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.

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

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. 

I've finished more BHD optic mounts:
- Downstream HWP
- BHDBS
- 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.
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.

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.

• 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.

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.

[Murtaza, Radhika]

PRM UL counts normal

We removed the extra DB25 cable (with cut wire isolating pin 5 [Attachment 1]), restoring the original PRM UL/UR/LL connections ---> UL counts ~650

Recap:

It may have been that the foil caps were causing pins 1 and 5 to short in the first place, so removing the caps and restoring the original cable fixed the issue. Final state in Attachment 2.

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

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 (0.5degC_pp) -> 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 (2degC_pp) -> 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 (2degC_pp) -> JC lowered the setting by 2 degF (=1.1degC) -> Vertex temp trend didn't change. Does not make sense.

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

X Arm

66°F ---> 68°F

Vertex

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.

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
  • 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)

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.
• TP2 serial communication (Paco volunteers)
• Vacuum gauges (FRG calib etc) (JC to look into it)
  • Super Bee is the reference

Other maintenance

• Lab A/C issue (Warm @ Vertex and Yend) on going [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.

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.

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.

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.
 

[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.

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.

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.

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%
 

- 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.

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)

• 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

[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. 

[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.

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.

Resolved

• 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. 

Unresolved

• PDR1V rotation stage -> in search

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.

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.

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.

[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.

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.

[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. 

[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.

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.
https://docs.oracle.com/cd/E19121-01/sf.x4600/819-4342-18/html/z40007ed1015419.html

[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.

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?)

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

The polarization and alignment of the fiber for the OMC setup were adjusted. The polarization ratio before the PBS was 50:1. Then, the P-pol was sent to the OMC via two steering mirrors.
As a result of the beam alignment, the OMC cavity is flashing with a good amount of occasional TEM00.

Fiber alignment and polarization refinement

- NPRO power ADJ was "-29". The initial fiber output was 6mW.
- The input fiber collimator and an input steering mirror were adjusted to maximize the fiber output. The output power increased to 12mW.

- Adjusted the output fiber mount to minimize the PBS reflection.
- The initial ratio of the P/S was checked. 3mW was reflected by a PBS out of 12W. (i.e. 3:1).
- Went to the PSL table and repeated 1) rotate the fiber coupler 2) maximize the input beam/coupler alignment.
- Again, adjusted the output fiber mount to minimize the PBS reflection.
- Went back to the PSL to repeat the input side adjustment.
- Determined that I could not do it better.

- Increased the NPRO power ADJ to -20, just to have more power.
  Polarization ratio was ~50:1 (Trans 43mW, Refl 0.82mW).

The beam alignment into the OMC
- Set up the steering mirrors.
- Align the input beam so that I can see the input spot on the center of the second curved mirror (CM2).
- If the alignment is perfect, the input beam should hit the center of the first cavity mirror (FM1)
- The deviation can be adjusted by the mirror/spot position on the last steering mirror.
- So: Adjust CM2 spot by the last steering mirror, Adjust FM1 spot by the penultimate steering mirror.
- This made the cavity flashing. After a bit of alignment, the TEM00 mode was visible.
- A CCD was set at the transmission of CM2

Nice recovery of the lock!

Do you think the spot distance at PR2 makes sense if we consider the dispersion?

https://wiki-40m.ligo.caltech.edu/Optical_Layout#A.2BJbo-Effect_of_the_wedge

[Murtaza, Paco, Shoki, Radhika]

IR arm cavity flashing recovered after input optic beam centering - arms locked

Today we picked up from yesterday's work aligning input optics. First we confirmed that the beam spots were still centered vertically after yesterday's progress. Today's goal was to recover IR horizontal alignment on PR3 and BS, and further downstream. Since the PR3 suspension was translated towards the edge of the table (GTRY now unclipped), we now had to consider the risk of the PR2-PR3 path clipping on the bellows of the vacuum tube. 

1. Visually observed IR beam hitting edge of PR3

2. Adjusted PR2 yaw to shift IR beamspot on PR3 towards green spot reference.

3. Tested limits of PR2 yaw adjustment - scanned until beam was clipped by bellows (video of this in google photos album).

4. Once the IR and green spots were aligned on PR3, we tried to steer PR3 to hit BS. We maxed out the range of the CDS offsets, so physically rotating PR3 proved necessary.

5. Paco rotated PR3 and recovered its alignment. Once the IR beam was hitting the BS, fine tuning was performed to ensure the GTRY reference spot and IR coincided at each optic [Attachment 1 at BS; Attachment 2 at PR3; Attachment 3 at PR2 - note distance between green and IR].

Arm cavity flashing was recovered and the arms were locked at low power [Attachment 4].

[Murtaza, Tomo, Paco, Radhika]

LInk to google photos album for today.

