Koji suggested going through the following steps to check the ETMX suspension:

1. Do a free swing test to obtain the input matrix
2. Run the coil balancing script to change the gains on the them
3. Do the ring down test without closing the loop with the OPLEV and just with the OSEM to get Q~5
4. Tune the OPLEV servo gains

Suggestions welcome.
Tuning the ASC would make more sense once ETMX has been calibrated. Will run the free swing test tonight.

After I came back to Japan, I wrote and revised some Elog entries that I was not able to finish during my stay.
I am sorry for the late submission and revision.

Toward locking PRFPMI

• elog #17777
  Modification of the automated locking of FPMI.
   
• elog #17817
  MICH noise in various conditions.
   
• elog #17821
  ALS noise on Aug. 10th.

Flow sensor

• elog #17765
  I additionaly attached the schematic of the wiring to this existing entry.
   
• elog #17779
  Calibration of the flow sensors.

Others

• elog #17822
  Location of the beam chopper used in T&R measurement.
   
• elog #17823
  Location of the diode laser (iFLEX-1000) that might be used as the replacement of the He-Ne laser for OPLEV.

I went to Section Y7 to check the stock DB9-MF cables. The custom dsub cables are also there.

• DB9 1FT / QTY 26
• DB9 2.5FT / QTY 42
• DB9 5FT / QTY 49
• DB9 10FT / QTY 30
• DB9 15FT / QTY 9

Let's say this is (26, 42, 49, 30, 9)

My estimation was:
1Y0/1 (9, 26, 8, 10, 0)
1Y4 or 1X9 (0,8,2,0,0)
1X3/4/5 (11,30,10,12,0)
And the rest was for acromag.

This means that:
No matter how my estimation was wrong, we have prenty of cables for the 1X3/4/5 electronics swap.

The vertex electronics transition work will begin on Monday. We expect the ongoing ASS-X work to be completed by then. But if it needs more time, we must hear a shouting signal from the ASS team.
Is there any other preparation to be done this week to reasonably compensate for changes in gain and TF associated with the transition?

In preparation for the transition, we want to have long custom DSUB25 cables (D2100675) approximately laid out (I mean on the floor, etc) this week. JC takes care of this.

• The lengths of the cables can be found in the attached wiring diagram.
• Both ends of the cables need to be labeled.
• At which side do we want to absorb the slack?

Transition Plan

• Suspension damping and watchdogs are appropriately taken care of, although we soon stop/remove everything.
• We first remove any existing units not going to be used in the circuit (except around the Eurocard crate oplev interface P2 of the wiring diagram).
• The wirings at the side cross-connects are removed. This includes the removal of the thick cables on the cable racks. This would become a heavy work.
• The DC power strips are attached to the racks, and the DC power wiring should be done at this point. We check the DC supply voltages.
• Install the new units as per the above rack layout and proceed with the DSUB connections. We have sufficient number of DSUB cables (this ELOG).
• Turn the units on one by one to detect any unit failure, just in case. If they are all on, we start work on the CDS restoration work.

We are ready to do the transition from Wed 1PM.

The items for the upgrade was collected around the vertex area (Attached photo).

- aLIGO-style DC power strip (+/-18V) x3
- DC power cables (orange +/-18V)
- Electronics units for the upgrade.
- DSUB (DB9) cables
- Custom DSUB15-DSUB25 cables
- Custom DSUB25 cables

Note on Sorensen:

- Eurocard crate requires +-15V. We can place two 15V Sorensens on 1X4 for Eurocard crate or just leave the current +/-15V supplies.

- The aLIGO units requires +/-18V. We can place two 15V Sorensens on 1X5 or just leave two of the current supplies and set them to +/-18V.

• [OK] Reflected the sorensen setup (minimal change from the conventional config. (See the attachment)

• Before destroying the current setup, bring the alignment biases for the vertex 8 sus to zero and record all the OSEM values.
  => Radhika did it (next ELOG)
  -> This will give us the ratio of the OSEM error signals to know the gain ratios between before and after. Also this will make it easier to bring the alignment back.

• [OK] I suppose the oplevs are still aligned. We don't need to be too nervous about the oplev spot too much.

• How to compensate the coil force cal? Do we know the ratio from the ETM coil driver swap? (What were the coil output Rs? What are they now? Are the ratios reasonable?)

  • Currently:
    - PRM/BS/ITMX/ITMY DAC output for face coils differential
    - SRM/MC2/MC1/MC3 DAC output for face coils single ended
    - All 8 SD coils single ended
    - Coil Output Rs
      According to D1700218
      PRM unknown to be checked
      BS 100Ohm
      ITMX 100Ohm
      ITMY 100Ohm
      SRM 100Ohm
      MC2 430? unknown to be checked
      MC1 430? unknown to be checked
      MC3 430? unknown to be checked

  • New setup
      DAC output differential
      AI has the gain of 1 / HAM coil driver has a gain of 1.2
      Coil output Rs:
      For all the face coils 1.2k // 100 ~ 92Ohm
      For all the side coils 1.2k

OSEM values for 8 vertex optics ~before~ electronics upgrade (averaged over 60 s):

['C1:SUS-BS_ULSEN_IN1', 'C1:SUS-BS_URSEN_IN1', 'C1:SUS-BS_LRSEN_IN1', 'C1:SUS-BS_LLSEN_IN1', 'C1:SUS-BS_SDSEN_IN1', 'C1:SUS-ITMX_ULSEN_IN1', 'C1:SUS-ITMX_URSEN_IN1', 'C1:SUS-ITMX_LRSEN_IN1', 'C1:SUS-ITMX_LLSEN_IN1', 'C1:SUS-ITMX_SDSEN_IN1', 'C1:SUS-ITMY_ULSEN_IN1', 'C1:SUS-ITMY_URSEN_IN1', 'C1:SUS-ITMY_LRSEN_IN1', 'C1:SUS-ITMY_LLSEN_IN1', 'C1:SUS-ITMY_SDSEN_IN1', 'C1:SUS-PRM_ULSEN_IN1', 'C1:SUS-PRM_URSEN_IN1', 'C1:SUS-PRM_LRSEN_IN1', 'C1:SUS-PRM_LLSEN_IN1', 'C1:SUS-PRM_SDSEN_IN1', 'C1:SUS-SRM_ULSEN_IN1', 'C1:SUS-SRM_URSEN_IN1', 'C1:SUS-SRM_LRSEN_IN1', 'C1:SUS-SRM_LLSEN_IN1', 'C1:SUS-SRM_SDSEN_IN1', 'C1:SUS-MC1_ULSEN_IN1', 'C1:SUS-MC1_URSEN_IN1', 'C1:SUS-MC1_LRSEN_IN1', 'C1:SUS-MC1_LLSEN_IN1', 'C1:SUS-MC1_SDSEN_IN1', 'C1:SUS-MC2_ULSEN_IN1', 'C1:SUS-MC2_URSEN_IN1', 'C1:SUS-MC2_LRSEN_IN1', 'C1:SUS-MC2_LLSEN_IN1', 'C1:SUS-MC2_SDSEN_IN1', 'C1:SUS-MC3_ULSEN_IN1', 'C1:SUS-MC3_URSEN_IN1', 'C1:SUS-MC3_LRSEN_IN1', 'C1:SUS-MC3_LLSEN_IN1', 'C1:SUS-MC3_SDSEN_IN1']

