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New entries since:Wed Dec 31 16:00:00 1969
ID Date Author Typeup Category Subject
  17973   Mon Nov 13 00:53:02 2023 KojiUpdateGeneralEP30-2 kit brought from Downs

EP30-2 Kit + Bonding Kit (= Two bottles of silica powder) were returned to Modal Lab @ Downs.

  17974   Mon Nov 13 03:14:43 2023 KojiUpdateBHDOMC input beam alignment

To Do:

  • Set up the OMC refl optical path and the refl PD
  • Set up a trans monitor PD at CM1
  • Set up a platform position marker to ensure the reproducibility
  • Moku setup:
    • Temperature sweep
    • Laser PZT sweep
    • Moku RF modulation demodulation setup for PDH locking

What we need more to make the work better/easier in/around the HEPA table:

  • Proper fiber protection
  • Proper stray beam blocks (anodized Al plates)
  • Electronics rack or shelves at the north side of the booth
  • Parts table at the south side of the booth
  • Rotate the table 180 deg and put a storage shelf beneath the table (Wire rack?)
  17976   Mon Nov 13 16:01:17 2023 JCUpdateCDSFB1 fan replacement (fb1 alarm)

[KA: Copied from JC's entry on Mon Nov 13 14:15:40 2023]

I replaced the middle of the 3 fans.


I received the fans today and went ahead to replace the fan. Koji mentioned that the middle of the 3 fans was dead. in elog 17962.

For some odd reason, when I took off the top to frame all 3 fans were spinning normally. Maybe it was a one time failure for the fan ? Well, either way, I changed the fan so that we could check the fan replacement off the list if this issue happens again.


When replacing the fan, I reused the same connector from the previous one. I just cut the cables and soldered the cables together to the new fan. I attached the new fan to the plastic mount and connected it to the system. Please note that the other 2 fan which are remaining should pick up speed when any of the 3 fans are removed. Once I connected the fan and all 3 began running, the speed drops back down. After placing the fan, I put a label of today's date.

  17977   Mon Nov 13 16:08:47 2023 JCUpdateCDSFB1 fan replacement (fb1 alarm)

I checked how FB1 is and it has no alerting red LED anymore! Great

But I still can hear beeping sound. It can be from the JETSTOR intelligent storage connected to megatron, or megatron itself which has a yellow alering LED on 🤮

Megatron is Sun Microsystems Sun Fire X4600. The function of the yellow LED is "Service Action Required LED". But the manual says: "Slow Blinking: An event that requires a service action has been detected", while the LED is solid yellow in our case.


  17978   Tue Nov 14 18:30:45 2023 RadhikaUpdateGeneralBeam spot position measurements after in-chamber alignment

[Murtaza, Paco, Radhika]

After the input beam path alignment was complete (arm flashing recovered), we attempted to run Yuta's beam centering measurement script (scripts/ASC/measureALLBeamSpotPosition.py). I was able to align and lock the arms at low power following the procedure here. The resulting ITM/ETM beam mis-centering measurements can be seen below.

Next I struggled to lock MICH to measure mis-centering on the BS using Yuta's instructions. We noticed the AS beam was clipping horizontally. Paco and I aligned the AS beam using SR2/AS1 and the beam now appears unclipped. We found the demod angle that minimized AS55_I to be 86.56 deg, not far off from Yuta's value. We mananged to lock MICH with: 1. ASDC trigger matrix element: -30; trigger threshold lowered to -0.5 (enable). We then obtained the BS mis-centering measurement below. Note that the uncertainties here are on the order of the mis-centering value.

Attachments 1 and 2 compare the vertical and horizontal beam mis-centering values before and after the in-chamber alignment. In summary, beam spots on ETMs and ITMs have more or less converged towards center vertically (BS is the exception). However, the beam spots seem to have diverged horizontally from center. This means our pitch corrections were in the right direction, but we'll need to take measurements on PRM/PR2/PR3 to confirm this. It seems like trying to mitigate horizontal clipping at PR3 has propagated mis-centering downstream.

Measuring the beam spot on PRM/PR2/PR3 requires PRY locking, but it seems that little to no light is hitting REFLDC or any of the RF REFL PDs. This will be debugged next.

  Vertical (mm) Horizontal (mm)
ETMY 0.97 +- 0.43 -0.39 +- 0.65
ITMY 1.89 +- 0.22 2.07 +- 0.24
ETMX 2.56 +- 0.26 7.86 +- 0.50
ITMX 2.19 +- 0.20 -1.62 +- 0.12
BS 5.15 +- 5.05 -6.43 +- 3.88
  17979   Wed Nov 15 15:49:34 2023 JCUpdateDaily ProgressInput Chamber Door Removed

[Koji, Paco, JC]

The door of the Input Chamber Has Been Removed

We removed the chamber door off of the input chamber. Koji and Paco worked on removed the bolts while I was preparing the crane for use. When removing bolts from the chamber doors, we were careful not to remove them all at once, Koji decided to leave 4 loose bolts remaining until the crane has a tight lift on the door. 

As for the crane, to remove this door, we needed to extend the swing arm out. The crane itself JUST BARELY makes it over to where the hook can hover nicely over the door. Next, I lifted the door until the sling was nice and tight. Then Koji process to remove the 4 bolts holding the door in place. We lifted the door all the way up and slowly swung the arm to bring the door by ITMX Chamber. Here, we lowered the door and placed it flat onto a Piano Dolley. The door is now wrapped in AntiStat and laying flat onon a piano Dolley by the ITMX Chamber. 


