We don't need a high quality calibration for the optical levers. ~50% accuracy is fine.
For that you can use the OSEM calibration of ~1.7 V/mm (its less than 2 since the OSEMs have been degrading) or you can use the cavity power method that Kakeru used; it worked just fine. There's no benefit in trying for a 1% number for optical levers.
This modification of the LSC model made the rows of the LSC output matrix shifted. This caused the ASS scripts nonfunctional.
Kiwamu fixed the channel names in the ASS script.
[Jenne, Mirko, with supervision from Jamie]
I modified the c1lsc model to have shmem outputs that go from the degrees of freedom to the OAF, and shmem inputs from the OAF's output to sum into the DoFs, just like Yoichi's FF stuff. I also removed the old OAF_OUT, because it would only allow me to select one DoF at a time, and I will eventually want the ability to do multiple amounts of OAFing at the same time. Hopefully.
The pzt driver for PZT1 has been installed.
As there was unknown resistive connection in the vacuum chamber as described below,
the PZT out cable at the PJ driver module should always be disconnected.
The sensor cables have no problem to be connected to the controller.
In fact, they are a good monitor for the state of the PZTs.
In this configuration, Pitch and Yaw direction of PZT1 is under the control of the EPICS value as we expected.
- At the beginning, we tested the PZT driver output with low voltage level (~10V). We did not see any oscillation of the opamps.
The pitch output was observed to be OK, while the YAW output exhibited a half of the expected output voltage.
The opamp was holding correct voltage, however the voltage after the 1K output resister was about a half.
This indicated there was a voltage division happening.
- The cause of the voltage division was tracked. We found that the yaw red (=hot) line is connected to pitch black
in the vacuum chamber with a resistance of 1.4kOhm. The black cables are shorted to the ground level in the PJ driver.
- We decided to unplug the PJ's cable so that we can isolate the black cables while hoping the PZTs were drived only
by the red and white cables. And they did.
- This means that we should not connect the PZT driving cable to the PJ's driver. The sensors have no problem to be connected.
|. o| 5
|o | 17
| o| 4
|o | 16 Yaw Black
| o| 3 Pitch Black
|o | 15 Yaw White
| o| 2 Yaw Red
|o | 14 Pitch White
\ o| 1 Pitch Red
* Pitch White and Yaw White are connected to the ground at the amplifier side.
* Yaw Red and Pitch Black is connected with 1.4kOhm and isolated from the others.
The f2a filters were installed on ITMs and ETMX.
Now all of the suspensions has the f2a filters.
[Anamaria / Kiwamu]
The incident beam pointing was improved by using PZT1 and PZT2.
With some triggers the lock of PRMI became smoother.
For the DRMI lock, the MICH and SRCL signals on AS55 are not quite decoupled, so we should find cleaner signals for them.
(what we did)
+ locked the Y arm
+ aligned incident beam by using PZT1(#5450) and PZT2. The spot positions on ITMY and ETMY are now well-centered.
+ tried activating C1ASS but failed. It needs some gain changes due to the new PZT1 response.
+ locked the X arm
+ aligned the TRX PD (Thorlab signal PD) and set the trigger.
+ C1ASS also doesn't work for the X arm
+ realigned the PRM and BS oplevs. the PRM oplev was clipped at a steering mirror on the optical bench
+ locked PRMI and aligned the PRM mirror such that the optical gain was maximized
+ optimized the demod phase of AS55 and REFL11
+ checked the UGF of the MICH and PRCL lock. The UGF of MICH is about 100Hz with gain of -20, and the UGF of PRCL was 85 Hz with gain of 0.1
+ adjusted the output matrix such that the MICH control doesn't couple into the PRCL control.
+ set the triggers for the MICH and PRCL control to make the lock acquisition smoother.
+ tried locking DRMI and it was sort of locked. However the SRCL signal showed up a lot in AS55_Q, where the MICH signal is extracted.
Actually the clipping of POP wasn't in the chamber but it was on the first lens on the optical bench.
So I repositioned the lens to avoid the clipping and now there are no clipping on POP.
We found that POP beam is clipped by the steering mirrors inside the tank.
