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ID Date Author Type Category Subjectup
  9238   Mon Oct 14 17:51:40 2013 JenneUpdateIOOinput beam to PMC drifted again

Quote:

I wonder what's drifting between the laser and the PMC? And why is it getting worse lately?

 The PMC refl is bad in pitch today, and the transmission is only 0.76, rather than our usual 0.83ish.

I did a quick, rough tweak-up of the alignment, and now we're at 0.825 in transmission.

  2072   Thu Oct 8 22:17:15 2009 ranaConfigurationDMFinput channels changed

I changed the input channels of the DMF recently so that it now uses 3 Guralp channels in addition to the 3 ACC and 1 Ranger.

op440m:seisblrms>diff seisBLRMS-datachans.txt~ seisBLRMS-datachans.txt
4,7c4,7
< C1:PEM-ACC_MC2_X
< C1:PEM-ACC_MC2_Y
< C1:PEM-ACC_MC2_Z
< C1:PEM-SEIS_MC1_Y
---
> C1:PEM-SEIS_GUR1_X
> C1:PEM-SEIS_GUR1_Y
> C1:PEM-SEIS_GUR1_Z
> C1:PEM-SEIS_RANGER_Y
op440m:seisblrms>pwd
/cvs/cds/caltech/apps/DMF/compiled_matlab/seisblrms

The seisBLRMS channels still have the wrong names of IX and EX, but I have chosen to keep them like this so that we have a long trend. When looking at the historical seisBLRMS trend, we just have to remember that all of the sensors have been around the MC since last summer.

  1679   Tue Jun 16 16:10:01 2009 peteUpdateLockinginput matrix experiments

Last night Rob ran senseDRM and loadDRMImatrixData and came up with the following for the input matrix:

tdswrite C1:LSC-ITMTRX_b2 0.065778 \
C1:LSC-ITMTRX_d2 2.2709 \
C1:LSC-ITMTRX_f2 2.9361 \
C1:LSC-ITMTRX_122 0.42826 \
C1:LSC-ITMTRX_b3 -0.064839 \
C1:LSC-ITMTRX_d3 -0.016913 \
C1:LSC-ITMTRX_f3 -0.021576 \
C1:LSC-ITMTRX_123 -0.0025243 \
C1:LSC-ITMTRX_b5 0.3719 \
C1:LSC-ITMTRX_d5 1.3109 \
C1:LSC-ITMTRX_f5 -0.16412 \
C1:LSC-ITMTRX_125 0.39574 \
C1:LSC-ITMTRX_33 0 \
C1:LSC-ITMTRX_42 0 \
C1:LSC-ITMTRX_155 0

Today, I reran these and got the following, and DD_handoff remained happy:

tdswrite C1:LSC-ITMTRX_b2 -0.10329 \
C1:LSC-ITMTRX_d2 2.0344 \
C1:LSC-ITMTRX_f2 3.2804 \
C1:LSC-ITMTRX_122 0.22516 \
C1:LSC-ITMTRX_b3 -0.076292 \
C1:LSC-ITMTRX_d3 -0.014603 \
C1:LSC-ITMTRX_f3 -0.12101 \
C1:LSC-ITMTRX_123 0.0054128 \
C1:LSC-ITMTRX_b5 0.33521 \
C1:LSC-ITMTRX_d5 1.1425 \
C1:LSC-ITMTRX_f5 -0.32759 \
C1:LSC-ITMTRX_125 0.25877 \
C1:LSC-ITMTRX_33 0 \
C1:LSC-ITMTRX_42 0 \
C1:LSC-ITMTRX_155 0

I wanted to remeasure with the canonical output matrix (-0.7 from MICH to PRM and 0.7 from MICH to SRM), but the DRM freaked out when MICH to PRM went below -0.3.

  8225   Mon Mar 4 19:52:03 2013 Jamie, YutaUpdateGeneralinput pointing mirror (TT1/TT2) control improved

We improved the active tip-tilt (TT) controllers such that they now have filter banks at the PIT/YAW inputs, and at the coil outputs:

TT.png

This allowed us to do a couple of things:

  • normalize the matrix to unity, and move overall gains into the filters (we moved x100 gain into PIT/YAW)
  • slider control is now PIT/YAW OFFSET
  • potentially do coil balancing
  • allow for input excitiations
  • automatically record EPICS values

These are all big improvements.  The TT MEDM screens were appropriately updated.

