ID |
Date |
Author |
Type |
Category |
Subject |
1447
|
Tue Mar 31 09:42:32 2009 |
steve | Update | PEM | ETMY sus damping restored again |
The Caltech gasoline storage tank is being upgraded.
They are jack hammering and digging with bulldozer 50 yards south of ETMY |
1446
|
Mon Mar 30 17:02:46 2009 |
Yoichi | Configuration | General | AP OSA aligned |
I aligned the AP OSA, which had been mis-aligned for a while. |
1445
|
Mon Mar 30 15:51:27 2009 |
steve | Update | Electronics | HP4291A left the lab to be repaired |
Eric Gustafson is handling the old HP4291A rehabilitation. Tarac picked both units up today.
March of 2008 Tucker Electronics failed to fix it's intermittent ~25MHz 0.5V oscillation at the swept sine output
See 40m-elog id:398 on 3-24-2008 by Rob Ward
|
1444
|
Mon Mar 30 13:29:40 2009 |
Yoichi | Update | SUS | MC1 drift investigation continued |
Quote: | Maybe we can temporarily just disconnect the bias and just use the SUS sliders for bias if there's enough range? |
We could do this, but I'm suspicious of the cables between the coil driver and the coils (including the satellite box). In this case, disabling the bias won't help.
Since the MC1 has been quiet recently, I will just lock the MC and resume the locking. |
1443
|
Mon Mar 30 12:46:36 2009 |
Yoichi | Configuration | IOO | IOO QPDs were missing the beam |
When I re-locked the MC, I wanted to check the trend of the IOO QPDs to see if the input beam pointing has changed.
Then I found that the QPDs were not receiving light.
The attached trend plots show that the QPDs missed the beam on March 23rd.
The IOO-QPD_ANG was installed on Mar 11th by Kiwamu and Kakeru. Since then, they were serving as a reference of the PSL beam pointing.
But there is no record of the past week. This is very bad because then I cannot tell if I should relieve the MC WFS to make the mirrors follow the input beam or not.
I found that someone has moved the beam splitter which picks up the beam going to those QPDs. But there is no elog entry on this around March 23rd.
I re-centered the beam on the QPDs.
Since the X-arm locked to TEM00 with the MC WFS on (i.e. the MC beam axis is following the input beam axis), I guessed that the input beam has not drifted that much. So I relieved the WFS and centered the WFS QPDs. |
Attachment 1: IOO-QPDs.pdf
|
|
1442
|
Mon Mar 30 12:29:17 2009 |
Yoichi | Configuration | | MC1 glitches not seen during the weekend |
The attached is the MC trend for the past 12 hours.
There is no MC1 glitches in the OSEM signals. Moreover, the total amplitude of the drift is smaller than it used to be (now the amplitude is less than 100 but it used to be a few hundreds).
There still is a small step in the OSEM signals at around 6AM this morning, but the amount of the jump is very insignificant.
The cause of the glitch in the TMP1, DRUM1 and APTEMP (LL, UL and UR coils respectively) at 7AM is not known.
Since the MC1 has been behaving OK during the weekend, I removed the probes from the MC1 coil driver board and locked the MC.
Hopefully the replacement of the broken connector fixed the problem, but I'm not sure. |
Attachment 1: MC_drift.pdf
|
|
1441
|
Mon Mar 30 09:07:22 2009 |
rana | Update | SUS | MC1 drift investigation continued |
Maybe we can temporarily just disconnect the bias and just use the SUS sliders for bias if there's enough range? |
1440
|
Sun Mar 29 17:54:41 2009 |
Yoichi | Update | SUS | MC1 drift investigation continued |
The attached plots show the trend of the MC OSEM signals along with the voltages across the output resistors of the bias current buffers.
The channel assignments are:
MC_TMP1 = LL coil
MC_DRUM1 = UL coil
OSA_APTEMP = UR coil
OSA_SPTEMP = LR coil
Although the amplitude of the drift of MC1 is much larger than that of MC2 and MC3, the shape of the drift looks like a daily cycle (temperature ?).
This time, I reduced the MC1 bias currents to avoid saturation of the ADCs for the channels measuring the voltages across the output resistors.
This may be the reason the MC1 has been non-glitchy for the last day.
OSA_APTEMP (UR Coil) shows a step function like behavior, although it did not show up in the OSEM signals.
This, of course, should not happen.
Today, I went to the MC1 satellite box and found that the 64-pin IDE like connector was broken.
The connector is supposed to sandwich the ribbon cable, but the top piece was loose.
The connector is on the cable connecting the satellite box and the SUS rack.
I replaced the broken connector with a new one. I also swapped the MC1 and MC3 satellite boxes to see if the glitches show up in the MC3.
I restored the bias currents of the MC1 to the original values.
The probes to monitor the voltages across the output resistors are still there. For OSA_SPTEMP, which was saturating the ADC, I put a voltage divider before the ADC. Other channels were very close to saturation but still within the ADC range.
Please leave the MC unlocked at least until the Monday morning.
Also please do not touch the Pomona box hanging in front of the IOO rack. It is the voltage divider. The case is connected to the coil side of the output resistor. If you touch it, the MC1 bias current will change.
|
Attachment 1: Drift1.pdf
|
|
1439
|
Sun Mar 29 13:44:27 2009 |
steve | Update | SUS | ETMY sus damping restored |
ETMY sus damping was found to be tripped.
It was retored.
All fluorecent light were turned off. Please try to conserve some energy. |
1438
|
Fri Mar 27 17:52:16 2009 |
Yoichi | Update | IOO | MC glitch investigation |
Per Rob's suggestion, I put the probes across the output resistors of the bias current buffers instead of measuring the output voltage with respect to the ground.
