Ibrahim, Betsy, Anamaria

Upon first in-chamber BBS01 inspection, we found 3 large clumps of spots approximately 100mm from the edge. We're consulting GariLynn at CIT for steps on how to clean.

Acetone swab: We tried to go over the spots with a cotton swab with acetone, but the spots remained.

First contact: We then tried to first contact a small portion with one thin layer, but the spots remained.

While there's no evidence that the beamsplitter was contacted, dinked, touched or scratched in anyway, this might be a cause for the damage. There is texture to the spots upon brushing them with a swab and while it seems more likely that these are above the surface, we are not totally sure.

Hypotheses (and their problems)

1. Peek In-Vac cable scratch: maybe an in-vac cable fell on that area but they would have had to imprint multiple times with some force to show something like this. 

2. Falling foil: maybe a piece of foil fell onto the surface and scratched it that way? No foil was used or wrapped at height during BBS and again, the foil would have had to fall with some heft.

3. There-the-whole-time: Maybe the spots were there the whole time and are invisible to non-chamber conditions. Because this is on the AR side, there is no good scatter plot of the surface. Since we did not see this in normal light conditions, but immediately saw this in chamber (dark) conditions, this may have been there all along. The spots are quite large (as attachments show), so this makes that less likely.

4. Dry first contact: Maybe it's dry first contact? We went over some of the spot with acetone but it stayed. We also first contacted a thin layer on one part but it stayed. The nature of the spots do look like they're small first contact bubbles. We found the first contact sheet that we used on that side and indeed, there are some similar streaks in size but nothing conclusive. We're looking at matching the spot with the first contact to see if there is a streak in this region. Problem is - first contact wouldve come off quick with the acetone treatment. So this is also not likely it.

What to do next:

- Analyze with Dino-Lite: We're going to zoom in on the spots with our DinoLite mount to get a better look. This could tell us if they are truly scratches or stuck particulate.

- Match first contact sheet with spots: Seeing if these spots were visible during FC (done on May 6) - alog 90149. Nothing visible. 

- Anamaria suggested at any rate shining a gaussian beam at it to analyze the damage in a short experiment to characterize. 

Ibrahim, RyanS, Betsy, Corey, Anamaria

Today we pulled the forst contact fabric from ITMY. 

First we de-installed the jig around the cage, leaving only the fabric still attached to the HR of the test mass. We used the top gun to blow away particulate on the sides of the quad, the CP and in between as much as we could before pulling the FC. We note that there are still small, albeit sparse, visible "dot" particulate on these surfaces. These were observed at LLO as well, so nothing too surprising.

The first contact came off nicely, as an even layer. There were two spots at the edge, about 1-1.5 inch from 10 o'clock and 2 o'clock that left some residue so we painted those two little spots to remove it. We did it twice because the first time we left a bit of a line at the edge, but that was more petty than necessary. There was a small hair-like piece, 2mm long, that didn't come off with the top gun so we used a dry cotton swab to swipe it off.

We replaced the face EQ stops and the cage baffles. The quad is locked and the ACB is still wedged up. 

Ibrahim, Ryan, Betsy, Anamaria

This morning we poured the first contact onto ITMY. All went well. We had 3 minor drops at the bottom, but they dried fast and didn't continue leaking. We finished pouring about 09:35, took some 10 min. We then kept pushing the pico motors until the level stopped changing and the picos started to bottom out. 

It took us a bit to get the camera setup with reasonable lighting, so for next time: we should turn off the illuminator from the getgo and set up a tripod just for light, next to the camera. (Because of the CP, we are looking through 3 surfaces to see the HR of the test mass so it's quite hard to not have all the reflections cover what we really want to monitor.)

Ibrahim, Anamaria

This morning we:
-  set up the FC fabric on the drum;
- lowered the ITMX ACB to take its wedge, and then used it to swing the ITMY ACB out of the way;
- inserted the peek "Kurt fingers" between ITMY and its CP in preparation for installing the FC jig this afternoon.

This afternoon we:
- set up the jig around the test mass;
- tightened the drum with the fabric onto the test mass while watching the fibers on camera;
- added the grid+mesh for pressing, as well as picos on the ring of the drum;
- added the funnel and hose setup, connected to the spigot.

We will add more details and photos later. For now we are dumping photos in the common FC google drive. Folders named by date and activity.

Ibrahim, Betsy, Oli

BBS01 AOSEM flag standoffs were removed, concluding gluing.

BBS01 was flipped to the HR Side via the inspection fixture.

Betsy and I then first contacted the HR Side (S1) and peeled an hour or so later.

We did not see any features or defects as we did with S2.

Ibrahim, Betsy, Rahul

Today we glued two of the four AOSEM flag standoffs onto S2 of BBS01.

After gluing, we wanted to make sure we were contacted evenly so an hour and a half later, we used magnets to remove the flags from the glued-on mounts.

We discovered that some glue was touching the bottom of the magnet bushings, so we elected to use some foil as shims to create more space between S2 and the bottom interface of the bushings.

