As noted in alog6341, the gain on the Dual PD Amp board was set to 30dB (photo 1). I have reduced the gain to 10dB (photo 2). However, I still see saturation at 10V in the external PD monitor. Tomorrow I will try reducing the gain to 0dB.
I have reset the internal PD gain to 30dB (since we were never saturating there), and set the external PD gain to 0dB.
For the external PD:
Transimpedance = 20kOhm
Responsivity = .268A/W
Power @ ext PD = 0.93mW (w/ a drift of 7% of the ref cav alignment)
Gain = 0dB
Volts = (resp) x (power) x (trans) x (gain) = 5V
...Ignore above calculation for external PD...
Since we postponed the HAM1 in-vac mission today, we moved on to the interferometer alignment for now.
Here are what I did:
The attached is a screenshot of the resultant vertex alignment.
Travis, Angus and Alastair contued with the weld practice at end Y. Travis welded in all 4 practice fibres on the test set up and hung the dummy mass. We re-arranged the weld trolley and fibre preparation table positions to allow line of sight for Doug's alignment tooling during the welding. All tooling is functioning as expected. Tomorrow first thing we will remove the "old" ETM from the structure to allow TCS to work on the ring heater and then pop in the "new" ETM in the afternoon and do full alignment of the masses in preparation for welding again on Thursday
Days Activities
[Jeff Dave Arnaud]
After Keita reported he couldn't access to tip tilts medm screen to damp the suspension (which hasn't been updated yet), I looked at RM1_M1_OSEMINF signals to see if I could damp it from the command line. Although, the readback was zero even though we were seeing numbers out of the ADC, which directed us to a model issue. Some modifications from last week would prevent the model to compile properly so we undid some of the changes and fixed some other issues. After restarting the models after the changes, the channels were back alive. Last thing to do is to resurrect the medm.
Modifications made on
**h1sushtts.mdl** (1st screenshot)
1) Grounded the calibrated ISI signals outputs from HTTS
2) Linked the ISI signals directly from the IPC to OM1/2/3, instead of the ones going out of HTTS
3) Changed ADC7 to ADC0
4) Modified the channels to match with 3)
**HSSS_MASTER.mdl** (2nd screenshot)
1) M1/ISIINF CdsEpicsOuput banks changed to CdsFilt banks
As soon as we flipped the beam diverter open we got the REFL beam on ISCT1.
Then we went into HAM1 and noticed that the beam was moving by a huge amount in PIT. TTs were not damping at all. Turns out that that was a TT model problem. SUS people and Dave Barker are working on it.
We will resume our work when TTs are fixed, and in the mean time we'll look at the IFO alignment.
We made one measurement using NanoScan by misaligning the 50% BS after the HWP to direct the beam to the head. The BS and Nanoscan were approximately 8"x44" apart (give or take an inch).
1/e^2 (13.5%) diameter mean | stddev | Goodness of Gaussian fit mean | stddev | Profile Averages | |
X (axis 1) | 3851.01 um | 1.982 um | 0.01 | 0.000 | 10 |
Y (axis 2) | 3959.23 um | 1.232 um | 0.01 | 0.000 | 10 |
45 deg (axis 1) | 4117.74 | 1.475 | 0.02 | 0.000 | 10 |
45 deg (axis 2) | 3845.62 | 0.763 | 0.00 | 0.000 | 10 |
These are just the numbers NanoScan software dumped. As was partially captured by https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=8437, our experience is that Nanoscan, ModeMaster (takeing the beam size at the head) and hand-driven knife edge agree with each other within 10%.
power before AOM :31.1mW
after single pass: 24.1mW 77% single pass effiicency
after double pass: 20.45mW 66% double pass efficiency
The beam position on the iris after the retro reflecting mirror has not changed.
I tuned the upper periscope mirror pitch, this brought the transmitted PD voltage back to 1 V.
We have 5.8 mW in the ALS path before the Faraday, 5.33 mW after the Faraday, 4.3mW going towards the fiber, and 1.04 mW going towards the fiber launch PD (external on the fiber dist box).
In this configuration, I measured ~3.1mW at the input of the ALS fiber distribution and 100uW at the MSR.
and the end station we see 40 uW coming out of the fiber, not really enough.
After 11 days of pumping the vertex volume - HAM2,3, BSC1,2,3, and the X manifold.
