...
The noise performance of the LCLS laser locking system was measured to have an RMS laser-to-RF-reference timing jitter of 25 fs between 100 Hz and 100 kHz. Below 100 Hz, phase noise is dominated by the noise of the linac RF reference.
Time Tool
To surpass overcome the limitations of this jitterposed by timing uncertainties, experiments involving the fastest femtosecond physical phenomena (e.g. , such as transitions of core-shell electrons) , employ X-ray/optical cross-correlation techniques to measure the relative timing between the laser and X-rays on a shot-by-shot basis by means of X-ray/optical cross-correlation techniques. This technique, referred to as the time tool , pictured in and depicted in Figure 5. Ultrafast ionization by the x, aims to determine the timing information precisely. By utilizing ultrafast ionization induced by the X-ray beam in YAG windows allows its , synchronization relative to with the MEC laser to can be precisely setaccurately established. The ionization causes process renders the window to become opaque showing definite opaque, enabling t0 (the edge of before/after) timing . By angling a window relative to observations. The time tool employs an optical probe split from MPA1 with 1mJ and 120Hz rep-rate, routing through the designated compressor, delay lines, and telescope cross-correlating with the x-ray beam , the time tool gives synchronization to within a few fs. The time tool is cross-referenced on a YAG crystal. To reference the time tool to the target plane using , another YAG window is positioned at the laser focus positionlocation, with and a small f-stop aperture is temporarily inserted to spread the laser focus at the target plane. The time tool measures exhibits an RMS jitter of ~ approximately 100 fs femtoseconds between the MEC laser and the xX-ray beam.
Figure 5. Image of the MEC timing tool.
...