[1943.7368693033854, 1597.8396443684896, 1667.4166076660156, 1709.3347656250003, 1760.058290608724, 1013.2686828613281, 1833.5396423339844, 2096.6071411132816, 786.2030975341798, 1152.7826700846356, 923.4767690022786, 447.51257578531903, 678.4539184570312, 971.2538736979167, 720.261508178711, 2458.092639160156, 2245.09764811198, 710.1112263997396, 258.2382120768228, 1225.202982584636, 3048.1043741861986, 3092.901733398437, 77.94405148824053, 181.08351745605466, 5145.644441731771, -6879.474226888021, -6954.500219726562, -3615.385673014323, -5468.913354492189, -3260.200516764323, 1555.9213073730468, 1625.1883911132813, 348.9968526204428, 1011.3114247639974, 1386.0941060384114, 1014.3825622558594, 1218.7048522949217, 1642.9303202311198, 1621.7448221842449, 720.2911783854166]

- 4x 1064nm NPROs are OFF. The lab hall is laser safe, although the oplev lasers are on.
  The Laser Warning Signs were turned off by the interlock switch at the PSL enclosure (control room side)

- Watch dogs were turned to "disabled"
- Halted c1sus using dolphin fencing. This worked very well.
The previous report of dolphin fencing not working was due to a typo in my instruction (wrong -disable -> correct --disable).

controls@fb1:~ 0$ ./dolphin_ix_port_control.sh --disable 192.168.113.40 1
--disable
Disabling switch_ip 192.168.113.40, port 1
Complete - csr write addr=0x0001C050, val=0x20820090 (with ret=0)

ssh c1sus

controls@c1sus:~$ rtcds stop --all

[Radhika, Paco, Murtaza, Koji]

- Removed all the units that will not be used in the new setup.
- Removed the sidepanel crossconnects
- Removed most of the sidepanel power lines except for the top eurocrate at the top of 1X4 (requires +/-15 pale orange and blue).
- Removed the acromag connections
- Removed the connectors of the long suspension cables

We'll resume the work at 10AM. (We'll have breaks for lunch and the seminar at 3PM)

=== Next steps ===

- Continue to remove the long suspension cables.
- Attach the DC power strip
- Continue to clean up the power lines on the rack side
- Prepare the power lines (Guralp requires +/-15V, the Eurocard crate +/-15V, new power strips (x3) +/-18V)
- Install the units on the racks.

[Radhika, Paco, Murtaza, Koji]

Morning work:

• Power Strip assembly
• Power Strip cable crimping
• c1lsc fiber routing (the PCIE fiber was in danger) / c1lsc machine was stopped after dolphin fencing
• We tried to reroute the c1lsc fiber above the racks such that it does not get pitched by the rack doors,
  but it seemed that the fiber was damaged (Attachment 1) and the c1lsc can't talk with the IO chassis anymore. We need to replace the fiber.
  It seems that P/N is PCIEO-4G3-100.0-11 (Samtec)

Afternoon work:

• Removed the sidepanels of 1X3 and 1X4 for easier work
• Removed the long DB25 cables from the old sat boxes.
• DC power strips are installed.
• Finished cleaning up the side cross-connects
• Checked the DC supply conditions.
  • +/-15V Eurocard crate + Guralp requires 0.5A / 0.6A
  • +/-18V appered on the DC power strips correctly
• Cleaned up the floor a bit
• Murtaza noticed that there was some strange intermittent noise around the 1Y0/1 racks.
  It looks like one of the fans for the c1ioo IO chassis are dying.

Evening work:

• Made coil driver short plugs (Attachment 2). This enables the coils while the coil modes are set to be Acquire mode.
• Rack nuts inserted

Tomorrow plan (10:30AM):

• c1sus IO chassis installation
• Unit installation
• Unit powering tests (before connecting them)
• Cabling between the units
• Long DB cable installation (sat box removal)
• c1lsc fiber replacement
• Some above cable removal (fiber, old custom DB25 for MC1, etc)

[Radhika, Paco, Murtaza, Koji]

We made great progress today. It's going well so far.

Morning work (10:30AM~):

• Installed c1sus IO chassis
• Installed all units
• Removed long (previous) custom DB25 cables for MC1

Afternoon work

• Connected all the units to the DC power strip
• Unit powering test was done before the inter-unit DSUBs were connected.
  • We found one AA chassis don't turn on even though internal +/-15V seems supplied. We pulled the unit out.
  • All the other units were fine.
  • Typical current draw of the units: (unit name, positive supply current, negative supply current)
    • AA 0.5A 0.5A (18W)
    • AI 0.3A 0.3A  (11W)
    • BIO 0A 0A (0W)
    • Trillum I/F 0.1A 0.1A (0.4W)
    • Sat amp 0.3A 0.3A (11W)
    • Coil Driver 0.3A 0.2A (9W)
• Cabling between the units
  • Done except for the extracted AA unit and for the BIO units (not needed until we have Acromag).
• Long DB cable installation (sat box removal)
  • Halfway
• c1lsc fiber tracking/replacement (not yet done)
  • We found the spare box with 3 more cables behind the X-arm tube. The replacement has not been done yet.

