0, t1 of the XUV wavefront are absorbed at different spatial positions x0, x1 on the sample, providing a spatio-temporal decoding. A largely collimated near-infrared pulse under normal incidence is used to probe the optical transmission change within the surface during the absorption. The transmitted light is imaged onto a CCD. (b) Series of single shots recorded with 10 Hz acquisition rate. The black shading represents the increased optical opacity due to an increased electron density within the conduction band of the sample surface. The spatial position of the transient bottom edge on the x axis is dependent on the relative arrival time between the probe laser and the FEL pulse. The solid line indicates the extracted arrival time.
