Alexa, Stefan, Sheila and Kiwamu

Yesterday, we set up an optical spectrum analyzer on the PSL table to measure the characteristic of the EOM. The results look good except for the 24 MHz resonance . The resonance for the 24 MHz sideband is apart from the modulation frequency by 250 kHz or so. However the IMC doesn't need a large modulation depth and the IMC locking has been OK, we are good. Also, I took some impedance data and will put those data together into a DCC document for a record purpose.

The plots below are the measured modulation depth when driven hard as a function of the modulation frequencies. The vertical dashed-lines represent our actual modulation frequencies i.e. f1 = 9099471 Hz , f_mc = 24078360 Hz and f5 = 5 x f1.

LVEA Laser Hazard

08:28 Justin	To End-Y to check on laser setup
08:45 Mark	Moving ARGO arm to End-Y
08:45 Thomas	Optical lever work at ITM-X 
09:00 Sheila	Removing viewport cover for IM2
09:15 Mark	Craning ITM-Y lower structure over beam tube
09:25 Filiberto	Pulling cables by BSC3
09:40 Richard	Out to End-Y
10:30 Scrap metal recycler on site to swap recycle bins
12:55 Cyrus	At X-Arm spool area to terminate Cat-6 cables
13:15 Corey	Out to End-X TMS lab to recover tools for End-Y	
14:30 North Gate Electrical on site to deliver part

Removed gasket from 4.5" CFF blank on BSC9 (location of to be installed ESD interlock gauge) and left flange loose to exhaust wet purge air over the weekend -> Started QDP80 and Turbo -> Began pumping on BSC9 annulus

Safe.snap files were updated for every SEI platform involved in PRMI.

Soft links were checked, and safe.snap files were commited in the svn.

ISI
HAM2, HAM3                  - r6572
BS, ITMY, ITMX, ETMX  - r6576 

HPI
HAM2, HAM3                   -r6574
BS, ITMY, ITMX, ETMX   - r6577 

Below is a summary of the available controls on SEI platforms, for PRMI. Platforms should run under their preferred configuration at all time.

HAM1:

• HEPI: Floating

HAM2:

• ISI: Lv3 Isolation, fed by 01_28 generic blend.
• HEPI: Position loops ON

HAM3:

• ISI: Lv3 Isolation, fed by 01_28 generic blend.
• HEPI: Position loops ON

• ISI: Lv3 Isolation, fed by:
  • Stage 1: T250mHz blend, with T100mHz_N0.44 on X and Y
  • Stage 2: 250mHz
• HEPI: Position loops ON

"Quick" circular AMP connectors had been added to this gauge pair wiring to facilitated disconnection/connection without the need to access the wiring terminations at the gauges themselves.  I suspect a voltage drop across this additional connection accounts for the apparent signal error.  Accessibility is not good to correct -> will live with this until opportunity to correct presents itself

During the last suspension model updates, many SUS models started reporting some additional status bits. I did a first round of cleanup of the overview screens to show all bits.
- fixed the number of bits and the mask names in a series of model specific ODC screens.
- ODC overview screen update:  fixed the numer of bits and switched to the _LATCH version of the ODC channel ( this channel latches for 1 sec.)
- set the bit mask for all SUS and SEI models.

Still to do: 
- number of bits for the BS is different than ITMs - it needs it's own BSC screen
- set the string bit label s
- update IMC model
- in collaboration with SEI: the ISI scripts currently incorrectly set he desired state channels.

A set of matlab transfer functions has been ran on the TMSX this afternoon after BSC9 was closed out, and while the ISI was damped. The pitch degree of freedom shows some excess noise between 0.7Hz and 3Hz, which is something I was not expecting to see since the measurement after the last work accomplished on TMSX was clean.

It might be related to some excess motion at the time of the measurement during the afternoon, which I will check by running undamped and damped TFs overnight in a quiter environment. We will see how repeatable the measurement is tomorrow morning.

It might also be the position of the cables that could have changed by themselves because of their weight. Or maybe some work that I'm not aware of that was done after the last measurement taken. In those cases we would probably need to physically check what is going on.

Results attached are described below :

(1) Comparison between the model and last TMSX TF

(2) Comparison between TMSX after the work done on Nov 20th (Orange trace), after the last time work has been done on Nov 22nd (black trace), and today (pink trace).

See the 5th page of (1) and (2) for the pitch dof

I am leaving the IMC locked for the night in order to see its stability. The ASC loops are all engaged.

It must be rock-solid because we fixed the EOM !!

An auto-locking script is locally running on opsws4. The script itself resides in /opt/rtcds/userapps/release/ioo/h1/scripts/imc/sballmer/ and it is called MClockwatch.

The PSL enclosure is now back in science mode. PMC/FSS/ISS are running fine.

