FIrst loop ISS status

Aligned beam onto the PDB photodetector in the ISS PD box.  Also realigned the beam onto the quadrant photodiode.
The effect of which can be seen in the attached plot.

    Engaged the first loop power stabilisation this morning without much hassle.  The calculated diffracted power
percentage is off as the coefficients need to be calculated.

    Without doing some loop measurements, the gain slider setting of 18 dB maybe the wrong value.

Old coefficients for calculating the diffracted power percentage are displayed in OriginalCoeffs.png.  The new coefficients are
displayed in NewCoeffs.png.

    With the reduced diffracted power, I changed the limits of the plot in the ISS MEDM screen from 20 to 5.

ISS second loop model change

Due to hardware BIO logic change in the ISS 2nd loop board (D1600298, HIGH/LOW=NO/NC in V2, HIGH/LOW=NC/NO in V3), I removed or added NOT in all relevant BIO control and readback channels in psliss frontend.

I removed  H1:PSL-ISS_SECONDLOOP_REFERENCE_VALUE_CAL filter and H1:PSL-ISS_SECONDLOOP_REFERENCE_VALUE EPICS channel, these were necessary before as the slow offset loop and digital excitation combined had one dedicated analog input, now these are added together with the 3rd loop. This analog input was reassigned to the BNC input on the chassis.

I just saved the model but hasn't compiled yet.

HWS SLED replacement summary

Summary:

We're reviewing the HWS SLED situation.  We have only one spare for the ITMX SLED and no spares for the ITMY SLED.

We're averaging about one SLED every 8 months during intensive usage.

ITMY

• April 2015: replacement [ITMY: QSDM-840-5 12.02.44]: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=18069
• July 2016: replacement [ITMY: QSDM-840-5 07.14.264] https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=28162
• October 2016: replacement [ITMY QSDM-840-5 07.14.265] https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=30257
• May 2017: replacement [ITMY - QSDM-840-5 7.14.266]: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=36174

ITMX (not used as much before in-vac lens fix)

• March 2016: status check [ITMX QSDM-790-5: 12.05.21]: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=25907
• July 2016: replacement [ITMX QSDM-790-5: 07.14.256]: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=28358
• April 2017: replacement [ITMX QSDM-790-5: 07.14.254]: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=35486

In storage cabinets next to BSC3.

• QSDM-790-5: 07.14.255 [should be okay]
• QSDM-790-5: 07.14.256 [dead]
• QSDM-840-5: 07.14.265 [dead]

 

 

 

Turned on High Voltage at End Y

F. Clara

Turned on High Voltage at End Y

starting squeezer seed beam alignment at AS port

Terry McRae, Sheila

This afternoon Terry and I started to prepare for measuring the mode matching of the squeezer to the OMC. 

• We changed the crystal temperature as we scanned the OPO to find a co-resonance where there is much less nonlinear gain, so that we can generate a stable seed beam for alignment and mode matching.  With the OPO locked we see co-resoance for a temperature setting of 43.4C.  For nonlinear gain the co-resonance temperature in air is 33.47 C
• We injected this into HAM5 and saw some light on AS B.  With the fast shutter open (see 41409) we were able to manually move OM1+OM2 to center the beam on the AS WFS, which also put beams onto the OMC QPDs. 
• To engage the AS centering loops, we had to change the sign of all the gains.  This doesn't make sense, and it looks like there are lots of things that don't make sense in the SDF files for the OMs.  
• We need to set dark offsets on the OMC QPDs, this might have been part of the problem with using OMC alignment loops that our mode matching crew have experienced. 

ETMX rebuild status

Yesterday, Gerardo helped me flip the new PUM ITM03 mass up onto the optics table in the bonding lab and I embarked on gluing prisms to it, using the standard T1300322, and assoc procedures.  This morning I glue the second of 2 - it's in it's fixtures overnight.  

Down at EndX, Calum helped Travis and I use the install arm to pull the ETMX lower structure from the chamber, again.  The unit is not back in it's 8-legged LSAT on the small trolley in the staging room near the chamber.  

Please garb as per the sign at the entrance to this room, even to pass through.

 

Ops Day Shift Summary

Fast shutter and PZT2 shutter woes

Sheila, Keita, TVo

Last night I ran into a funny situation while trying to scan the OMC with the IFO beam in single bounce off ITMX.  In order to do this scan, we need to have the fast shutter down and the PZT2 shutter down and the outputs enabled so that you can actually do the sweep.  Effectively, there are two shutters we want to have open FASTSHUTTER_A and PZTSHUTTER_A.

However,  when we tried the logic here to open the fast shutter by setting the threshold to negative (H1:SYS-MOTION_C_SHUTTER_G_THRESHOLD), this would shut off the PZT2 output. Then setting the same threshold to zero or positive, the PZT2 output would be enabled and the fast shutter would close.  SO, there must be some logic that I am missing.  Keita suggested  power cycling the Fast Shutter Driver which Sheila noted having some funky readings (pictures attached).  However, this doesn't seem to have fixed the problem.

Double-beam hunting

Robert, Sheila, Nutsinee

Today we removed a view port cover on HAM5 north door (faraday side) to look for the IFO beam reflected off AR side of the thin film polarizer. Attached a couple photos we took with our IR camera (Nikon D7100 with IR filter removed)-- We found the beam hitting the HAM6 side of the ZM2 cage. The beam moved towards HAM4 when we did positive yaw on SR2 and moved up when we did negative pitch. This is consistent with how the rejected polarization beam moved in HAM6.

