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- ssh mec-laser
- mecpython
- import meclas
- meclas.YFE.On()
- There will be a series of events that will happen to stabilize the seed laser prior to turning on the current to the YFE laser heads. If and when all conditions are stabilized, a series of audible ringing chimes can be heard coming from the e drives. It can take anywhere from 10's of seconds to several minutes for the conditions to be sufficient that the e drives can be turned on. This is the indication that the YFE laser is operating the that a beam is present at the LSS shutter S4.
Open LSS shutter, LPL Control window, and scope menu
To confirm YFE is running and a 10Hz beam is present on amplifier table without having to open the roll up door:
- Open LSS shutter S4
Confirm YFE operation before firing shots- Open Long pulse laser operation from MEC home
- Open Lecroy B scope to monitor 10Hz pulse shape
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- 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 at 10Hz YFE only on the orange paper when the paper is placed just after the final telescope before the beam reflects up from large periscope. 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.
As an alternative to using the orange paper as the indication on good beam quality through the pinhole, the Cam 3 and Cam 4 can be used. To do this, the large roll up doors will need to be opened so that the Nd filters in front of these cameras can be temporarily removed. This procedure and additional steps necessary for a more detailed alignment of the YFE beam through the amplifier heads can be found in this link:
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- If the trace is not present, confirm shutter 4 on the LSS is on
- If the trace is still not present, it may be necessary to cycle meclas.YFE.Off() and meclas.YFE.On() until the trace is present
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.
- It may be necessary to repeat meclas.LPL.psefc10Hz(numIterQ=150) if the blue trace is not fit well to the red trace.
Open the beam monitor cameras -minimum cameras needed for
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spatial beam quality check
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, only 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).
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