This way, we can measure the current flowing the resistor. The change was made around 17:30.
Quote: |
Attached plots are the result of the MC1 trend measurement.
See the attachment #1. The first two plots show the drift of the MC1 alignment as seen by the OSEMs. It is terrible. Other MC mirrors also drifted but the scale is smaller than the MC1.
From the VMon channels, you can see that the control voltages were quiet.
The monitor channels we added were:
MC_TMP1 = UL coil bias. Input to the coil driver board.
MC_DRUM1 = UL coil bias. Output of the current buffer.
OSA_APTEMP = LR coil bias. Input to the coil driver board.
OSA_SPTEMP = LR coil bias. Output of the current buffer.
The bias voltages show no drift except for a glitch around 7AM. This glitch did not show up in the SPTEMP channel (LR coil bias output). This was because the probe was connected to the coil side of the output resistor by mistake.
The second attachment shows a zoomed plot of MC1 OSEM signals along with the bias monitor channels (signals were appropriately scaled so that they all fit in +/-1).
There is no correlation between the OSEM signals and the bias voltages.
Since we were only monitoring UL and LR coils, I changed the monitor points as follows.
MC_TMP1 = LL coil bias. Output of the current buffer.
MC_DRUM1 = UL coil bias. Output of the current buffer.
OSA_APTEMP = UR coil bias. Output of the current buffer.
OSA_SPTEMP = LR coil bias. Output of the current buffer.
I will leave the MC unlocked for a while.
|
|
1437
|
Fri Mar 27 15:05:42 2009 |
Yoichi | Update | IOO | MC glitch investigation |
Attached plots are the result of the MC1 trend measurement.
See the attachment #1. The first two plots show the drift of the MC1 alignment as seen by the OSEMs. It is terrible. Other MC mirrors also drifted but the scale is smaller than the MC1.
From the VMon channels, you can see that the control voltages were quiet.
The monitor channels we added were:
MC_TMP1 = UL coil bias. Input to the coil driver board.
MC_DRUM1 = UL coil bias. Output of the current buffer.
OSA_APTEMP = LR coil bias. Input to the coil driver board.
OSA_SPTEMP = LR coil bias. Output of the current buffer.
The bias voltages show no drift except for a glitch around 7AM. This glitch did not show up in the SPTEMP channel (LR coil bias output). This was because the probe was connected to the coil side of the output resistor by mistake.
The second attachment shows a zoomed plot of MC1 OSEM signals along with the bias monitor channels (signals were appropriately scaled so that they all fit in +/-1).
There is no correlation between the OSEM signals and the bias voltages.
Since we were only monitoring UL and LR coils, I changed the monitor points as follows.
MC_TMP1 = LL coil bias. Output of the current buffer.
MC_DRUM1 = UL coil bias. Output of the current buffer.
OSA_APTEMP = UR coil bias. Output of the current buffer.
OSA_SPTEMP = LR coil bias. Output of the current buffer.
I will leave the MC unlocked for a while.
Quote:
|
Yoichi, Pete
The MC loses lock due to glitches in the MC1 coils.
We do not know which coil for sure, and we do not know if it is a problem going into the board, or a problem on the board.
We suspect either the UL or LR coil bias circuits (Pete would bet on UL). If you look at the bottom 4 plots in the attached file, you can see a relatively large 3 minute dip in the UL OSEM output, with a corresponding bump in the LR (and smaller dips in the other diagonal).
These bumps do not show up in the VMONS which is why we are suspicious of the bias.
To test we are monitoring 4 points in test channels, for UL and UR, both going into the bias driver circuit, and coming out of the current buffer before going into the coils.
We ran cable from the suspension rack to the IOO rack to record the signals with DAQ channels.
The test channels:
UL coil C1:IOO-MC_DRUM1 (Caryn was using, we will replace when we are done)
UL input C1:IOO-MC_TMP1 (Caryn was using, we will replace when we are done)
LR coil C1:PEM-OSA_SPTEMP
LR input C1:PEM-OSA_APTEMP
We will leave these overnight; we intend to remove them tomorrow or Monday.
We closed the PSL shutter and killed the MC autolocker.
|
|
Attachment 1: MC1_Drift.pdf
|
|
Attachment 2: MC2_Drift.pdf
|
|
1436
|
Fri Mar 27 02:50:54 2009 |
Yoichi | Update | Locking | DD demodulation phase suspicious |
I noticed that the gain of PD6_Q (before the phase rotation) was 0 whereas PD6_I gain was 15.
This means the demodulation phase of the PD6 had no meaning other than changing the gain.
According to the conlog, it has been zero since March 2nd. I don't know how it happened.
While I was re-adjusting the DD phase, the MC started to unlock frequently (every 10 minutes or so).
MC1 is again drifting a lot (it is getting step-function like alignment changes intermittently).
This practically made it impossible to work on locking. So I decided to fix the MC first.
See Peter's elog entry for the MC work. |
1435
|
Fri Mar 27 02:40:06 2009 |
pete | Summary | IOO | MC glitch investigation |
Yoichi, Pete
The MC loses lock due to glitches in the MC1 coils.
We do not know which coil for sure, and we do not know if it is a problem going into the board, or a problem on the board.
We suspect either the UL or LR coil bias circuits (Pete would bet on UL). If you look at the bottom 4 plots in the attached file, you can see a relatively large 3 minute dip in the UL OSEM output, with a corresponding bump in the LR (and smaller dips in the other diagonal).
These bumps do not show up in the VMONS which is why we are suspicious of the bias.
To test we are monitoring 4 points in test channels, for UL and UR, both going into the bias driver circuit, and coming out of the current buffer before going into the coils.
