A quick rundown of today's activities in HAM6:

• Installed mirror into ZM1 suspension
• Balanced the tip-tilt as best I could without a laser. When we have a beam I will most likely need to adjust the pitch slightly and then recenter the OSEMs.
• Rerouted the beam diverter cable and placed the BD on the South side og the table. The iris used to keep the alignment for ZM1 is currently in the location that this BD needs to be, so we will have to put it in its final position when we can get the iris out of the way.
• Cleaned up some of the other cables below the table since I was already down there for the BD cabling.
• Routed and cabled ZM1.
• Sheila and I then connected the correct cables to each respective OSEM, took and open light measurement, and then proceeded to center them with their new offsets. They will need to be recentered after the pitch is adjusted with a beam.
• We packed up the extra screws, tools, and such and left only what we think we will need. I also removed the cable tags that Hugh had placed to identify each cable.
• Jeff K had mentioned that the OPOS was rubbing, so I poked around and found the H3 OSEM cable to have twisted a bit in one of its cable brackets which was causing it to lightly touch the suspended platform. Hopefully that fixed it.

Pictures to come tomorrow.

J. Oberling, E. Merilh, M. Heintze

Today we looked into the scatter issue noted yesterday.  We removed the new FE pick-off and looked at the scatter again, see attached pictures.  As can be seen, still a lot of scatter.  The going theory is that we are not optimally mode matched from the NPRO to the MOPA, and the scatter is being caused by amplified spontaneous emission (ASE) due to the unused gain from the mode mis-match.  Since the FE is running good, we have good visibility to the PMC, and the mode scan from the most recent DBB measurements indicated low higher-order mode content in the beam, our solution will be to create a spatial filter to block this scatter; this will likely be installed in front of WP02.

We then reinstalled the new pick-off and optimized the alignment, being sure to tilt it off enough to avoid saturating the PD.  It is currently not calibrated, we will have to do that at some point in the future (all PDs that measure power will be re-calibrated at the end of the install).  There was a request to take a transfer function of the FSS out to 10MHz to investigate a bump at ~5MHz noticed at LLO.  Thinking this would be an quick thing to do (famous last words...), we decided to get it in before lunch.  Unfortunately, the FSS would not lock.  After playing with several settings for tens of minutes, Matt was finally able to get the FSS locked.  We then set about tweaking the alignment, which was actually a good bit off.  At this point we broke for lunch.

After lunch, having abandoned the "quick" FSS TF to make progress on the 70W install, we began setting up for measuring the beam caustics of the FE for mode matching.  WP02 was re-installed in the system (we had to remove it to fit the Wincam for beam profile measurements during the installation of the FE pick-off, AMP_WP01 and AMP_PBS01).  We then removed all of the unnecessary optics in the FE DBB path (M09, M10, CCD01, CCD02, L05, L06, the bullseye sensor and its mirror) and set up a ruler for accurate moving of the Wincam during the caustic measurement.  Matt gave me an output coupler to use to dump the majority of the FE power, and we mounted a pump light filter (to keep any pump light from contaminating the measurement).  We also confirmed that lens L15 has a 200mm focal length, and the rough location of this focus for ease in setting up for the measurement.  This complete, we called it a day.  Tomorrow morning we will measure the beam caustics of the FE and begin modeling for a mode matching solution.

TITLE: 03/01 Day Shift: 16:00-00:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

CP4 Bakeout begins, HAM6 Squeezer work continues, EY Pcal work completed, EY TMS checked.
LVEA is Laser HAZARD now & EY is back to SAFE.
LOG: (All times UTC)

• 16:03 Resetting EY Dust Monitor (Jeff B.)
• 16:08 MY--CP4 Bakeout will be beginning at 16:30, may get alarms (Chandra)
• 16:16 Moving snorkel from MX to MY, for MY electrical/camera work by Ken (M&M)
• 16:50 EY--PCal alignment work for the day begins (Rick, Travis, Niko, Marek, Dennis)
  • 19:44 Breaking for lunch
• 17:05 EX--Moving legs of Test Stand out of the way at EX (M&M)
• 17:21 HAM6--ZM1 & beam diverter work (TJ)
• 17:42 PSL work (Jason, Ed)
  • 17:58 Matt joining
  • 22:25 Continuing work