Evening work

• c1sus powering up and CDS check
  • After the people had left, I tried to start up c1sus. I had used dolphin fencing, but it worked like a charm!
• ADC1 AA chassis repair

To Do on Mon (10AM~)

• Long DB cable installation (contd)
• DSUB cable labeling
• Sus control system recovery
• c1lsc fiber reinstallation and system recovery
• Tool / Debris cleaning

Eventual needs:

• We need good crimping tools.
• Supply shortage of the crimping connectors.
• Fibers should not be routed together with electronics cables. Fibers should be distributed through tubes hanging on the cable racks
• Cable strain relief
• Move the noisy CDS and DC power supplies to the drill press room.

Rack nut policy

Out rack nut / screws are so much contaminated.
It's a mixture of #10-32 (standard) / M5 (wrong) / M6 (wrong).
Even the labeled bottles are contaminated.
Don't believe the installed rack nuts/screws, even if they seemed to work fine. They may be a metric pair.

Golden standard (Attached photo)

• rack nuts marked 1032
• small washers
• 10-32 tapered-round head screws

If you find other hardware, don't mix them with any stocks. Give them to Rack Nut Police (=Koji). He will hide them to some where secret.

c1sus ADC1 AA chassis fix.

• Brought the chassis on the workbench.
• Opened the chassis and "alas!" The internal power cables were not connected to the PCBs. This makes sense why there was no current draw at all.
• The cables were connected.
• The unit was tested with +/-18V power. At least, the diff outputs of the AA boards were all 0V.
• A missing connector screw for the external power connector was fixed

The unit was installed on the 1X5 rack, and the DB9 cables were connected.
Repair mission completed.

I've turned on the Eurocard crate (+/-15V) and the AA units (+/-18V) to check if the oplev channels are working. (It seems to be running well)
Also, the AA units are not too hot so far.

[JC, Paco, Radhika, Koji]

Morning/Afternoon work:

• Long DB cable installation (contd)
  • 14 DB25 cables went through the cable-rack bridge above the ITMX chamber. It's twice the previous # of cables.
  • These cables were connected to the chamber flanges. ITMY Flange1 had been having the 2nd connector malfunction. So the cables were connected to the connector 1 and 3 (as before).
• DSUB cable labeling
  • All the (long) cables connected to the units were labeled appropriately.
• c1lsc fiber reinstallation
  • We found one fiber cable (AlpenIO Inc PCIe 4x10G 100m AIO-PCIe4X-100 (2010)) already routed from 1Y4 to the PSL rack. This is the spare JC told us. We routed the host end to 1Y7.
  • c1lsc is up and running as before. All the models are up an running (burtrestore still needed).
• c1sus channel assignment
  • We have the swap of ADC0/1/2 so that the oplev ADC will have ADC0 (duo tone at CH31)
  • The channel assignments were modified:
    • SUS numbering "n": (0-PRM / 1-BS / 2-ITMX / 3-ITMY / 4-SRM / 5-MC2 / 6-MC1 / 7-MC3)
    • Face OSEMs ADC1 CH (n x 4 + 0~3, UL/LL/UR/LR)
    • Side OSEM ADC2 CH n
    • Oplev Ch ADC0 CH (n x 4 + 0~3)
    • Face OSEMs DAC0 CH (n x 4 + 0~3)
    • Side OSEM DAC1 CH n

• Sus damping control recovery
  • We need to lookin to MC3 UL/UR, PRM SD, SRM UL/LL/UR, ITMX all, ITMY face. See next post.
• Tool / Debris cleaning

[Koji, Paco, Radhika]

We recorded the 5 OSEM sensor readings for each of the 8 upgraded optics.

1. The correct scale factor seems to be 9x for the sensible OSEM readings. This is consistent with the scale factor calculated here.

2. The expected counts for each sensor is between 10,000-15,000 cts.

3. Several OSEM sensor values have bad readings of ~0 cts, or a few orders of magnitude smaller than expected:

4. Several OSEM sensor values have readings < 0 (there's overlap with the previous group):

5. MC1 has a consistent scale factor of 2.15, quite smaller than expected. Note that its OSEM readings were negative before the upgrade and now positive; hence negative MC1 ratios below.

Here is the full matrix of OSEM ratios after/before upgrade:
 

Next steps
 

We will debug the corresponding circuits tomorrow.

- Here is the thought how does the factor of 9 come from:

• We are driving OSEM LEDs at 35mA rather than at 25mA. (Honeywell LED SME2470 has quite a linear response for  Irradiance vs. Forward Current.)
• The TIA of the OSEM PD is now 121K instead of the previous 39.2K
• The OSEM output is received by differential AA.

--> Naive estimation is (35/25) x (121k/39.2k) x 2 = 8.64.

- MC1 sat amp has already been replaced with the aLIGO version by Gautam. I wonder where this factor of 2.15 came from (not 2...?).

- Coil driver response:

Previous setup

• BS/PRM/ITMX/ITMY had the differential receiver (cf https://nodus.ligo.caltech.edu:8081/40m/17840)
• All the removed coil drivers have output Rs of 100 Ohm
• The coil resistance is 16~20Ohm.

--> BS/PRM/ITMX/ITMY 2 V_DAC/118 Ohm = 1.7e-2 A/V x V_DAC

--> MC1/MC2/MC3/SRM V_DAC/118 Ohm = 8.5e-3 A/V x V_DAC

--> All the side coils V_DAC/118 Ohm = 8.5e-3 A/V x V_DAC

New setup

• The AIs have the gain of 1.
• The coil driver has a gain of 1.2.
• The output Rs for the face coils are 1.2k//100Ohm = 92Ohm

--> 2 V_DAC * 1.2 / (92+18) Ohm = 2.2e-2 A/V x V_DAC

BS/PRM/ITMX/ITMY face coils will have x1.3 more actuation.

MC1/MC2/MC3/SRM face coils will have x2.6 more actuation.

• The output Rs for the side coils are 1.2k

--> 2 V_DAC * 1.2 / 1200 Ohm = 2.0e-3 A/V x V_DAC

MC1/MC2/MC3/SRM will have less actuation by a factor of 1/4.25.

