[Keita, Nutsinee, Sheila, Jenne]
We went in to HAM6 today, and believe that we have finished all ISC/SQZ related tasks, and are ready to begin closeout procedures tomorrow. (Betsy, who has the final say, will write an alog or talk to the relevant folks for the actual final start of closeout.)
After Richard opened the PSL shutter and Ed locked the IMC, we pretty easily were able to get beam onto AS_C. To check our alignment, Sheila aligned the Michelson, then made sure we were still centered on AS_C. Since we don't have arms, we just assumed that the input beam is pretty close to its usual, and only adjusted ITMs and BS for MICH. Around this time, Keita noticed that there was a bit of a 'tail' on the beam as seen on an IR card. Sheila walked SR2 and SR3 until the tail was gone, but we were still centered on AS_C. After this we aligned SRY (restored SRM, misaligned ITMX) to get good fringes, so that we could trust the SRM position for squeezer-related work. We also took the IMC offline (which misaligns MC2) to remove the main IFO beam, injected the SQZ beam, ran the squeezer's ASC loops, and noted that the ZM1 actuators were very close to the edge of their ranges (as Sheila made a quick note about in alog 52405). We deferred action on this until after the main IFO path checks were complete.
Once we were happy with all of our alignments we brought the main IFO beam back and Nutsinee took photos of the beam in several different places, including the septum window, the position on OM1, the position relative to the fast shutter's wire, the position on OM2, the position going into and returning from the OMC shroud, and some photos to ensure that we don't see any obvious scattered light at the shroud apertures.
Having completed this, and deciding that it was still quite early in the day, we began work on relieving the ZM1 actuator. Sheila noted that the pico that is on/near the OFI is closer in Gouy phase to ZM2 than ZM1, so would not be a satisfactory way of relieving ZM1. Sheila and Keita went in and adjusted the last steering mirror on the VOPO platform that sends the beam to ZM1 about 1/4 of a turn in yaw, clockwise if you are standing at the endcap. After I damped the VOPO we re-ran the squeezer alignment loops, and found that instead of having outputs of nearly 29k the ZM1 outputs were at most about 7k. Excellent! We note that the ZM2 outputs are around 22k, but this is the same that they were during O3a, it hasn't drifted, and if we need to we can relieve ZM2 using the pico, so we are leaving things as-is.
With these 2 sets of checks and work, I believe that we are done with ISC/SQZ work in HAM6. Nutsinee will comment with her photos.
Nice work team!! We'll mobilize to do the chamber unlocking and closeout tomorrow!
Attached photos of beam at various places.
1) Beam coming out of septum window towards OM1 -- taken as close as possible to the beam height, vertical view
2) Beam coming out of septum window -- camera aligned to the beam as much as possible, horizontal view
3) Beam towards OM1 just before the fast shutter
4) Beam towards OM1 just after the fast shutter
5) Beam reflecting off OM1, in front of the fast shutter
6) Beam reflecting off OM1, behind the fast shutter
7) Beam next to the toaster again after a small alignment change. The beam location stayed pretty much the same.
8) Beam on OM1 (vertical view)
9) Beam on OM1 (horizontal view)
10) Beam on OM2 (vertical view)
11) Beam on OM2 (horizontal view)
12) Beam on OM2 (IR camera)
13) Beam going into OMC, reflects off OM3
14) Beam going into OMC, vertical view
15, 16, 17) OMC input output port area (IR camera looking for scattering)
18) Beam relative to the wire when fast shutter closed
19) OMC refl on beam dump
20) Beam reflects off fast shutter to beam dump
Before-swap pictures were posted in alog 52310.
Oct 11, 2019 Close-out sweep of HAM6 photos are here.
Since Resource Space appears to no longer be functionable/useable, here are some photos of the septum flanges/viewports.