Fri Jan 30 10:07:58 2026 INFO: Fill completed in 7min 54secs

TITLE: 01/30 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 3mph Gusts, 1mph 3min avg
    Primary useism: 0.04 μm/s
    Secondary useism: 0.40 μm/s 
QUICK SUMMARY:
LVEA is LASER HAZARD with HAM1 & HAM7 still open for in chamber work.

Potential HAM7 work: 
 Tweak Alignment from cable Rubbing, OBO & TF

Potential HAM1 work: 
Align Path out
IOT2L Beam profile measurement at 100 mW
Replace JM1/JM3 fixed mirrors with HTTS
Lock MC with HAM1 in air
Bifricate LVEA HAM1/South Bay/Work at Height all Laser Haz, rest of LVEA Laser Safe



 

This morning Rahul took a transfer function of the OPO suspension and found that adding a zip tie to the new connector didn't help the transfer function, which is still similar to 88921.  We decided with Jeff to live with this as it is, and we spent the rest of the day working on resolving the clipping through the VIP introduced by alignment shifts that happened as we were addressing the cables.  

We moved A:M3 enough that we no longer see evidence of clipping in the SFI1 both passes, we measure 0.96mW out of the OPO and about the same power in transmission from SFI1 on the the return from the filter cavity.  We then saw that the beam was clipping in SFI2, and adjusted B:M1 until we were measuring about 0.88- 0.9mW after SFI2, but we had clipping on the aperture attached to B:L2.  We had nearly lost the beam to SQZT7 by this time, so we spent some time restoring that by adjusting pitch on B:M3 and yaw on B:M4 (with the platform unlocked it is difficult to adjust pitch on the tough pitch knob for B:M4).  This brought us to a point where we can see 0.7 counts on the OPO IR PD on SQZT7.  

At the end of the day, we were still seeing loss at B:L2, where the beam was only about 0.82mW.  We also need to restore the alignment onto the irises on SQZT7.  

We will need to readjust the alignment onto the filter cavity QPDs before we close the chamber. 

1. EOM was put in chamber and moved to its final location. One temporary iris, a cable bracket for the picomotors and one dog clamp for the last lens for JAC needed to be relocated as they interfered with the EOM pivot base.
2. In-vac cables were identified and were connected to the EOM. Minor annoyance about the cable strain relief.
3. EOM S11 coefficients were measured and were acceptable though the dip frequencies were not the same as in the lab, so we haven't retuned it.
4. EOM was connected to the RF sources (now we're modulating!).
5. The light goes into and comes out of the EOM.
6. We forgot that the EOM wedge has a big effect to deflect the beam. We started working on the alignment downstream of the EOM and this will continue tomorrow.

Details to follow.

TITLE: 01/30 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: EOM is in!! Still some work to be done for HAM1 and HAM7. LVEA IS LASER HAZARD
LOG:                                                                                                                                                                                                                                                                    

Thu Jan 29 10:07:23 2026 INFO: Fill completed in 7min 20secs

Closes FAMIS#39852, last checked 88845

Corner Station Fans (attachment1)
- MR FAN1_170 has been relatively loud since it was turned on on Tuesday.
- All other fans are looking normal and within range.

Outbuilding Fans (attachment2)
- MY FAN1_270_1 is quite noisy, but since it's at the midstation I think that's okay
- All other fans are looking normal and are within range.

Sheila, Jeff, Rahul

Yesterday afternoon we moved around two more cables on the OPO (see picture attached for reference). For the first cable (marked by circle) we lifted the cable connector from the OPO and attached it to the nearby pillar using a PEEK tie. For the second cable (marked by arrows in my picture) I provided more relief to it.

This morning I took transfer function measurements for Y dof (0.02Hz bw and 5 averages, with Yaw dof. un-damped and other dof. being damped during the measurement) - see screenshot attached below. I don't see any improvement (in frequencies splitting) - red trace is the latest measurement and blue is the previous one taken by Jeff two days ago.

Yesterday Rahul and I went to HAM7 and adjusted A:M3 in the negative pitch direction to relive the saturation of ZM1 noted in 88939.  This was partially sucsesful, after the shift the beam was no longer clipping on the SQZT7 periscope without offsets on ZM1, but it was a little low in pitch on the first iris and the power on the OPO IR trans PD was 0.4 rather than 0.6 counts.  With the power meter we can see that there is still clipping between the input to SFI1 and the return beam from the filter cavity out of SFI1. 

