Measured the 80 MHz RF level at the output of the balun in the distribution panel in the PSL rack. This provides the local oscillator for the ISS AOM driver. Originally a 5 dB attenuator was at the output of the balun. All RF powers were measured with the Agilent RF power meter. +13.0 dBm at the balun +8.2 dBm at end of cable to the AOM driver with a 3 dB attenuator installed +10.2 dBm at end of cable to the AOM driver with a 1 dB attenuator installed Left the 1 dB attenuator in place as this yields the right RF level for the AOM driver input. Anecdotally it seems to me that the RF level has been dropping over the past few months.
Attached are some FSS transfer functions, all with a common gain slider of 20 dB. The input modecleaner was locked for all these measurements. C20F4TF.jpg: FAST gain 4 dB C20F10TF.jpg: FAST gain 10 dB C20F16TF.jpg: FAST gain 16 dB C20F22TF.jpg: FAST gain 22 dB
Attached are all the transfer functions on the one plot. One can see that with the FAST gain as high as 22 dB, the dip associated with the crossover between the PZT and EOM is noticeable. The raw ASCII data is attached: frequency, magnitude, phase, magnitude, phase .... etc. for the 4 FAST gain settings.
Is 0 dB = 0 dB, or is -10 dB = 0 dB? If the latter, can you please make it so 0 dB = 0 dB?
Replaced the analog camera looking at the BS with a GigE camera. Camera 29 on the MEDM. Ran the network cable from the camera to SUS-R2 Patch panel port 5. This is a run to the CER. In the CER plugged the unit into port 35 on the network switch. We have a view that will need to be refocused when the IFO relocks. Also have the illuminator on so we have a better view. This needs to be unplugged at the illuminator.
Chandra, Gerardo, Travis
Today we attempted to install both the X and Y arm ITM camera housings. We successfully installed both of the viewports adapters with the new 1/4" dowel pins. The installation of the X arm camera housing went smoothly (see pics 1 and 2). However, when attempting to install the Y arm housing, I noticed that the gap between the expansion bellows of the vacuum system and the camera housing side plates was non-existent (see pics 3 and 4), whereas the X arm has ~1/8' of clearance. Gerardo measured the length of the bellows in both cases and noted that the Y arm bellows were ~1/4" shorter in length than the X arm, meaning that the height of the peaks of the bellows would be greater. We'll have to modify the Y arm camera housing to accomodate this difference. I hope LLO does not have the same issue.
Calum checked with the designer, Joe Gleason. These units are not installed properly. They need to be mounted so that the base plate is perpendicular to a radial line from the center of the vacuum spool, as shown in:
By mounting in this orientation there should be ~1" of clearance from the bellows.
19:08 UTC The PSL is back up. All servos are locked. The original ISS AOM driver is back on the table after being checked out in the EE Lab. Replaced a blown +15V regulator and its 10uF aluminium electrolytic input bypass capacitor.
Left LD (not running) and helium etc. at Y-end RGA location -> Wasn't able to actually do any testing as the helium background was too high and ran out of time abating it (still x20 too high) - to be continued at next opportunity
Gerardo, Chandra GV 5 & 7 were soft closed at 9am local for Pcal camera mount installation on X/Y beam manifolds per WP 5988. GV5 opened at 45 psi; GV7 opened at 43 psi (11:30 am local) Attached are pressure trend data at gauges on each side of GVs. We did not pump out gate annuli because of short duration in isolation.
[Evan, Sheila, Jenne]
Yesterday we had 3 locklosses in a row at AnalogCarm, which is quite unusual for us. Sheila tracked it down to a big glitch when we enabled the IN2 of the A summing node. The signal coming into that input looks the same as it had during a successful smooth aquisition sequence, so it's not a change in what's coming in.
I ended up changing the guardian a bit, so that it starts with much smaller gain (-32 dB rather than -4 dB), hits the enable switch, then ramps up the gain to -4 dB before continuing the rest of the sequence as before. The ramp up to -4 is quite fast - it has worked at least once, but if it ever fails, we may consider putting in a few small sleeps.
【 Jenne, David, Matt, Evan 】
We spent some time trying out 2 W interferometer operation with lower modulation depths for the 9 MHz and 45 MHz sidebands. Nominally, the modulation depths are 0.22 rad for 9 MHz and 0.27 rad for 45 MHz.
I have attached scripts which can be used to step the modulation depths up or down using the Siggtronics EOM drivers in the PSL. These will adjust all digital photodiode gains appropriately, so that the interferometer stays locked. The only thing needing manual adjustment is the CARM gain.
