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. 

With Jeff in chamber, me outside with the B&K laptop, and Josh taking notes next to me, we did three measurements with three dofs on the ISIK breadboard in its current state without the shroud on. Results have two large peaks at 198Hz and 214Hz. The Y hit looks to have rung up the 214Hz much higher than the other dof hits, so much so that the 198Hz is barely visible. The 198Hz feature was seen in the MC2 scraper baffle B&K results for L1 back in 2017 (alog39750, see the last plot on the attached pdf). That said, I don't really see it for our results back then. 

Setup

Accelorometer axis lined up with IFO axis, hooray! The acc was placed between the M_M2 and R_B3 (photos - attachment 4, attachment 5).

Results

Jennie W. called to let me know that they need the Pico Motor Drivers turned back on.

We're checking the grounding of things in HAM2. IM4_TRANS QPD, ISS array QPD and all 8 ISS array PDs are fine.

IM4_TRANS and ISS array QPD:

Disconnected the DB25 cable from the transimpedance amp (ISC R4 slot 31) and measured the resistance between the pins and the chamber ground. (Ground potential for the chamber and the racks are significantly different, so we connected one cable directly to the chamber and measured the resistance between that cable and the pins.) 

All pins are isolated from the chamber. pin13 is tied to the shielding.

ISS array PDs:

Disconnected two DB25 cables from the second loop chassis (D1600229) in the PSL rack and measured the resistance between the pins and the chamber ground. Same caveat about chamber VS rack ground.

All pins are isolated from the chamber. Pin 13 is not connected to the shielding. This is fine, as this is a special cable made to convert four pairs of coax cables (total 8 coax) into DB25. Shielding of 8 coax is connected to pin14 through pin21 which are tied to the ground inside the second loop chassis. Pin13 is also connected to the ground inside the chassis. See D1600321.

Fil is done with SUS, some issues were found and he'll work with Rahul to try to fix them. He will also test picomotor grounding later.

[Begum, Camilla, Ryan S., Madi, Sheila]

Measurements taken on 2026-06-08 and 2026-06-09:
After the new OPO installation, beam profiles measured on HAM7 table (Sheila 90345) indicated that the OPO mode is different for the new OPO. This of course would both affect OMC mode matching as well as FC mode matching. The following measurements are beam q-parameter measurements measured on the FC path (green path in attached diagram), for beam upstream of ZM2 (p6,p7,p8,p11,p12) and downstream of ZM2 (p9,p10). The camera/profiler used is Phasics SID4 (MIT unit). 

Phasics camera is capable of giving us a beam waist and how far away that waist is from the camera position (- upstream of cam, + downstream of cam), however the fidelity of these values are dependent on where the camera is placed with respect to the waist: if it is too close to the focal plane (where the beam divergence is small), or if the beam is too large for the sensor the extracted values don't make sense. So, we have measured at least two positions with known distance from each other evaluate the fidelity q parameters obtained. 

Multiple measurements were taken at p10 point, varying ZM2 curvature. The strain gauge values are given in the table, 1.2 V and 6 V strain gauge correspond to 0 and 200 V pzt supply voltage to ZM2 psam. For points p6,7,8,9,10 the A:L2 lens was sitting in the "middle" position, both edges of the stage is lines up with its rail (will add photo here). Below table is from measurements taken on 06-08. The camera reports three numbers for each parameter, major, minor, radial. Major and minor do not necessarily line up with horizontal and vertical axes. The screenshots for each case report what the angle is. The .txt file for each data point also reports wx and wy for the near field beam, so we can potentially infer from there.

There are two readily available beam parameter tuning options we have for the FC path: the ZM2 curvature via psam, and the A:L2 lens via the translation stage it lives on. In the afternoon, we parked the Phasics camera on p11 and p12 positions (between p7 and p8) and recorded beam parameters for A:L2 lens on three positions (middle:0mm, -13mm: lens closer to ZM1 by 13mm, +17mm: lens further away from ZM1 by 17mm). Below table is from measurements taken on 06-09.

Raw data is in the attached .zip 

We've been continuing the CRS build in the H2-PSL and prepping everything to eventually be moved chamber side. 

Yesterday we cleaned the half-wave plates which were delivered late and the last part of the HoQIs needed. We are planning to dust them off with an ion gun and install them in the rest of the HoQIs today.

Finished constructing the rest of the HoQIs minus the half-wave plates and the two HoQIs with broken PD connectors.