  17980   Wed Nov 15 17:37:17 2023 KojiUpdateSUSPRM SUS UL PD not responding

Radhika reported that the PRM UL OSEM PD is not responding. This PD has been identified to have a shorting problem, but the short existed only at the bias pin of the PD. We disconnected the bias voltages and the PD was working with no (=0V) bias.

It seems that it lost the signal about 8 days ago and the signal intermittently appeared and disappeared.

I suggested to Radhika to remove the Al foil suspecting the other pin of the PD is not shorting.

  17981   Wed Nov 15 18:50:23 2023 RadhikaUpdateGeneralREFL path bug hunting

[Paco, Vittoria, Radhika]

Yesterday and today I noticed that REFLDC/REFL RF PDs sense verry little light, under 0.02 counts [Attachment 1]. We opened the table with REFL PDs and observed the beam, trying to steer it onto REFL55. No increase in counts was observed. The optical response of REFL55 was verified by shining a flashlight on it (reached 2 counts). We tried touching the RF PD box and wires to ground them in case there was some weird electrical response. The counts did not increase on the PD. 

We then borrowed the power meter from the PSL table to measure the REFL beam power in watts. Oddly, measuring the beam as upstream as possible (before all the beamsplitters) only recorded 5 mW of light. This was bizarre, since by eye the beam is quite bright on the beam card. Such low power would explain the PDs not picking up the light; Koji theorized that it might be a ghost beam and the actual REFL path might be blocked inside the vacuum volume. On the other hand, PRM alignment shouldn't have changed that much to result in a misdirected REFL beam. We will investigate tomorrow.

  17982   Thu Nov 16 14:39:34 2023 JCUpdateBHDUpdate on BHD Parts and Cleanroom Accomodations

Task Completed Today :

  • D2200122 Spacer Rings have been machined and ready for C&B
  • The North siderail of the cleanroom has been raised.
  • Parts SM05RR, LMR1V, D2300352-01, -02, -03, -04 have been C&Bed.
  • A New Cart has been Cleaned and added for working purposes to the cleanroom

D2200122 Spacer Rings have been machined and ready for C&B

I walked over to the GALCIT Shop today after receiving an email notifying me that the Spacer Rings are ready. We received 5 rings instead of 4 because the machinist made a mistake on one and was a couple thousanths of an in thicker. This ring is marked red on the photo in attachment #1. I have given these rings to Maty and she will take care of the C&B process since I will be out tomorrow. She said she expect them to be done sometime early next week.

The North siderail of the cleanroom has been raised.

I raised the North Siderail of the cleanroom to give us some more freedom moving the steel cart around in the cleanroom. This also allowed me to rotate the cart and add a bit more space inside. While doing this I had the particle counter running and 0.5 Micron count < 50 and the 0.5 Micron count < 10.

Parts SM05RR, LMR1V, D2300352-01, -02, -03, -04, and D2300208, D2300209, D2300210 have been C&Bed.

SM05RR, LMR1V, D2300352-01, -02, -03, -04, D2300208, D2300209, D2300210 are ready as of today. These have been placed in a plastic box on the middle space of the newly added steel cart. The Plastic boxes have the DCC/Part number on top so you will know what parts are inside.

A New Cart has been Cleaned and added for working purposes to the cleanroom

I brought the steel cart over from the shed area. I thoroughly wiped it down with IPA after cleaning with Windex and a rag. I also used the air gun to blow of any heavy dust from the wheels. I placed foil over each level of the cart and wiped down again with IPA. After, I made some AntiStat curtain around the cart to keep out anything heavy. Here are the plastic boxes containing parts SM05RR, LMR1V, D2300352-01, -02, -03, -04, D2300208, D2300209, D2300210.


  17983   Thu Nov 16 18:29:52 2023 RadhikaUpdateGeneralREFL path bug hunting

Today Yuta and I opened the BS chamber and found that the REFL beam was misaligned in pitch and yaw [Attachment 1]. We steered PRM until REFL and input beams overlapped [Attachment 2]. From there, we moved PRM around until we recovered the REFL beam on the camera. This means bright REFL (prompt reflection from PRM) is aligned onto the AP table. Now some steering mirror alignment on the AP table should recover REFLDC/REFL55 signal response.

Lastly we removed the foil caps on the PRM face OSEMs (before/after in Attachments 3,4). We noticed the SD OSEM foil cap had already fallen off. 

Momentarily PRM UL sensor counts returned, but then went back to 0. We couldn't see any shorting and then gently touched the top two sensors to see if counts would return. No luck.

  17984   Thu Nov 16 18:46:30 2023 KojiUpdateGeneralREFL path bug hunting

I took over the IFO after Radhika left. She found the REFL beam earlier and the PRM alignment offset for the refl beam on the refl camera was (P,Y)=(469,2558).
When the REFL11I responce is maximized to be -6 (presumably because of the RF residual AM), (P,Y) was (379,2548).
When the PRMI fringe like feature shows up in the AS camera, (P,Y)=(429,2028).
I left the PRM at (469,2558), so that the REFL spot is obvious on the REFL camera.

The PSL shutter was closed at the end of the work.

  17985   Fri Nov 17 13:06:27 2023 KojiUpdateBHDBHD Platform Inventory

I went through the inventory list and the parts in hand to figure out what was still missing

The list was made on E2200464, and the PDF snapshot was added to this entry.


