This entry will summarize past working days (sorry for the delay)
New Optical scheme and wiki sections :
The new optical scheme (v 31) ".svg" has been updated in the wiki. The ".png" is attached to this entry.
The available lenses have also been added to the "Optics" section of the wiki.
EOM alignment and p-pol power :
The 2 steerings mirrors before the EOM have been remplaced by PBSW-1064 which should only transmitt 5% of p-pol each.
When doing this, we saw that the lens before the EOM was a bit tilted so we aligned this EOM path again.
We now have
| before EOM | 10.0 mW |
| after EOM | 8.7mW |
| p-pol after EOM | 100 um |
Note that the power values where chosen to compute easily the % transmission.. We can increase a bit the power if needed. However to lock the OPO, it is planned to use a similar photodiode to the one used to lock the FC where the power is ~200 uW.
It seems that p-pol inside a modulator can lead to amplitude fluctuations. Is this power low enough to avoid them or should install an additional PBS before the EOM?
P-Pol and CC beam characterizations :
In order to characterize this 2 beams, we did as for the FC green reflection.
We added one f=100mm lens and check the beam profiles after it.
This 2 characterizations are attached to this entry.
The lens after the EOM was then moved a little in order to match more precisely the beam waists.
The 2 beams were aligned before the first sterring mirrors of the OPO telescope using 2 irises and checking the power transmitted.
The 2 beams are now quite well overlapped on the rail as we can see on the beam profiler.
OPO telescope :
Using the CC beam as our reference, we designed a telescope that is now placed between the 2 last steering mirrors before the OPO on a rail.
Our first simulation didn't match the data. It seems that we need to understand it a bit better. Please note that the value of the FC relfected green beam parameter before the lens is wrong!
Using Jammt for the moment we could recover the beam parameters before the lens and design the telescope.
It consists of 2 lenses as attached to this entry (sol2).
Before the storm we found a mean beam waist of 36.3 um quite close to the nominal one!
A better characterization of the 2 beams will be performed tomorrow.
