some work on ISCT1

As planned (see alog from yesterday), I restored the POP path on ISCT1. The POP beam is now detectable with both POPAIR_A and POPAIR_B. Also, I did some clean up on the table.

Here are summary of the work:

• Moved the POP camera from the temporary position to the permanent one.
• Realigned the bottom periscope of the POP path. It needed a slight touch in yaw.
• Took out a BS which was intended for a measurement of Doppler noise for ALS comm.
  • Put it in a stash in the squeezer bay.
• Centered the beam on POPAIR_A and POPAIR_B
• Increased the gain for the DC signal of POPAIR_B by a factor of 10 as the signal was puny.
  • This was done by toggling the mechanical switch on the front panel of the generic PD interface box.
• Cleaned up apparently-not-in-use optics and put them in the stash in the squeezer bay.
• Moved the REFL PD camera back in place and focused it.
  • This is the one which had been used for monitoring green light for ALS temporarily.

OM1/2/3 Pitch<->Yaw coupling reduced for the ISC inputs

Summary

- OM1/2/3 showed huge angle to angle off-diagonal coupling of the order of 100% during the commissioning last week.

- Yesterday I figured out that the reason was incorrectly and sneakily set non-identity DRIVEALIGN matrix.

- Once DRIVEALIGN was fixed, I could measure the Pitch-to-Yaw (P2Y) and Yaw-to-Pitch (Y2P) couplings.
They were about 30% and 10%, respectively.

- A small arithmetic calculation revealed that these P2Y and Y2P can't be elliminated by the four coil gains.
Namely we need different coil balance for elliminating P2Y and Y2P independently.

- This has been done by adjusting the offdiagonal elements of DRIVEALIGN. As a result the P2Y and Y2P have been reduced
  smaller than ~3%, even though the decoupling matrix (DRIVEALIGN) so far is a frequency independent one.

- One question: Why do we have the decoupling matrix only in the ISC signal chain on the every suspension?
This way, we can't enjoy the benefit of diagonalization for the other actuation signals such as alignment offsets,
damping servo outputs, test inputs. Is there a philosophie behind the current design?

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Details

1. DRIVEALIGN

It turned out that the all elements of the DRIVEALIGN matrix (3x3) were the unity. Alas! This meant that any input (L, P, or Y) result in
the same actuation. This was overlooked because the matrix button still indicated only the diagonal elements were active (green)
even though that was not true. The warning in the DRIVEALIGN screen tell (in a very dark texts), the indicator criteria is different
between the diagonal and off-diagonal elements. It saids FM1 needs to be turned on to turn on the green indicator for the off-diagonal
elements. This is confusing as the frequency independent element in the off-diagonal element does not trigger the indicator. I strongly
feel that we should use the same criteria for the off-diagonals as the one for the diagonal elements.

For now, FM1 of the P2Y and Y2P elements have dummy k=1 filters so that we can activate the indicators.

2. P2Y/Y2P coupling measurements

Once the DRIVEALIGN was modified to be an identity matrix, more reasonable angle-to-angle coupling started to show up in the measurements.

The measurements have been done with no damping in order to avoid confusion caused by the coupling coming from the damping loop.

140826_TT_P2A  and 140826_TT_Y2A show the measured transfer functions from the Pitch or Yaw excitations to the Pitch and Yaw local readings.
As I did not have the beam, the OMC QPD signals were not used. The coupling ratios (P2Y/P2P or Y2P/Y2Y) were picked up at 0.5Hz and 5Hz.
P2Y is ranging from 0.18 to 0.39 while Y2P is from ~0 to 0.13. They are summarized in the following table

	|	P2Y@0.5Hz	P2Y@5Hz	|	Y2P@0.5Hz	Y2P@5Hz
OM1	|	0.394	0.326	|	0.088	0.100
OM2	|	0.236	0.176	|	-0.015	0.014
OM3	|	0.369	0.313	|	0.109	0.126

The OM2 Y2P coupling is basically such small that the measurement crossed the zero due to noise and had unstable sign.

For the decoupling calculation, the average of the LF (0.5Hz) and HF (5Hz) numbers were used.

