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  9776   Wed Apr 2 16:34:15 2014 SteveUpdateVACMaglev controller needs service

Quote:

Quote:

 The date is correct on this monitor.

Last stored RGA scan data Dec 20, 2013

IFO pressure at CC1 5.8e-6 Torr

Valve configuration: Vacuum Normal, confirmable only by manual checking of position indicators and pressure gauge controllers  readouts

 

 The Osaka TG390MCAB maglev turbo pump's controller TC010M has passed the 40,000 hrs of operation. This triggered the " alarm" LED  warning light to come on. 

It is normal maintenance.  Maglev TP-1 is running perfectly.  Osaka will send us a loaner-controller that we can use while they do the std maintenance.

I'm thinking of ~ February to do this.

 We just received the loaner controller that will be swapped in it tomorrow morning.

The vacuum pressure will rise somewhat during this action.

  14189   Wed Aug 29 09:56:00 2018 SteveUpdateVACMaglev controller needs service

TP-1 Osaka maglev controller  [  model TCO10M,  ser V3F04J07 ]  needs maintenance. Alarm led  on indicating  that we need Lv2 service.

The turbo and the controller are in good working order.

*****************************

Hi Steve,

Our maintenance level 2 service price is $...... It consists of a complete disassembly of the controller for internal cleaning of all ICB’s, replacement of all main board capacitors, replacement of all internal cooling units, ROM battery replacement, re-assembly, and mandatory final testing to make sure it meets our factory specifications. Turnaround time is approximately 3 weeks.

  RMA 5686 has been assigned to Caltech’s returning TC010M controller. Attached please find our RMA forms. Complete and return them to us via email, along with your PO, prior to shipping the cont

Best regards,

Pedro Gutierrez

Osaka Vacuum USA, Inc.

510-770-0100 x 109

*************************************************

our TP-1 TG390MCAB is 9 years old. What is the life expectancy of this turbo?

                        The Osaka maglev turbopumps are designed with a 100,000 hours(or ~ 10 operating years) life span but as you know most of our end-users are

                        running their Osaka maglev turbopumps in excess of 10+, 15+ years continuously.     The 100,000 hours design value is based upon the AL material being rotated at

                        the given speed.   But the design fudge factor have somehow elongated the practical life span.  

We should have the cost of new maglev & controller in next year budget. I  put the quote into the wiki.

 

                         

 

  14262   Mon Oct 22 15:19:05 2018 SteveUpdateVACMaglev controller serviced

Gautam & Steve,

Our controller is back with Osaka maintenace completed. We swapped it in this morning.

Quote:

TP-1 Osaka maglev controller  [  model TCO10M,  ser V3F04J07 ]  needs maintenance. Alarm led  on indicating  that we need Lv2 service.

The turbo and the controller are in good working order.

*****************************

Hi Steve,

Our maintenance level 2 service price is $...... It consists of a complete disassembly of the controller for internal cleaning of all ICB’s, replacement of all main board capacitors, replacement of all internal cooling units, ROM battery replacement, re-assembly, and mandatory final testing to make sure it meets our factory specifications. Turnaround time is approximately 3 weeks.

  RMA 5686 has been assigned to Caltech’s returning TC010M controller. Attached please find our RMA forms. Complete and return them to us via email, along with your PO, prior to shipping the cont

Best regards,

Pedro Gutierrez

Osaka Vacuum USA, Inc.

510-770-0100 x 109

*************************************************

our TP-1 TG390MCAB is 9 years old. What is the life expectancy of this turbo?

                        The Osaka maglev turbopumps are designed with a 100,000 hours(or ~ 10 operating years) life span but as you know most of our end-users are

                        running their Osaka maglev turbopumps in excess of 10+, 15+ years continuously.     The 100,000 hours design value is based upon the AL material being rotated at

                        the given speed.   But the design fudge factor have somehow elongated the practical life span.  

We should have the cost of new maglev & controller in next year budget. I  put the quote into the wiki.

 

                         

 

 

Attachment 1: our_controller_is_back.png
our_controller_is_back.png
  3100   Wed Jun 23 11:25:14 2010 Katharine and SharmilaUpdateWIKI-40M UpdateMaglev

Weekly update


Lab work

We compared the magnetic field strength for 4 magnets in the original setup. The standard deviation was 3.15 G which corresponds to a variation of 2.4%. We had encountered difficulties with the stability of the Gaussmeter. The tip of the Gaussmeter was unsteady and wobbling which led to huge variations for a small change in distance. We stabilized the meter by taping it to a pencil and securing it with wire ties to an aluminum block. We then used translation stages to find the point of maximum field strength for each magnet, which allowed us much more stable readings.

Readings

We are reading and learning about feedback control systems. 

Modelling

Learning to model in Comsol. Our goals for the 1X1 model include incorporating the gravitational force in the measurements and find the distance for which attraction is the strongest, and experimenting with the mesh density and boundary conditions of the domain.

Meetings/seminars

Attended many meetings, including:
Laser safety training
SURF safety training
LIGO seminars
Journal club
LIGO experimental group meeting

  3212   Wed Jul 14 01:05:27 2010 Sharmila,KatharineSummaryelogMaglev

Yesterday we hooked up the Quadrant Maglev control to the power supply to test the components in the Input/Output part of the circuit.

The output from the buffer was an unexpected high noise signal which was caused by some circuit components.

Consequently these were replaced/removed after confirming the source of noise.

The following is a story of how it was done.


To test the components of input/output, we measured the output across TP_PD3(Test Point -Photo Diode 3).
We got a high noise signal with a frequency of several kHz.

We tested the values of various electronic components. The resistances R5 and R6 did not measure as mentioned(each had a value of 50 K in the schematic). The value of R6 was 10 K and we replaced R5 with a 10 K resistor. We still got the noise signal at 5.760 kHz with a Pk-Pk voltage of 2.6 V. The resistors in R-LED measured 1.5 K instead of the marked 2.2 K.

P7120278.JPG
We had three suspects in hand:

  • BUF634P : A buffer from the Sallen-Key filter to the LED.
  • C24 : A capacitor which is a part of the Sallen-Key filter.
  • C23 : A capacitor in the feedback circuit of the Sallen-Key filter.