01-SN008 and 02-SN008 were internally aligned with the following fringe viability:
01-SN008: Sin-81.5%, Cos-78.8%, MCos-81.9%
02-SN008: Sin-84.4%, Cos-82.6%, MCos-78.5%

Created/built a simulink model for the CRS. on HAM3 and got the channel names all worked out. With the library part /isi/common/models/crs_block.mdl and the proc /isi/h1/common/h1crsproc.mdl

At about 15:30 UTC I started to put all HAM2 Suspensions to safe so Fil can do some ground loop check on HAM2.
List of suspensions includes: 
MC1 
PRM
MC3 
PR3
IM1-4

TITLE: 06/10 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 8mph Gusts, 4mph 3min avg
    Primary useism: 0.10 μm/s
    Secondary useism: 0.13 μm/s 
QUICK SUMMARY:
Some of the work that may be attempted today.:
Corner Station vacuum chamber is still open. 
Beam splitter team is still working on First contacting the Beam splitter.
Faro team is still faroing near HAM3 and BSC2.
Ground loop checks will happen.

SPI team is still working on their install and may request Laz Haz in the afternoon.

CDS overview screen has red indicators:
H1EDC is red and has the following channels with errors: 
H1:HPI-PUMP_CS_DIFF_PRESS_PUMP_CTRL_SETPT_HIGH
H1:HPI-PUMP_CS_DIFF_PRESS_PUMP_CTRL_SETPT_LOW
H1:HPI-PUMP_CS_DIFF_PRESS_PUMP_CTRL_SETPT_OOR
This may be due to Jim and crew not being done with SEI  adjustments.

GRB-SHORT  E639712

Summary

Whatever happened to IM1, Rahul did make it better again. Reasons for improvement is unknown but we proceeded with the alignment and we're mostly done.

There is a mystery scattering or maybe clipping somewhere close to the IFI output but not on the output baffle nor DKDP baffle. It could be a scatter from the CWP surface, or a ghost beam somewhere, or something else. It will take a LONG time to diagnose this, and quite likely this existed for a long time. I'm tempted to leave it at this time. But I'll try to take some more pictures.

There's also something weird about the 1st pico mirror PIT actuator for ISS array.

We'd still like to take pictures/measurements here and there on Tuesday.

Done: ASC REFL centering

Following the morning work (alog 90525), REFL ASC censors were centered using RM1 and RM2. About ~30% of DAC range was used for RM2 (RMs_happy_again.png). FYI, using flash peak, [P,Y]=[-0.003, 0.015] for REFL_A and [-0.020, 0.001] for REFL_B. (Doesn't matter how close these are to zero as far as they're within +-0.1 or so and the SUM is decent, but it feels better to be able to get close to zero.)

Done: ISS array centering

Then we looked at the ISS array and the QPD was not centered. A quick adjustment of the second pico that is closer to the array was all it needed (keita_ISS_happy1.png). [P, Y]=[-0.03, 0.05].

Done: IFO REFL baffle (HA13) adjustment

We looked at the IFO REFL baffle (HA13) in front of the HAM2-HAM3 septum window and it was too high even though it was not clipping, so we lowered it by a couple mm. Before: lower edge height = 105.5mm; upper edge = 206.8mm. After: lower edge = 103.6mm; upper edge = 204.5mm.

This baffle was already moved by a couple mm in +Y direction last week (because the beam was closer to +Y edge). See  IFOREFL_baffle_before_relocation.jpg and IFOREFL_baffle_after_relocation.jpg though it might be difficult to see the difference from this picture.

IFO REFL beam looked like IFOREFL_HA13_baffle_after.mov after the height adjustment.

Mystery flashes seen inside IFI output baffle aperture

We proceeded to check the IFI output baffle and I was bothered to find that something that looked like clipping was visible close to the left edge of the baffle using the IR camera. See IFI_OUT_clipped_720p.mov, this is a view from +Y door. But this was less frequent than the flashing itself. In a retrospect, this was probably the reflection from the PRM when the beam was swinging to the left of the video, but anyway we did various things:   

• We got suspicious about PRM somehow misaligned, checked it on the retroreflection check iris but it was fine in YAW (it was off in PIT so changed PIT offset from -1185 to -1115, not sure if it was PRM that changed or something else, but the important thing was that it wasn't off in YAW and that this is not something that I worry about now that we have a decent headroom for RM2 DAC).
• We closed the HAM3 door cover (which did quiet down the beam motion a lot) as well as the HAM2 -Y door cover. I used IR viewer and thought that nothing changed at the time. The bright thing didn't disappear after blocking the beam between PRM and IM4, again using the IR viewer, I thought.
• However, revieweing videos shot later, I haven't found anything to the left of the output baffle after the beam motion was reduced by closing unnecessary open door covers. But that revealed the next issue.