3. Coil balance is incapable for P2Y/Y2P decoupling

Suppose we have perfect coil balance. The pitch and yaw actuations (P and Y below) are distributed to each coil equally (the middle matrix).
The actuation forces are recombined at the suspension (the left most matrix below). This reproduces pure pitch and yaw motions (the right most P&Y)

Now we have the actuator response modified by alpha, beta, gamma, delta.

As you can see, the decoupling terms come in symmetrically. We can't decouple P2Y and Y2P independently by the coil balance.
Note that this is obviously not true for A2L, L2A couplings.

4. Decoupling by DRIVEALIGN

For the above reason the DRIVEALIGN matrix was used for the decoupling. This was easy to implement as we just plug in
the inverse matices of the 2x2 coupling matrix. The below is the matrix plugged in.

OM1	Lin	Pin	Yin
Lout	1	0	0
Pout	0	1.0352	-0.0976
Yout	0	-0.373	1.0352

 

OM2	Lin	Pin	Yin
Lout	1	0	0
Pout	0	1	0
Yout	0	-0.206	1

 

OM3	Lin	Pin	Yin
Lout	1	0	0
Pout	0	1.0419	-0.123
Yout	0	-0.356	1.0419

5. Resulting improvement of the coupling

After the new DRIVEALIGN matrices were plugged in,the same measurements wererun. The result for Pitch and Yaw excitations are found
in 140826_TT_P2A_after.png and 140826_TT_Y2A_after.png. The coupling is reduced to ~0.03 or better. This is enough for the further
work on the alignment servo.

If the further decoupling we should install a frequency dependent decoupling.

6. Decoupling topology

But a question arose:

In this topology, only the ISC signals enjoy the benefit of the decoupling.
The alignment offsets (i.e. the alignment sliders), test inputs, and damping actuations do not go through the decoupling matrix.?

Is this what we want? Don't we want to have a DRIVEALIGN FM matrix after the summing node before the euler-to-osem matrix?
Of course, we can convolve the decoupling into the euler-to-osem matrix, in principle, but I don't want to mess up that matrix.
 

Unable to restart the EndY HEPI Pump Station

This has been down since 12 Aug.  The Input Line Lugs were tightened during the power outage.  The VFD while powered, does not respond in the usual manner.  It displays STOP and does not respond to the FWD button.  It should not be looking like this anyway as the the FWD lugs have been jumpered and it should just run as soon as it's given command voltage.  At McCarthy's suggestion, I toggled the main power which then required restarting the 'FE' but this changed nothing...

CDS model and DAQ restart report, Tuesday 26th August 2014

no restarts reported.

ISC HAM-Aux driver Vmon repair

The OM1 and OM2 coil drivers were found to have bad Vmon channels. Chassis S1200614 was found to have -14VDC present on the output of IC5 (OP27) on Ch2. Similarly, S1200612 exhibited the same symptoms on Chs 2&3 (-13V and +14V respectively). In all cases, IC5 was replaced and this DC issue was reolved and the chassis were placed back into service. IC5 is the Vmon-N circuit. All Vmon circuits were examined (P & N).  If there are any further issues with this circuit please let me or Filiberto know. Original post: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=13585

PRMI aligned; ready for real commissioning

I continued working on the PRMI alignment (see alog 13592) today and finally obtained good alignment. This should be good enough for proceeding with the next steps.

With the new alignment, the PRMI flashes without loosing the POP beam at ISCT1. In fact, one can now see PRMI fringing in the POP camera.

We are almost ready for some locking activity.

 

(Next steps)

• Re-configure the POP path on ISCT1. (Right now, an analog camera is blocking the beam and no beam is on the POP photodiodes.)
  • POP is necessary for triggering the LSC feedback.
• Setup a digital camera in the ASAIR path.
• Align and lock MICH
  • We can now use the AS demodulated signals !
• Lock PRMI

 

(alignment)

From the experience yesterday, I learned that a combination of PR2 and PR3 did not improve the POP/PRMI alignment situation for some reason. In fact, it made the forward propagating beam hit the west side of the PR3 suspension cage. Therefore, I wanted to move the input pointing in order to introduce a translation in the cavity axis in the downstream after PR2 while keeping the POP beam angle (almost) the same. To do so, I touched IM4 in yaw. This then required re-alignment of PRM in order to maintain the beam at the REFL port. Also, every time I changed the alignment of IM4, I compensated it by steering PR2 such that I keep the POP beam at ISCT1. I repeated this process multiple times. This was successful. I could eventually obtain an alignment setting where the PRMI flashes with the POP still visible at ISCT1. The attached is the new alignment settings.