I replaced the lenses that were there with a -150mm lens followed by a +250mm lens. This gave a significantly reduced beam size at the QPDs. With the beam analyzer up and running it should be possible to optimize this later this afternoon. Next I will remove the SRM QPD from the path and make measurements of the beam spot position movement and corresponding OSEM values for different DC mirror offsets. I will then repeat the process for ITMY.
I've got the bench set up for the measurement of the beam spot change with DC SRM alignment offsets. The ITMY oplev is aligned and fine to use, but the SRM one isn't until further notice (probably a couple of hours).
I made the first measurements towards oplev calibration measurements: calibrating the oplevs in SRM YAW. The measurements seemed fine, I had a range of between -1.5 and 1.5 in SRM DC alignment before clipping on mirrors on the oplev bench became a problem. This seemed to be plenty to get a decent fit for the spot position against DC alignment value - see attached plot. The fitted gradient was -420um oplev yaw count. I calculated oplev yaw values as UL+LL-UR-LR. Pitch next.
The following optics were kicked:
Mon Sep 19 15:39:44 PDT 2011
Earlier measurements of the modulation index were less than optimal because we had too low transmission through the cavity. Contrary to what was believed you actually need to modematch onto the cavity.
Earlier transmitted power was about 8.5uW.
With a 250mm lens we archived 41uW.
Impinging power on the cavity is 1.7mW.
PD TF approx 0.1V / uW.
Carrier power: 4.1V => 41uW
41uW/1.7mW = 2.4 % transmission. Manufacturer clain for peak transmission: 20-30%.
11MHz SB: 28.8mV => m=0.17
55MHz SB:36mV => m=0.19
As you can see on the pic the SNR of the SBs is not too good.
The gain of whitening filters on AS55 was decreased from 21 dB to 0 dB for the Y arm locking.
- - (Background)- -
Since the modulation depths became bigger from the past (#5462), the PDH signal from Y arm was saturated in the path of AS55.
Due to the saturation the lock of the Y arm became quite difficult so I decreased the gain of of the whitening filter from 21 dB to 0 dB.
In this condition, a required gain in C1:LSC-YARM_GAIN is about -0.3, which is 10 times bigger from the default number.
For the MICH locking tonight, it may need to be back to a big gain.
Same measurements for SRM pitch (as previously done for yaw in entry 5460) are complete. The QPD is back in the path and aligned. I will be doing the same measurements for ITMY now though, so please ask before activating the SRM or ITMY oplev servos, as I may be blocking the beam.
Kiwamu: The bad medm screens have been fixed. There are no blank fields and all the links are correct.
I've found that a few of the screens still have Whited-Out fields due to naming changes (OL SUM and ALS-> TM OFFSET). I attach a screen shot of it.
The OL screens have the wrong SUM names and the IFO ALIGN screen is pointing to the wrong SUS screens.
Really? I found this one with ~15 seconds of clicking around.
I changed some colors on the Summary of Suspension Sensor using my italian creativity.
I wrote a script in Python to change the thresholds for the "alarm mode" of the screen.
I've started to fix up the script somewhat (as a way to teach myself some more python):
* moved all of the SUS Summary screen scripts into SUS/SUS_SUMMARY/
* removed the hardcoded channel names (a list of 190 hand-typed names !!!!!!!)
* fixed it to use NDS2 instead of try to use the NDS2 protocol on fb:8088 (which is an NDS1 only machine)
* it was trying to set alarms for the SUS gains, WDs, Vmons, etc. using the same logic as the OSEM PD values. This is non-sensical. We'll need to make a different logic for each type of channel.
New script is called setSensors.py. There are also different scripts for each of the different kinds of fields (gains, sensors, vmons, etc.)
pianosa:SUS_SUMMARY 0> ./setDogs.py 3 5
Done writing new values.
Another Hamasutu S3399 photodiode was tested with the electronic circuit as described in LIGO-D-1002969-v.
RF transimpedance is 1k although the DC transimpedance is 2k.
The noise level is 25pA/sqrt(Hz) which corresponds to a dark current of 1.9mA or 1.7mA in the independent measurement.
At all frequencies the noise is larger compared to Koji's measurement (see labbook page 4778).