We ran cable from the suspension rack to the IOO rack to record the signals with DAQ channels.
The test channels:
UL coil C1:IOO-MC_DRUM1 (Caryn was using, we will replace when we are done)
UL input C1:IOO-MC_TMP1 (Caryn was using, we will replace when we are done)
LR coil C1:PEM-OSA_SPTEMP
LR input C1:PEM-OSA_APTEMP
We will leave these overnight; we intend to remove them tomorrow or Monday.
We closed the PSL shutter and killed the MC autolocker. |
Attachment 1: MC1_Drift.png
|
|
1434
|
Thu Mar 26 09:08:18 2009 |
Kakeru | Update | oplevs | arm cavity oplev calibration |
I uploaded a document about my oplev calibration.
/cvs/cds/caltech/users/kakeru/oplev_calibration/oplev.pdf
At same place I put my matlab codes for calibration.
/cvs/cds/caltech/users/kakeru/oplev_calibration/oplev_calibration.m |
1433
|
Thu Mar 26 04:27:26 2009 |
Yoichi | Update | Locking | 3.8kHz peak as a function of the arm power |
During the power ramp-up, I actuated CARM using ETMs and measured the transfer functions to the PO_DC at several arm powers.
The peak grows rapidly with the power. It also seems like the frequency shifts slightly as the power goes up, but not much.
Some sort of an RSE peak ? An offset in the PRC lock point ? |
Attachment 1: CARM-PODC.pdf
|
|
1432
|
Thu Mar 26 04:09:38 2009 |
Yoichi | Update | IOO | Single X arm lock spectra with different MC lock schemes |
The attached plots show MC_F, FSS_FAST_F and XARM IN/OUT spectra with different MC locking modes.
The conventional locking means the FSS is used. The direct frequency lock is the new way.
You can see that at low frequencies, the frequency actuator is working hard to suppress the MC pendulum motions.
The X-arm also sees a lot of frequency noise at low frequencies because of this.
The transmitted power of the X-arm fluctuates a lot making it difficult to align the mirrors.
The zoomed plots show that the structures in the kHz band are also present in the case of the direct frequency lock, although the frequencies are somewhat different. |
Attachment 1: XarmSpectra.pdf
|
|
Attachment 2: XarmSpectraZoom.pdf
|
|
1431
|
Thu Mar 26 04:01:24 2009 |
Yoichi | Update | PSL | FSS Open Loop Gain |
Yoichi, Peter, Jenne
Attached is the open loop transfer function of the FSS as of today with the common gain = 12dB and the fast gain = 16dB.
The UGF is only 250kHz. If we increase the common gain, the PC goes crazy. Exactly the same symptom as before I fixed the oscillating op-amp.
I wanted to check the cross over frequency but there is no excitation point in the fast path nor PC path. Therefore, it is not easy. |
Attachment 1: OpenLoopTF.png
|
|
1430
|
Thu Mar 26 00:45:24 2009 |
Jenne | Update | IOO | Mode Cleaner Servo Board Transfer Functions (to be updated) |
Quote: |
netgpibdata.py is giving me weird data. When I plot the data it has saved from the 4395A, it's some wierd other universe's version of my transfer function. I don't really know what's up.
|
Yoichi, in all his infinite wisdom, reminded me that the netgpibdata script saves the data as the REAL and IMAGINARY parts, not the Mag and Phase. Brilliant. Using that nugget of information, here are the TFs that I measured earlier:
The last attachment is the .dat and .par files which contain the data and measurement parameters for the 3 TFs in the plots. |
Attachment 1: MCwithandwithoutfilter25Mar2009.png
|
|
Attachment 2: PomonaBoxMCfilter25Mar2009.png
|
|
Attachment 3: MCServoData25Mar2009.tar.gz
|
1429
|
Wed Mar 25 20:41:43 2009 |
Jenne | Update | IOO | Mode Cleaner Servo Board Transfer Functions (to be updated) |
When all things fail (netgpibdata.py is giving me weird data. When I plot the data it has saved from the 4395A, it's some wierd other universe's version of my transfer function. I don't really know what's up. I'm pretty sure I'm getting the 'correct' data, since each TF looks vaguely like it should, but with some crazy humps. I'll talk to Yoichi in the morning about it maybe.) (also, we're low on emergeny floppy discs), you can always take a picture of the Agilent 4395's screen, as shown below.
* Mode cleaner and PMC are both relocked after my shenanigans, and I'll try again in the morning (I assume locking is going on tonight) to get real TF's with real data, as opposed to the photo method.
Note to self: post the data of the TFs in the elog along with the plots, for posterity.
These TFs are of the Mode Cleaner servo board, exciting IN1 (or the 3.7MHz notch pomona box which is connected to IN1), and measuring at the SERVO out of the board.
One with the box, one without the box, and one of just the box for good measure. |
Attachment 1: MCwithBoxsmall.JPG
|
|
Attachment 2: MCnoBoxsmall.JPG
|
|
Attachment 3: PomonaBoxforMCsmall.JPG
|
|
1428
|
Wed Mar 25 17:22:58 2009 |
Yoichi | Update | IOO | MC lock without FSS |
I made 40k:4k passive filter in a POMONA box and connected it to IN1 (not TEST IN1) of the FSS box.
With this modification and cut-and-tries with the gain sliders, I was able to lock the MC with 80kHz bandwidth by feeding back directory to the laser frequency.
The attached figure shows the open loop transfer function.
The phase margin is thin at 80kHz. Because of this, I could not turn on the MC super boost filters.
But I believe that we can increase the gain further by modifying the filter shape.
