Cold cathode pressure gauge (PT-120) read back is noisy starting ~ 11 UTC (3am local) on Jan. 18th. Not sure why.

J. Kissel

I've designed and installed some primitive damping loops in the H1 SUS OFI's DAMP bank. I mocked up a plant model in Foton using the in-air measured data from LHO aLOG 39033,  copied over some basic filters from the OMs, and had foton model the open loop gain of the loops. Without any requirements or specifications, I've arbitrarily chosen a loop gain of ~5 around the resonances as a start. Once we get all electronics figured out, I'll characterize the new loops via measurement and adjust the gain / design accordingly.

Design details:
H1:SUS-OFI_M1_DAMP_L: 
    FM1 (0:100,100) -- a complex pair of poles at 100 Hz with a Q of 0.87 between them
    FM5 (cheby5) -- a 2nd order Chebyshev low pass, with a 5 Hz corner frequency and 2 dB of pass-band ripple
    FM6 (gain) -- a x200, gain only "filter"
    FM9 (PendL) -- [DO NOT USE] the plant model, to be used for offline design assistance only

H1:SUS-OFI_M1_DAMP_T:
    (Same as L, but the FM6 gain "filter" has a value of x4000)


H1:SUS-OFI_M1_DAMP_T:
    (Same as L, but the FM6 gain "filter" has a value of x50)

Same issue as reported in alog 40054.

Images of the TCS{X, Y} beam samplers.  Look okay.  Slight damage on the TCSX one at around 4:30 in the attached image.  Could be schmutz.  Not near the centre of the optic.

• the HAM2 East door analog camera is not installed, the camera housing is there, but no camera inside, lenses I currently have are not working out to give enough field of view and clear focus, mount inside the housing was moved for one camera lens, but needs to move back more to center
• looked at IM alignment, meant to reset, highlights of how the alignment was left
• IM alignment, different based on IMC differences (in-air2now), IM4 Trans, beam at PR2, and light on QPDs
• looked at alignment downstream, image below has two beams at/on the SRM baffle (upper left and lower right), investigating meant beams were much less obvious when I left (center spot never moved, maybe OSEM light?)
• no snapshot of the alignment, and can't recall IMC changes in slider values, but 1 slider count = 0.05urad, and the total ideal range of the IMs is 120000 slider counts, which is a change of +/-3mm at 1 meter from the optic, which doesn't account for IM curved mirrors, but is a staring point for approximating the change

Increased the diode current for DB1 from 60A to 63.5A and adjusted the temperature of diode 3.  Laser power went from ~152 W to
~187 W as reported on the Beckhoff screen.

J. Kissel, M. Pirello

Marc and I sat down with the mess of wiring diagrams today (see below) in order to verify that all cables had been connected and chassis have been turned on after the several month delay in re-arranging and installing the HAM5/6 suspension electronics due to vent activity. We found a few chassis not turned on, and a few cables in the wrong place, but those problems were easily rectifiable. I've now begun the verification process that all is well with that which are easy: the OM1, OM2, and OM3. 

I had to flip the sign of the damping loops from -1 to +1 (now captured in the safe.snap SDF file), but now all damping loops are functional. I've confirmed so by taking damped M1 to M1 transfer functions, which look clean and healthy, regardless that HAM6 is still at air and the ISI and HEPI are locked. I attach screenshots of the L to L transfer function, though I took all three DOFs. I'll process them fully in due time (likely once we're closing up HAM6).

Next up -- ZM2 and OFI.

