After Vicky and Louis's alog 64819 revelation that scattering shelves are not correlated with clipping on OFI_PD_A.
Louis and I checked the scattering shelves this morning using the same settings in alog 64819. Lowest scatter was with a slightly different ZM4 value than last night (ZM4 P 750 > 820), see attached, but the IFO had been re-locked. It didn't take much ZM4 alignment change to increase the shelves:
- With ZM4 P 820: scatting shelf increases at ZM4 Y: -24, lowest at Y -50, shelf increases at Y -110.
- With ZM4 Y at -50: scattering increases at ZM4 P 870, lowest at P 820, shelf increases at P 763.
Robert took photos of HAM7 with the ZM alignments for the lowest scattering shelf ZM alignments.
| Photos Start GPS time | State of ZMs |
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1346184898
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Least scatter ZM4(820, -50), ZM5(-304, 510), ZM6(742, 820)
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1346185255
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More scatter, yesterday's IFO alignment ZM4(-568, 376), ZM5(-304, 510), ZM6(742, 820)
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1346185577
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Settings at scatter model settings alog 64816 ZM4(-218, 309), ZM5(-396, 426), ZM6(880, 816)
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We also wanted to understand the clipping on OFI_PD_A (B:PD1) so that in chamber we know the amount to move it (in alog 60447 Betsy measured 14mm of motion at ZM5 for 10600 slider counts in ZM4 Yaw).
Started with same (c) "optimal for no PD clipping" alignments ZM4(400, 50), ZM5(-384, 432), ZM6(772, 780) as alog 64811 then just moved single DOF of ZM4. Lost lock before we finished measurements, 30secs after last ZM move.
| Start GPS time | State of ZMs | Power on OFI_PD_A (uW) |
| 1346185841 | ZM4 (900, 50) expect clip LOW | 15 |
| 1346186212 | ZM4 (-620, 50) expect clip HIGH | 14 |
| 1346186457 | ZM4 (400, -1020) expect clip LEFT | 14 |
| 1346186709 | ZM4 (400, -1470) expect more clip LEFT | 2 |
| 1346186956 | ZM4 (400, -2535) expect completely clipped LEFT | -1 (no light) |
| lost lock :( | RIGHT |