I used the following settings:
[MC Board]
C1:IOO-MC_REFL_GAIN 14
C1:IOO-MC_REFL_OFFSET -4.2381
C1:IOO-MC_BOOST1 0 (You can turn it on if you want, but turn it off for locking)
C1:IOO-MC_BOOST2 0
C1:IOO-MC_POL 1 (Minus)
C1:IOO-MC_VCO_GAIN 4
C1:IOO-MC_LIMITER 1 (Disable)
[FSS box]
C1:PSL-FSS_SW1 0 (Test1 ON)
C1:PSL-FSS_INOFFSET 0.1467
C1:PSL-FSS_MGAIN 30
C1:PSL-FSS_FASTGAIN 14 (Do not increase it, at least while locking. Otherwise the phase lag from the PZT loop gets significant and the MC loop will be conditionally stable).
I also turned down the FSS slow servo's RC transmission threshold to zero so that the slow servo works even without the RC locked. |
Attachment 1: MC-loop-gain.png
|
|
1427
|
Wed Mar 25 09:55:45 2009 |
steve | Update | IOO | glitching sensors of MC |
SUS-MC1_SENSOR_SIDE and SUS-MC2_SENSOR_UL are glitching
Yesterday's 4.8mag earthquake at Salton Sea is shown on Channel 1 |
Attachment 1: glitchesofMC.jpg
|
|
1426
|
Wed Mar 25 04:18:28 2009 |
Yoichi | Update | Locking | Tuesday Locking |
After the new PO_DC PD was installed, I tweaked several gains to make the locking scripts work right.
First of all, I increased the gain of PD12 (PD12_I is SPOB) by a factor of 1.4 to compensate for the power decrease
by the insertion of the BS. SPOB is used by the PRM alignment script. I was too lazy to modify the scripts.
Then I optimized the SRC DD signal which is taken from the POB.
I also had to do some gain adjustments for the CARM loop.
The attachment (AO path open loop TF) shows a depressing fact that the 3.8kHz peak is still there with the new PO_DC PD. So it was not a problem of the SPOB PD.
Next, I will check the cross over frequencies of the PZT and PC paths in the FSS and the VCO/MCL cross over. |
Attachment 1: AO-Loop-p9.png
|
|
1425
|
Wed Mar 25 01:37:35 2009 |
rana, yoichi | Summary | IOO | No Reference Cavity Required |
We were wondering if we need to have a reference cavity. One possible reason to have one is to reduce the free running
frequency noise by some level so that the MC can handle it. According to my manifesto,
the free running noise of the laser is (10 kHz / f) Hz/rHz. The mode cleaner loop gain is sufficient to reduce this to
0.001 Hz/rHz everywhere below 1 kHz - radiation pressure noise and coating thermal noise limit the mode cleaner below
these levels.
So, since it seems like the reference cavity is superfluous (except for the 1 - 10 kHz band), we unlocked it and locked the
MC by feeding back directly to the laser.
In the old set up, the low frequency feedback is to MC2 and the high frequency to the VCO which actuates the FSS which
drives the NPRO PZT and the Pockel cell.
In this new way, we take the MC board's output to the VCO (the TNC monitor point) and send that to the TEST IN1 of the FSS
box. The FSS box then splits the drive to go to the PZT and the PC path. We also turned off the 40:4000 filter in the MC
board and inverted the sign of the MC FAST path.
Good settings for acquisition:
MC INPUT GAIN = 6 dB
40:4000 Disable
FAST polarity MINUS
VCO Gain -3 dB
MC LIMITER Disable
FSS TEST1 TEST
FSS CG -3 dB
FSS FG 13 dB
After our initial locking success, we realized that the new MC-FSS loop is conditionally stable: the old loop relied on
the 40 kHz refcav pole to make it stable. The new loop has a 4 kHz pole and so the phase lag in the MC-PZT path is too
much. We need to build a passive lead filter (40 kHz : 4 kHz) in a Pomona box to compensate.
There are several more issues:
- I think this will make the whole CM servo handoff easier: there is no more handoff.
- This will make the lock acquisition fringe velocity higher by a factor of the arm/mc length (40 m / 13 m) since
the frequency will be slewing around along with MC2 now. However, Jenne's FF system ought to take care of that.
- Having the laser frequency stabilized to the MC during lock acquisition will make all of the error signals quieter
immediately. This can only be good.
- If we can make this work here, it should translate to the sites directly since they have exactly the same electronics. |
1424
|
Tue Mar 24 23:23:05 2009 |
rana | Update | LSC | New PO DC |
We also found that the SPOB RF cable was going through a splitter before going into the SPOB demod board. The other
input of the splitter was open (not terminated). Using 50m Ohm devices without terminated inputs is illegal. It
makes there be standing waves in the cables and makes the RF phase very dependent on cable lengths. We took away
the splitter and ran the cable straight. So expect some change in the SPOB gain and phase plus some shame. |
1423
|
Tue Mar 24 19:55:24 2009 |
Jenne | Update | LSC | New PO DC |
[Rana, Jamie, Jenne]
SPOB DC hasn't been so good lately, so we installed a new PO DC PD on the PO table. We used a 30% reflecting beam splitter (BS1-1064-30-1025-someotherstuff). We didn't check with a power meter that it's a 30% BS, but it seems like that's about right. The beamsplitter is as close as we could get to the shutter immediately in front of the regular POB/SPOB PD's, since that's where the beam gets narrow. The new picked-off-pickoff beam goes to a Thorlabs 100A PD. We haven't yet checked for reflected beams off the PD, but there is a spare razor blade beam dump on the table which can be used for this purpose. The output of this PD goes to the LSC rack via a BNC cable. (This BNC cable was appropriated from it's previous "use" connecting a photodiode from the AP table to a bit of air just next to the LSC rack.) Our new cable is now connected where the old SPOB DC cable used to be, at the input of a crazy Pomona Box tee.
