Rough Timing
- Skip this step and try fine timing. If you cannot find t0, then come back to this step.
- Insert the diode at the top of the TT paddle, and find rough t0 using the same protocol as rough timing at the IP.
Fine Timing
Video guide: A tour de force by the Director of Operations himself: Zoom recording
Goal and prerequisites
- Goal: find t0 at TT and set Offset Time to correlate t0 at IP and TT
- Prerequisite: t0 found at IP
Spatial Overlap of the Timetool
Needs:
- camViewer -c Timetool
- TT screen
Move paddle up using TimeTool Y to frosted YAG.
Zoom in and Turn off X-ray and white light
Open X-rays at 1% transmission
Turn off X-rays after setting crosshairs, turn on funky white light beam, move Pico Z (horizontally) until within crosshairs
Timing: setup spectrometer analysis
Move paddle back down to clear YAG
Open Timetool camera from the DAQ: shows white light dispersed through spectrometer. All shots being recorded displayed on Channel A
Sum spectrum onto X to get profile
Plot signal integral against DG2 wave8
Timing: theory
X-rays change the timetool transmitted light: we want to see a correlation between the intensity of the white light and the wave8 intensity.
Turn on 100% X-rays, monitor on clear YAG, check trend
See what happens if laser moved 10ps earlier: X-rays arrive after the white light so have no effect whatsoever on the white light
Notice the long-lived effect by checking long positive delays
Timing: application
Notice drop with -8ps and -9ps
See clear discontinuity ("edge") in the TimeTool window: in this case, time-zero is roughly in the center. Half the white light is affected by the X-rays, half is not.
At this stage, we know that the time-zero at the TT is off by 9ps compared to time-zero at the IP, so we need to move the "Time tool delay stage" by 1350 mm (in Time Tool at DSB window). Concept: Light travels roughly 300 um in 1 picosecond. So for every 1 ps difference in t0 between the current fs timing experiment and the previous one, the white light path needs to be changed by 300 um total. However, the time tool delay stage has a double bounce mirror setup, meaning that changing the time tool delay stage value by 100 um increases the white light path by 200 um. Take the difference in t0 compared to previous measurement (Δt0 in ps) and do the following calculation: (Δt0 * 300 um/ps /2).
Change the time tool delay stage by the calculated value (it is not guaranteed that adding the number actually increases the path length so try one direction and if that doesn't work, try the other. If both don't work then you did something wrong).
Extra things that we can do
Setup a filter