Hugh noticed that some HEPI ITMY slow channels were not correct in the DAQ. I did some investigation and found:

Of the slow channels (datarate=16) in H1ISIITMY.ini :

channels associated with the FEC were correct

channels associated with Filter Modules were correct

other slow channels were incorrect, either showing zero or other data (like channel hopping)

Fast channels appear to be OK (within the limited sample I used)

The problem is not seen with HEPI BS or ETMX. Looking at the models they all look identical.

Reboot/Restarts:

I first restarted h1hpiitmy. Then tried restarting all models on h1seib1. Then tried a restart of the mx-streamers. Then recompiled and reinstalled the h1hpiitmy model and restarted it, followed by a DAQ restart (DAQ status was good, so this should have been unnecessary). All to no avail.

The only thing I haven't done is reboot the computer.

It appears this problem appeared when we upgraded to RCG2.8 on Tue 12 November.

Stefan, Sheila and Kiwamu with remote assistance from Rich A. and Volker

The mysterious jump in the RF phase (see alog 7941) is now understood and fixed. It was due to a loose connection at DB15 connectors in the EOM box and not due to the SMA connector (see alog 8811 and 8813 for our early detective story). We applied two small in-situ modifications on the EOM box. As a result, now it doesn't show the mysterious RF jump any more.

The box:

I briefly explain the EOM box for those who are not familiar with our custom-made EOM box. The EOM box consists of two boxes -- one contains LC resonant circuits and the other contains the EOM crystal. This two-boxes-design allows one to tune the resonant frequencies by tweaking the LC circuits without messing up the alignment of the EOM crystal because one can simply take out the electronics box and leave the crystal box for solder or tuning some parts in the circuits. To apply voltage across the EOM crystal for normal operation, the LC circuits need to be connected to the EOM crystal. This is done by a DB15 connector attached on each box -- female DB15 on the crystal box and a male DB15 on the electronics box (see pictures shown below). In this way, the two boxes are electrically connected.

A picture of the actual EOM box. The gloved hand is me pressing the SMA downward in order to reproduce the RF jump.

When I pressed the SMA connectors downward in this morning, the RF characteristic of the EOM box changed as if something jumped. This was repeatable, although it seemed that the condition to make it jump was random -- occasionally, pressing the SMA didn't make it jump and sometime pushing the SMA toward the box made it jump. Anyways, at this point, it was clear that the EOM box was the culprit and not the RF cables.

The causes:

• The mechanical connection between the two boxes was not solid.
• The DB15 connectors were not completely all the way in.
• The above two facts resulted in different amount of stray capacitance in the DB15 connectors depending on the relative orientation of the two boxes.
• Though, this doesn't explain the bi-stable impedance modes we have observed. Maybe there was some sort of bi-stable condition in the physical orientations.

At the beginning, we thought the culprit was the SMA connectors (see alog 8811 and 8813). However, this turned out to be wrong as we investigated it further. With a remote assistance from Volker, Stefan and I took the electronics box apart from the crystal box while keeping the crystal alignment. In the process of removal, we found that the electronics box was attached to the crystal box merely by friction of the DB15 connectors and three pieces of adhesive tape. So the orientation of the electronics box was not so solid with respect the EOM box. We then checked the return loss of the LC circuits without connecting the EOM and confirmed that wiggling the SMA connector didn't change its impedance. Instead, we discovered that the DB15 connector can easily change the amount of its stray capacitance -- the frequency of the resonant notch could shift by approximately 1 MHz by very gently touching the DB15 connector with our latex-gloved-hand. We put the electronics box back on the EOM crystal box and wiggled the orientation of them. Indeed, it changed the resonant frequency by about 1 MHz in a discontinuous way. So we determined that the loose connection in the DB15 connectors was the culprit and the mysterious RF jump was induced by some change in the orientation of the two boxes.

It seemed that the DB15 connectors were not all the way in because the two aluminum boxes contacted first.

The repair/modification fixed the issue:

We did the following two repair/modification:

• We put washers in the DB15 connector of the electronics box to make the connector stick out a bit more.
• We introduced four screws to mechanically tighten the connection between two boxes.

The DB15 connector have two screws to support it and we put a washer for each screw. They raise the height of the DB15 connector like shims. Also, we newly installed four screws to make the connection of the two boxes more solid. There were already four screw holes on each box to accommodate them. So we just installed them. After these modifications, we checked the return loss of all three RF ports. We didn't observe the mysterious jump at all, even when the electronics box was wiggled hard. Of course, strongly pressing the electronics box downward shifts the notch position by an order of 10 kHz due to the change in the stray capacitance at the DB15 connectors, but the shift is smooth and not in a discontinuous way any more. So the RF jump issue is now solved.

A picture of the electronics box when apart from the EOM crystal box. This DB15 connector was shimmed by washers.

A picture of the EOM crystal box when the electronics box is taken away. There is a threaded screw hole on each corner and these are the ones we used for installing the new screws.

A top view of the EOM box with the lid off. The green circles indicate the screws that we newly installed.

