With IP stepper motor, I centered the beam to the center of the QPDs.

Now the current status:

IP SET: L:-105, P:11, Y:240

IP stepper motor: 1:1000 steps, 2:-5000 steps, 3:-15000 steps

F0 SET: 0

F0 FR: -550000 steps

F1 SET: 488

F1 FR:  2400000 steps, This number does not reflect the real steps because the motor is at its limit and won't pull F1 below ~430.

BF SET: 0

BF FR:180000 steps

IM:L:-35, T:-156, V:134, R:-50, P:-1051, Y:784

TM:L:-5, P:33, Y:-10

These values are taken when the control systems were on and with all IP output counts less than 2000 and other output counts well below 1000

For this time, SRM has all controls on during pump down and it was very stable. In one ocassion, the number of counts of the IP output went over 10000 so I off-loaded the IP LVDT actuation with stepper motors (while the controls were still on).

In combination of IM picos, IP stepper motor and yaw stepper motor, I off-loaded the IM yaw offset from 1600 to -44, the IP yaw from -5100 to -3600, while centering the beam to the QPDs.

Now the current status:

IP SET: L:-400, P:-50, Y:-3600

IP stepper motor: H1:340000 steps, H2:515000 steps, H3:600000 steps

F0 SET: -1600

F0 FR: -750000 steps

F1 SET: 0

F1 FR: -250000 steps

BF SET: 0

BF FR:-100000 steps

IM:L:164, T:-74, V:172, R:261, P:694, Y:-45

TM:L:3, P:-2, Y:-21

These values are taken when the control systems were on and with all output counts less than 1000

Just a report.
I restarted mx_stream of k1omc0, but I noticed that the status went back to 0x2bad in ~ 1 hour.
I remember it was 0x2bad the day before yesterday, if my memory is correct.

[Lucia, Eleonora]

After the start of ITMs cooling-down we obserbed that a slow drift of the payload vertical postion of ITMX and ITMY brought the IM photosensor RMS monitors above the set threshold, triggering the dackills.   As a consequence, the controls of the whole tower opened.  Pic1 (long trend data),  Pic 2(ITMX),   pic3 (ITMY))

In fact, the logic of the dackills is such that the presence of a red watchdog flag EITHER in the tower OR in the payload zeros ALL the DAC outputs. (pic 4)

In order to reset the dackill we were forced to increse the rms treshold. This happend few times.

Apart from choosing a proper threshold, we wonder if the watchdog/dackill logic could be improved to avoid this kind of events.

Updated OL2EUL matrix

rotational angle: 2.3 ° (TILT), 2.2 °(LEN)

off-center: 1.4 cm (-V), 1.3 cm (+T)

Calibration factors of the length QPD: 0.002471 mm/counts (vertical), 0.002451 mm/counts (horizontal), see attachment for the calibration graph.

Other parameters can be found in 8481, 8417 and 8430.

After a few rounds of trial and error, I got:

rotational angle for tilt QPD: 2.5 °

rotational angle for tilt QPD: 3.5 °

beam off-center: 0.02 cm (+V) and 0.083 cm (+T)

With these correction implemented, the diagonalization matrix is:

I also fixed a subtle mistake (the effect of this mistake is that it will introduce some Y2P coupling) in my code that generates these matrice. So, please see other entries for the corrected diagonalization matrice for SR2 and SRM (didn't have time for correcting that of SR3).

I turned the previous L2P cancellation filters off and changed all TM coil output filter gains back to unity. They are likely to be invalid.

All cross-couplings are likely to be well below 1%. I didn't have time to confirm it with more averages. See attachments for the TM transfer functions.

I have also implemented damping filters for the TM.

mistake

See attachments for an updated setup for the BS optical lever.

Updated length parameters:

optic to steering mirror: 996 mm

lens to LEN QPD: 397.2 mm

With Terrence and Fabian.

Today we implemented the fix to the BS IP mentioned yesterday in klog 8476. Recent IP TFs had shown a frequency of 39 mHz, which is on the edge of instability, and yesterday the IP started behaving unpredictably as we tried to center it.

We removed the tank lid and locked the IP.

We did an audit of the arc weights: there were 11 x 38 mm x 120°, 2 x 10 mm x 120° and 4 x 3 mm x 120°.

