I looked into the mode telescope model I've been using for T1900649 to root out why my modes aren't what Sheila and Keita have been measuring. I commented on LHO58323 that I was calculating the OPO pump sequence using an incorrect path and that the current matching plan was good and that now the model matches the measurements.

In debugging that path, I traced out the OPO cavity calculation and realized I had the crystal placed off center. This is because I used the mirror and crystal coordinates from T1700104, but assumed the crystal coordinate was its center, and it was actually an edge. Surprisingly, due to the index of the crystal, it matters where it is placed due to the lensing effect of the beam crossing either side of the PPKTP material. I should have found this earlier, since the mode reported in T1900649 Fig 16 coming from the OPO did not correspond to the (big) waist size in T1700104. Now, it is much closer, getting 99.4% overlap with Sheila's post-L1 measurement in LHO58316. I nudged the mirrors 0.5mm more to get the matching to 99.6%, which is probably about as good as we'll get given the astimatism in the OPO.

Ok, so my OPO model was to blame for the discrepancy, this means that my telescope needs to be adjusted. Luckily we can do this pretty well. There are two options.

A:Option1.png The first is to move A:L1 about 0.3" closer to A:M2, get rid of A:L3, and make A:L2 a 100mm ROC while moving it one inch further from the SFI, sortof putting it between the current positions of A:L2 and A:L3. This option is good because A:L2 stays on the translation stage.

A:Option2.png The second option is to leave A:L1 where it is, and make A:L3 a 100mm ROC, remove A:L2 and rename A:L3 to be the new A:L2, or alternatevely slide the stage very near the edge of its range to sit it where A:L3 is now. This maybe allows the translation stage to work, but only in one direction and it is nearly crashing into A:DC2.

I'll update T1900649 before too long. I'll also need to perturb the B:paths now.