  • 2" pedestal post with a bottom vent hole (QTY 1+spare 1) 1 in hand / to be drilled / to be C&Bed
  • 2.5" pedestal post with a bottom vent hole (QTY2+spare 1) 2 in hand / to be drilled / to be C&Bed
  • Thorlabs NB1-K14 mirror (QTY1 + spares 3?) 2 in hand
  • Need to find 5 Y1-1025-45P collected various 45P mirrors. In principle we have all.
  • Faraday Rotator Riser D2200378 (Already ordered by Don) To be delivered / To be C&Bed
  • D2200122 ring spacers (Coming in soon from Caltech machining shop)
    -> They are ready for C&B on Nov 16 (JC)
  • Polaris-K1-2AH on the flow bench in the C&B lab. 


  • PDR1V rotation stage -> in search
  17986   Fri Nov 17 17:27:19 2023 VittoriaUpdateGeneralPRMI Flashing Recovered; PRM OPLEV Centered

[Yuta, Vittoria, Radhika]

PRMI flashing recovered; haven't yet been able to lock PRY

This morning the recovered REFL beam was steered onto REFL55 to maximize the REFLDC signal to 1.4 (consistent with around a factor of 10 laser power reduction).

Since PRMs alignment was changed a lot to recover REFL beam, we noticed that light was no longer hitting the PRM oplev QPD. was no longer detecting any light. We moved onto recovering PRMI flashing:

- Radhika and Yuta moved PRM around until they saw flashing at the antisymmetric port

- REFL DC read 1.4 counts, and then PRM was aligned to drop it to 0.3 counts

- While in this state of good alignment, Radhika and Vittoria went inside and centered the REFL beam on the camera

- We checked that the REFL beam was centered on the REFL RF PDs

- Then we moved on to OPLEV centering for PRM

- Then we identified the PRM QPD and couldn't find the beam

- We traced back the beam and found that it was hitting the bottom, plastic part of an optic

- We adjusted one of the steering mirrors of the input OPLEV beam so that it hit the mirror it was initially clipping on

- Then we moved around two steering mirrors to center the OPLEV.


  17987   Tue Nov 21 19:02:00 2023 RadhikaUpdateGeneralAll beam spot measurements after in-vacuum alignment work

[Yuta, Radhika]

PRY locked and PRM/PR2/PR3 beam spot positions measured

We aligned the arm cavities and locked at low power, then measured beam spot positions on ITMs and ETMs to verify nominal centering.

Moving onto MICH locking, we noticed what could be AS beam clipping in pitch. We struggled to lock to dark fringe and measure a reasonable beam spot position, so we decided to move onto PRY since we already had a BS spot measurement.

We restored PRM alignment and brought it back to rougly center of the camera. PRCL started to flash and we aligned PRM to until REFLDC flashed down from 1.5 to 0.3. Next ITMX was misaligned by 1500 cts so that it wouldn't contribute to AS fringing. REFLDC flashed down to 1.3 cts at this point, and we were able to lock PRY [Attachment 1] with REFL55 demod phase: 166.02; PRCL gain: -0.4.

Beam spot positions for PRM/PR2/PR3 are below and plotted in Attachments 2, 3. Attachments 4,5 are reposts of the beam spots for ITMs and ETMs. Overall, vertical mis-centering was generally reduced across optics (except for a slight overcorrection in PRM and worsening in the XARM). Horizontal mis-centering was generally made worse in most optics, while reduced in PR3 (magnitude). We plan to open the chambers to verify by eye that the beamspots are where we expect, and we may have to make some adjustments according to the measurements. It could be that the references used at PRM/PR2 were not actually reliable, e.g. oplev beam height. 

  Vertical Horizontal
PRM -2.84 +- 1.86 -2.80 +- 4.54
PR2 3.17 +- 3.74 -6.88 +- 1.51
PR3 3.86+-1.15 9.98 +- 1.51
  17988   Wed Nov 22 19:55:21 2023 KojiUpdateBHDBHD Platform Inventory
  • PDR1V rotation stage was found
  • 2" pedestal post x Qty 1 / top and bottom vent holes machined -> to be C&Bed
  • 2.5" pedestal post x Qty 2 / top and bottom vent holes machined -> to be C&Bed
  17989   Sat Nov 25 19:41:27 2023 KojiUpdateGeneralLab Temp

Vertex is extremely hot. I'm reluctant to go into the HEPA with clean garbings....

It seems that it started about a week ago. So this is not related to the holiday.
(Although I don't know where the sensors are)

  17990   Sun Nov 26 16:06:22 2023 KojiUpdateBHDBHD/OMC table work

- Setup the fiber protection and stray beam shields
- Replaced brand new wedged Y1-45P mirrors used in the OMC input path with stock Y1-45S mirrors. The wedged Y1-45Ps are going to be used for the optics on the BHD platform.
  Note: 45S mirrors are the same as 45Ps, but just their coating precision was not enough for 45P. So most of the cases 45S is sufficient for 45P purpose.
- All the remaining mirrors / CCDs / a lense / an RF PD (PDA-10) were setup and aligned.

- Found a DS345 is broken. The sinusoidal output does not swing and only has weird constant offsets dependent on the setting ==> need fix.

- An old analog function generator was brought for laser PZT scan test.
- Fast PZT cavity scan test: fine alignment & prelim visibility: REFL PD DS unlocked 5.50V vs TEM00 230mV -> estimated mode matching 95~96%
- When the OMC was detached from the kinematic mount and returned to the position: Relection at TEM00 230mV -> 1V. This corresponds to ~15% degradation of the alignment.
- OMC retainer screws (white PTFE screws) to hold the OMC vertically deforms the breadboard and cause the misalignment. Use something compliant or just release the screws.