Patrick coverage from 18:00-19:00

• 18:05 Rick called to say EY is laser hazard
• 18:07 Dave tried to add reservation and crashed reservation code. I restarted display on nuc2. Display on video4 needs restarting.
• 18:19 Betsy to end X to move furniture
• 18:33 Well testing company through gate
• 18:36 Tour leaving CR

• 19:44 EY Laser SAFE
• 19:45 Laser safety hardware work in LVEA (will kill lasers...i.e. at EY)
  • 19:47 Turned OFF TCS x & y  lasers (Corey for Richard)
• 21:38 Cabling for Chiller summing chassis in CER (Dave & Fil)
• 21:38 Squeezer Table cabling (Fil)
• 21:50 Continuing HAM6 work (TJ, joined by Sheila, Nutsinee, Terry)
• 21:58 LVEA being transferred to Laser Hazard (Sheila)
• 21:53-23:09 EY TMS work (Georgia, Keita)
  • Also transitioning to Laser Hazard/Safe
• Cheryl noticed Y3_PT210B_PRESS_TORR slowly increasing on Wall TV (video0); usually these are flat.  Gerardo consulted, he said it was due to the temperature increase.
• 22:09 Guardian work for HAM2, BS, ITMy (Jamie)
• 22:11 Increase transimpedance for OPO Trans DCPD (Marc)
• 23:36 EY TMS transfer functions (Betsy)

[Keita, Georgia]

With the new EY alignment, Keita and I adjusted the TMS pitch and yaw to steer the green ALS beam (reflected off ETMY) back onto the in-air table.

Keita adjusted one of the weights on the TMS table to improve the alignment in pitch. It is now 4" from where it was in O2, in the -y direction.

The TMS slider values are now P = 14.6 urad, Y = -217 urad, with the reflection roughly aligned. The full slider range in pitch is +/- 608 urad, so we think even with this rather large offset there is enough range to steer the beam 1m over 4km.

Finally, some of the OSEM sensors on the upper stage of the TMS suspension are not in the center of their range, something we might want to go back in and fix.

J. Kissel

While confirming the at-vacuum driven health of H1SUSITMY, I've found that -- although we've cured the RO RT OSEM shorting problem (LHO aLOG 40787) --  the main chain (M0) still *sometimes* needs as 50000 ct vertical offset in order to prevent noisy, potentially rubbing-like V and R transfer function results. I say *sometimes* because I measured the M0 V and R TFs on 2018-02-26, saw noisy results, and the first vertical mode was ~0.04 Hz higher than expected. Suspecting that we still needed the 50000 ct vertical offset that was used during most of O2 (I couldn't find an aLOG to reference), I turned ON the offset, measured V and R (and the rest of the DOFs) today, 2018-03-01 and saw that the TFs cleaned up nicely with the 1st vertical mode in the right place. But -- just to be sure -- I took the V transfer function again *without* the offset, and saw that the transfer functions still look acceptable.

The first attached image shows the results and what I mean regarding "noisy". Hopefully the legend straight-forwardly labels the above described measurements.