ITMX 400Ohm
ITMY 400Ohm
BS 100
PRM 100
SRM 100
MC2 427.5/410/411/409.4/410
MC1 434.5/428.4/430.6/432.5/434.0
MC3 432.2/409.4/409.3/410.6/413.8
 

MC1 is ready for the damping test

Trouble shooting plan

• Is the LED on? => Check all the LED mon outputs of the sat amp. It should show 5V if the output current is 35mA. If the constant current loop is open (eg no LED / connection failure etc), it rails at the supply voltage.
• Also the CCD videos should show the status of the LEDs (at least for the TMs and the MC mirrors)
• Then is the PD out responding? => Check all the PD mons.
• If the PD mons are normal, but there is no signal it can be the AA problem. Inject test signal to that channel on the AA and see if we can see some number on the CDS.
   
• Is the coil current flowing? => Check if the coil drv mons are responding.
• If not, check if the AI output has the DAC output in that channel.
• If the DAC signal is there, but no current it can be the driver issue, or the coil/cable/flange connection issue.

MCs OSEM input / coil output gain tuning

Seeing that MC1, MC2, MC3 OSEM readings looked reasonable and consistent, I worked on updating the input OSEM cts2um filter for the 3 suspensions. MC1 OSEM input gains were changed by a factor of 2.15; MC2 and MC3 OSEM input gains were changed by a factor of 8.64 (see previous ELOG for source of these factors).

OLD cts2um gains (units are um/ct):

NEW cts2um gains (units are um/ct):

Next, I moved onto the coil output filters for MC1, MC2, MC3. There was no gain filter already in place for these coil outputs, so I created one called V2A. (This name can be changed. Note: for other optics the coil actuation scaling filters are titled "xN" for scaling N. Eventually we will find an elegant way to set these scalings.)  The coil outputs for MC1, MC2, MC3 were changed by a factor of 1/2.6, or 0.385 (see previous ELOG for source of this factor).

I ran into an issue saving the foton filter coefficients: the filters appear to be saved; however, "Load Coefficients" does not load them onto the medm screen for MC2_URCOIL and all MC3 coils. I've tried toggling the save button and Load Coefficients button, but no luck. I checked and the filters are saved in opt/rtcds/caltech/c1/chans/C1MCS.txt. When changing an existing filter gain, the change is not being applied to the output channel.

MC1 damping

Since all MC1 coil filters saved and loaded successfully but not MC2 or MC3, I was only able to test the damping of MC1. Turning on the damping filters did not supress motion, so I made the following changes:

Attachment 2 shows the damping of MC1 after these changes were made. It looks side the SIDE mode is underdamped and we may want to increase its servo gain. (I flipped the sign of the coil output and confirmed it ringed up, so the sign is correct.)

Next steps

1. Debug why foton is not saving new coil output scaling filters for MC2 UR and all MC3 coils.

2. Assess MC2 and MC3 damping.

[Koji, Radhika]

Update to the Foton/Load Coefficients issue:

- "Save" in foton writes/updates filters correctly to chans/C1MCS.txt. However, "Load Coefficients" is currently not reading C1MCS.txt and therefore not loading any changes at all.

    - We saved a backup of C1MCS.txt and replaced it with one from this morning, hoping to see that the new V2A filters vanish from MC1 coil outputs. When we loaded coefficients, the V2A filters remained.

- We then checked if this issue was happening with C1SUS by adding a test filter to ETMY_ULCOIL. Indeed "Load Coefficients" loaded the filter. So it seems to just be a C1MCS issue.

- We restarted C1MCS twice and no change.

[Paco, Murtaza, JC, Koji, Radhika]

MC1/MC2 was working fine.

At this point MC3, SRM, and ITMY are also working fine.

The custom DB25 cables between the sat amps and the flanges are difficult to mate.

• The finger tight was not enough to make all the contacts. Fastening the screws with a screwdriver made MC3 start working fine on CDS.
• The custom cable fastening screw on PRM(1st) was stripped at the flange side. It needs a thread dyeing. The SRM(2st) has the hex nut broken on the sat amp. Need to be fixed.

We checked if the LED mon shows the correct values. When it is connected it shows 5V. If the LED is not connected it shows 0.8V. It goes 0.08V in an unknown state.

• SRM1 all channels were 0V. It turned out that the connection inside the vacuum chamber seemed mirrored. Right now we have temporary mirror ribbon cables to fix this issue. We need two shielded mirror cables for SRM1 and SRM2.
• SRM2 was random (5V, 0.8V, and 0V)
• BS1/2/ITMY1 looked fine.
• ITMY2 was strange.
• ITMX1/2 were completely silent.

We suspected the cable pinouts/ cable mating issue etc, but it turned out that the SRM2 cable was mislabeled and the ITMY2 cable was connected to the SRM sat amp. That's why it was so random. We corrected the connection and SRM and ITMY started working fine on CDS.

We used the OSEM simulation box to test the sat amps. That suggests that the BS/PRM/ITMX problem may be coming from the SAT amps. We need to look into the sat amps.

[Murtaza, Koji]

ITMX / BS / PRM sat amps were removed from the rack and checked on the workbench. They all work fine with the OSEM simulation box.

With the correct circuit, the LED mon should be 5V, and the PD readout should be 2.6~3.0V (i.e. the differential output has twice the voltage difference of this number).

ITMX Sat Amp fixed:

• The internal wiring for CH1-4 was not connected (or disconnected by mechanical impact) (Attachment 1)
• PD1 channel for CH1 had a metal debris on the transimpedance opamp (Attachment 2)
• The internal board for CH5-6 was connected in the opposite direction. This was because both connectors on the board had the wrong genders.
  This was replaced with a spare. (There was two spares and I consumed one now) (Attachment 3)
   
• Put a ventilated lid instead of the solid lid.

BS Sat Amp:

• All the CHs just worked fine.