BUF634P : The data sheet for the BUF634P instructed a short across the 1-4 terminals in the presence of capacitive load.  We followed this to overcome the effect(if any) of the extra-long BNC cables which we were using. The oscilloscope still waved 'Hi!' at a few kHz. We removed the buffer and also the feedback resistor R42 from the circuit, what we were testing boiled down to measuring the output of the Sallen-Key filter. The output still contained the funny yet properly periodic signal at a few kHz.      

.P7120284.JPG    


C24: Removing C24 did not do any good.

C23: As a final step C23 was removed. And ... We got a stable DC at 9.86 V(almost stable DC with a low noise at a few MHz). C24 and the buffer were replaced and output seemed fine. The output was a high frequency sine wave which was riding on a DC of 9.96 V.

 

P7120281.JPG


We rechecked if the LED was on and the infrared viewer gave a positive signal.



We went ahead obtaining the transfer function of the feedback control for which we used a spectrum analyzer.

The input for feedback system is a photo current whereas the spectrum analyzer tests the circuit with a voltage impulse.  Hence the voltage input from the spectrum analyzer needs to be converted into current of suitable amplitude(few microamps) for testing the spectrum analyzer.  Similarly the output which is a coil current needs to be changed to a voltage output through a load for feeding into the channel of the spectrum analyzer. We used a suitable resistance box with BNC receiving ends to do this. We obtained a plot for the transfer function which is shown below.

P7140292.JPG


Future plans:

- Check the calculated transfer functions with the plot of the spectrum analyzer

- Model the entire(OSEM, magnet, actuators etc.) system in Simulink and calculate the overall transfer function

- Stable levitation of the 1X1 system

  3250   Tue Jul 20 11:55:15 2010 Sharmila,KatharineUpdateelogMaglev

We plotted the transfer functions for the maglev control circuit and compared them with the plots from the spectrum
analyzer. We were stuck for sometime because

1) we had wrongly entered the value of one of the resistors which was off by a factor of 2000.
2) The plots were not done in right units. So we couldn't figure out differences quite well.

The two plots are shown below. We are still off by a factor of 3 which we'll figure out soon.

P7140292.JPG

  3305   Wed Jul 28 12:09:06 2010 Sharmila,KatharineUpdateWIKI-40M UpdateMaglev

We have modeled our maglev setup in simulink but we have a few corrections to make since the system goes into undamped oscillations for an impulse in the input.

We have made a stable mount for the system and started to work on the 2X2 system using this mount. We have to figure out a way to match the magnets with the gain. We have attached the simulink block.

Picture_1.png

  4120   Thu Jan 6 00:06:01 2011 JenneUpdateIOOMagical absorbing PZT mirror

[Kiwamu, Jenne]

We have a measely 465mW going into the MC.  We lose a boatload of power on the PZT mirror that is part of the last zigzag for steering into the MC.  Just before this mirror, we measure 1.21W .  Just after this mirror, we measure ~475mW.  Then a teeny bit gets picked off for the PSL POS/ANG.  But we're losing a factor of 3 on this one mirror.  Need to fix!!!!!!!!!

  1513   Thu Apr 23 21:13:37 2009 YoichiSummaryEnvironmentMag. 4 earthquake in LA tripped the watchdogs of the most optics
So far, no damage is noticeable.
restoreWatchdog script was useful Smile
-------------------------------------------------------
Magnitude    4.0
Date-Time    * Friday, April 24, 2009 at 03:27:50 UTC
             * Thursday, April 23, 2009 at 08:27:50 PM at epicenter 
Location     33.910N, 117.767W
Depth	     0 km (~0 mile) (poorly constrained)
Region	     GREATER LOS ANGELES AREA, CALIFORNIA
-------------------------------------------------------
  1183   Sun Dec 7 16:02:46 2008 ranaUpdateGeneralMag 5.1 EQ halfway to Vegas
There was a Mag 5.1 EQ Friday night at 8:18 PM.

It tripped most of our optics. They all damped down passively except for MC2. Further more, ITMY seems to have come back to a different place.

Don't know why MC2 was so upset but I think maybe its watchdog didn't work correctly and the side loop is unstable when there are
large motions. After I lowered the side gain by 10x and waited a few minutes it came back OK and the MC locked fine.

I have just now put all the WDs into the Shutdown state so that we can collect some hours of free swinging data to see if there's been
any damage. Feel free to redamp the optics whenever you need them. Someone should do the eigenfrequency check in the morning and compare
with our table of frequencies in the wiki.

I excited the optics using the standard SUS/freeswing-all.csh script. Here's the output:
Excited all optics
Sun Dec  7 16:07:32 PST 2008
Attachment 1: g.png
g.png
Attachment 2: Untitled.png
Untitled.png
  345   Thu Feb 28 16:19:37 2008 josephbConfigurationComputersMafalda rewired and multiple cameras running
1) Mafalda is now connected via an orange Cat5E ethernet cord to the gigabit ethernet switch in rack in the office space. It has been labeled at both ends with "mafalda".

2) Both the GC650M camera (from MIT) and the GC750M are working. I can run the sampleviewer code and get images simultaneously. Unforutnately, the fps on both cameras seems to drop roughly in half (not an exact measurement) when displaying both simultaneously at full resolution.

3)Discovered the Gigabit ethernet card in Mafalda doesn't support jumbo packets (packets of up to 9k bytes), which is what they recommend for optimum speed.

4)However, connecting the cameras through only gigabit switches to Mafalda did seem to increase the data rate anyways, roughly by a factor of 2. (Used to take about 80 seconds to get 1000 frames saved, now takes roughly 40 seconds).

5)Need to determine the bottleneck on the cameras. It may be the ethernet card, although its possible to connect multiple gigabit cards to single computer (depending on the number of PCI slots it has). Given the ethernet cards are cheap ($300 for 20) compared to even a single camera (~$800-1500), it might be worth while outfitting a computer with multiple.
  3714   Thu Oct 14 10:29:33 2010 josephbUpdateComputersMafalda ready for NDS2, updated Rosalba, Rossa repos

At John Zweizig's request, I installed a couple of packages from the lscsoft repository, along with libtools, automake, autoconf, and several kerberos packages, including cyrus-sasl, cyrus-sasl-lib, cyrus-sasl-devel, cyrus-sasl-gssapi, and krb5-libs.  All it needs now is John to come down and install the NDS2 server.

I copied the lscsoft.repo file from /etc/yum.conf.d/ on allegra to mafalda, as well as rosalba and rossa, just for completeness.  I also added the epel repository to rossa and installed the yum-priorities package and set the priorities on rossa's repositories. 