After the PRMI alignment, I re-adjusted the PR3 alignment such that the beam reaches HAM6 and ISCT6. I did not check the beam centering on the SR mirrors.

 

(fun locking)

Since I was running out my energy, I decided not to try the PRMI locking tonight. Instead, I locked PRX for fun. I just used REFL_A_RF45 for now. The ASAIR_LF signal was used to check if it is locked on the carrier or rf sidebands. The attached is time series of some DC signals at the AS port when locking PRX. It is locked on the carrier.

Since PR2 and PR3 are close in the Gouy phases, this combination is not very good for the prc alignment. IM4, PRM and PR2 (which is almost same as PR3 and BS in G phase) have some separations each other. A combination of these three will work.

ISCT6 in place, ASAIR and OMC_R successfully extracted

Kyle, John, Keita, Dan, Koji, Filiberto, Gerardo, Kiwamu

The ISCT6 enclosure is now in place by HAM6 with two light pipes installed. ASAIR and OMC_R are successfully extracted to the table.

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We craned the ISCT6 table from the squeezer bay over to the north side of HAM6. We carefully adjusted the position of the table by rolling it. The table legs were then secured on the floor. With help from Gerardo and Filiberto (a big thank you for Gerardo and Filiberto who machined the holes for us even though the working hour was over !), we made a 10 inch beam penetration hole on two back panels of the enclosure . These are for the ASAIR and OMC_R beams respectively. Note that we could not see a bright enough OMC_T beam this time and therefore we did not try to make a hole on the last back panel. This will be don once we reliably confirm the OMC_T beam position. We put the flanges and light pipes for the two beams and now the beams are successfully coming out to the table.

Also, in the process of trying to find the OMC_T beam, we turned on the PZT high voltage. We need to make sure that the high voltage is off when we pump down the chamber tomorrow.

HAM6 Viewport Installation

Installed 3 high quality viewports on the North door of HAM6, positioned on A2F3, A2F4 and A2F5. Two ZV-800 viewports were installed on the East door, positions are BF2 and BF3.

Checking ESD wiring at ETMX and comparing with ETMY

Borja

I just came back from a quick visit to End-X (UTC 2014-08-27 00:25:00).

I took some pictures (see attached) at the feedthrough wiring for the ESD at BSC9 (ETMX chamber). I compare it with the ones I took a while back at ETMY (see attached).

There is an obvious difference, the red insulating tape at ETMY wiring which does not show at ETMX. The wire which has the insulating tape carries VBIAS to the ESD at ETMY. The reason for the insulation is that the coax cable's shield is cut off because the corresponding coax cable inside the chamber has the known issue of having the shield connected to the center lead. This problem is non existen at ETMX.

This is another big difference between both masses which may be related to the more stable results on the charge measurements observed at ETMX.

We need to fix the shielding in any event. The shield now acts as a large capacitance coupling of the electrode to the chamber and
will inevitably cause cross talk and noise in later operations.

Ops Shift Summary

7:58 – Checked the Crystal Chiller water level (Maintenance)- Operator
8:15 - 8:30 Morning Meeting
8:25 – SPRAGUE on site
8:47 - Pulling cables all around the LVEA – Aaron/Ed
8:48 – Heading into H2 PSL enclosure in LVEA – Peter
9:15 – Cameras installation in LVEA – Filiberto
9:22 – Heading into the LVEA to work on SR3 Optical levers – Jason
9:44 – Back from LVEA – Peter
9:45 – Getting 3IFO(Quad#8)ready to be moved to its storage location – Jeff B.
10:04 – Working on ASC model – Dave
10:12 – Returned from LVEA – Jeff B.
10:22 - Reset HEPI overflow counters for HAM2, HAM3, HAM4, HAM5, ITMX, and ITMY (Maintenance) – Operator
11:43 – Back from the LVEA – Aaron/Ed
12:41 – Heading to End X (Cleaning) – Chris
13:37 – Heading to End Y (Cleaning) – Karen
13:46 - Heading to End Y to work on Low frequency microphone – Sudarshan
14:14 – Returning from End Y – Karen
14:18 – Back from End X – Chris
15:01 – Heading into the LVEA – Jason
15:07 – Working at End Y (Valves operation) - Kyle

H1 installation milestone: The last chamber was closed.