For reference, the new levels of POB DC and SPOB DC, as measured by their BNC DC out connections is ~4mV each. Since the beamsplitter is 70% transmissive, we used to be getting about 5.7mV on each PD.
The new photodiode puts out about 40mV, but it has an ND1.0 filter on, so if more gain is needed, we can take it off to get more volts.
|
1422
|
Tue Mar 24 13:54:49 2009 |
Jenne | Update | SUS | Op Levs Centered |
ITMX, ITMY, BS, SRM, PRM op levs were all recentered. ETM's looked okay enough to leave as-is. |
1421
|
Tue Mar 24 13:10:07 2009 |
Alberto | Configuration | PSL | new mirror installed on the AP table |
New flipping mirror installed on the AP table on the beam path to the REFL199 PD.
If you're missing the double demod signal, please check that it is actually down. |
1420
|
Tue Mar 24 09:04:02 2009 |
steve | Update | SUS | 4.8 mag earthquake |
SRM, ITMX, ETMX, ITMY and ETMY lost damping at 4:55am this morning from 4.8 magnitude earthquake.
Their damping were restored.
C1:SUS-ITMX_URSEN_OUTPUT swich was found in off position. It was turned on.
MZehnder and MC were locked.
The WFS qpd spot needs recentering |
1419
|
Tue Mar 24 03:05:25 2009 |
Yoichi | Update | Locking | Locking tonight |
MC1 issue:
The MC1 seems to be drifting still. I found it was off from the SUS drift-mon reference values and restored the alignment using the SUS drift-mon before I went home for dinner.
But when I came back being happy with the Japanese victory over S-Korea at the WBC final, the MC was unhappy again.
I restored the alignment of the MC1 using the SUS drift-mon once again and centered the WFS QPDs.
I will leave the MC unlocked again tonight to see the drift. You are welcome to lock the MC in the morning as I will have corrected enough data by the time people come in.
Computer overloads:
I removed some filters from suspensions to off load susvme computers.
Nonetheless, both susvme1 and susvme2 are still over loaded during the dither alignment. The alignment results are in general ok. So this is not a too serious problem.
But still it would be nice to resolve.
3.8kHz hunting:
I made several measurements of the AO path loop gains (using the SR785) and the transfer functions from the CARM excitation (actuation to the ETMs) to the PO_DC signal as the arm powers are increased.
There is a similar structure as in the AO loop found also in the CARM->PO_DC transfer functions. This implies that the problem is likely to be in the PO_DC sensor not in the MC->VCO actuator. But the MC and the VCO could still be the
cause of the problem because they were in the control loop when the CARM->PO_DC TF were measured.
The peak frequency does not seem to depend on the arm power, but the conclusion is not definite because I was only able to measure the TFs from arm power 5 to 10 (not much difference).
I will make plots and post them later.
To Do for tomorrow:
Tonight the CARM error signal was noisier than the reference spectra (broad band white noise appeared). I should check the beam centering of the SPOB PD.
Also someone should center the oplevs of the mirrors as some of them are off.
Continue to measure the TFs at various power levels.
Try to put another (Thorlabs?) PD at the POB port to get PO_DC from it. |
1418
|
Mon Mar 23 15:50:44 2009 |
rana | Configuration | LSC | filters deleted, lsc rebooted |
The LSC time had gone too high. I deleted ~20 filters and rebooted. CPU time came down to 50 usec.
The filters all looked like old trash to me, but its possible they were used.
I didn't delete anything from the DARM, CARM, etc. banks but did from the PD and TM filter banks. You can always go back in time by using the
filter_archive/ |
1417
|
Sun Mar 22 23:16:41 2009 |
rana | DAQ | Computer Scripts / Programs | tpman restart |
Could get testpoints but couldn't start excitations. Restarted tpman on daqawg. Works now.
Still no log file.  |
1416
|
Sun Mar 22 22:47:58 2009 |
rana | Update | DMF | seisBLRMS compiled but still dying |
Looks like seisBLRMS was restarted ~1 AM Friday morning but only lasted for 5 hours. I just restarted it on megatron;
let's see how it does. I'm not optimistic. |
1415
|
Sun Mar 22 22:39:24 2009 |
rana | Summary | LSC | Calibration of the ITM and ETM Actuation |
I used the following procedure to calibrate the ITMX actuation signal.
Free Swinging Michelson:
------------------------
- Restore Michelson
- Align Michelson: Minimize AS_DC (PD3_DC_OUT) by tweaking BS alignment.
- Enable Whitening filters for PD1_Q and PD3_DC.
- Run offsets script to get rid of DC and RF offsets.
- Use DTT Triggered Time Series to get time series and measure peak-peak
amplitude of PD1_Q using DTT horizontal cursors. (Templates/Calibration/090322/FreeSwing.xml)
Michelson Sweeps:
-----------------
- Lock Michelson
- Drive ITMX_LSC_EXC using ITMX-MI-Sweep.xml template.
- (Next time remember to turn on a low pass in the MICH loop so that its an open loop measurement below 50 Hz).
- Fit and so some math.
Arm Sweeps for the ETMs:
------------------------
- Lock a single arm
- Sweep ITM & ETM.
- Then sweep MC2 and record drive signal from MC board to the VCO driver.