PRM Sat Amp:

• Found the bias selector jumpers had not been installed. Fixed. (Attachment 4/5)

Plan for Sept 20, 2023

For morning people:

• We don't need to replace the long cables. They seem all fine.
• Close the lid of the repaired sat amps. Use a lid with ventilation slits (there is an extra with the empty unit on the same desk).
• Install the sat amps back to the racks. Connect all the cables us. Check if this makes the OSEM values to positive 10~20k counts.
  • If not, check LED mons and PD mons. If they are OK the sat amp is working fine. Track the signal down to the AI chassis to see if the units after the sat amp are working well.
• The SRM2 and ITM2 cables ( connected to the sat amps at the back of the units) cross (i.e. have twisted) at the rack. Please reroute and nicely coil them up.
• Fix the custom cable issues: "The custom cable fastening screw on PRM(1st) was stripped at the flange side. It needs a thread dyeing. The SRM(2st) has the hex nut broken on the sat amp. Need to be fixed."
• Put the proper labels on the long cables at the flanges and the sat amps. The labels should indicate where the connectors are supposed to be connected.
• Clean up the mess and the tools from the lab.

The

After the weekly meeting, we'll continue to work on the suspension control. The lab will be turned to be LASER HAZARD in the afternoon.

I asked CDS mattermost for help. Chris (Wipf) checked it and reported it is working fine as usual (without fixing anything).

I've reverted the copied C1MCS.txt back in the chans dir (/opt/rtcds/caltech/c1/chans). The filter coefficients were loaded from the GDS screen. The filters were properly updated.

Here is the info from Chris:

Some transient NFS problem, maybe?

One possible clue is that the filter file that the FE actually loads is not chans/<model>.txt,
but chans/tmp/<model>.txt. Before loading, the filter file is copied into the tmp directory,
and a diff of the two files is written to chans/tmp/<model>.diff.
This diff file should normally be an empty file, indicating that the two files match.
But it was not empty at first, so there must have been some issue with the previous load.
After I reloaded, the diff then became empty.

I found the actuator calibration is more complicated. The numbers I reported in the previous elog was not correct.

Here I summarize the numbers of the voltage-to-current conversion.

=== Previous===

=== New ===

e.g. ITMX face coil electronics are x4.6 stronger than the previous coil electronics.

MC1/MC2/MC3 damping restored

I tweaked the coil actuation gains for MC1/MC2/MC3 according to Koji's updated calculations:

With foton and load coefficients working as expected, these coil output filters were successfully added to MC2 and MC3.

Damping tests

Note: While burt restoring C1MCS to a pre-upgrade state, a "NOT OK" flag popped up and the coil balancing gains for MC1/MC2/MC3 were reset to +-1. Koji showed me how to access the original values in c1mcs.snap (using grep) and I restored the coil gains to their values from 9/12/2023.

Next steps

[Paco, Radhika]

IMC LOCKED

We used the pre-upgrade C1:SUS-MC1/2/3_SUSPIT/YAW/POS_INMON values as a baseline to restore IMC alignment.

Procedure we followed:

I noticed the same issue today with C1RMS.txt, when trying to update the coil actuation gains for SRM. The filter changes were saved to chans/C1RMS.txt, so next I checked chans/tmp/. There is no chans/tmp/C1RMS.txt, or chans/tmp/C1RMS.diff. The updated filters do not load.

Update from Chris:

C1RMS.txt is a remnant from some model that doesn't exist anymore. It can be removed.

I went ahead and deleted chans/C1RMS.txt and chans/tmp/C1RMS.txt.

[Koji, Murtaza, JC]

Regarding PRM/BS:

• PRM2 cable and BS2 cable were wrongly connected. This was corrected.
   
• This makes the BS face OSEM values reasonable.
  However, the side signal is still close to zero. We confirmed that the sat amp outputs (LED mon/PD mon/PD diff out) looked reasonable for all five BS OSEMs.
  The side signal issue stays downstream of the Vertex ADC adapter.
   
• PRM2 has no issue with the sat amp.
• PRM1: We found that all the LED mon goes down to 0.17V when the vacuum flange is connected.
  It was found that the reference voltage for the LED (TP11 of D080276) went down to low number (like 0.15V) when the in-vac OSEMs were connected.
  I found that this output was not stable. So, I replaced the U4 chip (AD8672), but this didn't help the voltage sagging issue.
• Murtaza and I started checking the short circuits on the flange. We found that Pin 5 (OSEM PD1 Kathode) and Pin 1 (invac cable shield?) only have 5.1 Ohm. Pin 1 is connected to the vacuum chamber.
  • What does it mean? The PD has the reverse bias voltage of 10V applied on the PD Kathode. This bias voltage is shorted to ground via 5 Ohm. To keep the bias line at 10V, we need 2 A.
  • We don't have many options:
    - We can disconnect the internal wire for pin5 from the cable. (Prepare a ribbon cable). This should make the other OSEM PDs properly biased.
    We may be able to use an independent power supply to provide some amount of reverse bias (10V 2A is too much. Probably 1V 0.2A or 2.5V 0.5A?) so that the UL PD somewhat work.

I recalculated the scale factors between OSEM sensor readings after/before the upgrade. The expected factor is 8.64, although we may want to rethink this if measurements are disagreeing.]

If ITMY can be restored, we can proceed to locking the YARM while PRM/ITMX/BS are worked on.
 

1. BS values seem reasonable

The SD reading is positive and nonzero, even though its still smaller than the face sensor readings by a factor of 2.
 

2. ITMX SD still negative

3. ITMY SD flipped from positive to negative ~3pm 9/21. LL is too small.

4. PRM still not reliable

5. SRM positive but scale factors widely inconsistent, order of magnitude greater than expected (~8.64).

Today we tried to debug the unreasonable OSEM readings (see previous ELOG)

PRM process

Starting state: PRM face + side values bogus (~0)

1. Somehow through retightening connections, PRM LR+SD counts looked reasonable (and positive). Yay!

2. Toggled on and off the PRM SATAMP; removed Ch1-4 and Ch5-8 PRM inputs

    - Result: BS SD becomes negative when PRM SATAMP is on and Ch 5-8 cable is connected.

2. We disconnected the PRM SATAMP and plugged the PRM inputs into the SRM SATAMP. The SRM SATAMP output was routed to the PRM input on the SATAMP adapter.

    - Result: PRM UL/UR/LL readings still 0.

                 BS SD still negative when SRM SATAMP is turned on and Ch 5-8 from PRM are connected.

                   ---> SRM SATAMP gives same results as PRM SATAMP; PRM SATAMP likely not faulty.

3. Replaced PRM chamber connections with satellite test box for channels 1-4.

    - Result: reasonable PRM UL/UR/LL readings ---> Pin 5 shorting on chamber side is causing issues with Ch1-4.