Gerardo has just torqued down the bolts for HAM6 viewports. We're done with H1 in-chamber installation (for the current configuration)!

~1525 hrs. local -> Valved-in IP11 @ Y-end, Valved-out turbo

At request of Borja

Low Frequency Microphone

S. Karki, Dave Barker

Troubleshooting low freq Mic at ENDY and CS:

1. The power to the DAQ (sitting on top of each microphone) was reset by pugging off the power supply cable and plugging it back in.

2. The signal cable were switched to a known working channel.

Both resulted in no difference to the signal output suggesting that the microphone itself could have been damaged. The signal from the mic seemed to have stopped since the last power glitch.

Switching from the currently used CS microphone to the extra one sitting on the floor solved the problem, suggesting that microphone is bad.

Removed Ring Heater and Cable Assemblies from H2 ITMy

Removed the Ring Heater Assembly from the ITMy quad structure going into 3IFO storage. Before starting I noticed the lower ring heater assembly had a crack in the glass former. Not sure when the break happened, but this one also displayed a lot of movement inside the ring heater shield. The pictures show how the former has pushed pretty far out of position. 

The ring heater cables were also removed. This includes the "antlers" (D1001755) but not the plate (D1002420) which the earthquake stop is attached to.

The assemblies removed were:

ASSY-D1001895-V5 #001 (lower ring heater, broken)
ASSY-D1001517-V7 #612 (cable assembly)
ASSY-D1001838-V6 #005 (upper ring heater)

That should read

ITMx (not y)

and

ASSY-D1001838-V6 #002 (upper ring heater)

not #005. typos.

One more fix. The lower ring heater should be:

ASSY-D100195-108

Made a mistake with a V5 and V6 part.

EndY ETMY Yend HEPI Pumps off since 12 August

This last occurred at EndY 5 Aug but it wasn't restarted until 11 August.  So barely 24 hours later it dropped out again.  14 August was the power outage and it appears no restart attempt was made at EndY.  EndX is running at this time.  Borja is taking data at the moment and asks the optic not be disturbed.  This restart will require a trip to the EndY MR.

OM1 and OM2 coil driver Vmon are not properly working

Keita and Kiwamu

In order to investigate the large cross coupling issue in OMs (alog 13575 by Dan), we checked the OM driver electronics.

We found that the OM1 and OM2 coil driver Vmon are not properly functioning. However, this does not explain the cross coupling that Koji and Dan experienced.

Anyway, these two coil driver chassis (S1200614 and S1200612) need to be swapped at some point.

 

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(some details)

When we started looking at the OM screens, we immediately noticed the LL voltage monitor of OM1 and OM2 displaying anomalously high voltage while the zero DAC voltage were requested. OM1_LL showed approximately 23000 cnts and OM2_LL showed approximately -23300 cnts. Even so, these channels were still sensitive to the bias we sent through the DAC -- we could change the readout values by changing the biases. But they did not go to the other sign in the readout voltages.

We then went to the electronics room to check out the analog circuits. Looking at DB9s' signals for the Vmons by inserting a 9-pin breakout board, indeed we saw LLs exhibiting a funny voltage. LL of both OM1 and OM2 were at -14 V when the zero DAC voltage were requested. Then we went to the AS port rack to check if this is also the case for the actual drive signals. However the drive signals looked healthy on both OM1 and OM2. We checked this by looking at the signals at the input of the satellite amplifiers. All the signals could swing from -22 to 22 V as we changed the DAC voltages.

We are concluding that the Vmon part is not properly functioning in the OM1 and OM2 coil drivers. But, since the actual drives are healthy, this issue is independent of the cross coupling issue.

By the way, the OM3 coild driver looked healthy and its Vmon looked fine. So we did not check them.