With these initially confusing results, I started trending temperature and vertical positions of corner-station BSC suspensions.  The history: after the short vent to repair the ITMY R0 RT OSEM, the vertical position dropped to ~ -100 [um], then at 2018-02-26 08:58 UTC (about 01:00a PST local!!), shot up to ~ -80 [um], stayed there until 2018-02-27 20:55 UTC, then it began to exponentially continue to rise to pre-vent quick-vent value of ~ -50 [um]. The 2018-02-26 measurement I took happened to be in the ~1.5 day 80 [um] time, where I suspect the suspension was/is just subtly rubbing like it was in O2 that drove whomever to add the 50000 ct V offset originally. 
I also show a 50 day trend of all BSC SUS. All suspensions show the same vertical position evolution as ITMY, indicative of a corner-station-wide, in chamber temperature trend, not something quirky about ITMY.
The in-loop, averaged corner station temperature sensor for Zone 1A near the BSCs reports a flat temperature for many moons, not unexpectedly.
The vertical position of ITMY during the extra clean 2017-12-20 measurement was +30 [um]. That measurement was taken in air, just before the doors went on over the holidays (see LHO aLOG 39829) -- showing that if the suspension is riding high due to cool temperatures, it's possible to get a very clean transfer function, even at air, so something is clearly interfering / rubbing / messed up when the SUS runs hot.

Frustrating. Especially, and probably because, it's intermittent -- we forgot about the need for this offset, and didn't address it either times we opened up BSC1 to play with ITMY. And we *always* forget about temperature during the chaos of a vent. Stinks. 

So, for now, I leave the 50000 ct offset in place (this is about 1/4th the range of the DAC), but we should continue to watch this suspension with respect to vertical position and temperature, hoping that it regains more of its vertical position and continues to improve whatever is going on.

The .pdf attachments show the full suite of M0 and R0 transfer functions taken on 2018-02-26 when the main chain was low / rubbing, and on 2018-03-01 when the 50000 ct vertical offset was applied (and the temperature had risen a bit) showing clean transfer functions. I did not take a full suite today (2018-03-01) without the offset.

On a happier note that the Reaction (R0) chain looks clean after the repair of the R0 RT OSEM. And for the record, the attached results are with and without the 50000 ct main chain V offset, and they show no difference -- implying that whatever is going on with the Main Chain is an independent problem.

Overall:  EY, HAM6, & PSL work looking good

HAM6: 

• TT testing, cabling work, and then would like to go to laser hazard tonight/morning (will stay hazard for a while). 
• NOTE:  If you can avoid walking around HAM6 this would be good, it's a congested area & there will be an IR laser in operation there.). 
• Work on making a work platform on south side of chamber. 
• Possibly ready for beam mid-next week (so need covers off Septum window). 
• "VOPO might be rubbing," Jeff K. 
• Will need viewport simulator.

EY: 

• Today:  TMS Check (Keita & Georgia)
• Tomorrow:  B&K (Jeff K, Jim), Ground loop checks (Fil)

EX (Next Week)

• ALS/PCal Lock & Tag Out
• Door off Monday
• Need to be thoughtful of visits to EY & limit traffic there.

Guardian work ongoing, so will be going up & down. (Jamie)

HVAC Work in OSB Labs slated for next week.  Need to cover optics tables for this work (Corey).

J. Kissel
FRS Ticket 9683

Checking in on the top-mass health of H1 SUS ITMY after the corner station volume has passed below 1e-5 Torr, I've gathered an high frequency, amplitude spectral density of the Main (M0) and Reaction (R0) chain top mass OSEMs. All sensors show a flat noise floor consistent with the expected self noise of the OSEM (~5e-11 / m.Hz^{-1/2} above 10 Hz)  and no longer show any significant comb-like features. 

As such, I recommend we close out the above cited FRS Ticket.

Noticed that the Observatory Mode for H1 was set to "Locking" this morning (, so I set it back to the nominal "Planned Engineering".  It was like this since Tuesday morning, so I'm assuming something was booted during Maintenance and took us back to this "default" setting.

So have about 45hrs of "Locking" which should be "Planned Engineering".