ITMX - ITMY process

Starting state: ITMX SD counts negative, ITMY SD counts negative (depends on ITMX connection)
To test ITMX (SD negative since change), ITMY (SD negative dependent on ITMX)

 We first switched [ITMX, ITMY]  in the following sequence to get the following results (F = average face values, S = side value)(0 = OFF, 1 = ON)

- [0,0] -> ITMX[F,S] = [300, -5000] ITMY[F,S] = [0, -800]

- [1,0] -> ITMX[F,S] = [~, ~] ITMY[F,S] = [1000, -3000]

- [0,1] -> ITMX[F,S] = [-30, -3000] ITMY[F,S] = [~, ~]

- [1,1] -> ITMX[F,S] = [15000, -10000] ITMY[F,S] = [10000, -3000]

A separate test was done to test ITMX-ITMY coupling on ITMY-side

1. ITMX SAT AMP OFF -> ITMY SIDE GOOD 

2. ITMX SAT AMP ON (Ch 1-4, 5-8 DISCONNECTED) -> ITMY SIDE =/2

3. ITMX SAT AMP ON (Ch 1-4 CONNECTED) -> NO CHANGE FROM 2.

4. ITMX SAT AMP ON (Ch 1-4, 5-8 CONNECTED) -> SAME MAGNITUDE AS 2., FLIPS SIGN

To check if ITMX was faulty from the chamber end for the SIDE DOF, the satellite test box was used for CH 5-8

ITMY SIDE SIGN STILL NEGATIVE 

For the final sanity check for the effect of ITMX on ITMY side sign, we swapped the ITMX and SRM SAT AMPS ({front -> PD OUT 1, 2}, {back -> Ch 1-4, Ch 5-8})

ITMY SIDE SIGN STILL NEGATIVE 

Summary

PRM Ch1-4 shorting issue on chamber side (UL/UR/LL)

BS/ITMY/ITMX SD <0 all seem to be caused by SATAMP adapter or downsteam in ADC2

SUSPECTED FAULTY SAT AMP ADAPTER for ITMX-ITMY SIDE COUPLNG

[Koji, Radhika, Murtaza]

All upgraded suspensions have reasonable OSEM readings! Ready for damping tests and alignment next week.

We fixed PRM OSEM reading by isolating pin5 of the first DB25 [17871]. This makes the PRM UL unbiased by the PD seems to be receiving some light.

The PRM/BS/ITMX/ITMY SATAMP adapter was removed and the front-end pins were checked for shorting. Indeed, a short was found in the SIDE1-4 ribbon cable inside the sat-amp adapter, from the wires being compressed to one side of the dsub-ribbon adapter at the input joint [Attachment 1]. We reclamped the ribbon and verified there was no shorting and that the pins were properly aligned [Attachment 2]. This means PRM/BS and ITMX/ITMY SIDE signals should no longer be cross coupled.

All OSEM counts looked good after these fixes. Only a few ITMY OSEMS looked low, but Koji checked both PDMON voltages for ITMY, and we confirmed with calibration that the OSEM counts were reasonable.

PRM CHANNEL 1-4 (BS FEEDTHROUGH 1-3)

[Koji, Radhika, Murtaza]

Connector on the BS Chamber that feeds to PRM UL/LL/UR coils (PRM 1 in Attachment 1) has pin 5 shorted to pin 1 inside the chamber 
- To resolve this, a DB25 connector was recycled from the old coil drivers
- pin 5 was isolated by cutting (green cable on the DB25 connector)
- The connector was attached between the chamber and the cable that runs through to the rack (Attachment 1)
- The connector was labelled (Attachment 2)

The PD outputs were read on the PRM SATAMP (Pins 1-4, Pin 5 (Ground))

No need to apply an external bias to Pin 5!

Can be fixed during the next vent!

[Rana, Vittoria]

At 3 pm, we did some PMC alignment, and the transmission value went from 665 to 680.

Also, we aligned the reflected beam.

Now the unlocked value the reflected photodiode sees is ~440 mV, and when it's locked, it sees ~21 mV. Before doing the alignment, the unlocked value was ~400 mV.

I pulled out the YEND acromag chassis to check how a connection is made. I unplugged it and then opened it without removing any front panel connections, and then I proceeded to wire the XEND acromag chassis at the electronics bench. After the work was done, I pushed it back but I couldn't restart modbusIOC, even after running daemon-reload on c1auxey1. The ETMY watchdogs are down for now, as are the vertex and XEND ones. I tried restarting c1auxey1 but this didn't help, so maybe something was wrong when mounting the NFS? I will continue this restoration tomorrow and then replicate this at the XEND.

UPDATE Tue Oct 3 10:13:17 2023

I fixed this issue by ensuring the nfs mount was working. To do this, from c1auxey1 I ran:

and then I restarted the modbusIOC.service. Finally, I damped ETMY.

UPDATE Tue Oct 3 16:17:54 2023

[JC, Paco]

The ETMX acromag chassis wiring is complete (Attachment #1) including the optoisolator bit. JC is completing the front panel arrangement and labels and we should be good to go. I moved a binary output chassis from near the vertex rack to the XEND rack and plan to install it along with the acromag chassis to mirror the YEND rack. Finally, the next step is to correctly deploy the modbusIOC service and paying attention to recent changes, for example those in (40m/17702). Since the wiring is similar to YEND, maybe we can simply copy the db file contents.

I went to the Solidworks model of the ITMY invac table and checked where the center of mass is.

The center of mass (COM) of the loaded items is at (+34.0mm, +8.8mm) from the center of the table. (BTW, it is above the table by 115mm). The total mass is 86.2kg.

To bring the COM at the center of the table, we need to place the balance mass(es).
An example solution is shown in the attachment.
It involves two masses (8kg and 2.5kg).
The 8kg one is fixed on the BHD platform behind AS3. The other one will be placed on the table, well away from everything.

I've been meaning to attempt this method to measure the arm cavity length with negligible systematic error for calibration. I came this evening to assess the situation and make a plan.