We had to rebuild/restart c1ass, which reset the TT pointing.  We recorded all the values before hand and were able to recover the pointing easily.  Interestingly, there did appear to be hysteresis in pitch, which is maybe not entirely unexpected, but still worth nothing.

 

  6897   Fri Jun 29 22:56:35 2012 JamieUpdateVACinput telescope beam clipping on Faraday

[Yuta, Koji, Jamie]

We went into ITMX chamber to inspect the situation there.  We looked for clipping and flipping at PR2, and found none, although we noticed that the beam at PR2 looks a little clipped.

We then went back into the BS chamber and took a closer look at the beam incident on PRM, and the situation with PR3.  The PRM incident beam looked a little clipped, which we expected from the PR2 observation.  But the beam looks well centered on PRM and PR3.  As best I could tell the beam is reflecting off the front surface of PR3, as expected.

Looking at the beam around MMT1 and PJ2 (the second PZT on BS), we could tell that the beam incident and reflected off of MMT1 looked round, where as the beam incident on PJ2 looked clipped.  Using my tallness super power I was able to reach into the IMC chamber and confirm that the beam going from MMT1 to MMT2 clips fairly badly on the edge of the Faraday.   Koji speculates that this is the result of a misalignment of the PSL output beam into the MC.  In any event, it's not clear how this would be the cause of our PRC woes.

We decided to close up for the night, and let Yuta work on aligning PRMI.  We need to figure out what the heck to do now.

We've been watching the input power reduce, from 18 mW initially when we first went in, to about 5mW now.  It seems to be leveling out now.  It's unclear what would have been causing it.  Drift of the input polarization?

  6898   Sat Jun 30 18:31:38 2012 steveUpdateIOOinput telescope beam clipping on Faraday

  We could set up a simple pick  off after the Faraday  and bring it  out the north window of IOO chamber. No monitor needed, just take the cover off when you want to see it.

Most people have no idea how to get the MC through the F

  6336   Tue Feb 28 20:49:33 2012 kiwamuUpdateLSCinsalling OSA

I am installing an OSA on the AP table and it's ongoing.

I am leaving some stuff scattered on the AP table and I will resume the work after I come back.

  6285   Thu Feb 16 04:02:16 2012 kiwamuUpdateLSCinsane REFL165 DC output

I found that the DC monitor of the REFL165 was showing 9 V regardless of how much laser power goes to the diode.

I am worried about whether the RF output is also broken.

It needs to be checked and I will leave this to Suresh as one of his morning tasks.

  1123   Fri Nov 7 16:05:55 2008 steveBureaucracySAFETYinsect killer sprayed at kitchen area !

Bob and I cleaned out the sink area and sprayed
Spectracide's BUG STOP insect killer solution on the shelfs and sink
table top area.

NO eating or coffee drinking till Monday

This is an effort to stop the ants coming.
  5141   Mon Aug 8 15:20:49 2011 kiwamuUpdateSUSinspection on ETMY (round 1)

Since ETMY have been showing some strange behaviors we deeply inspect the ETMY suspension.

Here is a brief review of the ETMY suspension and a brief status update of the inspection so far.

The inspection is still ongoing.

 

(Review : How wrong ?)

First of all, let us summarize what were the observed phenomena on the ETMY suspension :

   1. unknown low frequency noise covering frequency range from 0.1 to 3 Hz in all of four face sensors (#5025, #5029).

   2. LR sensor showed a very broad bounce peak at ~ 17 Hz (#5025).

   3. The sign of some of the sensors are flipped.

   4. The control gains had to be higher than those of ETMX by 10-100 (#5025).

 

(Status update : Noise spectra)

Currently the ETMY suspension is sitting on the north side of the table for the inspection.

We took dark noise of the OSEMs when the OSEMs were taken off from the tower and put on the table.

The plot below is an example of the LR sensor spectra. Note that the whitening filters have been always ON.

Screen_shot_2011-08-08_at_15.08.23.png

The black curve is the dark noise when the sensor was off from the tower.

The blue curve is the free swinging spectrum newly taken today.

The red curve is the free swinging spectrum (damped spectrum ?) on 25th of July, this was still in vacuum.

 

The dark noise is below the free swinging spectrum from 0.2 - 30 Hz, which looks reasonable

The most interesting thing is that the free swinging spectrum became better in low frequency (below 3 Hz)

from the one measured in vacuum.

