betsy.weaver@LIGO.ORG - posted 11:31, Thursday 26 July 2012 - last comment - 14:13, Thursday 26 July 2012(3608)
MC2 Roll adjustment
This morning we adjusted the 0.4mm roll out of the MC2 lowest stage via rolling the optic in the sling. We were able to take the roll error from 0.4mm on each side to 0.003mm error, well within the 0.25mm guideline.
We reset the M3 stage AOSEMs and are now back to running TFs of MC2.
July 24, 2012 Norna's email exchange of roll tolerance requirements:
Colleagues
I found the email exchange I had with Dave R about clocking, see below.
1.5 mrad corresponds to a height mismatch of ~ 0.2 mm (0.1 mm up on one side and 0.1 mm down on other, with 75 mm radius). This value was not a concern to him as you see. Betsy's 0.4 mm up on one side and down on other gives a clocking of ~ 5 mrad. So someone (Luke?) should check the Zemax to see if 5 mrad (for example) is OK and then we should get a target value captured in a design requirement doc.
However Matt's practical advice and experience of getting it to 0.25mm sounds good for now.
Norna
TFs from before the roll fix showed some small cross-coupling between T and L. We fixed the roll of the optic and the modes are now degenerate as expected. Plots and more details coming.