  1497   Sun Apr 19 11:51:05 2009 josephbUpdateCamerasMafalda may need an update

I tried installing libusb-dev on mafalda in order to try getting the usb frame grabber to work on it, but could not as it could not download the package.

I then tried to do a sudo apt-get update, which failed completely, as the repository seems to have ceased existing.  Basically I had all 404 Not Found errors.

Turns out Mafalda is still running Ubuntu 7.04, whose support ended late 2008.  So there's a couple things that can be done:

1) Ignore it, and simply not update Mafalda anymore.  This also means some newer software and hardware simply won't work with it (like the usb frame grabber)

2) Try to find another, unofficial repository which still has all of the Ubuntu 7.04 packages.

3) Upgrade to a newer, still supported Ubuntu, such as 7.10, 8.04, or 8.10.

I'd personally lean towards the 3rd option, and go to the 8.04 long term support version.  If people agree with it, I could do the upgrade sometime Monday or Tuesday.

 

 

  1499   Mon Apr 20 11:57:27 2009 robUpdateCamerasMafalda may need an update

Quote:

I tried installing libusb-dev on mafalda in order to try getting the usb frame grabber to work on it, but could not as it could not download the package.

I then tried to do a sudo apt-get update, which failed completely, as the repository seems to have ceased existing.  Basically I had all 404 Not Found errors.

Turns out Mafalda is still running Ubuntu 7.04, whose support ended late 2008.  So there's a couple things that can be done:

1) Ignore it, and simply not update Mafalda anymore.  This also means some newer software and hardware simply won't work with it (like the usb frame grabber)

2) Try to find another, unofficial repository which still has all of the Ubuntu 7.04 packages.

3) Upgrade to a newer, still supported Ubuntu, such as 7.10, 8.04, or 8.10.

I'd personally lean towards the 3rd option, and go to the 8.04 long term support version.  If people agree with it, I could do the upgrade sometime Monday or Tuesday.

 

 

 

I don't see a reason to proliferate operating systems.  Is there any reason we actually need Ubuntu? Can we put CentOS on it?

  1501   Mon Apr 20 18:36:37 2009 ranaUpdateCamerasMafalda may need an update
Sadly, the sensoray crap doesn't seem to build on CentOS. I too would prefer a homogenous solution,
but I don't know how to make this happen without punishing Joe with sensoray driver development on CentOS.
  6991   Thu Jul 19 02:14:37 2012 JenneUpdateVIDEOMade a video gui

I learned a little bit of python scripting while looking at the videoswitch script, and I made a video medm screen. 

Each monitor has a dropdown menu for all the common cameras we use (medm only lets you put a limited # of lines on a dropdown menu...when we want to add things like OMCR or RCT, we'll need to add another dropdown set)

Each monitor also has a readback to tell you what is on the TV.  So far, the quads only say "QUAD#", not what the 4 components are. 

I put a set of epics inputs in the PEM model, under a subsystem with top-names VID to represent the different monitors.  The readbacks on the video screen look at these, with the names corresponding to the numbers listed in the videoswitch script.  The videoswitch script now does an ezcawrite to these epics inputs so that even if you change the monitors via command line, the screen stays updated.

For example, since MC2F's camera is plugged in to Input #1 of the video matrix, if you type "./videoswitch MON1 MC2F", the script will write a "1" to the channel "C1:VID-MON1", and the screen will show "MC2F" in the Mon1 cartoon.

This required a quick recompile of the PEM model, but not the framebuilder since these were just epics channels.

There is also a dropdown menu for "Presets", which right now only include my 2 arm locking settings.

All of the dropdowns just call an iteration of the videoswitch script.

  14164   Wed Aug 15 12:15:24 2018 gautamUpdateCOCMacroscopic SRC length for SR tuning

Summary:

It looks like we can have a stable SRC of length 4.044 m without getting any new mirrors, so this is an option to consider in the short-term.

Details:

  • The detailed calculations are in the git repo
  • The optical configuration is:
    • A single folding mirror approximately at the current SR3 location.
    • An SRM that is ~1.5m away from the above folding mirror. Which table the SRM goes on is still an open question, per the previous elog in this thread. 
  • The SRC length is chosen to be 4.044 m, which is what the modeling tells us we need for operating in the SR tuning instead of RSE.
  • Using this macroscopic length, I found that we could use a single folding mirror in the SRC, and that the existing (convex) G&H folding mirrors, which have a curvature of -700m, happily combine with our existing SRM (concave with a curvature of 142m) to give reasonable TMS and mode-matching to the arm cavity.
  • The existing SRM transmission of 10% may not be optimal but Kevin's calculations say we should still be able to see some squeezing (~0.8 dB) with this SRM.
  • Attachment #1 - corner plot of the distribution of TMS for the vertical and horizontal modes, as well as the mode-matching (averaged between the two modes) between the SRC and arm cavity.
  • Attachment #2 - histograms of the distributions of RoCs and lengths used to generate Attachment #1. The distributions were drawn from i.i.d Gaussian pdfs.

gautam 245pm: Koji pointed out that the G&H mirrors are coated for normal incidence, but looking at the measurement, it looks like the optic has T~75ppm at 45 degree incidence, which is maybe still okay. Alternatively, we could use the -600m SR3 as the single folding mirror in the SRC, at the expense of slightly reduced mode-matching between the arm cavity and SRC.

Attachment 1: SRC_MCMC_shortTerm.pdf
SRC_MCMC_shortTerm.pdf
Attachment 2: SRC_dists_shortTerm.pdf
SRC_dists_shortTerm.pdf
  7418   Thu Sep 20 08:50:14 2012 MashaUpdateMachineLearningMachine Learning Update

 Hi everyone,

I've been working a bit on neural network code for a controller, and thus far I have code that creates a reference plant neural network. This is necessary to perform a gradient-descent learning algorithm on a controller neural network (one that reads an error signal and outputs actuation force). Because the error signal is read after the previous output of the controller neural network has passed through the plant, in order to calculate the gradient, either the inverse of the plant needs to be calculated, or the plant can be simulated through a neural network, and the error signal can thus be back-propagated through the plant neural network to find the gradient with respect to the output (as opposed to with respect to the plant), and thus back-propagated through the controller network in order to learn. 