%% Details %%
Drawings used to identify cable names (which have three different naming schemes):
For SUS SR3, SRM, and OMC: D1002740-v6
For OM1, OM2, and OM3: First Sheet of D1200666-v11
For ZM1, ZM2, VOPO, and OFI D1700384-v6
For ADC / DAC connections and assignments for all of the above D1002740-v7

Data files:
/ligo/svncommon/SusSVN/sus/trunk/HTTS/H1/
    OM1/SAGM1/Data/2018-01-19_0101_H1SUSOM1_M1_WhiteNoise_L_0p01to50Hz.xml
    OM1/SAGM1/Data/2018-01-19_0101_H1SUSOM1_M1_WhiteNoise_P_0p01to50Hz.xml
    OM1/SAGM1/Data/2018-01-19_0101_H1SUSOM1_M1_WhiteNoise_Y_0p01to50Hz.xml

    OM2/SAGM1/Data/2018-01-18_0102_H1SUSOM2_M1_WhiteNoise_L_0p01to50Hz.xml
    OM2/SAGM1/Data/2018-01-18_0102_H1SUSOM2_M1_WhiteNoise_P_0p01to50Hz.xml
    OM2/SAGM1/Data/2018-01-18_0102_H1SUSOM2_M1_WhiteNoise_Y_0p01to50Hz.xml

    OM3/SAGM1/Data/2018-01-19_0102_H1SUSOM3_M1_WhiteNoise_L_0p01to50Hz.xml
    OM3/SAGM1/Data/2018-01-19_0102_H1SUSOM3_M1_WhiteNoise_P_0p01to50Hz.xml
    OM3/SAGM1/Data/2018-01-19_0102_H1SUSOM3_M1_WhiteNoise_Y_0p01to50Hz.xml

Daniel, Sheila, Nutsinee

Nominal laser output power measured (with a PDA100A) as 18 mW through a 98% beam splitter (Rp 98%). Transimpedance=1500 Ohms, responsivity=.221A/W (variable gain setting on PDA100A set to 0dB).

Green output power measured (with a PDA100A) as 2 mW through 95% beam splitter (~100mW IR -> 40mW green). Transimpedance=1500 Ohms, responsivity=.313A/W (variable gain setting on PDA100A set to 0dB).

NewFocus 1611 detector to lock laser to PSL: Beat frequency signal measured with spectrum analyser ~ -14dBm at 155MHz as measured from the -1dB coupled output on the TTFSS pre-amp. Note there is a signal decrease by around 5dB with large (squeezing) laser frequency shifts (~500MHz or more) that seems to be due to beam pointing errors on the 1611 detector. However locking signal depends on phase and is largely insensitive to amplitude fluctuations so we should be ok. Responsivity=.75A/W, Transimpedance=-10k Ohm, gain setting 0, Voltage = -1.6V.

Power to 1611 detector: .30mW from PSL + .67mW from sqz laser -> .49mW on detector after 50/50 beam-splitter. MEDM screen reads .21mW ?? If the transimpedance is adjusted to -5k Ohm MEDM screen reads correct, but I suspect something is still odd about this. 

Fibre (PSL) power rejected = 1.3 uW measured with a PD1A detector (2 K impedance).

Fibre (PSL) power launched = 27 uW measured with a PD1A detector from a 10% beam splitter. Disabled gain selection setting (alog 40161) has been corrected. Note the beamsplitter was changed from 2% transmission in the original drawing (BS8) to 10% transmission.

Turned the RF driver and the power supply on for the CO2Y laser, also connected the IR sensor, and was getting green lights for the control board. Using the PWM controller I tried to turn the laser on but wasn't getting any results on the power monitor. After double checking the power supply was set to 28V and 28A limit, and the RF driver was set to 40.68MHz, Fil and I found that the wrong RF cable was plugged in. After plugging the right one in the laser powered up in PWM mode and I was able to verify the rotation stage is working as well. Tomorrow I will check that the alignment hasn't changed significantly and that the periscope picomotors are operating correctly.