  17991   Tue Nov 28 02:01:38 2023 KojiUpdateBHDOMC locked

The OMC was locked with Moku Pro.

Attachment 1: Electrical setup. The RF part of the REFL PD signal was fed into Moku pro, while the DC part was monitored on a scope.
Attachment 2: Servo setup. The modulation amplitude is 100mV.
Attachment 3: Image rejection LPF setup
Attachment 4: Laser PZT servo during lock acquisition
Attachment 5: Laser PZT servo for stational operation
Attachment 6: Laser Temp servo setting
Attachment 7: CCD Images during lock. The REFL is still limited by the mode mismatching component.
Attachments 8/9: The REFL locked / unlocked = 340mV/5.4V = 0.06 --> Mode Matching 94%


  17992   Tue Nov 28 11:56:06 2023 RadhikaUpdateGeneralVertex optics alignment OK

Horizontal beam centering along XARM

I tried to improve beam centering along XARM from the control room. First I realigned IMC until counts were recovered on MC TRANS QPD. The final IMC alignment state resulted in 960 cts transmission [Attachment 1].

Next I aligned the arms until transmission in both arms reached ~0.08 [Attachment 2]. In that state I recorded ETM/ITM beam spot positions below. Note that although the beam was miscentered by over 5mm on ETMX (horizontal), it was under 1mm on ITMX. Thus it seemed like a pointing issue. I then tried to lock MICH to record the beam spot on BS, but it never locked stably and the measurements were bogus.

Optic    LSCDoF     freq.(Hz)    ampl. (counts)    gpstime    Opt. gain (counts/nm)    Opt. gain_std    v (mm)    v_std      h (mm)    h_std

ETMY    YARM    211.11    500    1385168096    112.24    4.68           -1.25   0.47  -1.48   0.41
ITMY    YARM    211.11    500    1385168173    100.55    3.18            3.39   0.74   1.71   0.40
ETMX    XARM    211.11    500    1385168993    70.39     4.36           -2.92   0.60   8.39   1.56
ITMX    XARM    211.11    500    1385169082    79.36     3.17            2.90   0.60  -1.64   0.85

I proceeded to try to walk the beam a bit along XARM by moving TT2 in yaw and compensating with PR2. I moved both by ~40 steps and XARM transmission improved to just under 0.1 [Attachment 3].  However, the beam spot measurements looked pretty much the same; mode-matching into XARM was improved while pointing stayed constant. Next I locked PRY to measure the final beam spots on PRM/PR2/PR3.

Optic    LSCDoF     freq.(Hz)    ampl. (counts)    gpstime    Opt. gain (counts/nm)    Opt. gain_std    v (mm)    v_std      h (mm)      h_std

ETMY    YARM    211.11    500    1385234260    133.31    6.03            2.28   0.75   -0.74   0.43
ITMY    YARM    211.11    500    1385234343    121.44    3.14            3.91   0.52   -0.82   0.43
ETMX    XARM    211.11    500    1385234433    88.98     3.75           -0.76   0.41    6.16   1.18
ITMX    XARM    211.11    500    1385234546    103.35    4.50            3.60   0.67   -0.90   0.23
PRM     PRY    211.11    1000    1385236336    5.57      0.73           -8.13   16.67  -2.75   2.38
PR2     PRY    211.11    1000    1385236409    8.65      1.88            2.17   0.54   -7.71   3.39
PR3     PRY    211.11    1000    1385236483    6.39      1.74            4.83   1.50    9.17   6.25

With such high transmission in the arm cavities, alignment looked good and we decided it was OK proceed with aligning the LO/POP beams.

  17993   Tue Nov 28 14:37:00 2023 KojiUpdateGeneralLab Temp

Lab temperature trend for 20 and 400 days:

- The lab temp significantly raised by 4 degC at Vertex and 6 degC at Xend. Yend saw no change.
  We have never seen such temp rise in the past 400days.

- The PSL temp went up at some point in the summer but we should check if this is real or any artifact.

  17994   Tue Nov 28 17:24:44 2023 RadhikaUpdateGeneralLO/POP beams aligned

[Paco, Vittoria, Murtaza, Radhika]

LO/POP alignment

We opened the ITMX and BS chambers for this work. First, both ITMs were misaligned to isolate the forward-propagating beam into the IFO. We saw that the transmitted beam through PR2 (LO) was clipping on the small POP mirror in front of LO1 [Attachment 1]. We decided to move that mirror out of the way and focus on aligning LO; then we would proceed to align POP.

Once the small mirror was moved, the LO beam looked fairly centered on LO1. At LO2, the beam was very misaligned in yaw, missing the optic [faint beam spot in Attachment 2]. I steered LO1 until the beamspot at LO2 was about centered [Attachment 3]. At this point, the beam was reflected off LO2 towards the ITMY table. 

I went back to check that the LO beam was not clipping anywhere on the ITMX table on its way to LO2 [Attachment 4].

Next I removed the spacer that was raising the height of the small mirror [Attachment 5]. ITMY was realigned so that we would recover the backwards-propagating reflection from the IFO. I placed the small mirror back to reflect the backwards-propagating beam transmitted through PR2 (POP) [far left beam in Attachment 6]. I verified that POP was hitting the next mirror and directed towards the in-air ITMX table [Attachment 7]. We closed up all chambers.

Next steps

Fine alignment of LO beam downstream of LO2 and and of POP out of the chamber will be done after PR2 is replaced.