The measurement procedure would go something like this:

1. Lock arm cavity to PSL using POX/POY.
2. Measure the PM to AM transfer function from the excitation at the PM (e.g. marconi FM-IN or another EOM) to the transmitted AM (Trans PD).
3. In the presence of an error point offset, the PM to AM TF should have a global minimum at the FSR frequency which can be read with high accuracy.

The issue with this is the FSR is ~ 3.75 MHz but the trans PD at the ends are Thorlabs PD520A, with a maximum bandwidth of 250 kHz. Browsing around the PD cabinet along YARM and the PSL table I found a PD10A (150 MHz bandwidth, but 0.8 mm^2 area). I mounted it but not yet aligned anything to it at the YEND table, right behind the current TRY PD.

Another issue is the measurement itself, given that the excitation needs to happen near the PM which is near the vertex area for the PSL, but the readback is at the end (transmission PDs). I considered briefly the alternative of using the AUX lasers, and indeed we have GTRY and GTRX PDs with ~ 10 MHz bandwidth (PD100A), but the issue is we don't have EOMs for AUX lasers, so we are stuck with the ~ 200 kHz PM from the piezo resonances...

I think the best bet is to proceed with the PSL as the PM, and use PD10A or PD100A if there is one around to calibrate the arm cavity lengths and use a long BNC from a moku or agilent high freq network analyzer to the vertex PM area since we don't necessarily care about the extra delays.

Finally, I couldn't find the cds laptop and wasted some time fiddling with my own laptop and shaky network at the ends.

!!We Now Have WiFi Through The Entire Lab!!

Paco and I connected the new routers and expanded the wifi network throughout the lab. These are connected in a "bridge" type of way so that our WiFi doesn't disconnect when we reach the ends. I have also added labels along the ethernet cable to make it easy for us to follow if we run into any issues later on. The Ethernet cable which runs down the Y-Arm is Red and the Ethernet cable which runs down the X-Arm is Blue. The router for the Y- Arm is located on top of the 1Y4 Rack and the X-Arm router is located on the

The BHD platform assembly is going well. I have gotten majority of the Helicoils into all of their components. The only Helicoils I have left to insert are those of the breadboard. I have finished assembling 4 of the D220392, and 2 of the D2200409. Next I will be inserting the HeliCoils into the breadboard and working on D200400, D200405, and D200406. If lucky, I will also be able to tackle the Optic Mount Assemblies D2100200 and 2100435 on Monday afternoon as well.

I've attached a photo of the finished components.

Today, I spent majority of my time insterting the Helicoils for the Platform Assembly, D2100435. 181 Inserts to be exact. and I also got around to setting up the build for up the D2200400, 405, and 406. I expect for the assembling of the BHD platform to be maxed by Friday. (Maxed as in we need to pull parts from which are currently in Vacuum). I want OMC to be added on Friday and for us to begin the following week with alignment of the BHD Assembly.

Tasks which still need to be done

• Assembly of D2200400, 405, and 406.
• Bring over OMC and install onto the platform.
• Alignment of the BHD and OMC.
• Optic-Fibre input to the cleanroom.

Thanks, JC for putting the parts together! I'll start collecting the instruments necessary for the OMC mounting / locking.

= BHD Platform assembly on the staging table =

• [Done] The assembly will be (mostly) done by the end of Thu (JC)
• [Done] OMC is going to be mounted on Fri (KA/JC)
   
• After the vent, we will bring out the BHD optic from the ITMY chamber.
   
• We'll continue to work on the BHD platform alignment on the staging table
  with the optics/optic mounts taken out from the chamber.
  + the OFI components (incl. the machines posts)
   
• Asking Dean for the mighty mouse connectors for the devices
  • -> Asked. We need the connectors and pins. Dean is working on the procurement.

= OMC mounting / locking =

• [Done] Bring the OMC#1 from the OMC lab (KA, Thu afternoon)
• [Done] Attach the kinematic mounting brackets on the OMC. 
• Blank OMC breadboard for counterweighting (KA, bring from the OMC lab) -> Brought
   
• Locking electronics 
  • [Done] Paco prepared:
    Moku, PDA10 (150MHz), HV Amp for Laser or OMC PZT
     
  • Prepare locking optics (steering mirrors, post, etc)
     
• OMC DCPD prep
  • [Done] Bring the DCPDs (Excelitas C30655) from the OMC lab
  • Remove the cap of the diodes (Asked Dean about the tool)
  • DCPD installation on the OMCs

= IFO work until the vent =

• [Done] X arm ASS repair (Radhika)
• FPMI / PRMI locking
  • BS is moving a lot -> fix

= Vent Prep =

• [Done] Watchdog implementation on all the optics
• Clipping investigation

= Vent =

• Table tilt check (digital tilt meter)
   
• Open ITMY:
  • pick up components for BHD platform
  • Turn SRM
  • BHD platform installation
  • Counter weight adjustment
     
• Open ITMX:
  • PR2 sus optic swap -> optic thickness 3/8" -> 1/2", needs adjustment
• Open BS / INJ
  • Clipping check
     
• Vacuum maintenance
  • Remove TP1 for maintenance
  • TP2 communication error problem

[Begüm, Koji]

We brought the OMC #1 / DCPDs / a glass breadboard from the OMC lab to the 40m. They are placed on the wagon next to the staging table.

Prepared the following components around the staging clean booth:

• SOS 2"->3" meal sleeve for thick optic (Attachment 1)
  • To mount 1/2" optic we will need two OD 2" (ID 1.8") x 0.125" Al spacers. -> need to be manufactured
• Other optic mounts (Attachment 2)
  • Vented screws / 1"&2" lens mounts / 1" Polaris mirror mounts

[Koji, Yuta]

We implemented software watchdog for BHD optics.
In order to make the logic the same for all of the optics, software watchdogs for vertex optics, ETMX and ETMY were also updated.
Now all the OSEM PD VAR are calculated from the fast channels INMON, and turns off suspension damping loops only when tripped.

Software watchdog for BHD optics:
 - Created a template db file for c1sus2 optics to do software watchdog. Now C1:SUS-<OPT>_<OSEM>PD_VAR are calculated based on RMS of C1:SUS-<OPT>_<OSEM>SEN_INMON, and turns off SUSPOS, SUSPIT, SUSYAW, OLPIT and OLYAW dampling loops (but not alignment offsets nor disable coil outputs C1:SUS-<OPT>_<OSEM>_COMM) if triggered.
 