It needs more investigation to answer the reason why it happened.

Note that before we moved the tower to the current position, we looked at the OSEM-magnets relations, and found nothing was touching.

 

  10897   Tue Jan 13 18:47:20 2015 ChrisConfigurationComputer Scripts / Programsinstafoton setup

To use instafoton, right click an MEDM screen, open the Execute menu, and choose "Foton".  Then click on the EPICS channel of a filter module as displayed on the screen.

Here's how it was set up:

  • Install instafoton.py in /opt/rtcds/caltech/c1/scripts; edit paths to localize for the 40m
  • Add instafoton to the MEDM_EXEC_LIST environment variable, newly defined in /ligo/cdscfg/workstationrc.sh:
    export MEDM_EXEC_LIST="Edit this screen;medm &A &:Probe;probe &P &:Foton (Pick filter PV);/opt/rtcds/caltech/c1/scripts/instafoton.py &P &"
  3986   Thu Nov 25 02:49:39 2010 kiwamuUpdateCDSinstallation of C1LSC: still going on

 [Joe, Kiwamu]

 We tried installing C1LSC but it's not completely done yet due to the following issues.

    (1)  A PCIe optical fiber which is supposed to connect C1LSC and its IO chasis is broken at a high probability.

    (2)  Two DAC boards (blue and golden board) are missing.

 We will ask the CDS people at Downs and take some more of those stuff from there.


( works we did )

 - took the whole C1ASC crate out from the 1Y3 rack.

 - installed an IO chasis to the place where C1ASC was.

 - strung a timing optical fiber to the IO chasis.

 - checked the functionality of the PICe optical fiber and found it doesn't work.

 

 

Fig.1  c1asc taken out from the rack                                                                         Fig.2 IO chasis installed to the rack

DSC_2723_ss.jpg      DSC_2724_ss.jpg

 

Fig.3 PCIe extension fiber (red arrow for an obvious bended point) 

DSC_2727_ss.jpg 

  4549   Wed Apr 20 23:20:49 2011 jamieSummaryComputersinstallation of CDS tools on pianosa

This is an overview of how I got (almost) all the CDS tools running on pianosa, the new Ubuntu 10.04 control room work station.

This is machine is experiment in minimizing the amount of custom configuration and source code compiling. I am attempting to install as many tools as possible from existing packages in

available packages

I was able to install a number of packages directly from the ubuntu archives, including fftw, grace, and ROOT:

apt-get install \
libfftw3-dev \
grace \
root-system

LSCSOFT

I installed all needed LSCSOFT packages (framecpp, libframe, metaio) from the well-maintained UWM LSCSOFT repository.

$ cat /etc/apt/sources.list.d/lscsoft.list
deb http://www.lsc-group.phys.uwm.edu/daswg/download/software/debian/ squeeze
deb-src http://www.lsc-group.phys.uwm.edu/daswg/download/software/debian/ squeeze contrib
sudo apt-get install lscsoft-archive-keyring
sudo apt-get update
sudo apt-get install ldas-tools-framecpp-dev libframe-dev libmetaio-dev lscsoft-user-en

You then need to source /opt/lscsoft/lscsoft-user-env.sh to use these packages.

EPICS

There actually appear to be a couple of projects that are trying to provide debs of EPICS. I was able to actually get epics working from one of them, but it didn't include some of the other needed packages (such as MEDM and BURT) so I fell back to using Keith's pre-build binary tarball.

Prereqs:

apt-get install \
libmotif-dev \
libxt-dev \
libxmu-dev \
libxprintutil-dev \
libxpm-dev \
libz-dev \
libxaw7-dev \
libpng-dev \
libgd2-xpm-dev \
libbz2-dev \
libssl-dev \
liblapack-dev \
gfortran

Pulled Keith's prebuild binary:

cd /ligo/apps
wget https://llocds.ligo-la.caltech.edu/daq/software/binary/apps/ubuntu/epics-3.14.10-ubuntu.tar.gz
tar zxf epics-3.14.10-ubuntu.tar.gz

