Figure 3: Example of the measured transmission change.
From: Single-shot pulse duration monitor for extreme ultraviolet and X-ray free-electron lasers
(a) Transmission along the sample when the optical probe pulse arrives a few picoseconds after the FEL pulse. The reflection change has fully evolved. This reference measurement is used to calibrate the measured signals to the spatial beam profile of the FEL (lineout A). Along the x axis, spatio-temporal decoding is achieved according to equation (7). (b) Transmission along the sample when the optical probe pulse and the FEL pulse arrived at the same time. The transient transmission change can be clearly observed (lineout B), compared with the reference in a. The areas between the white dashed lines indicate the regions of interest for calculating the lineouts. (c) The cross-correlation, S(Δt) (blue rectangles), is obtained by normalization according to the formula in the legend. The signal lineout is inverted by 1−B and normalized to 1−A. The multiplication with 1−min(B) accounts for the constant transmission level after the transient edge, which is around min(B)=0.7 in the presented case.