I have uploaded to my directory a directory neural_plant. The most important file is reference_plant.c, which compiles with the command

 gcc reference_plant.c -o reference_plant -lfann -lm

The code runs on a file called reference_plant.data, which consists of a series of delayed inputs i_1, i_2, i_3 ... i_{n - 1} of the plant signals and then an output that is i_{n}, the subsequent signal. Parallel streams may also be used, if more than one signal is to be read. The top of the file must contain the number of total training packets (input-output groups), followed by the number of inputs, and the number of outputs. reference_plant.c also has constant variables which specify the number of hidden neurons, which can be changed. 

 
All of this code runs on the FANN library. If the code doesn't seem to be compiling, then it means the library might have to be downloaded and built from source.
 
Thus far, I have created my own plant in simulink (the driven, damped harmonic oscillator, as before), and obtained results of 0.0002929292 training MSE after 5 epochs (subsequently lowered to 0.000)  and 0.000 training error. This, however, is due to the fact that my plant is overly simple, and seems only to need 3 time-delayed plant signals, rather 31 to specify it (since all motion is second-order). 
 
It should be fairly easy to use interferometer signals as input to this plant by just reading some signals and parsing them into time-delayed groups. (I tried this over the summer with my previous code, and it seemed to work, although I haven't accessed any of the channels to obtain data lately). 
 
In terms of LIGO stuff this week, I'm going to be finishing up (writing) my final report, but please let me know if you have any comments or concerns. 
 
Thanks!
  293   Fri Feb 1 17:17:05 2008 JohnSummaryPSLMach-Zender tweaking
I helped Rob adjust the alignment of the Mach-Zender to try and reduce any AM on the laser light. Our goal was to reduce the large offsets in the DD signals.

We reduced the MZ refl from 0.54 to 0.39. We were able to re-lock the mode cleaner without problems. We then centred the WFS heads.

No change in the DD signal offsets.
  1160   Mon Nov 24 17:14:44 2008 ranaUpdatePSLMach Zender trends
It looks like the MZ has gotten less drifty after the alignment on Friday.
Attachment 1: Untitled.png
Untitled.png
  1151   Fri Nov 21 16:11:26 2008 rana, alberto, robUpdatePSLMach Zender alignment
The Mach Zender's dark port DC voltage had gone up too high (~0.5 V)and was turning yellow
on the screen. I re-aligned by touching the knobs on the 166 MHz path. Doing alignment after the
166 EOM had very little effect. The main improvement came from doing yaw on the turning mirror
just ahead of the 166 MHz EOM; this is the one which as no adjustment knobs (duh).

During this procedure, I had the MC off, the ISS off, and the MC autolocker off. After finishing
the alignment, the power on the ISS PDs had railed and the dark port power was ~0.29 V. So we
put in a ND0.2 on the ISS path and now the voltages are OK (~2 V on each PD). We have to remove the
ND filters and change the first ISS turning mirror into a ~10-20% reflector.


So now the MZ alignment seems good; Alberto is on the MC periscope alignment like a cheap suit.
Attachment 1: PB210051-1.JPG
PB210051-1.JPG
  1155   Fri Nov 21 20:29:43 2008 rana, alberto, robUpdatePSLMach Zender alignment

Quote:
So now the MZ alignment seems good; Alberto is on the MC periscope alignment like a cheap suit.


And alignment is now mostly done - MC locks on the TEM00.
                 REFL_DC

Unlocked           4.50  V
Locked noWFS       1.30  V
Locked + WFS       0.42  V
and the 29.5 MHz modulation depth is really small.

We should be able to rerun the Wiener analysis on this weekends MC data.

I don't know what our nominal StochMon numbers now are, but after Alberto tweaks up the alignment he can tell us if the RFAM has gotten any better.
  2406   Sun Dec 13 20:50:45 2009 ranaSummaryIOOMach Zender Calibration

I ramped the MZ PZT (with the loop disabled on the input switch) to calibrate it. Since the transmission has been blocked, I used the so-called "REFL" port of the MZ to do this.

The dark-to-dark distance for the MZ corresponds to 2 consecutive destructive interferences. Therefore, that's 2 pi in phase or 1 full wavelength of length change in the arm with the moving mirror.

Eyeballing it on the DTT plot (after lowpassing at 0.1 Hz) and using its cursors, I find that the dark-to-dark distance corresponds to 47.4 +/- 5 seconds.

So the calibration of the MZ PZT is 88 +/- 8 Volts/micron.

Inversely, that's a mean of 12 nm / V.

why am I calibrating the MZ? Maybe because Rob may want it later, but mainly because Koji won't let me lock the IFO.

Apparently, we haven't had a fast channel for any of the MZ board. So I have temporarily hooked it up to MC_DRUM at 21:13 and also turned down the HEPA. Now, let's see how stable the MZ and PMC really are overnight.

EDIT: it railed the +/- 2V ADCwe have so I put in a 1:4 attenuator via Pomona box. The calibration of MC_DRUM in terms of MZ_PZT volts is 31.8 cts/V.

So the calibration of MC_DRUM1 in meters is: 0.38 nm / count


Attachment 1: Untitled.png
Untitled.png
  618   Tue Jul 1 21:45:48 2008 JohnUpdatePSLMach Zehnder script and screen
I've edited C1: PSL_MACH_ZEHNDER.adl and /cvs/cds/caltech/scripts/PSL/MZ/lockMZ
to reflect the changes described in entry #616.
  1922   Tue Aug 18 01:16:01 2009 JenneUpdatePSLMach Zehnder is realigned

The Mach Zehnder and I got to know each other today.  The reason for redoing the alignment was to improve pointing from the PSL table into the MC/IFO in hopes that this would solve the MC unlocking problems that we've been having lately.  Since Rana had aligned the IOO QPDs a few weeks ago when all of the alignments and things were good, I used them as a reference for my Mach Zehnder alignment activities. 

 
The order of operations were approximately as follows:

1. Block the secondary (west) arm of the Mach Zehnder using either an aluminum or razor dump.

2. Use SM1 in the MZ to align the beam to the IOO_QPDs (Pos and Ang).  I unfortunately also touched BS2 at this juncture, which made the refl path no longer a reference.

3.  Make sure that the QPD Sum on both Pos and Ang was sensible.  Since there are 2 beamsplitters in a Mach Zehnder, the power on the QPDs should be a quarter when only one beam is on them.  Be careful not to allow the beam no clip on anything.  The biggest problem was the bottom periscope mirror - if you hit it too high or too low, since it is a very thick optic, you end up coming out its side!  This is the frosty part on the edges, totally inappropriate for beams to go through!  Since the side of the periscope mirror isn't HR coated, when going through it like this, I was able to saturate the QPDs.  Not so good. 