In file idet_S3399.pdf the first point is not within its error bars on the fitted curved. This point corresponds to the dark noise measurement
I made this measurement again. Now it is on the fitted curve. In the previous measurement I pushed the save button a bit too early. The
averaging process has not been ready while I pushed the 'save' button.
Dark current is 1.05mA and noise is lower than in the previous measurement.
New file are the XXX_v2.pdf files
The last person out tonight should run the following scripts:
In command line:
Then in the morning, someone should do a BURT restore to early today (to get the default matricies back), and also restore the watchdogs.
We started to investigate the AM modulation mistery again. Checking just after the EOM, there are AM modulation about -45dBm. Even if we adjust the HWP just before the EOM, AM components grow up in 5 mins. This is the same situation as before. Only the difference from before is that we don't have PBS and HWP between the EOM and the monitor PD. So we have a simpler setup this time.
We will try to align the pockells cell alignment tomorrow daytime, as it may be a problem when the crystal and the beam are not well parallel. This adjustment has been done before and it didn't improve AM level at that time.
I have made some cleaning up of the LSC-related MEDM screens.
- LSC overview screen: ADC OVFL and WFAA indicators are now correctly matched to it associated PD signals.
- Whitening screens now have the correct indication of the associated PD signals.
- LSC Ctrl screen, which is invoked from the overview screen by clicking the servo filters, now has the switches of the servo filters.
- LSC tab of the sitemap was cleaned up by removing the broken links.
Keiko, Anamaria, Koji
We were not able to establish the stable DRMI tonight. We could lock MICH and PRCL quite OK, and lock the three degrees of freedom at somewhere strange for several seconds quite easily, but the proper DRMI lock was not obtained.
When MICH and PRC are locked to the carrier, REFL DC PD reading dropps from ~3000 counts to 2600~2700 counts as REFL beam is absorbed to PRC. We'll try to lock PRC to sidebands - but flipping gain sign didn't work today, although it worked a few days ago.
POP beam (monitor) is useful to align PRM.
I followed Jenne's instructions, ran the matrix filler script and then set the optics to freeswing. Someone has to burt resture and damp them in the morning.
Thanks! I'll give them a little more time, then restore things.
I began restoring the optics at ~9:30am, so I have a full 6 hours of data, in case I need that much to separate the Pos/Side modes on some of the optics. They are all damping again with their original matricies.
Since the MC wasn't able to capture the 00 mode in this morning I aligned the incident beam going to MC.
As a result C1:IOO-RFPD_DCMON went down to 0.6. However the beam on IPPOS is almost falling off from the QPD.
So, clearly this was a kind of dumb idea. There is nothing mechanical going on between our sensor inputs and our Pit/Pos/Yaw/Side DoF filter banks. It's just math. On the other hand, we now have a 3rd set of in-vac free swinging data, so I can (after all the suspensions are working) have a look at the drift in matrix elements over time.
In other news, after some meditation, and fitzing with DoF gain values, all of the IFO optics except for SRM now have their new input matricies, and are damping pretty nicely. I need to go through and do an "eyeball" check to make sure that everything has a Q of ~5ish. So far, I've kicked the optics, and watched that they damped fairly quickly, but I don't have a guesstimate of the Q's for each optic, for each DoF.
So, still to do:
Use another set of data and invert the SRM matrix DONE
Plug in the MC matricies, make sure they're okay. DONE
Check the Q's for all optics, all DoFs.
This is using data for the SRM from: 20 Sept 2011 03:20:00 PDT = 1000549215
You can see that there are still some funny peaks between Pit and Yaw, but I finnessed the peak-finding, and I was able to fit all of the correct peaks, and invert the matrix:
SRM now has its new matrix, and is damping happily.
pit yaw pos side butt
UL 0.877 0.983 1.105 -0.288 1.092
UR 1.010 -1.017 1.123 -0.145 -1.055
LR -0.990 -1.002 0.895 -0.091 0.848
LL -1.123 0.998 0.877 -0.234 -1.006
SD 0.089 0.064 3.752 1.000 -0.009
Can't we use Yuta's auto-Q adjust script?
Edit by KI :
Of course we can use it but first we have to fix some pynds sentences since his script was written for the OLD pynds.
[Suresh / Kiwamu]
The MC REFL camera is now available. The camera name is "MCR" and you can call it from the videoswitch script.