VERTICAL BEAM CENTERING

We first started with vertical beam spot centering. To recap, the IR beamspot started off being high on TT2/PRM and PR2 (see Attachment 1 for starting spot position at TT2). We wanted to vertically center each beamspot while monitoring the spot position at the BS (using the YAUX green spot as a reference.

Vertical alignment steps (all centering below is implied vertical):

1. Opened BS chamber

2. Adjusted TT1 to lower spot position on TT2 (lowered every downstream beamspot)

3. Adjusted PR2 to correct for TT1 motion, keeping beam spot at BS fixed (relative to green reference)

4. Iteratively performed steps 2 and 3; realized our step sizes were too small and that we should work sequentially downstream

5. Opened the ITMX chamber and saw spot position was centered on PR2

5. Moved TT1 and TT2 in differential mode until beam spot was centered on TT2; hoping to keep PR2 centering [Attachment 3]

6. Needed to compensate by moving TT2 to center on beam on PR2 [Attachment 4]

7. Adjusted PR2 to center beam on PR3/BS (relative to green reference) [Attachment 5]

HORIZONTAL BEAM CENTERING

To correct the clipping of GTRY on PR3, we needed to shift PR3 along its axis. 

1. There was a counterweight on the table blocking PR3 from being shifted longitudinally (towards table edge). Paco moved a cable clamp to make room to slide the counterweight and shift PR3.

NOTE: THE COUNTER BALANCE NOW SITS ON THE EDGE OF THE TABLE WITHOUT A CLAMP. BE CAREFUL WHEN THE BS CHAMBER IS OPENED.

3. Shifting PR3 affected GTRY reaching the camera. Steering mirrors were adjusted to realign the green beam with the camera. One of the GTRY steering mirrors was shifted to prevent it from blocking the IR beam between TT1-TT2.

4. We lost the beamspot on BS after moving PR3. We'll start with moving PR2-PR3 in YAW until the IR is pointed correctly on the BS tomorrow.

CLOSEOUT

1. To wrap up for the day we realigned the arms using the AUX lasers as a reference. With this configuration, the oplevs on the test masses were centered to use as a reference point [Attachment 2].

[Murtaza, Tomo, Radhika]

In preparation for alignment of vertex optics, went through the exercise of acquiring low-power IR lock of the arm cavities. Arm transmission ndscope in Attachment 1 (max transmission 0.1).

LSC settings and oplev positions in Attachment 2.

Tomorrow morning we plan to complete the alignment work.

I borrowed a small accelerometer from 40m and walked it to the cryo lab. It is pictured in attachment 2 in its box.

There are two accelerometers I can see on the table in the cryo lab. They are both pictured in attachment 1

Here are some beam centering strategies...

Beam height around PRC:
 - From our in-vac inspection today, we noticed that the beam is high on TT2 and PRM, and was slightly clipped (or maybe not) by the earthquake stop of TT2.
 - According to the beam spot position measurements (Attachment #1; includes measurements taken today), beam spot on PRM and PR2 are vertically mis-centered by +1 cm, but vertically pretty centered on PR3, BS and ITMs.
 - These imply we need to play with TT1 and PR2 to level the beam inside the PRC.
 - This is consistent with the height issue we found during the last vent on POP_SM4 (1 inch mirror in front of LO1). We had to place a spacer to make POP_SM4 high to extract the POP beam coming from PR3 to PR2 (40m/16832). So we should be able to remove the spacer after the fix.
 - This fix should be done iteratively without losing flashing in the arms, sacrificing BHD alignment.

Horizontal beam mis-centring on PR3:
 - According to the beam spot position measurements, beam is vertically centered, but horizontally mis-centered by ~1.5 cm at PR3.
 - This is consistent with beam clipping we have in Y green transmission in YAW (Y green is clipped in YAW at PR3).
 - Since the beam is horizontally centered on PRM and PR2, we probably need to physically move PR3 to center the beam and to un-clip Y green transmission.

Beam mis-centering around LO and AS:
 - After these fixes, we probably need to re-align AS path and LO path, as the beams are not centered on LO1, LO2, AS1, AS4.
 - Hopefully these will improve LO-AS mode matching...
 - These probably will not require physical moving of the suspensions.
 - AS RF path after AS2 (90:10 splitter) is also clipped in YAW. This issue also needs to be addressed when re-aligning AS beam.
 - It is probably better to install BHD platform first, before doing LO and AS beam alignment, as BHD platform changes the balancing of ITMY stack, which has AS1 and AS4 suspensions.

I made a script to untrip software watchdogs.

/opt/rtcds/caltech/c1/Git/40m/scripts/SUS/untripSoftWatchdog.py

It is available from the blue "Damp" button in the watchdog screen attached.

Happy in-vac work!

[Yuta, Vittoria, Radhika]

All photo documentation of the open chambers can be found on the 40m google photos account (foteee@gmail.com). Here are the albums for the ITMY, BS, ITMX tables.

We opened each chamber and captured photos of each suspension below. The photos on the google drive have the name of the suspension in the description.