In this way we were able to reduce the 9 MHz modulation depth by 6 dB without issue.
The interferometer became noticeably less stable with 4 dB of reduction of the 45 MHz modulation depth. In particular, the dHard loop gains seemed to increase, causing a loss of gain in the DARM loop around 20 Hz. The MICH and SRCL loop shapes did not change. Lowering the dHard loop gains by a factor of 2 enabled us to reduce the modulation depth by 6 dB compared to the nominal. There was also noticeable wobbling in the PRM yaw pointing loop control signal (maybe motion impressed by the 45 MHz PR3 loop?). If we want to run with lower 45 MHz modulation depth, a campaign of ASC loop measurement is probably a prerequisite.
After restoring the AOM driver back to its original power cable, the ISS would not lock and kept oscillating. The servo control voltage kept varying between ~0.2V and ~0.6V, meaning that the amount of diffracted light requested was varying from one extreme to another. I looked at the diffracted spot and all I noticed was the intensity of the diffracted order seemed fairly constant. The input RF was measured with an oscilloscope to be ~410 mVrms, which as I recall is not enough. I opened up the AOM driver and the +15V voltage regulator was no longer supplying 15V. The spare AOM driver has been installed for the time being. Whilst hardware-wise things are in place, I will have to wait until the computer maintenance tasks are completed before being able to test the ISS again. The external laser shutter - ie the one located in the high power oscillator - is closed for now, and the watchdogs have been turned off.
I nominally energize the turbo controllers during Tuesday maintenance periods so as to charge the external batteries. Today I found them still energized from last week. This means there have been four additional fans running in the LVEA during this time as well as any associated EMI-noisy supplies -> I de-energized them this morning.
J. Kissel I've reconciled what changes were made last night during commissioning, and begun bringing SEI and SUS to safe for this morning's timing upgrade. I'm leaving HAM23 SEI and SUS up and running because Peter's finishing up commissioning the ISS in the PSL. There are several changes in the PSL ISS SDF system (with respect to the down.snap) as a result of his commissioning; we'll make sure those are accepted before we upgrade the PSL front-end timing. There were only three things to reconcile - - some new(?) damping filters were turned on in the QPD portion the SUSETMYPI model (DAMP_MODES 3 and 4), - an ALS-C_COMM_PLL_PRESET was set at "No" instead of "Low" last night at Jul 19 00:13 PDT, and - a PSL-ISS_TR_LIMIT set to 1000 in the LSC model. Since this was set at Jul 18 22:48 PDT (so I'm assuming this is *not* Peter)
J. Kissel, H. Radkins We've completed reconciliation, and brought all (except HAM2 and HAM3) platforms and suspensions to OFFLINE or SAFE, respectively. Again, We'll wait until we hear from Peter on whether he needs HAM2 and HAM3 before bringing those platforms and SUS to offline.
Title: 07/18/2016, Day Shift 23:00 – 07:00 (16:00 – 00:00) All times in UTC (PT) State of H1: IFO locked at DC_READOUT_TRANS. 2.0W Wind is a light to moderate breeze. Microseism is low; seismic activity is slightly elevated in X, and Y but not out of line with wind conditions. Commissioning: Commissioners are commissioning. Outgoing Operator: Ed End of Shift Summary: Title: 07/18/2016, Day Shift 23:00 – 07:00 (16:00 – 00:00) All times in UTC (PT) Support: Jenne, Sheila, Incoming Operator: N/A Shift Detail Summary: Spent shift relocking in support of commissioning activities. Rode through a 5.5mag EQ in Chile with no apparent problems.
Sheila Jenne Matt Carl Jeff
Tonight we tried a repeat of what Kiwamu and I did last week, and we were able to restore a recycling gain of ~32 (according to the POP DC/ IM4 channel, which is more like 36 according to the way we calculated it durring O1) at 40 Watts. We moved PRM PIT 90 urad in the negative direction, and had to touch up SRM as we did that. We moved the spot on the POPX WFS enough that we railed the PZT and the spot was off center by 0.5. Again the spot on POP A was mostly on just the bottom 2 quadrants. The power on the baffle PDs also decreased as we moved the alingment. We also tried Yaw but this wasn't able to improve the recycling gain.
Since it seems like we might want to use pico motors on POPA, Jenne tried to repeat the PRM move at 2 Watts by moving PRM to match the witness sensors at 40 Watts, she could only go about half way before we lost lock.
Stopping for the night so I can come in for Tues maint. in the morning, but not a lot more progress.