- Compare and contrast. |
Attachment 1: free.png
|
|
1414
|
Fri Mar 20 15:54:29 2009 |
steve | Omnistructure | General | 480V crane power switch on MEZ |
CES Mezzanine is beeing rebuilt to accommodate our new neighbor: the 20ft high water slide...& .jacuzzi
All our ac power transformers are up there. Yesterday we labelled the power switch of 480VAC on the mezz
that we need to keep to run the 3 cranes in the lab. |
1413
|
Fri Mar 20 15:37:58 2009 |
Kakeru | Update | oplevs | arm cavity oplev calibration |
I calibrated several oplevs with OSEM signal as a confirmation of my fitting method the method is:
1) I tilted mirrors and get signals from oplevs (C1:SUS-XXXX_OPLEV_PERROR) and OSEM (C1:SUS-XXXX_SUS{PIT/YAW}_IN1).
2) I compared amplitudes of two signals and calculated conversion factors.
3) I calibrated factors above to microrad/counts with
i) The calibration factor of OSEM (2 V/mm)
ii) The calibration factor from count to V of OSEM; 1/16384 V/counts
iii) The shape of whitening filter of OSEM: 30, 100:3 (these values is taken from http://www.ldas-sw.ligo.caltech.edu/ilog/pub/ilog.cgi?group=40m&task=view&date_to_view=04/07/2005&anchor_to_scroll_to=2005:04:07:20:28:36-rana).
iv) The size of mirrors; 125mm for large optics and 75.5mm for small optics.
This calibration has some uncirtainties.
1) The calibration factor of OSEM looks very rough.
2) Output matrixes looks not to be normalized. It looks vary from 0.5 to 1.5 .
3) I don't know where OSEMs are put on mirrors accurately.
So, this calibration is very rough and may have uncertnty of a few factors, I could confirm my fitting calibration in orders.
From this calibration, I got calibration factors listed below.
ITMY Pit: 76 microrad/counts (257 microrad/counts with fitting method)
ITMY Yaw: 58 microrad/counts (206 microrad/counts)
BS Pit : 27 microrad/counts (70.9 microrad/counts)
PRM Yaw : 22 microrad/counts (79.9 microrad/counts)
For the other mirrors, OSEM outputs matrixes are not optimized and I couldn't get fine signals (I think this is not good!).
Each value is smaller than the value calibrated with fitting method in factor 3-4. There looks to be some systematic error, so there must be some difference in parameters used in OSEM calibration. |
1412
|
Fri Mar 20 12:07:19 2009 |
Yoichi | Configuration | ASC | ETMY beam centering |
I forgot to put this in the elog.
Last Sunday night, I centered the beam on the ETMY because it was too low.
To do so, I wrote scripts (beamCenterETMY-P and beamCenterETMY-Y) to continuously align the Y-arm while I'm moving the beam on the end QPD.
These scripts will continuously do the dithering servo and QPD centering in one direction (pitch for beamCenterETMY-P, yaw for the other).
So if you move the steering mirror in front of the end QPD, the servo will eventually move the beam spot on the ETM.
I centered the beam just by looking at the camera image.
No coupling measurements from Pitch/Yaw to length was done. |
1411
|
Fri Mar 20 11:01:02 2009 |
steve | Update | PEM | particle counts are high |
The outside particle counts for 0.5 micron are 3 million this morning at 9am. Low clouds, foggy condition with low inversion layer.
This makes the 40m lab 30-50K
I just turned on the HEPA filter at the PSL enclosure.
Please, leave it on high
|
Attachment 1: particles32d.jpg
|
|
1410
|
Thu Mar 19 10:45:43 2009 |
Yoichi | Configuration | IOO | A loose wire found for MC1 |
I attached a 6-hour trend of the MC mirror OSEM signals with the MC unlocked.
The drift of the MC1 is within 20 counts (0.6um in terms of each OSEM).
This is comparable to the other MC mirrors. |
Attachment 1: AfterWireFix-1.pdf
|
|
1409
|
Thu Mar 19 02:45:36 2009 |
Yoichi | Configuration | IOO | A loose wire found for MC1 |
I found a loose connection of a wire in the cross-connect between an ADC and the MC1 coil driver's UL bias input.
I tightened it.
To see if this fixes the MC1 drift problem, I will do another round of MC1 drift measurement.
You can lock the MC if you need to use the IFO but please note it in the elog.
Thanks. |
1408
|
Tue Mar 17 08:44:37 2009 |
Yoichi | Configuration | IOO | MC1 drift |
I'm done with the MC1 drift measurement.
The result is attached. It is clear that MC1 is in trouble. The small drifts in the MC2/MC3 are insignificant compared to the crazy MC1 behavior.
Since there is no drift in the coil feedback voltage monitors, it is probably not a problem of the DACs.
We may be able to fix this by pushing the cables for the MC1 satellite amplifier. But it may require replacement of the coil driver.
Quote: | There seems to be a large drift of MC1 even when there is no WFS feedback.
The attached plot is an example a 20min trend. You can see that MC1 OSEM signals drift significantly larger than that of MC2/MC3.
You can also be sure that there is no drifting voltage applied to the coils on the MC1 during this period.
If no one is working on the IFO today during the LV meeting, I'd like to leave the MC unlocked and see the trend of the MC1 OSEM signals.
Please do not turn on the MC auto locker unless you want to use the IFO.
If you want to do some measurements, please go ahead and lock the MC, but please write it down in the elog.
Thanks. |
|
Attachment 1: MC1_Drift3.pdf
|
|
1407
|
Mon Mar 16 15:19:52 2009 |
Osamu | DAQ | Electronics | SR785 |
I borrowed SR785 to measure AA, AI noise and TF. |
1406
|
Mon Mar 16 12:26:59 2009 |
Yoichi | Configuration | IOO | MC1 drift |
There seems to be a large drift of MC1 even when there is no WFS feedback.
The attached plot is an example a 20min trend. You can see that MC1 OSEM signals drift significantly larger than that of MC2/MC3.