Kyle, Gerardo

It would be desirable to remove all of GV11 and GV12's external AIP plumbing to aid in the installation of a bake-out enclosure scheduled to be installed as part of the CP4 decommissioning exercise.  Today we connected a Tee having a port with a conductance-limited needle valve attached and a small turbo pump (backed by pump cart) to GV11's annulus pump port.  Bottled UHP N2 was then plumbed to the needle valve which allowed us to administer a controlled amount of dry nitrogen into the inlet of the turbo pump.  With the turbo inlet pressure at around 1 torr or so, we de-energized GV11's AIP controller and valved-in our test setup.  The net effect is that we were slowly venting the annulus volume with dry nitrogen while monitoring PT210 and PT245 to see if any of GV11's inner O-rings were then leaking this administered N2.  As can be seen in the attached graphs, we confirmed that there was leakage into PT210 side.  We allowed the annulus volume to increase into the "tens of torr" before abandoning the experiment, shutting off the N2 and letting the turbo evacuate the administered gas.  

The laser power watchdogs are back on.

J. Kissel, R. McCarthy, M. Pirello

While trying to finally get around to finishing out the MEDM infrastructure for the new SQZ suspensions and the re-arranged OMs, we discovered that the RT and SD OSEMs are dead on SRM. They apparently died on Jan 10 ~19:30 UTC (about 11:30a PT). Remember, we know the problem is highly likely out of vacuum, since I was able to take successful transfer functions on Jan 3rd (LHO aLOG 40002). Much more likely -- Gerardo's Vacuum work mentioned in LHO aLOG 40090, or Fil and Liz's cable pulling mentioned in LHO aLOG 40085)

After tracing and confirming integrity and correctness of all HAM5/6 SUS cables from the AA chassis to the remote satellite amplifier, I noticed that two of the SRM (T3 LF RT SD) sat amp fault lights were on (see attached picture). Power cycling the respective SRM T3LFRTSD coil driver chassis didn't find the problem.  Talking with Richard, he suggested it was the last cable run from the sat amp to the chamber, since it's a tight squeeze getting the cable to seat properly at the feed through.

As suspected, he went out to diagnose and was able to wiggle the connection at the feed through enough to intermittently restore life to RT and SD, but didn't have the right tools to really make the connection secure, so he (or Fil) will finish out the fix tomorrow morning.

[TVo, Jenne, Cheryl]

There was a lot of random walking this morning, but with cameras newly focused and pointing at useful things, we now have the beam hitting the bottom of the SRM cage.  Once we found the beam, which required moving ITMX (ITMY misaligned), BS and PR3, we walked those optics back to their good locations from last night, while also moving SR2 and SR3 so that we kept the beam on the SRM cage.  Now all PRMI-related optics are back at their locations from last night, and we still have the beam at SRM.  I realigned ITMY and we have some nice MICH fringes.  Next up will be moving the beam up onto the SRM itself, then seeing if we can either get SRMI/DRMI flashes, or maybe get the SRM beam retroreflected back to the POP port.

Attached is a screenshot of where the SR2 and SR3 mirrors need to be, to get the beam to the bottom of the SRM cage.  Note that SRM's OSEMs are being looked at by the CDS/EE team, and so we may not be able to actuate it tonight, in which case we'll start here in the morning.

Richard informed me that the laser had tripped this morning.  I reset the laser without any problems.

    I increased the current for head 1 to the maximum of 60A and increased the diode temperature for
diode 3 to 23 degC.  The output of diode box 1 has taken a bit of a dive since the weekend.  So much
so that I would start to become concerned that the thermal lens in the NdYAG rod isn't what it should
be to make the resonator stable.

    At this point in time, we have two options as I see it, depending on commissioning constraints:
  i. replace the diode box
  ii. revert to low power mode
Both would take about half a day to do.

Daniel, Nutsinee

Here's a quick note of what we measured out there with the RF power coming in through (and monitored via) temporary cables. These RF power drive AOM1 and AOM2. There seems to be too much loss at Pmon2 compared to Pmon1 (almost 11 dBm loss versus 5dBm loss). The cable length going from CPL to Pmon are the same. The top RF input gets its power all the way from the CER while the bottom RF input gets its power from the SQZ rack. So the difference in the incoming RF power makes sense. Not sure if the factor of two difference coming straight out of the Cpl makes sense though.