+ repositioned and aligned the MCR camera.
+ checked the MCR camera.
=> found the camera view shows a negative image (i.e. the beam spot is dark and the background is bright !!)
+ replaced the camera by a spare one.
+ modified the videoswitch script because the input channel 3 was wrongly assigned to MCR.
MCR was correctly assigned to the input channel 18.
Modulation resonator box is removed and the modulation depth is small right now.
I have broke the BNC connector on the modulation resonator box. The connector was attached by the screw inside very loosely and when we connect and disconnect the BNC cables from outside, extra force was applied to the cable inside and it was broke. It is being fix by Kiwamu and will be back in a bit.
Resonator box and the modulations are back now. But the modulation depth seems to be a bit smaller than yesterday, looking at the optical spectrum analyser.
I have broke the BNC connector on the modulation resonator box. The connector was attached by the screw inside very loosely and when we connect and disconnect the BNC cables from outside, extra force was applied to the cable inside and it was broke. It is being fix by Kiwamu and will be back in a bit
Has the Q been checked? Still in progress...
So, update as of 6:17pm: I have tuned the damping gains for all IFO optics. Everything is good, except for ITMY Yaw. It's probably fine, the optic damps okay, but it doesn't look like a nice clean ringdown. I haven't taken the time to go back and look at it again.
I have to go to a dinner, but later (probably in the morning, so I don't disturb evening locking) I'll check the MC Qs.
[Jenne / Kiwamu]
Fb was sick. Dataviewer and Fourier Tools didn't work for a while.
After 10 minutes later they became healthy again. No idea what exactly was going on.
One thing we found was that : during the sickness of fb, it looks like daqd was restarting by hisself. Is this normal ??
Here is the bottom sentences of restart.log. Apparently daqd was rebooting although we didn't command to do so.
daqd_start Tue Sep 20 02:41:17 PDT 2011
daqd_start Tue Sep 20 13:18:12 PDT 2011
daqd_start Tue Sep 20 17:33:00 PDT 2011
The measured calibration factors for the oplevs are as follows:
Kiwamu noticed that the 1/L in the counts per radian should have just been L, which accounts for most of the discrepancy. We checked the input filters on the OSEMs, and they have 10dB of gain at DC. Accounting for this, estimates on the order of 20urad/count, which is much more reasonable!
This morning after Kiwamu maximised the PSL beam coupling into the MC we noticed that the MC2 face camera showed the spot position had moved away from the center by about a diameter. So I checked the beam spot positions with MCASS and indeed found that the spot on MC2 had moved to about 6mm away from the center in yaw and about 3mm in pitch. I adjusted the MC2 (and only MC2) to recenter the spots on all the three mirrors. The new spot positions are given below
spot positions in mm (MC1,2,3 pit MC1,2,3 yaw):
1.3337 -0.2660 0.6641 -1.0973 0.0468 -1.7130
The PSL beam into MC has been readjusted for maximal coupling into MC.
AM modulations are still there ... the mechanical design for the stages, RF cables, and connections are not good and affecting the alignment.
I write the activity in the time series this time - Because we suspect the slight EOM misalignment to the beam produces the unwanted AM sidebands, we tried to align the EOM as much as possible. First I aligned the EOM tilt aligner so that the maximum power goes through. I found that about 5% power was dumped by EOM. After adjusting the alignment, the AM modulation seemed be much better and stable, however, it came up after about 20 mins. They grew up up to about -40dBm, while the noise floor is -60 dBm (when AM is minimised, with DC power of 8V by PDA225 photodetector).
We changed the EOM stage (below the tilt aligner) from a small plate to a large plate, so that the EOM base can be more stable. The EOM stands on the pile of several black plate. There was a gap below the tilt aligner because of a small plate. So we swapped the small plate to large plate to eliminate the springly gap. However it didn't make any difference - it is the current status and there is still AM modulations right now.
During above activities, we leaned that the main cause of the EOM misalignment may be the RF cables and the resonator box connected to the EOM. They are connected to the EOM by an SMA adaptor, not any soft cables. It is very likely applying some torc force to the EOM box. The resonator box is almost hunging from the EOM case and just your slight touch changes EOM alinment quite a bit and AM mod becomes large.