This last lock, I engaged an extra offset of 0.4 in the PRC1 pit loop once we got to 40W. This puts the PRM in the same place as Sheila mentioned earlier, and brings up the PRC gain. I used a ramp of 100 seconds, which may have been a bit fast for the SOFT loops, but we held the lock.
I then got bold, and requested 45W (intending to stop there only momentarily on my way to 50W), but the ISS 3rd loop went unstable. Probably we need to reduce the gain, since we've got a bit more optical power, although I'm not totally sure why, since Kiwamu's measurement in alog 27940 shows that the loop is ultra stable. Probably we should measure the 3rd loop again at 40W.
Attached are some plots showing what happened as we powered up and moved PRM last night, compared to a power up from december.
In the first plot you can see that the recycling gain drops as we power up, with a similar trend in all three diodes that we use to monitor the power recycling gain. Last night's trends are in the first column, the trends from december are in the right column. Last night the ratio of IMC_PWR_IN_OUT to IM4_TRANS_SUM was pretty much constant, while in december it increased by 10%, which explains why the POP/IM4 power recycling gain monitor does not agree with the others in December. There is also an unknown overall gain change for IM4 sum between now and December.
The second row in the first attachement shows how the baffle PDs normalized to the input power (IMC_PWR_IN_OUT).
The second attachment shows pitch oplevs (you can tell that as we move PRM CSOFT P is changing) and QPDs durring this change.
[Matt, Carl, Jenny, Sheila, Evan, Jeff]
The SR785 monitorring the ETMY QPD transmission has not uncovered any large hidden test mass accoustic modes in the 65-75kHz band. It has however highlighted the fact that there is a strange 3kHz comb on these QPDs. See this first image showing the comb (3 peaks) and the second image showing the 65-75kHz band at 50W.
This comb is present on both the fast 10-80kHz PI channels and the normal QPD A channel. The comb appears in the X and Y arm but they are not identical. See third image. Also in this image the spectra before and after the whitening gain is changed (in guradian state DRMI_ON_POP) indicates that the source of these peaks lies before the whitening gain stage.
There is little indication of anything in OMC DCPDs other than these peaks being in the vicinity of violin mode harmonics - see last image.
J. Kissel, J. Driggers, B. Weaver, E. Merilh. E. Hall, H. Radkins, D. Sigg In prep for the timing system software update, which'll need all front-ends to be turned off and restarted tomorrow, we've reconciled the SDF system in the ISC_LOCK guardian's "DOWN" state (note that in this state, some front ends are using the "safe" some are using "down" and some are using "OBSERVE" snap files). Notable things that we accepted: - Bounce and Roll monitoring FMs (H1:OAF-BOUNCE_[ETMX, ETMY, ITMY, ITMX]) were found to have FM3 (a broad band-pass) in place instead of FM4 (a narrow band-pass). We reverted to have FM4 ON and FM3 OFF. - PCAL Y 1083.7 Hz line has been off since June 28. We couldn't find an aLOG, but I recall we turned the 1 kHz line off to preserve range on the PCAL. We've accepted that it's off. - The Beam Splitter M2 stage LOCK_P and LOCK_Y has bounce and roll mode notching filters for both the BS's bounce and roll modes at 17.7 & 25.7 Hz (FM5 "BounceRoll"), as well as for the QUADs at 9.63 and 13.4 Hz (FM7 "EvanBR"). We found that FM7 was OFF since Jun 28th, and we think we want it ON, so that MICH isn't affected by the ITM bounce and roll modes when actuated in Pitch and Yaw. - We found the IMC Master WFS gain at 0.09 instead of 0.1, and has been so since July 13th. Seems silly, so we reverted to the gain of 0.1. - The newish Daniel-style integrators for POP X WFS DC centering servo were found with there bleed-off engaged (via H1:ASC-POP_X_PZT_PIT/YAW_BLEEDEN), as desired since Jun 28. We accepted the bleed off ads engaged it. - The INP1 Yaw offset was previously -800, and is now 0.0. We accepted the 0.0, because this offset was used to PRC gain spelunking, and is now no longer in favor. After we went through one round of clearing out, accepting, and reverting, we got mid-way through the lock acquisition sequence and lost lock back to the DOWN state again. For any further channels and changes that occurred, (especially on the suspensions), I UN-monitored those channels.
Also, we added a limiter to the ISS third loop, but couldn't find this channel in SDF, even in the full list.
Also, note that even though people reconciled SDF with the mask applied, there are still diffs if you look at all channels, I'm not sure all of these channels are set by guardian to what they should be.