You can also be sure that there is no drifting voltage applied to the coils on the MC1 during this period.
If no one is working on the IFO today during the LV meeting, I'd like to leave the MC unlocked and see the trend of the MC1 OSEM signals.
Please do not turn on the MC auto locker unless you want to use the IFO.
If you want to do some measurements, please go ahead and lock the MC, but please write it down in the elog.
Thanks. |
Attachment 1: MC1_Drift1.pdf
|
|
1405
|
Mon Mar 16 01:20:40 2009 |
rana | Configuration | IOO | MCWFS noise filtered on the SUS-MC |
Recently, we noticed that the IOO-WFS system runs at 2048 Hz and sends its signals to the MC SUS
systems which run at 16 kHz. There is no upsampling filter or anti-imaging filter.
So, I've implemented an RLP666 filter as FM1 in the SUS-MCn_ASC(PIT/YAW) filter banks. This is like a 4th order
Cheby low pass with a low Q notch at 2048 Hz to catch the first image.
The attached PNG shows the ASCPIT_OUT signals before and after the filter is implemented. As you can see, the
big aliased spikes are gone. The reason that MC2 is different from MC1/3 is that they have a hardware 28Hz low pass
and MC2 doesn't. So MC2 had a 28 Hz low pass in software already to match the actuation phase between all the MC
mirrors. The apparent power law noise floor from 40-300 Hz in MC2 is not real - just the Hanning window tail.
And yes, it has been this way for several years and none of us noticed. It remains to be seen if this was causing
any noise in the MC coil drivers via slew rate limiting. |
Attachment 1: xarm.png
|
|
1404
|
Sun Mar 15 21:50:29 2009 |
Kakeru, Kiwamu, Osamu | Update | Computers | Some computers are rebooted |
We found c1lsc, c1iscex, c1iscey, c1susvme, c1asc and c1sosvme are dead.
We turned off all watchdogs and turned off all lock of suspensions.
Then, I tried to reboot these machines from terminal, but I couldn't login to all of these machines.
So, we turned off and on key switches of these machines physically, and login to them to run startup scripts.
Then we turned on all watchdogs and restored all IFO.
Now they look like they are working fine.
|
1403
|
Sat Mar 14 22:53:12 2009 |
Kakeru | Update | oplevs | arm cavity oplev calibration |
I finished a calibration of optical levers.
To calibrate oplevs, I locked appropriate cavity and tilted a mirror.
A cavity with tilted mirror decrease its arm power. So I can know how much the tilt is.
For calibration of ITMX and ETMX, I locked X arm and measured TRX.
For ETMX, ETMY and BS, I locked Y arm and measured TRY
For PRM, I locked PRC and measured SPOB
For SRM, I locked SRC and measured REFL166
I used, for example, C1:SUS-ITMX_OPLEV_PERROR as an oplev signal.
The calibration factors for each mirror is below. The attachment is figures of my fitting.
I used modified equation for ITM calibration from my last calibration, so the value become small around 30%.
ITMX Pitch: 142 microrad/counts
ITMX Yaw: 145 microrad/counts
ITMY Pitch: 257 microrad/counts
ITMY Yaw: 206 microrad/counts
ETMX Pitch: 318 microrad/counts
ETMX Yaw: 291 microrad/counts
ETMY Pitch: 309 microrad/counts
ETMY Yaw: 299 microrad/counts
BS Pitch: 70.9 microrad/counts
BS Yaw: 96.3 microrad/counts
PRM Pitch: 78.5 microrad/counts
PRM Yaw: 79.9 microrad/counts
SRM Pitch: 191 microrad/counts
SRM Yaw: 146 microrad/counts
It looks strange that ITMY, BS and SRM has different value. I think this is a fitting problem.
These data have some asymmetry and cause these 20%-30% difference.
Actually, PRM Yaw has a little asymmetry but the value doesn't differ from Pitch.
This means that this calibration factor potentially has below 30% error.
(These data are the most fine data. I think we must adjust Y arm yaw alignment. The beam spot of ETMY looks too low!)
For SRM, I couldn't get fine data because it was very sensitive to tilt and easily lose its lock.
When I tuned cavity enough, The data become almost flat, so I used detuned cavity.
It is also strange that ITMX and ITMY is different. I guess that this is caused by the difference of the QPD input. The sum of QPD is around 10000 for ITMX and around 4500 for ITMY.
The difference between BS or PRM and SRM is same, I guess. The sum of QPD input for BS and SRM is around 1500, but for SRM, it is around 10000.
I will write more detailed document and upload it with my calibration code. |
Attachment 1: oplev.pdf
|
|
1402
|
Fri Mar 13 22:07:14 2009 |
Yoichi | Update | Locking | Calibrated XARM error signal spectrum |
Of course I made a mistake.
I put a pole at 1525Hz whereas it should have been a zero.
The correct calibration factor is:
G: 4.2e-13
P:
Z: 1525
I attached a revised spectrum.
Quote: | I did a rough calibration of the XARM error spectrum.
See the attached calibrated spectrum.
I started from this Rana's elog entry.
http://www.ldas-sw.ligo.caltech.edu/ilog/pub/ilog.cgi?group=40m&task=view&date_to_view=04/07/2005&anchor_to_scroll_to=2005:04:07:20:28:36-rana
I first injected a 20Hz sin signal into C1:SUS-ETMX_LSC_EXC and measured the response to the ETMX SUSPOS.
Using the calibration of the SUSPOS given in the above entry, I calibrated the ETMX coil actuation efficiency.
It was 3.4e-12 m/cnt @20Hz for C1:SUS-ETMX_LSC_EXC.
Then I locked the X-arm and injected a calibration peak at 20Hz.