First we tried reverting to just the 11 x 38 mm x 120° (189.2 kg). This gave f = 120 mHz, which is too high (it would not have properly filtered the microseismic peak).

We tried adding back the 2 x 10 mm x 120° (9.06 kg). This gave f = 67 mHz, which would have been OK, but we decided to be a bit more conservative because of the time pressure.

So we tried removing the  2 x 10 mm x 120° and adding just the 4 x 3 mm x 120° (5.43 kg). This gave f = 80 mHz. The Q was reasonable and the IP had a good springy feel when pressed gently in L or T.

The IP position was then H1=558, H2=2600, H3=1642, L=-1220, T=184 and Y=2690.

We turned on the non-IP damping and the IP position did not change, indicating that nothing had started/stopped touching, even as the payload came to its correct height.

We used FR adjustments to get L≈T≈0. The IP responded predictably, unlike yesterday.

We used FR adjustments to get IP Y to -3900 µrad, which is what it had been after Nakano-san adjusted it on 3/18 up until yesterday afternoon. After we also undid the TILT QPD adjustment of yesterday, the TILT OL was roughly centered, indicating that we had successfully recovered the alignment.

We had plenty of FR range, so we decided to offload the IP yaw to F0 yaw. Manually and by eye, we applied about (-)3900/17778 = 0.22 turns clockwise to the F0 stepper shaft, and then used FR adjustments to get the IP to Y=0. After a few more rounds of tiny adjustments, we got a good state, with small values of IP-Y, IM-Y and OL-Y. 

We decided to arbitrarily zero the OL pitch by adjusting the TILT QPD in vertical. We only needed a small adjustment, which might be a good sign, but it could be a coincidence: up until yesterday it was at quite a different position in L (and there is some natural L->P coupling) and probably touching somewhere.

After we replaced the tank lid, the state was still very good:

• IP H1=99, H2=155, H3=166, L=-36, T=-20, Y=234
• IM L=-85, T=-128, V=123, R=-10, P=-738, Y=377
• OL TILT P=-28, Y= 22
• OL LEN "P"=21, "Y"=41
• OL DIAG L=-130, P=-49, Y=41

The IP FR positions were -10000, -15000, -15000.

Hmm... if the broken parts are only the micrometers and the part supporting the micrometers, those could be replaced.... but I'm not sure how much will it cost (and time)... Be careful.

Yano, Simon

In order to repair the damaged QPD-stage for the length-sensing OpLev of the beam-splitter setup (see 8417), I brought two (spare) translator-stages (1 x-translator and 1 z-translator) from our stock to VIS type-B team. Fortunately for us, we still had those! However, at the same time, these were the last ones. So if something similar happens to the other QPD-stages, we would have to order the parts. Please be careful!

In the attached photos, you can see some of the damage. It seems that the micrometer bracket took most of the damage in both cases, whereas the x-translator bracket is even broken a little while the z-translator is "just" bended. Actually, we still could move each of the translators itself. So, the ball-bearing is probably okay and we could get both stages repaired maybe.
Both stages are now stored in the AOS-shelf at IMC.

Yano, Simon

We have released the WAB at X-end, which is also the last one to be finished by AOS!

We stored the wire-protectors on the AOS shelf at EXC and brought the remaining screws and heat-links to AOS' storage at around IMC.

With Terrence.

Simon came by the center area and helped us repair the damaged QPD stage for the BS LEN OL.

We changed the clamping of the OL breadboard to make room for the QPD (we removed a C-clamp from the -X,-Y corner and replaced it with a dog clamp on the underside) and reinstalled the QPD.

In the course of testing the new setup, Terrence noticed that there were signs of something touching: small increments of IP-L used to test the LEN OL was correlated with large TM-Y. We quickly realized that this was because we'd been tolerating a large constant IP-L of some +3300 µm. In fact Terrence had deliberately captured this extreme position as part of the ALIGN state because that's where the IP wanted to sit, and the DCCTRL loop didn't have the strength to get it all the way back to zero with the LVDT actuators. 