GDS

I built GDS from svn, after I fixed some broken stuff [0]:

cd ~controls/src/gds
svn co https://redoubt.ligo-wa.caltech.edu/svn/gds/trunk
cd trunk
#fixed broken stuff [0]
source /opt/lscsoft/lscsoft-user-env.sh
./bootstrap
export GDSBUILD=online
export ROOTSYS=/usr
./configure --prefix=/ligo/apps/gds --enable-only-dtt --with-epics=/ligo/apps/epics-3.14.10
make
make install

dataviewer

I installed dataviewer from source:

cd ~controls/src/advLigoRTS
svn co https://redoubt.ligo-wa.caltech.edu/svn/advLigoRTS/trunk
cd trunk/src/dv
#fix stupid makefile /opt/rtapps --> /ligo/apps
make
make install

I found that the actual dataviewer wrapper script was also broken, so I made a new one:

$ cat /ligo/apps/dv/dataviewer
#!/bin/bash
export DVPATH=/ligo/apps/dv
ID=$$
DCDIR=/tmp/${ID}DC
mkdir $DCDIR
trap "rm -rf $DCDIR" EXIT
$DVPATH/dc3 -s ${NDSSERVER} -a $ID -b $DVPATH "$@"

environment

Finally, I made a environment definer file:

$ cat /ligo/apps/cds-user-env.sh
# source the lscsoft environment
. /opt/lscsoft/lscsoft-user-env.sh

# source the gds environment
. /ligo/apps/gds/etc/gds-user-env.sh

# special local epics setup
EPICS=/ligo/apps/epics
export LD_LIBRARY_PATH=${EPICS}/base/lib/linux-x86_64:$LD_LIBRARY_PATH
export LD_LIBRARY_PATH=${EPICS}/extensions/lib/linux-x86_64:$LD_LIBRARY_PATH
export LD_LIBRARY_PATH=${EPICS}/modules/seq/lib/linux-x86_64:$LD_LIBRARY_PATH
export PATH=${EPICS}/base/bin/linux-x86_64:$PATH
export PATH=${EPICS}/extensions/bin/linux-x86_64:$PATH
export PATH=${EPICS}/modules/seq/bin/linux-x86_64:$PATH

# dataviewer path
export PATH=/ligo/apps/dv:${PATH}

# specify the NDS server
export NDSSERVER=fb

[0] GDS was not compiling, because of what looked like bugs. I'm not sure why I'm the first person to catch these things. Stricter compiler?

To fix the following compile error:

TLGExport.cc:1337: error: ‘atoi’ was not declared in this scope

I made the following patch:

Index: /home/controls/src/gds/trunk/GUI/dttview/TLGExport.cc
===================================================================
--- /home/controls/src/gds/trunk/GUI/dttview/TLGExport.cc (revision 6423)
+++ /home/controls/src/gds/trunk/GUI/dttview/TLGExport.cc (working copy)
@@ -31,6 +31,7 @@
#include <iomanip>

#include <string.h>

#include <strings.h>

+#include <stdlib.h>


namespace ligogui {
using namespace std;

To fix the following compile error:

TLGPrint.cc:264: error: call of overloaded ‘abs(Int_t&)’ is ambiguous

I made the following patch:

Index: /home/controls/src/gds/trunk/GUI/dttview/TLGPrint.cc
===================================================================
--- /home/controls/src/gds/trunk/GUI/dttview/TLGPrint.cc (revision 6423)
+++ /home/controls/src/gds/trunk/GUI/dttview/TLGPrint.cc (working copy)
@@ -22,6 +22,7 @@
#include <fstream>

#include <map>
#include <cmath>

+#include <cstdlib>


namespace ligogui {
using namespace std;

  4698   Thu May 12 02:31:07 2011 SureshUpdateRF Systeminstallation of RF splitters in Demod boards

[Jamie, Koji, Suresh]

We replaced splitters in several demod boards as per the table given below:

 

Demod boards in which splitter has been replaced on 11May2011
Demod Board S. No. Power Splitter Frequency range of splitter (MHz) Phase unbalance from datasheet (deg) Amplitude Unbalance from datasheet (dB)
REFL55 118 PQW-2-90 30 to 90 90.14 0.92
AS11 021 PSCQ-2-51W 5 to 50 87.49 0.1
POY11 119 PSCQ-2-32 3.2 to 32 87.58 0.05
POY22 020 PSCQ-2-32 3.2 to 32 90.26 0.02
POY110 120 PSCQ--120 80 to 120 90.88 0.58

 

While doing a rough check of the boards I noticed that the REFL11 demod board had no signal on the Q output.