4. Also, make sure that this first beam is on the MZ Refl PD.  Do this using the steering optics after the beam has left the MZ.  Use a viewer to look at the PD, and see the small spot of the beam on the diode.  We closed the iris which is present and was standing fully open to remove a spurious beam which was a parallel split-off of the main beam.  Since it was very weak, it is fine.

5.  Unblock the west arm, and block the east arm of the MZ.

6. Align this arm to both the IOO QPDs and the MZ refl diode using the adjustments on BS1, the PZT mirror and if necessary, BS2.  Note that the adjust knobs on the PZT mirror have lock screws.  Make sure to unlock them before adjusting, and relock afterward, to avoid slipping while the PZT is moving.

7.  Unblock all the beams, and make sure there is only one spot both on the transmission side and the reflection side, i.e. the 2 spots from the 2 arms are completely overlapping.  For the Trans side, make sure to look both in the near field and the far field (even after the periscope) to ensure that you really have one spot, instead of just the 2 spots crossing at a single location.

8.  Look at the MZ refl DC out and the PD out from the ISS box (which is essentially MZ trans, looking at Morag and Siobhan) on a 'scope.

9.  Touch / gently wiggle BS1 or another optic, and watch the 'scope.  At the same time, adjust BS1, the PZT mirror and BS2 to maximize the contrast between light and dark fringes.  Ideally, the refl PD should go almost to zero at the dark fringes.

10.  Check that you still have only one overlapping beam everywhere, and that you're actually hitting the MZ refl PD.

11. Because I was concerned about clipping while still figuring out the status of the lower periscope mirror, I removed the beam pipe holders between the last optic before the periscope, and the lower periscope mirror.  The beam pipe had already been removed, this was just the pedestals and the snap-in clamps.

All done for now!  Still to be done:  Optimize the position of the EOMs.  There is a waveplate out front and the EOMs are mounted in such a way that they can be moved in several directions, so that we can optimize the alignment into them.  They ideally only should see a single polarization, in order to apply solely a phase modulation on the beam.  If the input polarization isn't correct, then we'll get a bit of amplitude modulation as well, which on PDs looks like a cavity length change.  Also, the little blue pomona-type box which has the RF signals for the EOMs needs to be clamped to the table with a dog clamp, or better yet needs to be moved underneath the PSL table, with just the cables coming up to the EOMs.  The SMA connections and the SMA cable kept interfering with the MZ refl beam...it's a wonder anyone ever made the beam snake around those cables the way they were in the first place. Right now, the box is sitting just off the side of the table, just inside the doors.

 
Something else that Rana and I did while on the table:  We moved the PMC trans optics just a teensy bit toward the PSL door (to the east) to avoid coming so unbelievably close to the MZ refl optics.  The PMC trans beam shown in the lowest part of my sketch was very nearly clipping on the MZ refl steering optic just near it.  This situation isn't totally ideal, since (as it has been in the past), the first optic which is dedicated to the PMC trans isn't fully sitting on the PSL table.  The pedestal needs to hang off the edge of the table a bit to keep this beam from clipping.  Unfortunately there really isn't space to make a better beam path.  Since we're planning on getting rid of the MZ when the upgrade happens, and this isn't causing us noticeable trouble right now, we're going to let it stay the way it is.

Also, we dumped the reflection from the PMC RFPD onto a razor blade dump. And we noticed that the PZT mirror and BS2 in the MZ are badly vibrationally sensitive. BS2 has a ~400 Hz resonance (which is OK) but a ~150 ms ringdown time!! PZT mirror is similar.

Q = pi * f * tau = 200!  Needs some damping.

Attachment 1: MachZehnderOptics2.pdf
MachZehnderOptics2.pdf
  1244   Thu Jan 22 11:54:09 2009 AlbertoConfigurationPSLMach Zehnder Output Beam QPD
I rotated by 180 degrees the 10% beam splitter that it is used to fold the beam coming from the Mach Zehnder (directed to the MC) on to the QPD.

The alignment of the beam with that QPD has so been lost. I'll adjust it later on.

The rotation of the BS had the (surprising) effect of amplifying the Absolute Length experiment's beat by 9 times. Maybe because of a polarizing effect of the Beam Splitter which could have increased the beating efficiency between the PSL and the NPRO beams?
  2021   Tue Sep 29 21:37:09 2009 ranaUpdateMZMZ work done : some noise checking

Since we used to run with a gain slider setting of +15 dB on the MZ, I wanted to check that the new setting of +30dB was OK. It is.

To check it I turned it up and looked for some excess noise in the ISS or in the MC. There was none. I also set the input offset slider by unlocking the PMC and zeroing the mixer monitor readback. The new slider setting is -6.5V.

I don't know why we would need more gain on the MZ loop, but we can have some if we want it by turning up the gain before the servo (optical or RF). The attached plot shows the MC_F and ISS signals with the ISS loop on and off. There was no change in either of these spectra with the MZ gain high or low.

Attachment 1: fsm.pdf
fsm.pdf
  2022   Tue Sep 29 21:51:32 2009 KojiUpdateMZMZ work done : some noise checking

The previous "+15" was Vctrl = 0.25 [V]. Which was +18 dB.

Quote:

Since we used to run with a gain slider setting of +15 dB on the MZ, I wanted to check that the new setting of +30dB was OK.

 

  2038   Thu Oct 1 19:04:05 2009 KojiUpdateMZMZ work done (Re: MZ Work from 13:00-)

MZ work has been done. I did not change anything on the circuit.

Recently we observed that the MZ PZT output was sticking at a certain voltage. I found the reason.
Shortly to say "we must return the PZT Ramp offset to 0, after the lock"

I am going to write a MZ auto lock script someday, to do it automatically.


According to the resister values used in the circuit, the PZT HV output voltage is determined by the following formula:

V_PZT = 150 - 12 V_ctrl - 24 Vramp

Here the ramp voltage Vramp moves from -10V to +10V, the feedback control voltage V_ctrl moves from -13V to +13V.
The baseline offset of 150V is provided in the circuit board.

When V_ramp is 0, V_PZT runs from 0 to 300. This is just enough for the full scale of the actual V_PZT range,
that is 0V~280V.

If any Vramp offset is given, V_PZT rails at either side of the edges. This limits the actual range of the PZT out.

This is not nice, but is what happened recently.