Otherwise, the mounts were flat on the surface. We put the bushings back on for the overnight cure. See pictures below.

Ibrahim, Betsy

Today, Betsy and I set up a Dino-Lite to image the spots we found yesterday (alog 90147).

Below are photos including before and after cleaning - according to the names of the files. None of the spots seemed to change after cleaning.

We also cleaned the spot that's in the center (not imaged with dino-lite) but it also did not go away.

Current most likely hypothesis is a coating defect due to circular nature of the spots and the resistance to cleaning.

Ibrahim, Betsy, Rahul

First contact was successfully poured on BBS01 AR side. Pictures below.

Ibrahim, Betsy, Rahul, GariLynn

Following AR side first contact removal, we did our first flashlight inspection of the AR side (S2) of the optic. We found that there were 4 spots of varying size all under 1mm, perfectly circular. They seem to look like water (look at image). We contacting COC (GariLynn), who informed us this may be some coating defect. Nontheless, we tried cleaning it.

There are 2 smaller spots on the side of the optic (see image). There are 2 other spots near the center, with one being pretty dead on-center.

First, we used acetone with a cotton swab to wet two spots (the ones on the side). This didn't work and the spots were still there.

Second, we followed T1800350 to clean two spots with water, then immediately apply first contact. This didn't work either.

We will continue to clean spots with water tomorrow. Images below.

I had a look at the three SRC gouy phase measurements listed in 88155, this is related to commissoning modeling git issue 33

To do this, Evan Hall helped get me started using the current version of finesse (3.13.13) in the control room.  Anyone can use this conda environment by using conda activate finesse.  

In the first plot, the upper left subplot shows the cold gouy phase measurement, which is reasonably close to the finesse prediction using nominal parameters from the LHO_O4.yml.  I've added traces to show what happens when the SR3 ROC and SR2 ROC are changed by the rss error given by Garilyn, +/-6mm for SR3 and +/-3.7mm for SR2, and varied the distance between SR2 and SR3 around the value in the finesse yml.  The gray band shows the measurement result, indicating that the gouy phase measurement could be explained by the nominal ROCs if the SR3-2 distance is longer than the value used in finesse by 3mm, or if the distnace is nominal the SR3 ROC could be shorter by 6mm to explain the measurement.  

The next two panels show the two measurements made in October 2019, before the ITM replacement (52638 and 52658).  The ring heaters were on for both of these measurement, decreasing the expected gouy phase, and central heating was also on which should increase the gouy phase.  Using the TCS actuation strengths from 90004 we cannot easily explain these measurements as compatible with the cold state measurement.  

The last panel shows the impact of each indivdual TCS actuator on the gouy phase measurement.  The fact that all these lines are fairly close to parallel suggests that a series of measurements where we change only one actuator at a time could be a useful check of the actuation strengths.  

In the second attached plot, I plotted the difference in gouy phase between having the heater on and off, which we can get from the comparison of the two 2019 measurements, with various parameter changes.  I was wondering if we could use this difference to get information about the SR3-SR2 distance if we trust the HWS measurement of the SR3 heater strength.  The 1.8 degree systematic uncertainty on the gouy phase measurements is large enough to make this seem not very promising.  

The script used to make these plots is in the commissoning modeling repo here commit 8635b914

Maybe this isn't the best place to share this, but life can be frustrating as a deuteranope. Matplotlib has an easy to use colorblind friendly style built in. It can be invoked by adding the line plt.style.use('tableau-colorblind10') before starting to setup your plot (if you've used the usual import matplotlib.pyplot as plt). Maybe this is common knowledge, but I just found it while working on a script.

The first plot is one of the plots produced for the weekly CPS noise monitoring famis for ITMX. The second plt is the same one, but I added the colorblind style to the script. For me, on the first image the H3 and V1 sensors on both subplots are almost the same color. It's especially difficult to go between the legend and the traces on the first plot. Reading these plots on a backlit monitor make this even harder. More than a 4-6 traces, I have a really hard time telling which line is which.

On the second figure, it's much easier. Add in some different linestyles and thicknesses, and everybody's pretty plots can be appreciated by more people.

Today, Travis and I pulled the ITMX-HR FIrstContact cleaning layer and inspected.  With bright light it was difficult to find many particulates in the main area of the center of the optic which was good. We fully suspended the 8 locked QUAD masses and returned the ACB back to it's nominal position (removed locking bracket and wedge).  We then inspected the ITMX OPLEV laser transmitter and receiver beam with respect to the new nozzle baffles, and also check to confirm that for this ITM, the optical lever readback SUM is the same as it was before the locking episode.  So all good there.  A few quick TFs identified that I left a stop rubbing on the CP top barrel which Travis found, but the TFs look better now.  Wafers are down in the chamber and we swept for tools, etc.

Nidhi is finishing the ITMY SUS TFs.

Jim is going to try to run ISI TFS of ITMX, ITMY, and the BS tonight.