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- Open Lecroy B scope to monitor 10Hz pulse shape
- If trace is not present on Lecroy B, make sure that 10Hz operation is enabled.
Physical inspection of the 10Hz beam
It may be desirable to physically inspect the beam alignment from the YFE laser through the amplifiers and SHG crystals. Go to class 4 and open the roll up doors to inspect the quality of the 10Hz 527nm beam. This is most easily done by placing the orange fluorescent paper in the beam path just after the expanding telescopes for both the East and West beams.
If the 527nm beam profile looks good, then proceed with firing amplifier heads. If the beam profile has spatial features that look irregular, it may be necessary to adjust the pinhole position in the VSF to confirm that there is no "flaring" of light at the pinhole.
If there are some visible sign of clipping in the pinhole and/or irregular profile when observing beam on orange paper, then make adjustments in both axis of the VSF pinhole to minimize the clipping/flaring of the beam. This adjustment, in turn, should improve the spatial profile of the beam when observed on the orange paper. Adjustments to the pinhole will have pretty significant affects on the spatial profile delivered to the amplifiers but there are not any conditions on the alignment or mis-alignment of this pinhole that can result in damage to the amplifiers.
Load the waveform recipe and shape the waveform
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Figure 5: choose the pulse recipe: use commend "meclas.LPL.psmenu()" Figure 6: shape the 10Hz pulse as designed.
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Open the beam
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Go to class 4 and open the roll up doors to inspect the quality of the 10Hz 527nm beam. If the 527nm beam profile looks good, then proceed with firing amplifier heads. If the beam profile has spatial features that look irregular, it may be necessary to adjust the pinhole position in the VSF to confirm that there is no "flaring" of light at the pinhole. If there is some visible sign of clipping in the pinhole and/or irregular profile when observing beam on orange paper, then make adjustments in both axis of the VSF pinhole to minimize the clipping/flaring of the beam. This adjusment, in turn, should improve the spatial profile of the beam when observed on the orange paper.
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monitor cameras -minimum cameras needed for operation
There are 2 cameras in the upgraded LPL layout used to monitor the East and West beams delivered to the TC. 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
For operation and monitoring purposes only LPL_100J_1, LPL_100J_3, LPL_100J_4, are needed to open. For full alignment, using these 6 cameras is recommended. These imagers locations and descriptions are as followed (figure below 2).
- 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)
It will be necessary to take an amplified shot to check the integrity of the 527nm beams from the combined legs on the East beam and the combined legs on the West beam because there are ND filters in front of both Cams 3 and 4 that are set to attenuate the full amplified energy from all beam legs. If the 10Hz beam quality through the amplifier legs is to be viewed on either of these two cameras, it will be necessary to open the doors, remove the filter assy in front of both Cam3 and Cam4 cameras, and trigger the cameras at 10Hz.
Figure 7. Open Long Pulse Laser Camview
Open the beam monitor cameras -All cameras needed for full alignment
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
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- 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)
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Figure 8. Long pulse laser cameras and irises layout
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