A new frequency overview screen is now available for the squeezer, see screenshot 1. The left side lists the relevant VC(X)Os, whereas the right side presents measured and calculated frequencies describing:

• The two AOM frequencies, the LO frequency, and the frequencies of the PSL/IMC VCO and the squeezer VCO. The AOM 1 frequency and the LO frequency are inputs that are set to 200.000 MHz and 3.125 MHz, respectively. The AOM 2 frequency is the readback of the VCXO frequency.
• The difference between the two AOMs, and its difference to the LO frequency. The later will be zero, once the CLF loop is locked.
• The difference between the beat frequency and double the squeezer VCO frequency. This will be close to zero , when the TTFSS is locked.
• The difference between the PSL/IMC VCO and the squeezer VCO. This describes the difference in laser frequencies between the main laser in the interferometer and the squeezer laser. This difference should be kept small, before the LO is engaged.

The squeezer VCO has available two error signals that can be used to tune its frequency using the tune offset (see screenshot 2):

1. Internal: The error signal is the difference between the measured VCO frequency and a given set frequency. The later is nominally 79.2 MHz, and identical to the PSL/IMC VCO.
2. External: This is the difference between the PSL/IMC VCO and the squeezer VCO. It can be used to keep the squeezer VCO at the same frequency as the PSL/IMC VCO.

The intended strategy during squeezer locking is:

1. Before the IMC is locked, the squeezer VCO should be kept near its nominal set frequency.
2. Once the IMC is locked, the squeezer VCO should follow the PSL/IMC frequency.
3. Once the the squeezer laser is locked to the OPO, the VCO tune input is no longer effective, and one has to use the OPO PZT position to keep the frequency of the squeezer laser close to the main laser.
4. After the LO loop is locked, the two lasers will be phase locked. This implies that both VCOs will be running at the same frequency.

The VCO capability to control its frequency has been copied over to the VCXO. The VCXO frequency can now be kept near a nominal set frequency, which is nominally 203.125 MHz. I doubt this feature is necessary, but it is there if needed.

TITLE: 03/01 Day Shift: 16:00-00:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Lock Acquisition
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    Wind: 12mph Gusts, 10mph 5min avg
    Primary useism: 0.06 μm/s
    Secondary useism: 0.41 μm/s
QUICK SUMMARY:

• CP4 bakeout starting this morning.
• VOPO/Squeezer work at HAM6 work continues
• Hardware Watchdog is RED at EY (known issue)

Completed final tests on bake enclosure heater today with contractor. We have four thermocouple readouts which all act as over-heat protection along with temperature read back. If temperature rises above set point plus up to 20 degC (user defined) then the heater trips off.

We secured four type T thermocouples in the enclosure (one touches a metal flange at bottom of CP4 and the other three float in air), plus one type K that floats in air and is connected to CDS at TE202A - formerly CP3 exhaust temp read out - for remote monitoring and alarm messaging. It currently reads 29degC, which is higher than the other four reading around 21degC.

We found a spill from the turbo's portable chiller this morning. The flex hose had slipped off a barbed connection, so Kyle replace with metal hose and threaded fittings. The fluid is DI water,  mixed with some residual anti-corrosion slime.

We will set or adjust text/email alarms for the following channels: 

• H0:VAC-MY_CP3_TE202A_DISCHARGE_TEMP_DEGC
• H0:VAC-MY_Y4_PT245B_PRESS_TORR
• H0:VAC-MY_CP4_253_REGEN_TEMP_ALRM_INTLK
• H0:VAC-MY_CP4_TE253A_REGEN_TEMP_DEGC

J. Oberling, E. Merilh

The last couple of days have been somewhat frustrating.  After installing the new FE pick-off last Friday, Ed and I attempted to re-acquire the PMC alignment, and failed.  While we were successfully re-aligning the beam to the PMC, we were also misaligning the beam path towards the future home of the 70W amplifier; the beam was being driven too low and was beginning to clip on PBS02.  We removed the FE pick-off and re-established our PMC alignment, and took the opportunity to install 2 irises; one between mirrors M04 and M05 and one between mirrors M06 and M07 (we would have preferred to have this iris between mirror M07 and the PMC, but there wasn't room to install the iris without blocking the reflected PMC beam).  This was completed by COB Monday.  This done, we re-installed the pick-off on Tuesday morning and, using primarily mirror M02 (but some adjustment of M01 was necessary), were able to recover the PMC alignment while mostly maintaining our beam path towards the 70W amp.  We then tweaked the pick-off alignment, which resulted in a necessary small re-tweak of the PMC alignment.  We took visibility measurements both before and after the pick-off installation:

