Evan G., Jeff K.

We moved a compensation zero out of the ESD output filter bank for each quadrant that had generated an uncompensated 5.2 kHz pole in the DARM loop (see LHO aLOG 33927). This resulted in an effective delay of ~20 usec. There is adequate roll off already from a low pass filter in the ESD driver, so moving this out of the DARM loop will be minimally impactful. Instead, the compensation zero will be a compensation pole in the CAL-CS path and doesn't result in an additional 5.2 kHz zero being added to the Foton filter.

We leave the filter in place and turned on, but the design string is now simply zpk([], [], 1, "n")

The new filter is installed in CS_DARM_ANALOG_ETMY_L3, FM5: zpk([], [3245.33075], 1, "n") (this comes from the mean of the summing node poles, see 27619)

Removing this from the DARM path means that we need to include these as an uncompensated poles in the DARM model and reduce the unknown actuation delay by 20 usec. This will bring the unknown actuation delay down to ~40 usec.

see WP #7343 

1630 hrs. local -> Lowered CP4's level via CDS PI control set point to 70% down from 75%.  I expect this new pump level value should be reached prior to my leaving tonight.

Will start tomorrow morning with step 2 of WP #7343 (as step 1 was done this weekend).  Delay is the result of competing employee requirement/task in addition to my desire to complete construction of a relay box that will act as a second interlock and isolate the scroll pump as a function of foreline pressure.  As is, the foreline isolates only at the absence of 120VAC as seen by the scroll pump motor windings (i.e. one layer of protection - prefer two layers).  

Cross-posting from LLO alog here: https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=37737 

Today, I knocked out the jig calculations for the AERM07 prism placements and updated the spreadsheet for all 4 new AERMs (05, 06, and 08 have been finished, spreadsheet E1000828).  Gerardo did a quick spotcheck of my work, then I went to the lab and glued the first prism on (specifically "180 ARM").  The EP30-2 epoxy is a newly procured vial and passed the usual pre-bake test, as usual.

TITLE: 02/12 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: PSL was shut down and 70W amplifier work began. More work continuing down at MY for CP4. Team SUS working on ETMY. And SQZ crew is prepping for next week's install.
LOG:

• 1602 Mark to LVEA to change out nitrogen bottle
• 1612 Mark out
• 1619 Terry to SQZ Bay
• 1730 Christina, Karen, Vanessa to LVEA
• 1741 Peter to LVEA to transition to laser safe
• 1743 Jason to LVEA
• 1753 Corey to optics lab
• 1754 Jason out
• 1758 LVEA is laser SAFE
• 1800 Terry back out to SQZ Bay and optics lab
• 1810 Peter, Marc out of LVEA and headed to MY
• 1817 Ed to SQZ Bay to talk to Terry
• 1821 Jason to PSL enclosure
• 1829 Travis, Fil to EY for ESD checks
• 1837 Peter, Marc back
• 1841 Jeff B to PSL enclosure
• 1842 Corey dropping off part to SQZ Bay, then out
• 1921 Peter to PSL enclosure to drop off valves for Jeff B
• 2031 Jason and Jeff B out for lunch
• 2049 Jeff K and Travis to EY for violin measurements
• 2113 Karen to MY
• 2143 Karen leaving
• 2145 Jason to PSL enclosure
• 2203 Bubba to LVEA
• 2210 Bubba out
• 2229 Nutsinee to SQZ Bay
• 2248 Jason out
• 2307 Ken done at MX

Given that we have no laser light, confirmed by images of the PSL and cameras looking into HAM2, I set the PSL ISS Second Loop Array QPD dark offsets.  I accepted the values into SDF, and also had to accept the offset switch being on for all 4 segments, and I've confirmed that these offsets were zero in Feb 2017, during O2.

OFFSETS: Seg1 = 0.180, Seg2 = 0.180, Seg3 = 1.540, Seg4 = 2.370, and the SUM, which had been at +4.2, is now oscillating around zero.

I put an offset of -2.0 on the SUM to prevent it from going negative.  I tried using -1.0, but the pitch and yaw signals were still occasionally railing +/-32K.  The SUM during Feb 2017 reached 60K counts, so an offset of -2.0 is small.

Changes are recorded in the attached screenshot:  Left side shows current settings, rich side shows a snapshot of the QPD segment settings as found (zeros).

Peter has transitioned the LVEA to Laser SAFE

PSL tripped this past Saturday. HPO has been bypassed and powered down for water removal and dry-out in preparation for the 70W amp install.