  17995   Tue Nov 28 18:28:10 2023 KojiUpdateBHDBHD Optics Prep

Continued on the BHD Optics Prep:

The following mounts were prepared (they are not 100% tightened yet)
- OMC Refl Mirror Mounts: OMCiRj (i=1,2, j=1,2,3)
- HWP (fixed) -> a thread adapter is missing
- TFPs
- HWP Actuator

We'll extract LO3/LO4/AS2/AS3/BHDBS from the ITMY chamber.

Fixed HWP mount had very thin room at the center. I wasn't sure if I could mount the 1/2" HWP in it. Fortunately the HWP was quite thin (~1mm) and it just barely fit. (Attachments 2/3)

The fixed HWP mount had no 8-32 to 1/4-20 thread adapter.
I'm asking the C&B of the adapters. (Attachment 4)

- AS2 2" post is being C&Bed
- LO4 2.5" post is being C&Bed

- BHDBS spacer ring is coming back from C&B soon
- BHDBS 2.5" post is being C&Bed

- Faraday Rotater Base was ordered. Waiting for the delivery.

  17996   Tue Nov 28 19:47:22 2023 RadhikaUpdateBHDBHD Optics moved to BHD cleanroom

AS2/AS3/BHD BS/LO3/LO4 moved to BHD cleanroom

Attachment 1 shows the labeled optics on the ITMY table (from Koji). I recorded the initial e-bubble reading on the ITMY table: (x,y) = (+0.03; +0.17). See Attachment 5 for orientation of the e-bubble (from chamber door: x-axis left to right; y-axis front to back).

I first cleared the extra steering mirrors (marked SM in Attachment 1). The e-bubble reading after clearing steering mirrors was: (x,y) = (+0.03; +0.18). Note that fluctuations of 0.01 are common for the e-bubbles, so this is a negligible change. The steering mirrors were placed on the XEND flow bench [Attachment 2].

Next I removed the BHD optics, in the order of (LO4, LO3, BHD BS, AS3, AS2). This was arbitrary but made it easy to work front-to-back and remember reverse numeric order. These were placed on the BHD cleanroom table behind the OMC platform [Attachments 3, 4]. See attachments for labeled optics. 

The final e-bubble reading was: (x,y) = (-0.00; +0.20). Similar (small) change in x and y directions. Final state of ITMY table in Attachment 5.

*Note: I used the spare e-bubble for ITMY level readings. It has no label on it - if anyone sees the e-bubble labeled ITMY, remove the label.

  17997   Wed Nov 29 12:53:25 2023 JCUpdateFrequency noise measurementSpectrogram Using GWpy

I started using this new code that Rana and I got from a random Git. It is for a Live Specgram. I was finally able to get it to pop up the plat atleast, but for some reason it is not platting the array from the C1:IOO-MC_F_DQ channel. The also does not seem to be in real-time yet. I will continue playing with this from home, but this is where I am now.



  17998   Wed Nov 29 18:45:54 2023 KojiUpdateGeneral40m BHD current status / plan

In-vac alignment / clipping

  • [Done] SUSs aligned: TTs / PRM / PR2 / PR3 / BS / ITMs / ETMs / SR2 / LO1
  • [Done] POP beam aligned
  • To Do: LO2/AS4 alignment waiting for the BHD platform
  • To Do: AS beam investigation: make sure the beam is not clipped with an IR viewer while AS1 is shaken
  • [Done] PRM UL OSEM issue - missing PD signal (Resolved - [ELOG 18002])

BHD platform

  • [Done] OMC external input/output optics
  • [Done] OMC was locked
  • BHD optics 85% prepared
  • [Done] Optics came out from the chamber [ELOG 17996]
    • [Done] AS3/LO3 assembled [ELOG 18004]
    • AS2/LO4/BHDBS waiting for the posts
  • To DoL C&B list
    • [Done] 2" x1 / 2.5" x2 OD1" posts
    • [Done] Thread adapter for HWP mount
    • Faraday Rotator Base (just arrived / in search)
    • [Done] set screws to be C&Bed
    • Mighty Mouse connectors - coming out from the C&Bed  soon
  • [Pending] Picomotor ball bonding (EP30-2)
  • DCPD installation
    • PD cans to be opened
  • OMC electronics function tests (PZT/DCPD/QPD)
    • External electronic units are still in prep (KA)

PR2 suspension

  • [Done] phi2"xt0.125" adapter ring -> A bag in the BHD clean room
  • Start the assembly work once the alignment work is done. At the bake lab, probably?
  • 40m lab clean booth is not vacant for more weeks

Other vent related maintenance

  • To Do: Ribbon cable stays to be ordered.
  • [Ongoing] TP2 serial communication (Paco volunteers)
  • Vacuum gauges (FRG calib etc) (JC to look into it)
    • Super Bee is the reference

Other maintenance

  • [Ongoing[ Lab A/C issue (Warm @ Vertex and Yend) [ELOG Thread]
  • Failed UPS (one at the control room, another at the 1X6 rack)
  • Collect Flange bolts/nuts
  • [Done] Put FB1 back [ELOG 18003]
  • Megatron error beep (Rana)
  • How to do with the drill press room.
  17999   Thu Nov 30 09:55:12 2023 JCUpdateGeneralLab Temp

I made modifications to the thermostats this morning in the lab:

X Arm

66°F ---> 68°F



71°F ---> 69°F


Y Arm

69°F ---> 67°F

I will update tomorrow moring with a trend of the temperature changes. Rana mentioned it will take ~24 hrs for a notable change to happen.

  18000   Thu Nov 30 13:22:43 2023 KojiUpdateGeneralLab Temp

The attached was the 2 days trend

Maybe I said X and Y moxed up in the meeting? The Yend A/C is the good one.