According to Koji's calculation and Corey Austin's response to our alog last night (alog41403) we suspect that our wedge is in the opposite direction.

mixing tabs and spaces for indentation not just a bad idea for python code

A word of caution that indenting code using a mixture of spaces and tabs will result in code which looks very different depending upon which editor is being used to view it. In the two attachments a snippet of the same C code is shown being viewed using the editors vi and gedit. The vi example shows consistent indentation, the gedit version shows erroneous indentation. This is because the code mixes tabs and spaces for indentation, and vi defaults to a tab size of 4 spaces, and gedit 8 spaces. This can be further compounded in that the code itself can redefine the tab size with the directive "-*- tab-width: 6;" which is honored by some editors (e.g. gedit) and not others.

Take home message: it is best to adopt Python's PEP8 standard of always using 4 spaces for indentation for all LIGO code to avoid this confusion.

WHAM6 ISI Balanced, yes, again. Pulled Cables 4 & 5 for ASC_OMCR_(QPD A/B & PICOMOTORS)

Refer to D1300122, sheet 8.  Pulled cables 4 & 5 completely from chamber along with their Cable Table Bracket (CB-5).  Cables disconnected from D6-F4 & F6.

With that out of the way and extraneous spode jettisoned, the ISI was unlocked and balanced to the locked Z & tilts.  Got within several um/urads, relocked, updated the target position, and unlocked.  Balancing then required just a 50g adjustment and locking/unlocking is again just a few micros.

Left the ISI locked

Cables removed:

D1000225-v2 180" S1105030--This is in ICS but was not in an any assembly.

D1000223-v8 216" S1202611--This cable is not in ICS & there is no D1000223 in the WHAM6 ICS Assembly D0901822.

Will stash these cables in the cable totes in the LVEA west bay. And uploaded to ICS.

HAM6 work today (SQZ)

Sheila, Terry, Daniel, Terra, T Vo, Koji, Nutsinee

 

SQZ beam came back!

This morning we checked that the SQZ beam went into HAM5 and still came back out on the other side to the OMC. The SQZ beam was not perfectly overlapped with the PSL beam but we declared that was good enough.

 

Double-beam

Corey Austin told us we should expect two beams reflected back from the .5 deg wedged thin film polarizer, we only saw one beam came into HAM6. Koji calculated the separation angle to be 2.2 deg. ZM2 diameter is 2", facing the beam at >45 deg left us with about ~1" diameter (2.5 cm). The beam separation at ~1m is ~4cm. It is very likely that the second beam doesn't hit ZM2 as the main beam hits the center of the optic.

 

Beam diverter

We moved the beam diverter such that the transmitted red beam from the VOPO shot out of HAM6 to SQZT6 parallel to the green refl and trans. A new back (right) panel for the SQZT6 has to be made, the beam is now 4 and 1/4 inches from the top of the panel and 9 and 1/4 inches from the -y edge of the panel. Here's a photo of the red trans beam position relative to the view port simulator. We also removed the apertures out of the way. Here's a photo of aperture #1 and #2 that shows their positions before we moved it, which was set after the realignment work in HAM5 last week.

 

IFO beam

The IFO beam that reflected to the squeezer side of HAM6 table measured 7.6 uW and was 6mm above aperture. A black glass beam dump was put behind the beam diverter at roughly 33 deg from the beam diverter's nominal. The sketch shows the angle that the beam came in relative to the beam diverter and how the reflected angle was calculated. The IFO trans beam into OMC measured 1.4mW. We also moved the silicon carbide beam dump to capture the OMC refl beam.

 

ETMX Fibers broken during installation

Today, Travis, Mark and I worked on installing the ETMX lower structure into the chamber.  After it was in, while reassembling cables, we noticed that the test mass was really jammed into it's lower stops - upon further inspection, we discovered that both fibers on the left side (viewed from back of the suspension) were gone.  We started looking for the debris and found it just outside of the chamber on the floor and on the trolley that the unit had been sitting in overnight last night and this morning.  We did not find anything like a bug nearby, but investigation ongoing.  Meanwhile, we're revising the schedule to back up a few steps and start the rebuild.  History of lower structure after it was welded:

- Welded main chain unit sat on it's trolly in weld room for ~a week before we were ready to install it.

- Yesterday, we rolled the covered main chain on it's trolly ~60ft from weld room cleanroom to the staging cleanroom.  We then uncovered it, and lifted it with the genie duct jack and placed it on the reaction chain trolley and mated the 2 units together.  The fibers were intact at this point.  We then covered it again and rolled the whole unit ~10ft from the staging cleanroom to the chamber cleanroom and parked it near the door.  We left the cover on it and the genie duct jack parked around it with the forks loose around the structure to aid in protection.

- This morning we uncovered the unit, and then lifted the unit off of the trolley with the genie lift and set it up on the install arm elevator.  We then continued with the installation of the unit into the chamber with the arm.  A few hours later we discovered the broken fibers.

All of the above is standard install procedure, with the same equipment (trolly, cover, genie lift, install arm) used in each of the previous QUAD installations.

Since we found the fiber debris all over the trolley and on the ground outside of the chamber on the floor, it must have happened between yesterday late afternoon when we rolled it there and this mornign after we picked it up and set it into the install arm.

 

TCS Chiller Pump Rebuild

The TCS chiller pump has been rebuilt and should be ready to act as a back-up now. In the future if the water pump needs to be rebuilt it uses a a type 21 shaft seal, 5/8" shaft size, 1 1/4" seat bore. The replacement o-rings are 4x dash number 012 and 1x dash number 242. It also uses a standard external retaining ring with a 5/8" OD. Use a light grease to seat the shaft seal, or else the rubber will tear (voice of experience here, oops).

 The chiller is currently running in a small closed loop to see if any leaks develop overnight, it is on the mezzanine with its other siblings.