PSL

    Starting 70W amp work after meeting.

Commissioning

    HAM6 looks good, DRMI was locked. Looking at HAM6 South door removal this week, as well as placing ISCT6 being placed just outside the cleanroom. Will capture SDF.

Vac

    MY CP4 work continues; craning, electrical, and piping work.

    More discussion on the HAM6 septum view port cover.

EX

    Activity will be ramping up at this end station, including: prepping cleanrooms, prepping weld room, PCAL alignment, ALS power supply, staging equipment, VE interlock.

Film crew will be on site Thursday Friday.

Will be going laser SAFE until we need lasers for commissioning. Work Safe!

Laser Status:
SysStat is good
Front End Power is 34.81W (should be around 30 W)
HPO Output Power is 29.17W
Front End Watch is GREEN
HPO Watch is RED

PMC:
It has been locked 1 days, 15 hr 1 minutes (should be days/weeks)
Reflected power = 3.255Watts
Transmitted power = 22.57Watts
PowerSum = 25.82Watts.

FSS:
It has been locked for 0 days 2 hr and 9 min (should be days/weeks)
TPD[V] = 0.7296V (min 0.9V)

ISS:
The diffracted power is around 2.7% (should be 3-5%)
Last saturation event was 1 days 15 hours and 2 minutes ago (should be days/weeks)

Possible Issues:
FSS TPD is low

I'll put in a Work Permit tomorrow that details the process of letting CP4 go "dry".  Starting from 75% full will give a little head start to the lengthly process.  Chandra R. has lots of activities related to CP4's decommissioning scheduled for this week so we don't have a lot of "wiggle room".  


This step may well result in CP4 level alarms tonight.  This is expected and is being monitored remotely. 

I'll be at Y-mid VEA making temperature measurements and/or adjustments or in the VPW tinkering with VBOC.  I expect to only be here 90 minutes or so.  Gerardo M. is my "phone buddy" and I'll make a comment to this entry when I am leaving the site. 

I came in to do some last DRMI/PRMI tests, and found the laser is off.  This happened about 4:15 am pacific time.  THe epics channels don't show any problems with the chillers, and it looks like the power watch dog tripped after the laser went off. (screenshot attached)

Terry, Nutsinee

Got some measurement of the EOT faraday isolator on the green path:

Over all transmission ~ 91% (S and P pol)

• 91% S-pol went through
• 91% P-pol rejected
• ~9% loss

Isolation ~ -26dB

Couldn't find a non-polarizing beam splitter for 532 so I used a dichroic beam splitter set at weird angle (~30 degree or so) to partially let light though. I used one of the precision photonics mirror found in the SQZ bay drawer to reflect transmitted light straight back into the faraday and measure the light that bounced back from the beam splitter. I couldn't measure the part of back reflected light that went though the beam splitter so I guesstimated the transmission knowing what came in and what gets transmitted on its way into the faraday. Terry thinks this number is disappointingly low, given the dodgy set up I'd take this number as an upper limit (in a sense that it can't get any worse). But again, given the nearly 10% loss maybe we just have a not-so-great isolator. 

This afternoon Georgia and I locked PRMI and ran a2l for PRM, PR2, and PR3.  

There is a file called by the a2l scripts (for the matrices) that is no longer in the place it used to be.  We added the ads matrix to the list of matrices used in ISC_library, so that these scripts now import and use that.  

[For the commissioning team]

We did a quick measurement of the loss in the x-arm after improving the pointing into the cavity using IM4 and PR2.

It is important to note that there were no angular loops closed when doing this measurement, so the power build up wasn't optimized ( LSC-TR_X_QPD_B_SUM ~ 0.95).   We were running short on time and verified that the DC angular alignment was good enough so that the locked vs unlocked state gave us a big enough dip to estimate a visibility.  

Comparing the above numbers to alog-38493. They are close, but I can't say anything definitive about the change in loss between the two ITMXs (before and after swap), we can redo this measurement when we have more time to close angular loops (and maybe try a more sophisticated loss measurement).  Also important to note, mode-matching contributes to the loss as well and this is not taken into account with this measurement.

Some recent modest ASC full data trend plots have shown gaps in the data with an accompanying popup error:

[Error] Purging failed. Increase 'Max drawing path length' in prefs.

It is not immediately clear what "purging" and "max drawing path length" mean, but if you increase it from the default of 20k to 100k the gaps disappear.

Attached is the 'gappy' plot with the popup, and the preferences with the increased max drawing path length