See IFI_out_another_view.mov, this is after the beam quieted down enough and after PRM PIT was changed. The bright thing at the left side of the baffle hole is not visible any more, but you can still see bright-ish scattering of some sort inside the baffle aperture which was there even when Rahul blocked the beam between PRM and IM4. IFI_out_another_view.jpg shows the same thing but with more useful exposure. This is concerning.

DKDP baffle behind the IFI output cwp baffle looked OK (IFI_DKDP_baffle.mp4). BTW, as was reported before, it looked to us that the IFI output baffle has an offset in -X+Y direction relative to DKDP. In the video, the beam on DKDP is slightly biased to the right on average because we tried to split the difference between two baffles.

We moved IM1 in YAW by +-200urad while observing the IFI output by IR viewer to see if there is a better beam position on IFI output. It seemed to me that actually we don't have much space here.

Look at IFI.png to see how the beam is routed through DKDP, output CWP and then passes by the parking beam dump pick-off.   

• If we give negative 200urad for IM1 YAW, the forward-going beam starts to interfere with the parking beam dump pick-off once in a while and the frosted barrel of that pick-off becomes bright. This is despite that the beam looks perfectly fine when IM1 is at the now-nominal position (see parkingBD_pickoff.mov, negative 200urad IM1 rotation would mean that the beam will be like 1mm to the right in this video).
• If we give positive 200urad for IM1 YAW, I thought that +X side of the IFI output cwp baffle starts to get brighter once in a while (my theory is that this is the same thing as shown in IFI_OUT_clipped_720p.mov where the edge of the baffle clips the back-propagating beam when the beam moves too much).

We'll be better once we're in vacuum because things will be quieter and the MC alignment will be better, so no beam motion and no HOM transmission, but I have to say that the clearance here looks to be unnecessarily narrow. I will NOT touch IFI itself so the only option for mitigation will be to move the parking BD pickoff, but it will be tedious to align that pickoff to steer the beam into the beam dump on top of HAM2. Given the limited time available I'll leave it as is.

We don't know what this scattering is, maybe it's the AR reflection of CWP or DKDP hitting something, maybe it's the surface scatter of CWP. I'll try to take the video from the back of the IFI output beamdump/CWP using a big inspection mirror.

Done: IM4 TRANS centering.

Rahul used pico mirror to roughly center IM4 TRANS while I was monitoring individual segments. IM4TRANS_ROUGHLY_BALANCED.png

Done: IM4 baffle (HA12) moved

As planned. The beam originally was offset in +X direction (IM4_HA12_before.jpeg shows the original location, IM4_baffle_HA12_before.mov shows the beam position), IM4 baffle was moved a bit in -X direction (IM4_HA12_after.jpg, IM4_baffle_HA12_after.mov).

Done but not really: Picturing the picos, one concern for the first ISS pico actuator.

J. Freed, J. Kissel, J. Wright, T. Sadecki

Today was the first day of ISIK Install. ISIK IS NOW IN CHAMBER!!!! Detailed notes for the install are located here

Removed the last cable clamp of the old feedthrough from the -x -y corner. Feedthrough hole covered with foil in prep to install new feedthrough tomorrow which will include the fibre routing and existing ISI cabling.

In order we did:

• Removed ISI ballast mass
• Install installation cylinders
• Install ISIK transceiver 
• Remove ISIK Handles
• Remove installation cylinders.
• Install ISIK shroud brackets.
• Routed picomotor and photodiode cables to +y -x corner in prep to connect to that feedthrough.

NB we might have to realign M_B1 and R_B2 as these mounts were bumped in install

We tried to diagnose the scattering or clipping or whatever that is visible inside the IFI output baffle aperture (alog 90536, especiall this video from that alog). It's not subtle, is always there even when the beam is blocked between PRM and IM4, and it's not just once in a while, it looks to be as frequent as strong flashes from IMC.

This is not the clipping of the forward propagating beam on the baffle as the beam height is pretty good (beamheight_dkdp_baffle.mp4) and YAW is also OK on dkdp baffle as well as IFI output baffle (dkdp_baffle_yaw.mp4, IFI_output_yaw.mp4).

We took a video of the back (i.e. -Y) side of the IFI output baffle through the output CWP by inserting a big dentist mirror between DKDP baffle and CWP and shooting from the +Y side. Video will be posted later (the raw video from IR sensitive camera exceeds 15Mb limit of alog and I don't have a good editor on my laptop).