Yend temp was stable (0.5degCpp) -> JC lowered the setting by 2 degF (=1.1degC) -> Yend temp went down by 1.5degC today. Makes sense.

Xend temp was high and unstable (2degCpp) -> JC raised the setting by 2 degF (=1.1degC) -> Xend temp trend didn't change. Does not make sense.

Vertex temp was high and unstable (2degCpp) -> JC lowered the setting by 2 degF (=1.1degC) -> Vertex temp trend didn't change. Does not make sense.

  18001   Thu Nov 30 14:25:42 2023 RadhikaUpdateGeneralLab Temp

YEND thermostat was restored from 67 °F ---> 69 °F.

  18003   Thu Nov 30 17:35:37 2023 KojiUpdateGeneralMissing PEM signals -> fixed

I saw FB1 was pushed into the rack (Attachment 1). Thank you very much for the work. But I did not see an elog about it.

Here is a good example of why timely elogs are so important.

  • I saw that the seismometer signals were lost 3 hours ago, looking at the StripTool display on the control room wall. I wondered if there was a CDS crash or anything (but there wasn't).
  • I went into the lab and found the FB was pushed in. I checked the rear side of the rack and found the ADC SCSI cable was half unplugged. (Attachment 2)
    Pushing the plug back into the connector made the PEM signals back into operation (Attachment 3)
  • Even if I asked whether there was a problem with PEM, people would say, "We did nothing." But, this kind of unaware cause of another issue just by the presense of you in the lab is very common.
  • If I could see an elog about the FB push written 3 hours ago, I could easily relate these two events, which were not so apparent to be associated.

Write your work of the day before you leave. You will not elog it tomorrow or even in the same evening at home.

  18004   Fri Dec 1 02:16:39 2023 KojiUpdateBHDBHD Optics moved to BHD cleanroom / More OMC locking
  • AS3/LO3 were assembled (Attachment 1)
  • The BHD Platform extension plate was attached to the platform. This will be removed upon the installation into the chamber.

Remaining things to do:

  • AS2 (DLC mount) / LO4 / BHD BS were fixed on the table but still waiting for the posts to come from C&B.
  • Waiting for the C&B
    • 2" x1 / 2.5" x2 OD1" posts
    • Thread adapter for HWP mount
    • Faraday Rotator Base (just arrived / in search)
    • #4-40 set screws to be C&Bed
    • Mighty Mouse connectors - coming out from the C&Bed  soon
  • Picomotor ball bonding (EP30-2)
  • DCPD installation
    • PD cans to be opened
  • OMC electronics function tests (PZT/DCPD/QPD)
    • External electronic units are still in prep (KA)

Tuning of the OMC locking

  • Tried to measure the open-loop transfer function of the OMC lock -> failed due to some broken instrument.
  • Added digital filter and spectrum tool on Moku Pro ("Multi Instrument" mode - Attachment 2)
  • Locking with "Multi Instrument" mode
    • Only 2 input CHs / 2 output CHs are available -> combined laser temp out and the modulation out (Attachment 3)
    • This somehow made the PZT range limited to the half of the past. The lock became a bit tricky.
  • Found that the oscillation is from 200kHz -> likely to be the PZT resonance
    • Implemented a low pass (Attachments 7/8)

The lock became less oscillative.
OMC REFL in-lock: 236mV
OMC REFL unlocked: 5.48
-> Mode-matching: 1-0.236/5.48 = 0.957

By the way, the above in-lock refl level was compared with the refl level with the cavity scan.
10Hz 800mVpp scan -> 524mV
  1Hz 800mVpp scan -> 324mV
Locked                       -> 239mV
I could be indicating the thermal effect?

A bunch of instruments are no longer functioning:

  • SR560 brought from the workbench
    • CHA and the 600Ohm output have their BNCs loose.
    • Is this unit noisy? Connecting a cable on CHB made the lock stable??? (The unit was inserted in the loop)
    • "SR560 deficit" How many functioning SR560 do we have?
  • 1201 Low noise amp (for alternative summing node)
    • The unit was brought from the cabinet -> simply broken
  • SR785 brought from the workbench
    • With nothing connected to the BNCs
    • CHA: No matter what is connected, the spectrum did not change. This channel (CH1A/B) had been labeled "FLAKY".
    • CHB showed "H.V" and was fixed at 34dBV input range -> Is it internally connected to AC???
  • DS345 shows the semi-constant voltage even though a sin wave was given.
  • Phillips function generator simply did not run.


  18005   Fri Dec 1 08:38:32 2023 JCUpdateBHDBHD Platform Parts

Productive Day for C&B

Beam Dump Bases (D1102371), PEEK Shims D1102372, Two 2.5 " pedestals, one 3" pedestal, Thread adapters #8-32 --> 1/4-20, #4-40 -1/2 Socket cap Screws, #4-40 set screws.

I have placed this on the middle stage of the outside cart. They have been labeled and placed on the center platform of the cart outside of the cleanroom.


  18006   Fri Dec 1 22:30:42 2023 KojiUpdateBHDBHD Optics moved to BHD cleanroom / More OMC locking

I've finished more BHD optic mounts:
- Downstream HWP
- Hex beam dump x2
- AS2
- LO4

The only remaining mechanics is the Faraday rotator base.

I'll start populating the optics in the mounts so that the final alignment can be done.