From the ratio of the peaks in C1:SUS-ETMX_LSC_IN2 and C1:LSC-XARM_IN1, I calibrated the X-arm error signal to be 4.2e-13 m/cnt.
We have to also take into account the cavity pole of the arm, 1525Hz (the design value, may not be actual).
So I used the following calibration in the DTT:
G: 4.2e-13
P: 1525
Z:
Note that the attached spectrum shows the actual motion of the X-arm (or equivalent frequency noise) after suppressed by the feedback servo,
unlike conventional noise spectra showing "virtual" displacement which would have been induced in the absence of servos. |
|
Attachment 1: XarmErrorSpeCalibrated.pdf
|
|
1401
|
Fri Mar 13 20:23:37 2009 |
Yoichi | Update | LSC | AO path transfer function with X-arm locked |
I measured the AO path transfer function while the X-arm is locked with the POX PDH signal.
The POX-I signal was already connected to the input 1 of the CM board. So I injected a signal from the EXC-B channel of the board and measured the transfer function from TP2B to TP1A. To open the loop, I disabled the switch befor the EXC-B.
The attached plot shows the measured transfer function.
There is a bump around 2kHz, which can also be seen in the AO path TF posted in elog:1399, but not the large structure at around 3.8kHz.
The 3.8kHz structure is probably created by the feedback. |
Attachment 1: AOPath-Xarm.png
|
|
1400
|
Fri Mar 13 19:26:09 2009 |
Yoichi | Update | DMF | seisBLRMS compiled |
I compiled seisBLRMS.
The tricks were the following:
(1) Don't add path in a deployed command.
It does not make sense to add paths in a compiled command because it may be moved to anywhere. Moreover, it can cause some weird side effects. Therefore, I enclosed the addpath part of mdv_config.m in a "if ~isdeployed ... end" clause to avoid adding paths when deployed. Instead of adding paths in the code, we have to add paths to necessary files with -I options at the compilation time. This way, mcc will add all the necessary files into the CTF archive.
(2) Add mex files to the CTF archive by -a options.
For some reason, mcc does not add necessary mex files into the CTF archive even though those files are called in the m-file which is being compiled. We have to add those files by -a options.
(3) NDS_GetData() is slow for nodus when compiled.
NDS_GetData(), which is called by get_data() stops for a few minutes when using nodus as an NDS server.
This problem does not happen when not compiled. I don't know the reason. To avoid this, I modified seisBLRMS.m so that when an environmental variable $NDS is defined, it will use an NDS server defined in this variable.
I wrote a Makefile to compile seisBLRMS. You can read the file to see the details of the tricks.
I also wrote a script start_seisBLRMS, which can be found in /cvs/cds/caltech/apps/DMF/compiled_matlab/seisblrms/. To start seisBLRMS, you can just call this script.
At this moment, seisBLRMS is running on megatron. Let's see if it continues to run without crashing.
Quote:
|
The seisBLRMS has been running on megatron via an open terminal ssh'd into there from allegra with matlab running. This
is because I couldn't get the compiled matlab functionality to work.
Even so, this running script has been dying lately because of some bogus 'NDS' error. So for today I
have set the NDS server for mDV on megatron to be fb40m:8088 instead of nodus.ligo.caltech.edu. If this seems to fix the problem
I will make this permanent by putting in a case statement to check whether or not the mDV'ing machine is a 40m-martian or not.
|
|
1399
|
Fri Mar 13 05:16:21 2009 |
Yoichi | Update | Locking | Locking update |
Yoichi, Osamu,
With adjustments of the loop gains during the CARM offset reduction, the IFO reaches arm_power = 25 sort of robustly unless the 3.8kHz oscillation rings up.
At arm_power = 25, the CARM and DARM start to oscillate at around 400Hz. Probably I need more gain tweaks.
Annoying thing is that the 3.8kHz oscillation sometimes rings up suddenly and kills the lock.
This can happen anywhere above arm_power = 6 or so.
Because of a strange structure in the CARM loop gain around 3.8kHz, we cannot increase the CARM UGF beyond 1kHz.
The attached plots are the AO path open loop transfer function (attm2 is the zoom of attm1) measured at arm_power = 13.
Tomorrow, I will lock the X-arm and measure the transfer function from the AO path input to the X-arm error signal to see
if there is the same structure at 3.8kHz (X-arm error signal has the 3.8kHz peak). |
Attachment 1: AOTF2.png
|
|
Attachment 2: AOTF2-zoom.png
|
|
1398
|
Thu Mar 12 20:59:04 2009 |
Kakeru | Update | IOO | MC drift is terrible |
After Rana went for his dinner, I aligned periscope to make the MC output 3.2 (Attachment 1).
After that, to align WFS, I unlocked the MC, unlocked the MZ and decrease the beam power to WFS QPD, and re-centerd WFC beam.
I restored MZ and MC lock.
I enabled MC autolocker, and change C1:IOO-WFS_Gain_Slider from 0 to 0.02 to lock WFS.
Quote: | Kakeru, Rana, Yoichi
We used the SUS DRIFT MON screen to set the MC biases such that the mirrors were returned to the old OSEM values.
To do this, we set the nominals and tolerances using the appropriate scripts in the mDV/extra/C1/ directory.
We then used the MC_ALIGN screen to set the angle bias sliders.
Then Kakeru and I went to the PSL table to the periscope magic and maximize the MC transmission. Kakeru seems to
have the careful Japanese alignment touch and I am hungry, so I am leaving him to optimize the power. After he
finishes he is going to align the beam to the WFS and turn the MC autolocker back on. The x-arm is locked on a
TEM00 mode so the MC alignment is maybe OK. |
|
Attachment 1: MCtrans090312.png
|
|