Per Workpermit 7158

Our plan of action today:

Prep work:

1. Remove PR3 baffle [TJ]

2. Wipe down goosenecks and assemble them with corner cubes [Jason]

3. TVo finds out channels to use to steer BS and SR3

The order of operations will be as follows:

1. Jason into BSC1 to align laser to ITMY

2. TJ into HAM5 to guide Jason into aligning laser to cross-hairs on SR3

3. TJ removes cross-hairs from SR3 and transfers to PR3 in HAM2. Close HAM5 cover.

4. TJ guides TVo (on computer) to steer BS so alignment laser is centered on PR3 cross hairs. Close HAM2 cover

5. Jason attaches first gooseneck to BS TMD and centers the corner cube on the BS reflection beam with iris mostly closed.

6. Jason attaches second gooseneck onto BS TMD and centers the corner cube on transmission through BS (heading to ITMX).

7. Aidan [HAM4 South] guides TVo to adjust SR3 alignment so main laser is aligned to the center of SR2.

8. Aidan replaces and aligns HWS STEER M1 making sure optic is in the correct position. Jon [HAM4 North] guides alignment to HWSX STEER M2

9. Jon remove 2” Siskioyu mount from HAM4 ISI OPLEV

10. Jon installs replacement DCBS mount on HWSX and aligns reflection halfway down the scraper baffle. Make sure laser is centered on the DCBS

11. Jon repeats step 9 for the HWSY path. Laser might be 6mm low from center on DCBS but beam is still about 2-3 beam diameter from the edge.

12. Jason removes corner cubes from BS

13. TJ removes cross-hairs from PR3 and reinstalls baffle.

Meeting Highlights:

• TCS Hartman Work (Aidan, John, T-Vo, TJ):  HAM4 alignment work (will take most time today), swap optics at HAM4‌ (~1hr).
• HAM4 cleanroom was mentioned as being off-center & possibly in way for TCS work, but may also have interferences (Hugh & Bubba)
• Baffle status:  HAM2 work, MC Baffle assembly work (TJ)
• Vacuum:  Gate Valve Y-beam Manifold (cont), CP1 work next week to look for leak (Chandra)
• DAQ reboot at noon ("be sure to note suspension values")
• OFI status update (Peter)

I happened to notice on the laser MEDM screen that the NPRO power monitor is significantly off.  No corresponding drop
in the output power of the front end though.

    Just checked the gain for the channel that monitors the NPRO power.  For (currently) unknown reasons the gain changed
from -1.013e-3 to -6.24e-4.  Maybe this was the result of a BURT restore to an out of date value?

    I took the liberty of changing the gain back to the old value.

The Faraday rotator (SN002) was removed from HAM5 since it was thought that it would used for the
output Faraday isolator rebuild.

    We noticed that there are two damage marks on the TGG crystal.  Perhaps consistent with a
tool impact at some stage due to the strong magnetic field.  In addition the TGG crystal is not
epoxied in place and is loose just like the one in SN003.

    Given the above, the output Faraday will be rebuilt using SN003.


  Gerardo / Peter

Came into the Control Room at 8:45am(after the GW170817 press conferences)

Day's Activities:

• HAM4 work locking up the ISI & collect contamination samples (Hugh)
• 17:20- 17:47 Removing MC1 iris from HAM2 (Ed)
• 18:05 Staging parts for TCS work (TJ & John Richardson)
• 18:09 Recon HAM2 for baffling work (Jim)
• 20:17 HAM2 Baffle Checks (Jim & TJ)
• 20:43 PSL Crystal (top) Chiller topped off (Richard notified us of beeping, and Ed filled w/ 375mL)
• 21:36-23:00 OFI work at HAM5 (Gerardo, Peter)
• 22:30 Inside H1 PSL (Peter)

I parked this here for us to see and for a viable link from the wiki page.

Laser Status:
SysStat is good
Front End Power is 35.93W (should be around 30 W)
HPO Output Power is 154.0W
Front End Watch is GREEN
HPO Watch is GREEN

PMC:
It has been locked 2 days, 18 hr 41 minutes (should be days/weeks)
Reflected power = 23.4Watts
Transmitted power = 48.02Watts
PowerSum = 71.42Watts.

FSS:
It has been locked for 0 days 13 hr and 45 min (should be days/weeks)
TPD[V] = 2.632V (min 0.9V)

ISS:
The diffracted power is around 3.0% (should be 3-5%)
Last saturation event was 2 days 18 hours and 40 minutes ago (should be days/weeks)

Possible Issues:
PMC reflected power is high

Corner Station signals are a bit all over, but I reckon this is to be expected with open chambers.

End Stations holding steady.

I added 375mL of water to the Xtal chiller. It had been in alarm.

No issues.  ISI locked cleanly and 3 CC wafers collected for study.  ISI damping and other chores on deck.

I popped into HAM2 and made this adjustment. Below are before and after pictures.