One issue I faced with today was that:

One of the BHDBS screws was stripped.
This pivot was supposed to swapped with a picomotor. I knew that these screws were tight and prone to strip the hex. So I carefully worked on it but it happened. crying
The other screw can still rotate. The pivot is still intact, but it'd be hard to replace it with a picomotor.

The impact is that we lost the horizontal translation of the OMC2 input beam. We have to move the OMC itself to correct the misalignment in the horizontal translation.
How much can we do that??? We inherently have no vertical translation of this beam, so it's not a big deal, maybe.
We'll face this operation when we install the second OMC.

  18007   Mon Dec 4 14:56:01 2023 JCUpdateVACVac Maintenance Work.

TP1 has been reinstalled and TP2 investigation has begun

This morning, Paco and I reinstalled TP1. Here are the following Steps we took: 

- Remove TP1 from the packaging and wipe down. 
- Clean the Adapter Flange and install onto the the Vacuum System
- Lift, flip, and mount TP1 onto the Vac System. 
- Connect the Exhaust hose to TP1.
- Connect the Power/Communication cable.

Remove TP1 from the packaging and wipe down. 


     TP1 was originally packaged and prepared to be sent to OSAKA Vac. , but it turns out they only needed to maintenance the controller. After taking out the Turbo Pump from the packaging, pieces of styrofoam were stuck to it. Paco and I clean this with some IPA Wipes and made sure to not remove the foil covering the Turbo Pump High Vacuum Flange. Though, please note that the High Vacuum flag does have a filter that would catch large debris as well.

Clean the Adapter Flange and install onto the Vacuum System. 

    There is an adapter flange between the V1 Gate Valve and TP1. We changed out the Copper CF Gaskets on these as well. There was in issue we had when removing one of the old CF gaskets, but after asking for some help from the Vac Team, Jordan recommended using the flat tip needle nose pliers with a green handle. After doing some searching, I found them in the C&B lab. I was easily able to remove the old gasket with this and placed the new one. Please remember that the copper CF gaskets can be found in the Vac Cabinet along the Y-Arm. These will be moved over to the X-Arm soon since we should keep the Vac Equipment by the Vac system.

Lift, flip, and mount TP1 onto the Vac System. 

    After changing the CF Gaskets and install the Adapting Flange to Gate Valve V1, we mounted TP1 onto the flange. There are set screws that are sticking up and TP1 will sit right in. Once we sat TP1 in, some of the set screws were not out far enough. Paco used a #4 Allen Wrench to bring the screws out more. We placed nuts on the sets screws and tightened uniformly around the Turbo Pump. 

Connect the Exhaust hose to TP1.

    Once the Turbo Pump was securely mounted, we connect the exhaust hose. This used a rotatable CF Flange to a fixed CF Flange.  A new Copper CF Gasket and new hardware have been added. 

Connect the Power/Communication cable.

    The connection for TP1 has been plugged and all that is left is to connect the controller. 

TP2 Investigation

    After doing some searching in the cds files, we have found the serial_clients/serial.py in controls@c1vac: ~/vac/python/serial

Paco has hunch that it is an error with the buffering rate of the signal. It seems like we are using a default buffering rate for all channels, regardless of what their nominal rate is. This could be what is causing the “flickering” to happen on the MEDM Screen.

We thought this could be reaching an “end-of-line” timeout, then read the voltage again after possibly every minute or so, but after viewing the trend, there does not seem to look like there is any pattern. This is still a working progress and we will update with more info. 

  18008   Mon Dec 4 21:02:20 2023 KojiUpdateGeneralLab Temp

Looks like the last setting change didn't make any effect.

  18009   Tue Dec 5 00:58:25 2023 KojiUpdateBHDMost of the BHD Optics populated / OMC mode matching / OMC servo actuator range

Populating the BHD Optics

  • Mounted Thorlabs NB1-K14 into OMC1R1 and OMC1R2 (Attachments 1/2)
  • Mounted CVI Y1-LW-1-1025-UV-45-P/AR into OMC1R2/3 and OMC2R2/3. (Attachments 3/4)
  • Mounted HWP and TFPs (Attachments 5)
  • 2 TFPs and 2 HWPs were aligned and adjusted to maximize the transmission.
  • OMC1R1 and OMC1R2 were aligned to take the refl beam from these mirrors.

OMC mode matching

  • OMC mode matching was <0.96.
  • Moved the last lens closer to the first lens.
  • This made the floor of the OMC refl output to be 74.4mV while the unlocked voltage was 4.78V. The dark offset was -5.4mV.
  • This gave us the mode matching of 0.983. This is close to the value I had in the OMC lab.
  • The image of the refl camera in a lock (Attachment 6) indicated that most of the mode mismatch is gone and the symmetric higher-order component remains.

OMC servo actuator range

  • Inserted Ithaco 1201 Low Noise Voltage Preamplifier after the Moku (Attachment 7). The gain was set to be 10.
  • The PZT output in Moku was set to be 0dB (instead of 14dB) and the output limitter was set to be 0~1V.
  • The gain of the digital filter (notch filter) was reduced to be 0dB.
  • This made the input swing for the PZT HV amp to be 0~10V. This is the full scale of the HV amp input range.
  • Consequently, the Moku's PZT output range was increased. This made both the lock acquision and the long term stability significantly improved.
  18010   Tue Dec 5 10:15:10 2023 KojiUpdateGeneral40m BHD current status / plan

To Do list clean up. Here is the latest tasks.