Rahul adjusted the cables a bit, adding more slack to the one for the OPO temperature controler (before photo shows this as the lighter colored  cable with the S routing on the nearby pillar).  The beam was still  After that the PSL FSS would not lock, preventing us from dither locking the OPO.  

Rahul moved the connector for the new translation stage from the lid of the OPO and zip tied it to the pillar on the rear blade spring.  

Oli and Jeff are looking at suspension transfer functions right now.  I was able to improve the power on the PD from the control room by pitching ZM1 + 400 urad and yawing +500 urad, but there is still not as much light as we expect on SQZT7 IR PD, so we will have to continue this in laser hazard today. 

TITLE: 01/29 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 4mph Gusts, 3mph 3min avg
    Primary useism: 0.04 μm/s
    Secondary useism: 0.58 μm/s 
QUICK SUMMARY:

HAM1 and HAM7 work continuing today

We've assembled the whole EOM assembly including the pivot base/plate assy and the strain relief post and confirmed that the EOM face/side/bottom plates are isolated from the pivot base/plate.

We've tuned the EOM such that S11 parameter at the modulation frequencies are all within 1dB of the bottom of the dip.

We still saw that the frequency shifted for 118 and 45MHz when we tapped the EOM body around, even though there was no appreciable change in 24 and 9MHz. Each jump was small, like 5kHz or 10kHz or nothing sometimes, but they jumped. Surprisingly, at least for 118MHz peak, after the frequency jumped in one direction due to my tapping on the side plate (e.g. the input side), I tapped the other side plate (e.g. the output side plate) and the frequency jumped back into the opposite direction. This was very consistent.

This means that my expectation was wrong. An expectation that somehow something (like coil wires) is caught by something else (like the core by the friction), and that tapping things will release these "something"s into lower potential state and that eventually they all settle.

Realizing this, we stopped tapping, we just tuned as good as we could and stopped.

Tools and parts were wrapped and bagged. EOM assy was wrapped in a foil. These things will be transported to HAM1 tomorrow. 

In the first two attachment, Elenna is tuning the trickiest frequency (118MHz). 

Following pictures show the fully assembled unit from the back (+Y), input (-X), output (+X) and front (-Y). In front.jpg, note that I'm only using one washer for the low profile 10-32 socket head cap screw. I used to use two, but the screw still stuck out just enough to make things tedious and inconvenient when lowering the pivot plate over the pivot base. Though the screw is 0.5" long and not the initially specified 10-32 x 0.375", with one washer it seems to work. 

Next, look at one 1/4-20 screw below the above mentioned 10-32 in caution.jpg. When tightening/loosening that screw, don't use a T-handle wrench unless it's a ball end tool, because you WILL damage the SMA connector thread. Even if you use an L-shaped tool, if you don't pay attention you can damage it. Be careful.

Last picture showcases a happy mood in the optics lab after the successful day.

Friday Jan 23rd Sheila, Karmeng, & myself removed 3 Irises, and swapped out a PD for a beam dump.
First Karmeng & I Turnt up the purge air & took pictures of the table.  
Then we found all the irises Sheila wanted to remove:
Iris 1.... which was one of the 3 Sheila wanted to remove along with Iris 2 and Iris3 near by.

We decided to swap a Photodiode for a Beam Dump due to the scattered light documented in this here FRS ticket, as putting a beam dump infront of the PD was not possible due to Space constraints.
Swapping this PD out required some expert level HAM7 Yoga so Shelia did the switcheroo.

I'm sure it will be fine, but the PD was in place to catch light that is there when the IFO is locked.... and well since the IFO wasn't locked... we Eyeballed the placement of that beam dump that took it's place.  So we are fairly sure the Beam Dump is in the right place.  Oh! I took a few before pics of the PD too just to do some comparing with the after pics of the Beam Dump.
We did check all the beam paths in HAM 7, but that last beam dump we can't check so ¯\_(ツ)_/¯ Looked good to us.

Thanks to Jordan for the last minute purge air cram session.

Later!





 

Jennie W, Jason O

Jason and I added four beam dumps - two before we turned the power up, two after.

There were no beams leaving the table at 100mW but we dumped two beams going towards the PSL septum plate (one was transmission through JM1).

Jason saw one leaving the table after we were at one watt so this and the transmission throuhg JM3 + JM2 are now dumped.