I've discovered HAM2 ISO_Z and ISO_RZ are well correlated to alignment changes in MC1 pitch and yaw, MC3 yaw, and anticorrelated with PR3 OSEM yaw.
It seems odd that the nm sized ISI ISO signals are showing up in the optic alignments, however this is what I find, and the optic OSEM alignment changes are not small.
I also looked at optical lever signals, and see that HAM2 and PR3 optical levers don't corellate to ISO or OSEM signals long-term. HAM2 oplev does occasionally see a large ISI excursion, and correlates with multiple ISO DOFs.
Plot 1: MC1, MC3, and HAM2 ISI ISO_Z and ISO_RZ, 400 days
- MC1 pitch, alignemt range of 80urad
- MC1 yaw, alignment range of 30urad
- MC3 ptich, increasing
- MC3 yaw, alignment range of 15urad
- HAM2 ISI ISO_Z
- HAM2 ISI ISO_RZ
Plot 2: PR3 OSEM yaw, oplev yaw, HAM2 oplev yaw, HAM2 ISI ISO_RZ, 400 days
- PR3 OSEM yaw
- PR3 oplev
- PR3 OSEM yaw, alignment range of 85urad
- PR3 oplev yaw is essentially flat (ignoring the large jump/recovery)
- HAM2 oplev long term
- HAM2 ISO_RZ, and I conceed the changes in this signal seem very small at a couple hundred nrad
Plots 3 and 4: HAM2 oplev pitch, HAM2 ISO_RZ, ISO_X, 400 days
- HAM2 oplev pitch does see large ISI excursions, and correlate to ISO_RZ and ISO_X, and not shown, ISO_Z and ISO_Y
Summary:
- HAM2 ISO_Z and ISO_RZ are showing up in HAM2 optic OSEM pitch and yaw signals
- MC1, MC3, and PR3 OSEMs see the ISO changes (likely other HAM2 optics, but I didn't look tonight)
- HAM2 and PR3 oplevs don't track the changes seen in the ISO_Z/RZ or optic OSEMs
- HAM2 oplev in it's current form is not going to provide a diagnostic for the IO chain as I had hoped
Very interesting Cheryl! A couple things of note and further info:
* There is an integration issue, FRS 5104 regarding the reversal of the HAM 2 & 3 ISI Oplev signals. Doug says he changed the matrix, Suresh says it was the medm, Oreilly says the medm was addressed... still looks like a problem.
* "HAM2 oplev does occasionally see a large ISI excursion, and correlates with multiple ISO DOFs." As soon as I saw these trends, I thought HEPI Pringle loops; I have a WP in to remove the Target Bias Restore for those DOFs, LHO aLog 31025. To date, TJ and I have been unable to understand why these won't go quietly; Jamie is back in country and may solve this. Still. interesting:
I guess I did not even look at the ISI but this restoration of the Target Bias into these AC couple loops literally distorts the HEPI platform until the Offset applied at restoration is easied as the band pass works. I did not imagine that the ISI itself was in turn distorting but that is what is going on: The Pringle loop pulls or squeezes the Crossbeams in turn doing the same to the Support Tubes' relative position, in turn distorting the ISI Stage0. This produces relative position changes at the CPSs and requires the ISO loop of the ISI to react. See attached with the HEPI HP DOF output in the middle. It makes sense that this would require alignment changes of the HAM2 Optics. Further support to raise the lower ugf of these Pringle loops and stop the restoration of the Target Bias.
I'm not surprised that this might be affecting other DOFs too and therefore Pitch as well as the more obvious Yaw. I will redouble my efforts to get these DOFs out of the Restore Bias list.
* Don't have anything to contribute as to the mamy other correlations reported.