Some time ago the transmission and polarisation rotation caused by the Faraday rotator was measured to be
98.8% and 15.6 degrees respectively.  At that time the TGG crystal was located towards one end of the
Faraday rotator - the "output" end. (see F1.jpg)

    After some effort in aligning the Faraday isolator we found that we could get good transmission but not
good isolation and vice versa.  Comparing the Faraday isolator with the unit installed in HAM5 revealed that
the TGG crystal is located in the middle of the magnet assembly.  Looking at the unit being worked on revealed
that the TGG crystal was loose within its holding cylinder.  Why and when it came loose is not obvious.  The
crystal was pushed more towards the centre of the Faraday rotator and the polarisation rotation angle was
re-measured.

    The new measurements suggest a transmission of 99.5% and a polarisation rotation angle of 46.1 degrees.
(see F2.jpg).  The angle plotted in both cases is the angle of rotation of a half waveplate.

    Anecdotally when the TGG crystal was pushed towards the centre, without any time spent optimising the
alignment we observed fairly good transmission and an isolation ratio of 30 dB.

    At present there is some confusion as to whether or not the TGG crystal is meant to be epoxied in place
or is held into place by what is rumoured to be a paramagnetic holder.  In either case the holding mechanism
failed.



  Koji / Gerardo / Peter

Will make comment to this entry when leaving.

J. Kissel

Took a set of Top to Top transfer functions for H1 SUS SRM this evening. Results look like the suspension remains free after Betsy & co re-engaged the OSEMs from having backed them off during the monolithic optic install. 

Data lives here (and has been exported to files of similar name):
    /ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/SRM/SAGM1/Data/
        2017-10-13_2122_H1SUSSRM_M1_WhiteNoise_L_0p01to50Hz.xml
        2017-10-13_2122_H1SUSSRM_M1_WhiteNoise_P_0p01to50Hz.xml
        2017-10-13_2122_H1SUSSRM_M1_WhiteNoise_R_0p01to50Hz.xml
        2017-10-13_2122_H1SUSSRM_M1_WhiteNoise_T_0p01to50Hz.xml
        2017-10-13_2122_H1SUSSRM_M1_WhiteNoise_V_0p01to50Hz.xml
        2017-10-13_2122_H1SUSSRM_M1_WhiteNoise_Y_0p01to50Hz.xml

Will post detailed graphical results with the usual comparison against previous measurements and the model on Monday. Attached is a sneak peak of the Pitch to Pitch TF, the DOF usually most sensitive to shenanigans.

The parts in question are D1101911 & D1101910.

HAM2: I've installed a QPD cable strain relief on IM4 trans. See first attachment.

HAM3: Done with MC2 trans and POPB, but not POPA.

For POPA, 1/4-20 screw wouldn't go in easily (I only tried for a minute or two) and I didn't bother to keep trying because I remember that this was a problem in the past for some of the QPDs (alog 19168 for TMSX).

One set of parts is left on the wire shelf on the work table in HAM2 cleanroom (top right of the wire shelf). If the 1/4-20 wouldn't cooperate, I would recommend to do the same solution as the above alog entry.

Krishna, Jim

This is a slight variation on an earlier duty cycle analysis by Jim. I'm trying to establish how the new ISI-Stage1 control scheme implemented in O2 at LHO benefited the interferometer. As a reminder, in O1, we only used feedback from the Stage 1 seismometer and switched between the 45/90 mHz blends to combat microseism/wind respectively. In O2 we used 'tilt-subtracted' feedforward at low-frequencies and 250 mHz blends as the nominal configuration on all platforms including the HAMs. The data lives in:  SeiSVN/seismic/Common/Data/LHO_O1_O2_duty_cycle_data

The first attachment shows plots for duty cycle versus wind for O1/O2. It uses the minute trends of ISC Lock State and the ETMY windspeed (max) signal. The first page simply shows the distribution of wind - fraction of time windspeeds were in a given bin (bins were ~2 mph) during O1 and O2. The second page shows the fraction of the time the interferometer was locked at a given windspeed. Not only is there a clear improvement in O2, but the curve looks flat up to a windspeed of ~30 mph unlike in O1. The overall duty cycle in O2 seems to have suffered a bit, possibly due to other reasons. Pages 3 and 4 show similar plots, but only comparing the 45 mHz blends used in O1, which are still the default configuration at LLO. Again, it is interesting to note the downward trend on page 4 for the 45 mHz blend, which suggests that even 10-20 mph winds would begin to impact the interferometer.

The second attachment has very similar plots for duty cycle versus microseism velocity, using the band-limited-rms ITMY_Z (max) signal in the microseism band. The O2 configuration looks better once again and there is a similar trend of nearly flat duty cycle up to ~1300 nm/s velocities in O2. The distribution of the velocities looks odd/different, partly because of the inclusion of Hanford summers in O2, which are very quiet in the microseism.