Quote:

I will investigate the MZ board. I will unlock MZ (and MC).

 

Attachment 1: MZ_PZT.pdf
MZ_PZT.pdf
  2020   Tue Sep 29 18:21:41 2009 KojiUpdateMZMZ work done

The MZ work completed. I replaced the bad cross connection terminal. The gain slider is working now.

I looked at the error spectrum on an FFT analyzer. I could see the lock was more tight.

Then I proceeded to the MZ epics panel.

1) C1:PSL-MZ_MZTRANSPD has no meaning (not connected). So I put  C1:PSL-ISS_INMONPD as the MZ trans monitor.

2) The EPICS setting for the MZ gain slider was totaly wrong.
    Today I learned from the circuit, the full scale of the gain slider C1:PSL-MZ_GAIN gave us +/-10V at the DAC.
    This yield +/-1V to V_ctrl of the AD602 after the internal 1/10 attenuation stage.
    This +/-1V didn't correspond to -10dB~+30dB, but does -22dB~+42dB and is beyond the spec of the chip.

    The gain of AD602 is calculated by

G [dB] = 32 V_crtl + 10,  for -0.625 [V]< V_ctrl < +0.625 [V].

    In order to fix this I used the following commands which overrode the EPICS parameters.
    The tip of EGUF/EGUL is to know how much the gain (virtually) goes for the full scale of the DAC output. 

ezcawrite C1:PSL-MZ_GAIN.EGUF 42
ezcawrite C1:PSL-MZ_GAIN.EGUL -22
ezcawrite C1:PSL-MZ_GAIN.DRVH 30
ezcawrite C1:PSL-MZ_GAIN.DRVL -10
ezcawrite C1:PSL-MZ_GAIN.HOPR 30
ezcawrite C1:PSL-MZ_GAIN.LOPR -10

   and for the permanent change I modified the db file /cvs/cds/caltech/target/c1iool0/c1iooMZservo.db
   This will be active when cliool0 is rebooted.

# This yields the output limited to -6.25V ~ +6.25V, which corresponds to -10dB ~ +30dB
# modified by Koji Arai (29-Sept-2009)
grecord(ao,"C1:PSL-MZ_GAIN")
{
        field(DESC,"GAIN- overall pre-modecleaner servo loop gain")
        field(SCAN,"Passive")
        field(PINI,"YES")
        field(DISV,"1")
        field(DTYP,"VMIVME-4116")
        field(OUT,"#C3 S5 @")
        field(EGUF,"42")
        field(EGUL,"-22")
        field(PREC,"1")
        field(EGU,"dB")
        field(HOPR,"30")
        field(LOPR,"-10")
        field(DRVH,"30")
        field(DRVL,"-10")
        field(LINR,"LINEAR")
        field(OROC,"0")
        field(DOL,"0")
}

# previous code
grecord(ao,"C1:PSL-MZ_GAIN")
{
        field(DESC,"GAIN- overall pre-modecleaner servo loop gain")
        field(SCAN,"Passive")
        field(PINI,"YES")
        field(DISV,"1")
        field(DTYP,"VMIVME-4116")
        field(OUT,"#C3 S5 @")
        field(EGUF,"30")
        field(EGUL,"-10")
        field(PREC,"4")
        field(EGU,"Volts")
        field(HOPR,"30")
        field(LOPR,"-10")
        field(LINR,"LINEAR")
        field(OROC,"0")
        field(DOL,"0")
}

Quote:

12:45 I started the work on MZ. Thus the MZ was unlocked.

Fond the bad connection on the FLKM 64pin cross connection board. We need the replacement.

I went to Wilson and got the replacement, two VME extender boards, three 7815, and three 7915. Thanks, Ben!

 

  2006   Sat Sep 26 13:55:20 2009 JenneUpdateMZMZ was locked in a bad place

I found the MZ locked in a bad place earlier today.  It was locked in a similarly bad spot yesterday after we fixed the cable situation for 126MOPA_126MON, with reflection of ~0.8, rather than the nominal 0.305.  It's good now though. 

  1149   Thu Nov 20 09:37:39 2008 steveUpdatePSLMZ vs temp
This 12 days plot shows that it can hold lock if the daily temp variation is not more than 3/4 of a degree C
The MZ is happy if it's HV is above 100V
Attachment 1: mztemp.jpg
mztemp.jpg
  2018   Tue Sep 29 12:47:08 2009 KojiUpdateMZMZ unlocked

12:45 I started the work on MZ. Thus the MZ was unlocked.

Found the bad connection on the FLKM 64pin cross connection board. We need a replacement.

I went to Wilson and got the replacement, two VME extender boards, three 7815, and three 7915. Thanks, Ben!

  616   Tue Jul 1 16:48:42 2008 rob, johnConfigurationPSLMZ servo switch problem resolved forever

Quote:
C1:PSL-MZ_BLANK switch (to turn on/off the servo) is not working again. The switch is always off regardless of the epics state.
I pushed the cables into the xycom card, but it did not fix the problem.


We have fixed this problem forever, by totally disabling this switch. Looking at the schematic for the MZ servo and the datasheet of the AD602, we found that a HI TTL on pin 4 disables the output of the AD602. Since the MZ servo was stuck in the off position, this seemed to indicate that it may be the XYCOM220 itself which is broken, constantly putting out a +5V signal regardless of the EPICS controls. We thought we might be able to get around this by disconnecting this signal at the cross-connect, but ultimately we couldn't find it because there is no wiring diagram for the Mach-Zehnder (!). So, we pulled the board and wired pin 9A of P1 to ground, permanently NORMALizing the MZ_BLANK switch. John has marked up the schematic, and someone should modify the MEDM screen and check the new screen into svn.

We can still the turn the MZ servo on and off by using the test input 1 switch.

Someone also will need to modify the MZ autolocker to use the test input 1 (MZ_SW1) instead of the old MZ_BLANK.
  611   Tue Jul 1 11:57:24 2008 YoichiConfigurationPSLMZ servo switch problem again
C1:PSL-MZ_BLANK switch (to turn on/off the servo) is not working again. The switch is always off regardless of the epics state.
I pushed the cables into the xycom card, but it did not fix the problem.
  221   Thu Jan 3 09:12:59 2008 steveUpdatePSLMZ servo
Here is MZ trend for one year and 40 days.
Now days it runs out of range on the low side.
This is the weakest link in the psl today.
Attachment 1: mz1y.jpg
mz1y.jpg
Attachment 2: mz40d.jpg
mz40d.jpg
  2032   Thu Oct 1 09:36:09 2009 KojiUpdateMZMZ relocked (Re:suspention damping restored and MZ HV stuck)

MZ stayed unlocked. Now It was relocked.