The digital tilt-meters (henceforth called e-bubbles) were assigned a label for each table by Yuta. We zeroed their level readings on the PSL table, assuming it is the most level surface around. We placed the e-bubbles as centered as possible on each table keeping distance from the suspensions. *Note: we didn't think to align the e-bubble with the tapped holes of the breadboard, so next time we'll make sure to do this.* These readings can be seen in Attachments 1-3 (ITMY, BS, ITMX).

Each chamber was closed and nothing was moved from any of the tables.

Thanks to Murtaza, now we have two emergency switches for the aux laser. One is on the PSL table, and the other is in the staging HEPA booth.

The fiber was put in a plastic spiral tube for protection and delivered to the staging HEPA booth. I confirmed that the light was coming out from the fiber but haven't checked the output power.

[Koji, paco]

First, ssh to fb1 and running sudo dmidecode -t1 we get

# dmidecode 3.2
Getting SMBIOS data from sysfs.
SMBIOS 2.8 present.

Handle 0x0001, DMI type 1, 27 bytes
System Information
    Manufacturer: Supermicro
    Product Name: Super Server
    Version: 0123456789
    Serial Number: 0123456789
    UUID: 00000000-0000-0000-0000-0cc47a699734
    Wake-up Type: Power Switch
    SKU Number: To be filled by O.E.M.
    Family: To be filled by O.E.M.

A quick google search on supermicro superserver "red LED blink" suggests fan failure.
After pulling out fb1 we confirmed the middle of three fans is dead.
The fan is a NIDEC Ultraflo (V80E12BHA5-57), 12 VDC, 0.6 A, 80x80x5 mm (see Attachments #1/#2).

We left the FB1 pulled out, but the dead fan and the lid were left as they were to keep the current airflow condition.

• FB1 has this "i" LED blinking and continuously beeping. What's wrong? 
• Also, one of the UPS at the bottom of 1X6 has the error "F06".
• Speaking about UPSs, the control room UPS has a continuous red light and frequent beeping.

Beam spot position measurements were done for the first time in air pressure at low power.
Dither amplitudes were increased to overcome lower SNR, but still the uncertainties are large.

Results:

# 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    1000    1383331863    64.55    3.78    -4.33    0.37    0.47    0.40
ITMY    YARM    211.11    1000    1383331936    65.15    2.67    -0.97    0.17    -0.20    0.11
ETMX    XARM    211.11    1000    1383331957    59.96    2.10    3.40    0.30    -1.33    0.18
ITMX    XARM    211.11    1000    1383332021    62.73    2.35    0.88    0.15    0.38    0.19
BS    MICH    211.11    3000    1383333747    0.02    0.00    3.21    3.90    -3.33    2.26
PRM    PRY    309.21    3000    1383335425    6.23    6.28    13.55    29.00    -2.05    2.82
PR2    PRY    309.21    3000    1383335499    7.57    4.51    7.70    7.09    3.67    12.17
PR3    PRY    309.21    3000    1383335562    5.88    1.17    3.60    10.33    -16.91    15.18
LO1    HPC    113.13    3000    1383336782    0.05    0.01    9.12    3.44    6.50    5.91
LO2    HPC    113.13    3000    1383336842    0.05    0.01    14.51    6.63    21.34    5.13
AS1    HPC    113.13    3000    1383336901    0.05    0.01    2.62    3.36    14.91    2.70
AS4    HPC    113.13    3000    1383336963    0.05    0.01    -5.84    3.28    14.56    3.47

Locking configurations:
 - YARM and XARM can be locked by increasing the trigger matrix C1:LSC-TRIG_MTRX elements by a factor of 10.
 - MICH can be locked by changing AS55 demodulation phase C1:LSC-AS55_PHASE_R from 2.1 deg to 92.1 deg (why?). Play with trigger matrix C1:LSC-TRIG_MTRX so that it does not trigger filters.
 - PRY can be locked by changing REFL55 demodulation phase C1:LSC-REFL55_PHASE_R from 76.02 deg to 166.02 deg (why?) and by increasing the PRCL gain by a factor of 10, C1:LSC-PRCL_GAIN from -0.04 to 0.4. REFL55 is glitchy and making the measurement uncertainties big. Play with trigger matrix C1:LSC-TRIG_MTRX so that it does not trigger filters.
 - ITMY single bounce-LO can be locked by increasing the gain by a factor of 10, C1:HPC-LO_PHASE_GAIN from 1.5 to 15.
 - These changes are summarized in the following script.

/opt/rtcds/caltech/c1/Git/40m/scripts/ASC/measureAllBeamSpotposition.py

Attachment #1 is the current PRFPMI BHD alignment, and Attachment #1 is the history of the measurements.

I retrieved the nitrogen pressure regulator from x arm vacuum cabinet and returned it to cryo. Reminder to replace the 40m regulator for the next vent.