To track the time jitter between X-ray and optical lasers on a shot-to-shot basis, a real-time diagnosis using the femtosecond X-ray/optical cross-correlation process is referred to as the time tool. The YAG crystal turns opaque to optical laser due to ultrafast ionization of the x-ray beam.  allowing t0 location. The time tool is cross-referenced to the target plane using another YAG window at the target center position, with a small aperture temporarily inserted in the drive beam to spread the laser focus at the target plane. The time tool measures an RMS jitter of ~ 100 fs between the MEC laser and the x-ray beam.

Layout

The new time tool beam split 10% (~1mJ) from MPA 1 out. The beam path (purple line in Fig. 1)is routing along the wall of the MPA2 box, across the stretcher box, elevating from 3.5" to 5.5" in height, routing around the big compressor, through TT-shutter, and elevating from 5.5" to 28" to the second floor of the time tool/compressor/delay box( red area). The second floor contains delay switches, a compressor, manual delay stage. Then a periscope sends the beam down to the first floor, which contains a remote delay stage and final pointing mirrors to send the beam to the YAG stag inside the vacuum chamber. 

Figure 1.