Alexa, Sheila, Kiwamu
The goal of the day was to get the retro-reflection from PRM all the way back to PSL. And this was achieved. We are ready for the HAM1 incursion.
This work involved:
In the process of aligning PRM, we looked at the in-vac WFS in HAM1 with a viewer and saw the reflection light hitting the WFSs. We didn't check the beam on the WFSs after obtaining the retro-reflection, but they should be pretty close to the good alignment. Then after obtaining the retroreflectin, we went to ISCT1 to see if we get some light on the table, but we didn't find it. Maybe it is blocked by an optic for some reason as we can see scattered light. So the first thing we should do before the incursion is to check the beam alignment in HAM1 and see if makes sense. It might be possible that the alignment in HAM1 is bad even though we have a retro-reflection back to PSL. In this case, we should steer IM1 and IM2 to change the rejection angle of the REFL beam while keeping the retro-reflection.
P.S. We left PSL in the commissioning mode. The IMC autolocker is running on opsws3. The attached is the alignment that we established. I tried steering the IM4 trans picomotor, but it seemed not moving at all.
Today, Jeff, Andres and I finished disassembling the lower structure and 4 lowest masses from the ETMy QUAD upper structure. This involved pulling all of the reaction lacing cables up the chain. As well, we had to cut the fibers off of the previously monolithic HIFOy masses in the suspension. When Travis went to cut the first fiber out, the lower mass was apparently under some small load and the fiber broke it and it's adjascent fiber off. We think there was still some load on the fibers even though all of the masses had been locked in place. We raised the test mass before proceeding to cut the next 2 fibers out. Jeff, Andres and I then split the chains and left the main chain resting on the Genie arms and the reaction chain on the 5-axis/scissor lift equipment.
After lunch, Angus and I pulled the PUM out of the suspension and canned it (Gerardo - we're missing a top o-ring plate in the empty can - so the canned pUM is missing it. We need to steal one from the next can out there). I then cleaned the lower sus via vacuum while Angus continued preps with Travis in the weld area. We then stuffed the new PUM and got practice fibers loaded into the practice suspension for welding tomorrow.
I'm now out the rest of the week, but here is the sequence of tasks that need to happen next:
TUE AM - Gerardo / Travis pull the Test Mass, park the Main in the weld room, park the Genie under the reaction chain for added safety
TUE mid-AM - Travis / Angus / Alastair start practice welding (make sure to get panels in place)
TUE mid-AM - TCS peeps swap the ring heater (yes, likely in laser hazard, sorry)
TUE aft - finish practice weld
TUE aft - Gerardo / one of the weld crew stuff the new test mass
WED - set LS main mass DOFs and start real welds
Y'all already have mad skills, so smooth running and good luck to you!
Sensor's rotatable 2.75" CFF had a significant "ding" on knife edge -> don't have spare -> messaged with stone -> likely to be a leaker -> marked for leak check
- Cable routing in beer garden for OptLevs - Fil, Aaron - Replacing sensor card on Aux Cart at EX - Gerardo, Kyle - Tour for documentary - Mike L - Viewport survey at EX - Hugh - Commissioning work - Alexa, Kiwamu, Sheila - Staging and preparing for fiber welding - Betsy, Travis, Agnes - Working on quad at EY - Jeff Bartlett
The roofing membrane work is complete. All that remains is to complete the lightning protection system and install a few runs of downspout. Once we get some warmer weather I expect this work will be completed in a few days.
There were several conversations this morning WRT outstanding general INS tasks that remain to be worked. The tasks Bubba and I had in mind were grouting at HAM5/6, removing aLIGO HEPI components from HAM7/8/9/10, and removing aLIGO feedthroughs from HAM7/8/9/10. The grouting work would be very dirty and very close to the SRs so Michael decided against that. Of the two remaining activities, the feedthroughs seemed the easiest to start. In conjunction with that work, Apollo will replace all Al blanks on H2 chambers with conflat blanks. Scott and Tyler spent the afternoon gathering materials.
All beam tube insulation has been removed. Enclosure has been nicely cleaned up.
(Kyle, Gerardo)
Replaced the dual pirani sensor card for aux pump cart #1, and started pumping BSC09 annulus.
Roughly 30 elk crossed route 10 a few hundred meters from the entrance to LHO this morning. Watch out while driving... cell photos attached.