I will replace the SMA connector between the resonator box and EOM to be a soft cable, so that the box doesn't hung from EOM tomorrow. Also, I will measure the AM mod depth so that we compare with the PM mod depth.
ETMX was ringing up when it was mis-aligned for Y arm locking. I restored the input matrix to something more diagonal and its now damping again. Needs more work before we can use the calculated matrix.
I found that some of the Optical Lever Servos were ON today and injecting nonsense into the interferometer optics. I have set all of the gains = 0 to save us more headaches.
I had previously set the gains to zero, see the first line of my entry on Monday 5468. I should have the servo and noise characterisation done today for these oplevs today, so we can review it soon.
RGA scan with maglev pumping speed at day 14 of the pump down.
The larger inserted box contains the tuning parameters of the SRS 200 amu RGA
Here are the open loop transfer functions for ITMY and SRM. The various settings for the OLTFs were as follows:
Oplev filter used for all OLTFs: 300^2:0
Gains for oplev servos (for each OLTF only the 1 servo for the measured TF was on. They are all set back to 0 now):
SRM yaw gain = 1
SRM pitch gain = -1
ITMY yaw gain = -1
ITMY pitch gain = 1
measurement band = 0.2Hz to 200Hz
points = 33
swept sine magnitude envelope: amp = 2 for f > 60Hz, amp = 0.1 for f < 60Hz
Measurement points were from e.g. C1-SUS-ITMY-OLPIT-IN2 to C1-SUS-ITMY-OLPIT-IN1 to give a TF of -(loop gain).
Next step is to divide this through by the sensor reponse (i.e. the calibration factor measured earlier) and the filter response to get just the actuator response.
The SUS SUMMARY screen is now fully activated. You should keep it open at all times as a diagnostic of the suspensions.
No matter how cool you think you are, you are probably doing something bad when trying to lock, measure any loop gains, set matrices, etc. Use the screen.
This is the link to the automatic snapshot of the SUS SUMMARY screen. You can use it to check the Suspensions status with your jPhone.
Auto SUS SUMMARY Snapshot
When the values go yellow its near the bad level. When its red, it means the optic is misaligned or not damped or has the wrong gain, etc.
So don't ignore it Steve! If you think the thresholds are set too low then change them to the appropriate level with the scripts is SUS/
I divided the open loop transfer functions by the filter response and the sensor responses (previously measured calibration factors) to leave just the actuator responses. I've attached the actuator responses plotted in radians/count and phase over frequency.
Next step: fit the actuator response with poles and zeros.
EDIT: I divided by the wrong filter function earlier - the plots there now are divided by the correct filter function
AM modulation depths are found to be 50 times smaller than PM modulation depths.
m(AM,f1) ~ m(AM, f2) = 0.003 while m(PM, f1)=0.17 and m(PM, f2)=0.19.
* DC power = 5.2V which is assumed to be 0.74mW according to the PDA255 manual.
*AM_f1 and AM_f2 power = -55.9 dBm = 2.5 * 10^(-9) W.
AM f2 power is assumed to be the similar value of f1. I can't measure f2 (55MHz) level properly because the PD (PDA255) is 50MHz bandwidth. From the (P_SB/P_CR) = (m/2) ^2 relation where P_SB and P_CR are the sideband and carrier power, respectively, I estimated the rough the AM modulation depths. Although DC power include the AM SB powers, I assumed that SB powers are enough small and the DC power can be considered as the carrier power, P_CR. The resulting modulation depth is about 0.003.
On the other hand, from the OSA, today's PM mod depths are 0.17 and 0.19 for f1 and f2, respectively. Please note that these numbers contains (small) AM sidebands components too. Comparing with the PM and AM sideband depths, AM sidebands seems to be enough small.
AM modulations are still there ... the mechanical design for the stages, RF cables, and connections are not good and affecting the alignment.
I'd like to see some details about how to determine that the ratio of 1:50 is small enough for AM:PM.
* What have people achieved in past according to the elogs© of the measurements?
* What do we expect the effect of 1:50 to be? How much offset does this make in the MICH/PRC/SRC loops? How much offset is too much?
Recall that we are using frontal modulation with a rather small Schnupp Asymmetry...