/cvs/cds/caltech/target/c1susaux2/template_soft_watchdog.db

 - Ran the following for <OPT>=AS1, AS4, LO1, LO2, SR2, PR2, PR3 to create db files for BHD optics.

python /cvs/cds/caltech/target/c1susaux2/createDbFromExcel.py <OPT>

 - Ran the following on c1susaux2

sudo systemctl restart modbusIOC.service

Software watchdog for vertex optics and ETMX:
 - Found that, for ITMX, ITMY, BS, PRM and SRM, oplev loops were not turned off even if they trip. They also disable coil outputs (ETMX as well).
 - Added the following to respective db files.

 record(calcout,"C1:SUS-<OPT>_OLP_DAMP")
{
    field(DESC,"Turn off OPLEV PIT SUS damping")
    field(SCAN,"Passive")
    field(INPA,"C1:SUS-<OPT>_OL_PIT_SW2R")
    field(CALC,"(A-1024)<0?A:(A-1024)")
    field(OUT,"C1:SUS-<OPT>_OL_PIT_SW2S PP NMS")
}

record(calcout,"C1:SUS-<OPT>_OLY_DAMP")
{
    field(DESC,"Turn off OPLEV YAW SUS damping")
    field(SCAN,"Passive")
    field(INPA,"C1:SUS-<OPT>_OL_YAW_SW2R")
    field(CALC,"(A-1024)<0?A:(A-1024)")
    field(OUT,"C1:SUS-<OPT>_OL_YAW_SW2S PP NMS")
}

 - Also commented out five lines below (ETMX as well) so that it does not turn off the coil output switch (we want them to be on so that alignment offsets are not turned off).

record(dfanout,"C1:SUS-<OPT>_PUSH_ALL")
{
    field(DESC,"Fanout for pushing all buttons")
    field(SCAN,"Passive")
    field(DISV,"0")
    field(SDIS,"C1:SUS-<OPT>_LATCH_OFF.VAL PP NMS")
    field(HOPR,"2")
    field(LOPR,"-2")
    field(OMSL,"supervisory")
#    field(OUTA,"C1:SUS-<OPT>_UL_COMM PP NMS")
#    field(OUTB,"C1:SUS-<OPT>_LL_COMM PP NMS")
#    field(OUTC,"C1:SUS-<OPT>_UR_COMM PP NMS")
#    field(OUTD,"C1:SUS-<OPT>_LR_COMM PP NMS")
#    field(OUTE,"C1:SUS-<OPT>_SD_COMM PP NMS")
    field(OUTF,"C1:SUS-<OPT>_LATCH_OFF PP NMS")
}

Software watchdog for ETMY:
 - Copied what was done for ETMX to ETMY db file. NOTE that it is /cvs/cds/caltech/target/c1auxey1/ETMYaux.db, and not c1auxey without 1 (40m/17948) !!!!!
 - Ran the following on c1auxey1

sudo systemctl restart modbusIOC.service

Next:
 - Make a new watchdog MEDM screen
 - Make a new suspension summary MEDM screen
 - Update the script to untrip watchdogs
 - Update the scprit to align and mis-align suspensions (use C1:SUS-$(OPTIC)_BIASPIT_OFFSET instead of using sneaky offset in coil output matrix?)

New watchdog and suspension summary MEDM screens were made, and IFO_ALIGN screen was updated.
We also implemented new misalign/restore scheme using C1:SUS-$(OPTIC)_BIASPIT_OFFSET instead of using C1:SUS-$(OPTIC)_TO_COIL OFFSETs in matrix elements.

Script for generating screens with multiple suspensions:
 - A script was made to help generating MEDM screens with multiple optics. A template adl file is used to place each optic in a defined grid.

/opt/rtcds/caltech/c1/Git/40m/scripts/medm/genAllSusMon/genAllSSusMon.py

New misalin/restore scheme:
 - Instead of turning on OFFSETS in C1:SUS-$(OPTIC)_TO_COIL matrices in pitch, C1:SUS-$(OPTIC)_BIASPIT_OFFSET is now used for misaligning.
 - The optic is considered to be misaligned if C1:SUS-$(OPTIC)_PIT_OFFSET and C1:SUS-$(OPTIC)_PIT_BIAS read different value. This can happen with BIAS(PIT|YAW)_OFFSET, C1:SUS-$(OPTIC)_(PIT|YAW)_OFFSET_ON being 0, C1:SUS-$(OPTIC)_BIAS(PIT|YAW)_GAIN being 0 etc.
 - When restoring, these channels are turned on in both pitch and yaw to make sure it is restored.
 - Updated script lives in

/opt/rtcds/caltech/c1/Git/40m/scripts/ifoAlign/sosAlign.py

New MEDM screens:
 - New C1SUS_WATCHDOGS.adl (Attachment #1), IFO_ALIGN.adl (Attachment #2; does not look new) and C1SUS_SUMMARY.adl (Attachment #3) are attached.
 - In the attached watchdog screen,
   - LO1 is aligned but tripped, not ready to damp because of PD RMS values are larger than MAX_VAR. C1:SUS-LO1_LATCH_OFF=1 and C1:SUS-LO1_LOGIC=1.
   - LO2 is aligned and tripped, but ready to damp. C1:SUS-LO2_LATCH_OFF=1 (this being 1 means it is tripped and not untripped) and C1:SUS-LO2_LOGIC=0 (ready to damp).
   - AS1 is aligned and tripped, but ready to damp. C1:SUS-AS1_LATCH_OFF=0 (this being zero means someone untripped, but does not mean any other) and C1:SUS-AS1_LOGIC=0.
   - AS4 is misaligned and damped. Misaligned meaning (C1:SUS-AS4_PIT_OFFSET != C1:SUS-AS4_PIT_BIAS) || (C1:SUS-AS4_YAW_OFFSET != C1:SUS-AS4_YAW_BIAS).
   - C1:SUS-$(OPTIC)_LATCH_OFF cannot be turned in this screen to show that it does not mean much.
 - For the suspension summary screen, I intentionally kicked AS4 to make PDVARs and alignment PIT offset red. Note that screenshot was taken after the vent, and some oplev values are also red.

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!

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.

[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.

[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, 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].