Anyway, it seems like something is maybe hitting the bottom edge of the baffle from the back, Disha and Rahul think that there's something at the top too but I'm not sure.

We don't know what it is but we've done everything that could be done in situ without resorting to drastic measures (like temporarily removing all suspension baffles that block our view, which takes time despite that we don't know if that helps or not, or moving IFI to the lab which I won't do at this point in time). Since I'm pretty sure that this is NOT the clipping of the main beam as was noted above, my recommendation is to give it up at this point and move on, knowing that this thing does exist.

Together with alog 90536, we're done with HAM1/2/3 alignment today. Let's hope that the IM1 mystery motion won't return.

Fil already started ground check of suspensions, we'll do the ISS unit and the QPDs in HAM2/3 tomorrow.

Sheila, Camilla, Begum, Ryan Short

Summary: Beam is aligned to filter cavity, and through SFI1 + SFI2, with only a couple of % loss.  We are clipping on B:L2 apperture, which we plan to remove tomorow.  

This morning Camilla and I worked on the alignment from the VIP to the filter cavity.  We started by looking at the centering on the A:L2 aperture, which Begum and Camilla adjusted yesterday using a power meter downstream (90528).  To me the beam looked a bit high on this aperture, but we have seen in the past that looking at the aperture isn't a good way to judge the centering and it is best to rely on the power meter, so we've left A:M1 and A:M2 as they were we plan to leave them this way. 

We adjusted A:M3 to center the beam on FC1, then walked ZM3 sliders to get the beam retro reflected in return off ZM1.  Camilla moved ZM3 off in pitch so we could better judge yaw, then off in yaw so we could better judge pitch.  This gave us a beam in transmission of SFI1, we adjusted  B:M1 to clear the aperture attached to B:L2, and to bring us close to centered on the SFI2 aperture.  The beam looks good in pitch on the B:L2 aperture but slightly to the -X side of the aperture, not enough to be concerned about clipping.  We also adjusted B:M2 and B:M4 to get the beam transmitted through SFI2 and the ZM4 iris, but it is clipping on the B:L2 aperture.  (Labeled cartoon)  We can see that the beam makes it through the SQZT7 iris and to the SQZT7 IR PD, but it is quite low on the first iris.   This afternoon we reset the positions of the irises in front of ZM3 and ZM1 to center on this new alignment which we believe is correctly retro-reflecting off the filter cavity, screenshot of these slider positions is attached.  

We made an attempt to use a non-magnetic allen key to remove the retaining ring for the apperture on B:L2, but ring is too tight for us to remove it from the akward angle.  We think that we will have to pull it out of the chamber so we have space to use the correct tool for the retaining ring.  

This afternoon, Ryan Short, Begum and I went back and tried to make some beam profile measurements of the beam returning off FC1 by inserting a beam splitter.  We ultimately weren't able to find a spot to place the beam splitter and phasics camera where the beam was the right size without blocking either the OPO reflected beam or the path to FC1.  

We did take 6 measurements with the phasics camera of the beam reflected off ZM1 towards the filter cavity, with the translation stage lens in 3 different positions at two different camera locations.

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.)

The EndX BRS was stuck in a damping loop (I'm assuming caused by the power outage). Usually when this happens increasing the damping thresholds temperately fixes the issue, so we went ahead and did that.
It seems to only be effecting the ETMX BRS, so we left the ETMY one alone
Jim and I increased the damping thresholds from:
H1:ISI-GND_BRS_ETMX_HIGHTHRESHOLD: 2000-->4000
H1:ISI-GND_BRS_ETMX_LOWTHRESHOLD: 800-->2000

It also looks like the ETMX BRS drifted out of range (maybe due to the heater losing power and not returning to the original level?) so I've increased the voltage going to the heating plates and will check back in tomorrow to see if it's been restored

[Sheila, Karmeng]

Today we checked and managed to reduce some of the saturation on ZM4, and offload it onto ZM6. The changes were undone for now.

We briefly did the power budget check, but the power measured at the output of the SFI1 is fluctuating (between 0.79mW to 1.6mW) when the input to SFI1 is at 0.79mW. The power is stable down the propagation (after AP1 and SFI2), unsure what causes the fluctuation. Will continue to look into this tomorrow.

We also did an OMC scan, the pink trace is the scan when ZM4 is in its original setting (YAW: 1779.5), and the red trace is correspond to ZM4 misalignment (YAW: 1769.5).