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This procedure is written for the LPL operation after the 100J upgrade. The LPL upgrade changed the beam size and relay imaging after the 1" CD amplifier. The upgraded setup employed new irises and new camera imagers for alignment checks with higher precision. The new procedure includes the hardware turn-on, the software turn-on, a new alignment routine (using imagers and irises), commands for SHG and HWP optimization, and recipes for new pulse shapes. 

Turn on hardware

  • Set hutch to “Class 1”, or “Class 4 Glass Laser”, or “Class 4 Dual Laser”, or “Class 4 Split Mode
  • At the LSS display, badge in and open Shutter S4, and press the “Press to reset interlocks"

  • Turn on four TDK Lambda power supplies. Power switch to “1” .Press the tiny “out” button at each of the 4 supplies.

Figure 1: TDK Lambda power supplies

  • Turn on six eDrives: keys and power buttons


Figure 2: six eDrives

  • Turn on four chillers

Figure 3: 4 chillers

  • Switch on NP Photonics Seed Laser: toggle the “pump” switch from position 0 to 1. You will see PWR ramp up to around 140mW.

Figure 4: NP Photonics seed laser

Turn on YFE

Do the following on the terminal:

  • ssh mec-laser
  • mecpython
  • import meclas
  • meclas.YFE.On()

Load the waveform recipe and shape the waveform

  • meclas.LPL.psmenu(): this command gives you a list of recipes to choose from (Fig. 5). Then type in the recipe from the menu list, for example, l56 == "U10ns00gradE100J"

  • meclas.LPL.psefc10Hz(numIterQ=150): this command will shape the 10Hz pulse until it reaches the target waveform. You can set numIterQ = x to run x times of iteration. In figure 6, the upper left shows all the parameters you can set. The right plot shows the 10Hz pulse (blue) and the target waveform (red). For more detail please check how to make a new recipe. 

Figure 5: choose the pulse recipe: use commend "meclas.LPL.psmenu()"                                Figure 6: shape the 10Hz pulse as designed. 

Open the beam monitor cameras

There are 6 cameras in the upgraded LPL layout: the new camview can be opened in mechome [detectors>view-long pulse Laser Cams> dropdown (figure below 1)]. For camview detail please check New Camview Feature

The full alignment using these 6 cameras is recommended. For operation and monitoring purposes LPL_100J_1,  LPL_100J_3,  LPL_100J_4, are needed to open. These imagers locations and descriptions are as followed (figure below 2). 

  • LPL_100J_2: the imager looking behind the 1" amplifier and before the relay tube 
  • LPL_100J_1: the imager looking behind the big Faraday Rotator
  • LPL_100J_5: the imager looking before the east side 2" heads (IJ, and GH input)
  • LPL_100J_6: the imager looking before the west side 2" head (AB and EF input)
  • LPL_100J_3: the imager looking at combined east 527nm (IJ+GH output)
  • LPL_100J_4: the imager looking at combined west 527nm (AB+EF output)

 

Figure 7. Open Long Pulse Laser Camview

Figure 8. Long pulse laser cameras and irises layout

Check alignment

  • align 10Hz pulse through the pinhole (visual check: should not see scatter light or adjust the pinhole position)
  • check i1 and i2: if it's very off, adjust with M3 and M4  (use LPL_100J_1 or IR card)
  • check i3: beam should be in the center of i3 (use LPL_100J_1 or IR card)
  • check i4: close i3 to create ring pattern (use LPL_100J_1 or IR card) adjust with the mirror befoer i3.
  • check i5 and i6: (use LPL_100J_5 and LPL_100J_6) adjust with M8 and M9
  • check i7, i8 and  i9, i10 (use LPL_100J_3) adjust with M2, M22 and BS3
  • check i11, i12 and i13, i14 (use LPL_100J_4) adjust with M10, M13 and M18
  • check i15, i16 (use card) first close i3 half way, block GH, adjust LWP15 and M26. Then open GH, block IJ, adjust with LWP10 and LWP12
  • check i17, i18 (use card) first close i3 half way, block EF, adjust LWP2 and M15. Then open EF, block AB adjust with LWP6 and LWP8

Optimize SHG and HWP

  • check if all TTL shutter are all working. If not, open all TTL shutter and run the command " meclas.TTL_shutter.Refresh() "
  • command  meclas.TTL_shutter.Status() shows TTL shutters status: in = 1, out = 0.
  • command  meclas.TTL_shutter.Toggle("openAB") opens shutter on AB heads.
  • command  meclas.LPL.SHG_opt()  will run four SHG crystal rotation stages and find the maximum one by one. You can only run one arm by meclas.SHG_opt(armsQ='XX')
  • You can open scope B to check if the SHG signal is there.

Figure 9: SHG optimization

Optimize HWP

Run " meclas.HWP.HWP_opt()". You can also run one or two arms by " meclas.HWP.HWP_opt(armsQ='ABIJ)".

Fire a shot

  • Make sure the final shutter, T3a and T3b, are closed. If it is open, make sure things are properly blocked inside the target chamber.
  • check event sequence configuration: play status "stopped" in case the lamps got misfired.
  • change camera trigger to "single shot": in MEC Home> EVR > New MEC LAS EVR > Front Panel B change to 182 (single shot) from 43 (10Hz)
  • change Ns Slicer and Lamps to single shot: Long pulse laser operation> click Single buttons on NsSlicer and Lamps
  • Charge: MEC:PFN> click "stop", "Stand By", "Ready" and "Charge"
  • Fire: click "single shot"
  • run postshot: "meclas.LPL.pspostshot(save_flag = True, display = True)" it shows a plot and energy output.
  • or show energy meter: "meclas.EMeters.Gall()"

Figure 10. left: Event Code Sequence, Middle: new MEC LAS EVR, the camera trigger is at cha 11 (Front Panel B), right: Long pulse laser operation and MEC:PFN

Figure 11. upper left: 10Hz YFE pulse shape (blue) and designed pulse shape (red). upper right: combined 100J shape. left: camview "LPL_100J_3" and "LPL_100J_4" showing single beam profiles, right: run "LPL.pspostshot()".






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