• Before pick-off installation
  • PMC locked: -0.043 V
  • PMC unlocked: -0.603 V
  • Visibility: 92.9%
• After pick-off installation
  • PMC locked: -0.034 V
  • PMC unlocked: -0.600 V
  • Visibility: 94.3%

One thing we noted was a loss of power incident on the PMC.  Before the pick-off installation we had ~25W incident on the PMC; after the installation and alignment we only had ~23W incident on the PMC.  We could find no obvious place where we are losing 2W of power; no obvious clipping or misalignments.  Perhaps some clipping in the new pick-off?  More on that below.

To begin this morning, we installed the Wincam to take a quick beam profile measurement of the FE beam to check if there was any obvious clipping from the new pick-off.  There wasn't, the beam looked as it did after our first install attempt last Friday, and very close to when we finished the NPRO swap in September 2017.  We decided to move on to installation of AMP_WP01 and PBSC01, the first new on-table components for the 70W amplifier; PBSC01 replaces mirror M02, and together with AMP_WP01 gives us the ability to switch back and forth between 70W amplifier and FE-only operation.  We reduced the power from the FE to ~300mW using the HWP inside the FE (thereby reducing the NPRO power delivered to the MOPA) and installed AMP_WP01.  We then made some rough marks on the table to roughly assist with installation of PBSC01, and then removed mirror M02.  PBSC01 was installed on the table in place of M02 and we began alternating translation of the mount and yaw of the optic to recover the PMC alignment.

During this process we noticed that the output power of the FE was changing.  Without touching any power control optics, the FE power had drifted from 300mW to ~6.9W.  We decided to lower the NPRO power by reducing the injection current from the NPRO power supply; we dropped it to ~1.26A from its operating point of 2.222A, which brought the FE output power back to ~300mW.  Continuing the alignment, the FE power continued to increase on its own, getting up to 1.5W.  At this point I noticed that I could adjust the HWP in the FE to reduce the power slightly, which indicates a possible shift in polarization from the NPRO.  At this point we broke for lunch and to consult with Matt regarding this.  Maybe they had seen similar behavior at LLO?  Turns out they had not.  We took some trends and to the best we could tell the FE power was following the NPRO power (I'll post the trends as a comment to this alog tomorrow).  At this time we also noticed that when the FE is running at full power, the new pick-off is saturating; we will adjust this after PBSC01 installation.  We decided to continue on with the alignment after lunch, this time putting the FE and NPRO output powers on a StripTool so we could monitor it in real-time while we worked.  Continuing the alignment, the FE outuput power continued to slowly increase on its own.  Once it got to ~800mW, we decided to lower the NPRO injection current again.  I dropped it from 1.26A to 1.0A; this lowered the FE output power to ~300mW, where it stayed for the remainder of the afternoon.  I have never seen this behavior before and am unclear as to the cause.

Regardless, by slowly translating and yawing PBSC01, using progressively further away alignment references, we are able to recover the majority of the PMC alignment; we did not have to touch mirror M01 at all.  We fine-tuned the PMC alignment with mirrors M06 and M07 and took a visibility measurement:

• Visibility after PBSC01 installation
  • PMC locked: -0.025 V
  • PMC unlocked: -0.508 V
  • Visibility: 95.1%

One thing to note is we are once again down in power incident on the PMC.  Before PBSC01 installation there was ~23W incident on the PMC; after installation there is ~20.5W incident on the PMC.  While there is some leakage from PBSC01 towards the 70W amplifier beam path, it's not 2.5W worth.  Once again we could find no obvious clipping or misalignment downstream of PBSC01 that would cause this loss of power.  Looking upstream however, we see a good deal of scatter.  Can't easily tell where it's coming from, I'm suspecting scatter from the new pick-off.  I've attached a couple pictures showing this scatter.