In-vac alignment / clipping

  • LO2/AS4 alignment waiting for the BHD platform
  • AS beam investigation: make sure the beam is not clipped with an IR viewer while AS1 is shaken.
    • [Done] ITMY Table releveling

BHD platform

  • Mighty Mouse installation
    • Came out from the C&B
    • Contacting Dean for the installation
  • BHD BS optic installation - after the mighty mouse
  • C&B: Faraday Rotator Base - Rework on the base - put it in the C&B
  • DCPD installation / PD can opening
  • OMC electronics function tests (PZT/DCPD/QPD)
    • External electronic units are still in prep (KA)

PR2 suspension

  • Start the assembly work once the alignment work is done. At the bake lab, probably?
  • 40m lab clean booth is not vacant for more weeks

Other vent related maintenance

  • To Do: Ribbon cable stays to be ordered.
  • [Ongoing] TP2 serial communication (Paco volunteers)
  • Vacuum gauges (FRG calib etc) (JC to look into it)
    • Super Bee is the reference

Other maintenance

  • [Ongoing] Lab A/C issue (Warm @ Vertex and Yend) [ELOG Thread] - HVAC guys are coming on Thu morning
  • Failed UPS (one at the control room, another at the 1X6 rack)
    • [Done] The control room UPS one battery replaced
  • Collect Flange bolts/nuts
  • Megatron error beep (Rana)
  • How to do with the drill press room
  • Take care of  the broken instruments


  18013   Tue Dec 5 16:41:49 2023 KojiUpdateGeneralLab Temp

I made a stone-age air flow sensor (stick and a flag) to see if the A/C is actually doing anything. (I know that the photos do not tell you how it is, but it was obvious when it is working)

Basically, we have no AC air flow (intake and outlet) at Vertex and Xarm. No wonder we didn't have any temp change with the AC setting.

The Yarm intake and outlet are working.

  18014   Tue Dec 5 17:10:07 2023 PacoUpdateGeneralTP2

[Koji, Paco]

We spent some time investigating the TP2 situation. Basically, the issue is still unknown. The behaviour is as follows:

  • The TP2 controller is able to report its status correctly over the serial interface (e.g. Stop / Failure / Start)
  • The TP2 controller is also able to report the temperature (at the pump?) correctly over serial, as well as its speed (for this we briefly fired the roughing pump then TP2 with the valve closed and verified this)
  • The TP2 pump does not respond upon actuation (e.g. to start spinning), instead one has to override the mode to Manual instead of Serial.
  • The serial client uses the "letter mode" described in the operations manual
  • The TP2 controller is set to 9600 baud rate (fastest), so probably ok.

The issue remains in terms of reading the voltage, current and actuating on the status of TP2... A few more notes:

  • The physical bus is an ethernet cable so the protocol implementation is really serial over TCP. In short, a service (serial_TP2.service) instantiates a client for each gauge/controller over TCP which streams all the status and monitor signals, and some of them are read as slow epics channels.
  • I checked the cables for bad connections but nothing seems obviously bad. This could still be a hardware issue, so if we own another such controller we could speed up the tests.

I would be tempted to switch the RS232 mode from "letter mode" to "window mode", just to test the controller using a local client.

  18015   Tue Dec 5 17:37:41 2023 KojiUpdateBHDFaraday Base issues

We got Faraday Rotator Base (D2200378) and it came back from the C&B.

I tried to build the assembly and was stunned with 2 issues.

1) The VOPO Faraday Rotator Riser (D1600160-v1) has 2" slot spacing, while D2200378 has a thread spacing of 1.5". (Attachment 1)

2) I could not manage to insert helicoils.

I made the investigation about 1). It turned out that it's a version control issue.
It seems that the riser we have is D1600160-v1 and has 2" slot spacing. DCC has this version.
However, the one in SolidWorks Vault was modified to have 1.5" slot spacing. It only exists in SW and even it claims it is V1. 😫

So our options are
a) Make the 1.5" space riser.
b) Make the 2" space base
c) Use as they are. If we rotate the base 90 deg, We can hold the riser with the base. It will become structurally weak as the riser is supported only on one side.

The issue 2) needs opinions from JC and Don. Depending on the assessment of 2), we'll decide which of a)~c) we'll do.

  18016   Wed Dec 6 10:16:39 2023 JCUpdateGeneralSpecgram

Spectrograph Update 

After a good amount of fiddling around with the spectrogram code Ran and I found online, I was finally able to get a graph to actually show and readout the channel “C1:IOO-MC_F_DQ”. I had trouble figuring out After walking through this code with Radhika, we found that there was this ’n’ parameter that was being passed into the “update_fig(n)” method that wasn’t defined ANYWHERE! After going though the FuncAnimation class online, we found this to be an iterating number that continuously counts. This is so that the figure can continuously update. The issue I’m encountering right now is updating the figure with the new data every couple of seconds. I’m currently still trying to understand parts of the code, but I will update soon! I feel like it’s pretty close now!

  18017   Wed Dec 6 15:32:08 2023 JCUpdateGeneralUPS Battery Replacement

Koji and I replaced the batteries to the SMART-UPS in the control room.
The batteries which were replaced 'Replacement Battery Cartridge 55 APRBC55'. When preparing to change the batteries:

  1. Shutdown the computers
  2. Turned off the UPS System
  3. Disconnect the UPS from the Wall Outlet. This outlet is directly behind the UPS and the wall outlet is labeled.
  4. Take off the plastic cover from the front.
  5. Unscrew the 2 bolts on the metal panel hiding the batteries.
  6. The battery has a plug. Disconnect the plug from the UPS and pull the battery out.
  7. Repeat step 5 for the second battery.
  8. Install new batteries.
  9. Restore everything with the reverse order.


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