A top view of the EOM box with the lid off. The green circles indicate the screws that we newly installed.

Steps taken to commission the ITMY ring heater pair:
- Updated to the recently committed Beckhoff code that Joe B and Adam M worked on yesterday.
- Added the calibration values that Aidan B had recommended for running the ring heaters.
- Opened up a strip tool to monitor the vacuum pressure with the closest gauge (HVE-LY:Y1_120BTORR)
- Turned the ring heaters on to low power (~.01 Watts) to make sure that the channels were working properly
- Increased the power to 1 Watt for a 4 hour period starting at 12:00PM Pacific Time, keeping an eye on the pressure gauge previously mentioned.


Upper:
Requested Power = 1.00 Watts
Measured Voltage = 5.94 Volts
Measured Current = 0.17 Amps 
Calculated Power = .99 Watts
Calculated Resistance = 34.94 Ohms

Lower:
Requested Power = 1.00 Watts
Measured Voltage = 5.92 Volts
Measured Current = 0.16 Amps 
Calculated Power = .98 Watts
Calculated Resistance = 37.0 Ohms

A four hour trend of the pressure gauge and ring heater settings is attached.

A quick, back-of-the-envelope calculations shows that the ring heaters are working properly. The next step for measuring the thermal lensing would be to measure the beam diameter of a single reflection off of the back of ITMX independently and then changing the radius of curvature of ITMY using the ring heater to match. This requires looking at the REFL beam either in the HAM1 chamber or on the ISCT1 table, depending on how much power we are able to get out of REFL.  The Thorlabs beam profile we have on site requires a minimum of ~1e-5 Watts of incident beam power to function.

J. Kissel, T. Vo

Because of the recent resonant features seen in ISI-ITMX that seemed to have been fixed by a simple lock and unlock of the ITMX Arm Cavity Baffle (see LHO aLOG 8632), I asked "has anyone ever taken B&K hammer transfer functions of the ACB?" The answer was a resoundingly loud "no" (I am Jack's complete lack of surprise). Me and my big mouth volunteered to do it, and there was a tiny window of opportunity before Thomas cleaned up the chamber, so Thomas and I pioneered the first B&K measurements of the ITM ACB. Details of the measurement setup and execution below.

Again, I don't know how to properly export the data (as indicated in LHO aLOG 8654), so you'll have to be patient regarding the results. Note that obtaining official plots of the results should not in any way be considered as a hold-up for chamber close out.

Of course, after taking the measurements and cleaning up the chamber -- because we *touched* the baffle -- we had Sebastien run a quick set of ISI-ITMX transfer functions, and it informed us we're not-at-all done battling this bumbling oaf of a baffle (see LHO aLOG 8653). This should be considered a hold-up for chamber close out. Round three, first thing tomorrow!

-----------
Details:
We took two distinct measurements: 
(1) With the accelerometer on the suspended baffle itself, using a unused slotted bolt hole in the inside middle, closest to the ITM HR surface. This test was just a shot in the dark, to see if we could get a nice driven transfer function of the suspended stage, since there have been no prior attempts with this generation of the ACB baffle. At first glance from the B&K software plots, it looks like a complete mess, so it will most likely either be a completely confusing / useless or completely depressing result.

DSCN0206.jpg (or pg 3 of the .pdf) shows a picture of the accelerometer from inside the baffle looking out back toward ITMX. As is (hopefully) resolvable in the picture, ACC +X = ITMX -L, ACC +Y = ITMX -T, ACC +Z = ITMX +V. The Y impact was on the (ITMX) +T face, bottom corner, closest to the ITM, in the (ITMX) -T direction. The X impact was along the bottom edge of the (ITMX) -L face, in the +L direction.

(2) With the accelerometer on the bottom of the support structure's tube (shown in DSCN0209.jpg). One can't see it in the picture, but the accelerometers axes were aligned with the global IFO's axes, such that ACC +X = Points down X arm towards ETMX, ACC +Y = Points down the Y Arm towards ETMY, and ACC +Z = Points up with local gravity (the same as ITMX's +V). The X & Y impacts were made towards the bottom of the outer, support structure, "eddy current damping 8 dia," tube (D1002564, of the assembly D1200275). Man, that thing rung like a bell when Thomas whacked it...

The files live on the B&K laptop only, in
C:Users\ligo\Desktop\SUS Hammer Test\ITMX\BandK\
and are called
(1x) SimpleHammerDisplay3-ArmCavityBaffleBaffle-ISIfloating-SuspendedElements_Ximpact.pls
(1y) SimpleHammerDisplay3-ArmCavityBaffleBaffle-ISIfloating-SuspendedElements_Yimpact.pls
(2x) SimpleHammerDisplay3-ArmCavityBaffleBaffle-ISIfloating-StructuralElements_Ximpact.pls
(2y) SimpleHammerDisplay3-ArmCavityBaffleBaffle-ISIfloating-StructuralElements_Yimpact.pls