Tomorrow our plan is to get a picture of the beam profile post-PBSC01 installation, and then to begin investigating this scatter.  We know we need to adjust the alignment of the pick-off to prevent saturation of the PD, maybe that will help with the scatter as well.  Once that is taken care of we plan on moving on to measuring the beam caustics of the FE for mode matching modeling.

Attachments:

• Pic 094829: Iris between M04 and M05
• Pic 094836: Iris between M06 and M07
• Pic 161946: AMP_WP01 and PBSC01 as installed
• Pics 154644 and 154712: Scatter seen around FE output

StephenA, AlenaA, NikoL, MarekS, JimW, RickS

Jim and crew completed the installation of the shield panels today.  They also adjusted the compression of the upper-right (when viewed from the ETM) flexure gap to ~0.220".

Everything seems to be installed as designed.

NikoL, MarekS, TravisS, RickS

Began assessing the centering of the Pcal beams on the input and output apertures using targets mounted to the Pcal window flanges on the A1 adapter.  We plan to continue this work in the morning, going inside the vacuum envelope to assess centering on the Pcal periscope relay mirrors. 

We plan to install the Pcal target on the ETM suspension cage for this work.

SQZ6 enclosure was moved south of HAM6. Cabling for table in the SQZ bay was moved to new table location. SQZ team will let us know if we missed a cable. Power and E-Stop cables still need to be terminated.

h1iscey front end glitched at 14:15 PST. We are holding off on its restart until we contact EY group.

After a lot of experimentation, I have found a way to improve the attenuation of frequencies below 9 Hz in the calibration by 1-2 orders of magnitude, without significantly increasing the computational cost or latency of the pipeline. Here is a list of what I've changed and what I've kept the same:

• In the actuation path, before the actuation filter, I have added a separate high-pass filter using Matlab's firls() function (documentation). firls() designs a linear-phase FIR filter that minimizes the weighted integrated squared error between the desired frequency response in specified intervals and the approximated response of the filter. The filter I've found most effective is designed to have a frequency response of 1 from 9 Hz to the Nyquist rate, and 0 from DC to 8 Hz.  I found improvement when I weighted the stop band more heavily by a factor of 100.  This filter was 2 seconds in length for the tests that I ran.
• I shortened the actuation filter itself from 6 seconds to 4 seconds. (The main reason we needed such a long filter before was to prevent spectral leakage, which is now taken care of by the previous high-pass filter.) It still contains half of a Hann window to the fourth power to roll off low frequencies, in order to further attenuate those frequencies. I found that this roll-off actually worked better than any version of least squares filter I tried in its place.
• In the inverse sensing filter, I replaced the half Hann window to the fourth power with Matlab's least squares filter using firls(). For some reason, this worked better in the inverse sensing filter than the Hann window stuff, even though it did not work better for the actuation. I designed this filter to have a frequency response of 0 from DC to 5 Hz (weighted by a factor of 100) and a frequency response of 1 from 9 Hz to the Nyquist rate. This is what seemed to produce the best results. I did not add a separate high-pass filter in the inverse sensing path, as it seemed unnecessary, and filtering at 16384 Hz gets expensive.

Of all the things I tried, this is what worked the best. Reasons I did not make this even better include:

• I haven't figured out a better way yet
• It is possible to do better with longer or more filters, but since we are doing this in the time domain with FIR filters, adding more filtering gets computationally expensive and adds latency. It is necessary to balance computational cost with quality, as we do not want the pipeline falling behind in low-latency or taking forever to produce offline data on the clusters.

Several plots are attached to show the new features. The first 5 plots are the frequency responses and comparisons to the ideal models for each of the filters used. The last 3 plots are comparisons of C01 data with data produced using the new filters. The attenuation is better by about 1-2 orders of magnitude, and there is just a very small amount of ripple added below 20 Hz.