Quote:

Earthquake  of magnitude 5.0  shakes ETMY loose.

MC2 lost it's damping later.

 

  639   Mon Jul 7 13:49:27 2008 YoichiHowToPSLMZ offset, gain tips
John, Yoichi

This morning John found that MZ servo is not working.
We were able to bring the MZ back by changing the output offset a bit. But we were not sure what was actually wrong.
So we pulled out the MZ board and checked several TPs to understand the behavior.
Here is the summary of what we learned this morning.

The MZ control board has the following stages:

[Mixer] -(error signal)-> [Sum amp for input offset] -(error + offset)-> [Variable Gain Amp] -> [Filter (x100 DC gain)] -(FB signal)-> [High Voltage Amp] -> output
(The HV amp also works as the sum amp for the output offset)

(1) We noticed that the Sum amp for the input offset has an output of -0.14V even when the offset input is 0V. This can be canceled by the input offset slider.
So for the moment, it is fine. But we might want to change the op-amp because the weird offset implies there might be something wrong with the chip.
The procedure to null the -0.14V offset is the following:
a) Enable Test 1 input on the MZ MEDM screen.
b) Move the input offset slider until the mixer monitor becomes 0V. Currently the input offset slider is at -7.5V to cancel the -0.14V offset.

(2) Because the gain of the Variable Gain Amp and the Filter combined is large, the Filter can be easily saturated if the output offset is not right.
This was the cause of the MZ problem this morning. The output offset slider was at a wrong position making the error signal slightly off centered from zero.
This residual DC error signal was amplified by the large gain chain and saturated the filter amp.
Our experience is that the output offset cannot go below -3V. We set it at 0V for now.
  1884   Tue Aug 11 01:21:55 2009 robUpdatePSLMZ needs some attention

the servo needs some work. 

 

2 day trend

 

Attachment 1: badMZservo.png
badMZservo.png
  931   Fri Sep 5 08:34:03 2008 steveUpdatePSLMZ locked
The MC is happy.
The MZ can be locked if you move the slider by hand.
Attachment 1: mzhv.jpg
mzhv.jpg
  1012   Wed Oct 1 02:10:03 2008 ranaUpdateIOOMZ is going bad
Here's a 2 day trend of the MZ. You can see that there is something bad with ERR - it should really be going to zero.

Also LODET is dead. We need to rejuvinate LODET somehow.

The next plot is a 90 day hour-trend of the same signals. You can see that LODET came back to us between
September 10 and 19 ??? I looked at a 4 year trend and it seems that this signal has always been zero
(nice use of disk space) except for a few days in Nov of 06 and then whatever happend on Sep 10.
Attachment 1: Untitled.png
Untitled.png
Attachment 2: Untitled.png
Untitled.png
  2017   Tue Sep 29 10:44:29 2009 KojiUpdateMZMZ investigation

Rana, Jenne, Koji

Last night we checked MZ. The apparent thing we found was the gain slider does not work.
The slider actually changes the voltage at the cross connection of 1Y2 (31 pin4?), the gain does not change.
The error spectrum didn't change at all even when the slider was moved.

Rana poked the flat cable at the bottom of 1Y2, we had no imporvement.

We coudn't find the VME extender board, so we just replaced AD602 (=VGA) and LT1125 (=Buffer for the ctrl voltage).
Even after the replacement, the gain slider is not working yet.

Today, I will put a lead or probe to the board to see whether the slider changes the voltage on the board or not.

Somehow the gain is sitting at a intermediate place that is not to low not to high. So I still don't know the gain slider
is the cause of the MZ instability or not.

  14547   Wed Apr 17 00:43:38 2019 gautamUpdateFrequency noise measurementMZ interferometer ---> DAQ
  1. Delay fiber was replaced with 5m (~30 nsec delay)
    • The fringing of the MZ was way too large even with the free running NPRO (~3 fringes / sec)
    • Since the V/Hz is proportional to the delay, I borrowed a 5m patch cable from Andrew/ATF lab, wrapped it around a spool, and hooked it up to the setup
    • Much more satisfactory fringing rate (~1 wrap every 20 sec) was observed with no control to the NPRO
  2. MZ readout PDs hooked up to ALS channels
    • To facilitate further quantitative study, I hooked up the two PDs monitoring the two ports of the MZ to the channels normally used for ALS X.
    • ZHL3-A amps inputs were disconnected and were turned off. Then cables to their outputs were highjacked to pipe the DC PD signals to the 1Y3 rack
    • Unfortunately there isn't a DQ-ed fast version of this data (would require a model restart of c1lsc which can be tricky), but we can already infer the low freq fringing rate from overnight EPICS data and also use short segments of 16k data downloaded "live" for the frequency noise measurement.
    • Channels are C1:ALS-BEATX_FINE_I_IN1 and C1:ALS-BEATX_FINE_Q_IN1 for 16k data, and C1:ALS-BEATX_FINE_I_INMON and C1:ALS-BEATX_FINE_I_INMON for 16 Hz.

At some point I'd like to reclaim this setup for ALS, but meantime, Anjali can work on characterization/noise budgeting. Since we have some CDS signals, we can even think of temperature control of the NPRO using pythonPID to keep the fringe in the linear regime for an extended period of time.