We tried to get the IP back to center with the FRs, but discovered that the IP is very close to unstable. The H2 LVDT varies particularly wildly, so probably IP leg 2 (at 11 o'clock looking towards +L, -X,+Y) is weak. After several attempts, the closest Terrence could get it to center without it falling over to the other side was L= 426 µm, T= -483 µm, Y = 331 µrad. The FR positions that gave this position were 20000, 23000 and 56000 counts. We redefined IP SET to hold it at that position and did some TFs with IM actuation to check that the payload was now fine, which it seems to be. 

However, this is not a good situation and we should probably remove the tank lid and remove a bit of weight from the IP to make it more stable.

The risk of not tweaking it is that if there's a disturbance (like a small earthquake or a big temperature change, or stresses from pumpdown) and if falls over, it takes a skilled operator to get it back close to center and it may not be possible to target the same point each time.

[Lucia, Enomoto-kun]

We noticed that the ITMX OPLEV signals were out of range. 

To recover them, Today  we changed the BF offset from -1670 to -570. Now the OPLEV signals are in range and the current values for PIT and Yaw are: 5 and -46

[Takahashi, Lucia, Eleonora]

Today we went at the Y-end station to finalize the IP recovery position. 

Here a brief report of what was done:

1) we swapped the stepper motor driver and we verified that H1 motor was working properly. 

2) we put back  the IP close to (0,0,0) by using the motors

3) Since the malfuntioning of H1 motor was due to the driver, we changed the channel assigned to H1 motor from Ch1 to Ch5.

4) we close the IP loops and we recovered  the OPLEV signal by movin g the BF_Y.

Next to do: we have to reconfigure the motor script to give the correct assignement of the motors. 

BIOs were shuffled. They are fixed now.

As entitled.
I put a network switch, which Yamamoto-san kindly rent to me, at rear side of ALS0 rack and there "splitted" the ethernet cable that had been connected to the FG for X PLL to connect cables to two FGs.
Now two FGs are accessible via network.
The IP addresses can be found in DGS wiki.

(Oshino, Yamamoto, Miyakawa)

Dolphin connection trouble between k1omc0 and k1lsc/k1asc was fixed. This was because iop model on k1omc0 had no declaration to use Dolphin.

Now all the status of Dolphin connection shows green.

Tuesday 3/19 and Wednesday 3/20.

I did an audit of the whitening and dewhitening for the Type B OLs. Yokozawa-san had set up the BS, so I used that as a model.

• The recipe is to enable one of the three hardware whitening filters on each segment of both LEN and TILT (switch 5 on the BIO Config card) plus any additional gain stages (switch 4 -> 24 dB, 3 -> 12 dB, 2 -> 6 dB, 1 -> 3dB) required to get the SUM up to about 20K-30K counts. (A higher SUM would give better S/N, but a SUM greater than 32K makes it difficult to check for uneven segments by directing the beam to one segment at a time.)
• Each whitening filter is then compensated for by a filter AntiWTN = FM5 = zpk([10],[1],1,”n”) in the OPLEVINF block.

I found and fixed the following issues:

• BS LEN had the AntiWTN filter installed in the OPLEVINF blocks but it was not enabled, so I turned it on and did a new safe.snap.
• SR2, SR3 and SRM did not have the AntiWTN filters in either the LEN OR TILT OPLEVINF blocks, so I copied them from BS (), enabled them, and did a new safe.snap.
• SR2 did not have the whitening filters enabled, so I turned them on.
• SRM had the wrong type of whitening chassis (with no whitening card!), S1808108, so the BIO Config cards didn't have any effect. I replaced it with one of the correct type, S1808656.

The final SUM values and switch settings (for now) are:

• BS LEN: 1600 (beam not on QPD); 5 (WTN), 4 (24 dB), 1 (3 dB).
• BS TILT: 25700; 5 (WTN), 4 (24 dB).
• SR2 LEN: 29400; 5 (WTN),  2 (6dB).
• SR2 TILT: 18600; 5 (WTN), 2 (6dB).
• SR3 LEN: 17900; 5 (WTN), 4 (24 dB), 1 (3 dB).
• SR3 TILT: 15400; 5 (WTN), 4 (24 dB), 1 (3 dB).
• SRM LEN: 18700; 5 (WTN), 2 (6dB).
• SRM TILT: 14000; 5 (WTN), 2 (6dB).