The signal offset due to the AM modulation is estimated by a simulation for PRCL for now. Please see the result below.
Too see how bad or good the AM modulation with 1/50 modulation depths of PM, I ran a simulation. For example I looked at PRCL sweep signal for each channel. I tried the three AM modulation depths, (1) m_AM=0 & m_PM = 0.17 (2) m_AM = 0.003 & m_PM = 0.17 which is the current modulation situation (3) m_AM = 0.17 & m_PM = 0.17 in which AM is the same modulation depth as PM. For the current status of (2), there are offsets on signals up to 0.002 while the maximum signal amplitude is 0.15. I can't tell how bad it is.... Any suggestions?
(1) m_AM=0 & m_PM = 0.17. There is no offset in the signals.
(2) m_AM = 0.003 & m_PM = 0.17. There are offsets on signals up to 0.002 while the maximum signal amplitude is 0.15.
(3) m_AM = 0.17 & m_PM = 0.17. There are offsets on signals up to 0.1 while the maximum signal amplitude is 0.2.
I will look at MICH and SRCL in the same way.
I found the PSL beam into the MC off in pitch by large amount. I readusted the PSL beam for optimal coupling.
The beam had shifted on the WFS as well. So I recentered the DC signal on the WFS with the MC unlocked. However both the DC and RF signals on the WFS shift when we lock the MC. This ought to indicate sub-optimal coupling of PSL into MC. But instead, if we were to reduce these offsets on the WFS by adjusting the MC axis it leads to higher reflected power from the MC.
The current plan is to retain these RF offsets and lock the WFS with a DC offset in the servo filters.
How about changing the x-axis of all these plots into meters or picometers and tell us how wide the PRC resonance is? (something similar to the arm cavity linewidth expression)
Also, there's the question of the relative AM/PM phase. I think you have to try out both I & Q in the sim. I think we expect Q to be the most effected by AM.
I used an fminsearch function to fit the SRM and ITMY actuator response magnitudes. The testfunction was just that for a single second order pole, but it gave what I consider to be good fits for the following reasons:
*for 3 of the 4 fits the residuals were less than 0.5% of the summed input data points. The worst one (ITMY pitch) was about 2.7%, which I think is due to the resonance happening to be right in the middle of two data points.
*the tolerance of 1 part in 10^9 was reached quickly from not very finely tuned starting points.
The test function was: G=abs(Gp./(1+1i.*f./fp./Qp-(f./fp).^2)), where G(f) is the actuator response magnitude, Gp is the pole gain, fp is the pole frequency, and Qp is the pole Q factor.
In the end I just fitted the response magnitude. I was initially fitting the complex response function, but ran into problems which I think were cased by overall phase offsets between the data and test function. Can I canvass for opinion if fitting the magnitude is OK, or should I try again fitting the phase too?
Anyway, here are the results of the fits, and I've attached plots of each too (each one in linear and log y axis because each on its own might be misleading for fits):
EDIT - I added more points to the otherwise sparse looking fitted curves
ITMY PITCH actuator response fit
-- Fit completed after 190 iterations--
Started with: Gain = 3e-06,
Q factor = 5,
Pole frequency = 1,
Fit results: Gain = 1.32047e-06,
Q factor = 4.34542,
Pole frequency = 0.676676
Residual (normalised against the sum of input datapoints) = 0.0268321
ITMY YAW actuator response fit
-- Fit completed after 156 iterations--
Fit results: Gain = 1.14456e-06,
Q factor = 8.49875,
Pole frequency = 0.730028
Residual (normalised against the sum of input datapoints) = 0.00468077
SRM PITCH actuator response fit
-- Fit completed after 192 iterations--
Fit results: Gain = 7.94675e-06,
Q factor = 7.16458,
Pole frequency = 0.57313
Residual (normalised against the sum of input datapoints) = 0.00301265
SRM YAW actuator response fit
-- Fit completed after 156 iterations--
Fit results: Gain = 3.34179e-06,
Q factor = 9.57601,
Pole frequency = 0.855322
Residual (normalised against the sum of input datapoints) = 0.000840468
Did you take the 180 deg shift into your account ?
Since your measurement was done when the loop was closed, there must be an additional 180 deg phase shift (in other words, minus sign).