  14571   Thu Apr 25 03:32:25 2019 AnjaliUpdateFrequency noise measurementMZ interferometer ---> DAQ
  • Attachment #1 shows the time domain output from this measurement. The contrast between the maximum and minimum is better in this case compared to the previous trials.
  • We also tried to extract the frequency noise of the laser from this measurement. Attachment #2 shows the frequency noise spectrum. The experimental result is compared with the theoretical value of frequency noise. Above 10 Hz, the trend is comparable to the expected 1/f characteristics, but there are other peak also appearing. Similarly, below 10 Hz, the experimentally observed value is higher compared to the theory.
  • One of the uncertainties in this result is because of the length fluctuation of the fiber. The phase fluctuation in the system could be either because of the frequency noise of the laser or because of the length fluctuation of the fiber.  So,one of the reasons for the discrepancy between the experimental result and theory could be because of  fiber length fluctuation. Also, there were no locking method been applied to operate the MZI in the linear range.
  • The next step would be to do a heterodyne measurement. Attachment #3 shows the schematic for the heterodyne measurement. A free space AOM can be inserted in one of the arms to do the frequency shift. At the output of photodiode, a RF heterodyne method as shown in attachment #3 can be applied to separate the inphase and quadrature component. These components need to be saved with a deep memory system. Then the phase and thus the frequency noise can be extracted.
  • Attachment #4 shows the noise budget prepared for the heterodyne setup. The length of the fiber considered is 60 m and the photodiode is PDA255. I also have to add the frequency noise of the RF driver and the intensity noise of the laser in the noise budget.
Quote:
  1. Delay fiber was replaced with 5m (~30 nsec delay)
    • The fringing of the MZ was way too large even with the free running NPRO (~3 fringes / sec)
    • Since the V/Hz is proportional to the delay, I borrowed a 5m patch cable from Andrew/ATF lab, wrapped it around a spool, and hooked it up to the setup
    • Much more satisfactory fringing rate (~1 wrap every 20 sec) was observed with no control to the NPRO
  2. MZ readout PDs hooked up to ALS channels
    • To facilitate further quantitative study, I hooked up the two PDs monitoring the two ports of the MZ to the channels normally used for ALS X.
    • ZHL3-A amps inputs were disconnected and were turned off. Then cables to their outputs were highjacked to pipe the DC PD signals to the 1Y3 rack
    • Unfortunately there isn't a DQ-ed fast version of this data (would require a model restart of c1lsc which can be tricky), but we can already infer the low freq fringing rate from overnight EPICS data and also use short segments of 16k data downloaded "live" for the frequency noise measurement.
    • Channels are C1:ALS-BEATX_FINE_I_IN1 and C1:ALS-BEATX_FINE_Q_IN1 for 16k data, and C1:ALS-BEATX_FINE_I_INMON and C1:ALS-BEATX_FINE_I_INMON for 16 Hz.

At some point I'd like to reclaim this setup for ALS, but meantime, Anjali can work on characterization/noise budgeting. Since we have some CDS signals, we can even think of temperature control of the NPRO using pythonPID to keep the fringe in the linear regime for an extended period of time.

Attachment 1: Time_domain_output.pdf
Time_domain_output.pdf
Attachment 2: Frequency_noise.pdf
Frequency_noise.pdf
Attachment 3: schematic_heterodyne_setup.png
schematic_heterodyne_setup.png
Attachment 4: Noise_budget_1_micron_in_Hz_per_rtHz.pdf
Noise_budget_1_micron_in_Hz_per_rtHz.pdf
  2349   Mon Nov 30 19:23:50 2009 JenneUpdateMZMZ down

Came back from dinner to find the Mach Zehnder unlocked.  The poor IFO is kind of having a crappy day (computers, MZ, and I think the Mode Cleaner alignment might be bad too).

  1875   Mon Aug 10 15:56:12 2009 robSummaryPSLMZ bad redux

Quote:

I think the MZ pzt is broken/failing.  I'm not sure how else to explain this behavior.

 

The first bit of the time series is a triangle wave into the DC offset (output) field, over approximately the whole range (0-250V).   You can see the fringe visbility is quite small.  The triangle wave is stopped, and I then maxed out the offset slider to get to the "high" power point from the triangle wave sweep. Then for a little while with the PZT is held still, and the power still increases.  The MZ is then locked, and you can see the PZT voltage stay about the same but the power continues to rise over the next ~10 minutes or so.

 

 

 

This plot answers the previous question, and raises a new one--what the heck is MZTRANSPD?  I'd guess the pins are unconnected--it's just floating, and somehow picking up the MZ_PZT signal.

 

 

Attachment 1: badMZtrans.png
badMZtrans.png
  1874   Mon Aug 10 15:24:17 2009 robSummaryPSLMZ bad

I think the MZ pzt is broken/failing.  I'm not sure how else to explain this behavior.

The first bit of the time series is a triangle wave into the DC offset (output) field, over approximately the whole range (0-250V).   You can see the fringe visbility is quite small.  The triangle wave is stopped, and I then maxed out the offset slider to get to the "high" power point from the triangle wave sweep. Then for a little while with the PZT is held still, and the power still increases.  The MZ is then locked, and you can see the PZT voltage stay about the same but the power continues to rise over the next ~10 minutes or so.

Attachment 1: brokenMZpzt.png
brokenMZpzt.png
  1099   Wed Oct 29 12:23:04 2008 YoichiConfigurationPSLMZ alignment touched and the alarm level changed
Since the MZ reflection is alarming all the time, I tried to improve the MZ alignment by touching the folding mirror.
I locked the X-arm and monitored the transmitted light power while tweaking the mirror alignment to ensure that the output beam pointing is not changed.
I changed the alignment only a little, almost like just touching the knob.
The reflected power monitor was around 0.6 this morning and now it is about 0.525. Still large.
I changed the alarm level (HIGH) from 0.5 to 0.55.
  1876   Mon Aug 10 16:37:27 2009 robUpdatePSLMZ alignment touched

I aligned the MZ.  The reflection went from .86 to .374

  607   Mon Jun 30 18:36:01 2008 YoichiUpdatePSLMZ alignment again
John, Yoichi

We re-adjusted the MZ alignment. The reason behind this is to make sure that the MZ dark port is not falling at a strange fringe, where it is only dark at the dark port PD. It can happen when the two beams poorly overlap.
We tried both the minimization of the MZ dark PD and the maximization of the MZ transmission at the same time.
We also placed another PD in the MZ dark port at a different distance from the original dark PD and tried to minimize this too.
If the MZ dark port is at a strange fringe, one of the dark PD can be dark where the other one is still bright.
If both of the dark PD get dark, the overlap between the beams should be ok.
We tweaked only the two mirrors of the MZ after the EOMs (mainly the one with a PZT).

Right now, the MZ dark power is 0.432.
BTW, we should change the name of the MZ dark port on the medm screen (it is now MZ reflection, where it is not a reflection).
I will try to change it later.

We wanted to put the beam position on the IOO-QPD_POS_* back to the original (before John tweaked the MZ alignment earlier).
However, the trends of IOO-QPD_POS_* show a lot of fluctuation and jumps, of which we don't know the cause. So we could not find reasonable original values.
We suspect a circuit problem in IOO-QPD_POS, especially because the jumps are very strange.
We will do this investigation later too.
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