Rana also advised that we must use the boards which have the piggy-back amplifiers on those signals which are most useful.  We referred to Alberto's thesis and chose POY55 (MICH and SRCL), REFL11(PRCL)  and AS55 (DARM) as the most useful signals.  We currently have these amps on AS11, REFL11 and AS55.  We need to convert either AS11 or REFL11 into a POY55.  Since we need to troubleshoot REFL11, I thought we might as well modify that and in the process also fix its Q output.  So I renamed AS11 as REFL11 and will convert the old REFL11 into POY55 tomorrow.

Power splitter of different types have different pin-outs.  The way we mount a splitter depends on which type we are using.   I will detail the mounting scheme in a separate elog tomorrow.

 

 

 

  4702   Thu May 12 10:27:02 2011 ranaUpdateRF Systeminstallation of RF splitters in Demod boards

Quote:

Rana also advised that we must use the boards which have the piggy-back amplifiers on those signals which are most useful.  We referred to Alberto's thesis and chose POY55 (MICH and SRCL), REFL11(PRCL)  and AS55 (DARM) as the most useful signals.  We currently have these amps on AS11, REFL11 and AS55.  We need to convert either AS11 or REFL11 into a POY55.  Since we need to troubleshoot REFL11, I thought we might as well modify that and in the process also fix its Q output.  So I renamed AS11 as REFL11 and will convert the old REFL11 into POY55 tomorrow. 

 I think we should leave them as is; the AS11 was made by taking into account the SB levels at the AS port and should not become REFL11. We should instead convert one of the old 25 or 33 MHz diodes into a POY55.

  4703   Thu May 12 16:50:22 2011 SureshUpdateRF Systeminstallation of RF splitters in Demod boards

We have no plan to change the AS11 PD. I was referring to the AS11 Demod board which currently has the "Demodulator Preamp" circuit installed as a piggy back. In future I will append "_Demod" when I am referring to a demod board, to avoid confusion.

Quote:

Quote:

Rana also advised that we must use the boards which have the piggy-back amplifiers on those signals which are most useful.  We referred to Alberto's thesis and chose POY55 (MICH and SRCL), REFL11(PRCL)  and AS55 (DARM) as the most useful signals.  We currently have these amps on AS11, REFL11 and AS55.  We need to convert either AS11 or REFL11 into a POY55.  Since we need to troubleshoot REFL11, I thought we might as well modify that and in the process also fix its Q output.  So I renamed AS11 as REFL11 and will convert the old REFL11 into POY55 tomorrow. 

 I think we should leave them as is; the AS11 was made by taking into account the SB levels at the AS port and should not become REFL11. We should instead convert one of the old 25 or 33 MHz diodes into a POY55.

 

  3302   Tue Jul 27 21:38:21 2010 kiwamuUpdateSUSinstallation of in-vac optics

[Alberto and Kiwamu] 

We put the PRM back approximately on the right place.

Also we installed the pick off mirrors and the PZT mirror.

Since the main beam after the MMT still has not been well aligned , we put those optics approximately on the right place. A fine alignment of those will be performed later

The offsets of the PRM OSEMs are still kind of okay.

The next things we have to do are

(1) installation of a tip-tilt for the SRC, (2) alignement of those optics by using the main laser and (3) installation of the green optics.

 


what we did

 1. put the PRM back to the designed place.

     - After this, we released the PRM from the earthquake stops and turned on the damping servo.

      - Now the earthquake stops are at a distance of approximately 1mm from the PRM. These separation distances were tuned by counting the turn number when we screwed them off.

 2. leveled the table

 3. adjusted the separation distances from the PRM to the OSEMs.

    - The table below summarize the current OSEM offsets. LL may still need to be adjusted.

  Max./2 [V]

measured offsets [V] 

after adjustment 

discrepancy [%]
UL 0.874 0.928 + 6.2 %
UR 0.848 0.777 - 8.4 %
LL 1.038 0.796 - 23 %
LR 0.967 0.845 -12 %
SD 0.840 0.745 - 11%

 4. put the PZT mirror on the right place.

      -  This PZT mirror is going to be used for beam steering after the MMT.

 5. put the pick off mirror and its associated optics.

     -  This pick off mirror provides with the beam eventually going to IP_ANG and IP_POS.

 


current status

The table below shows the current status of the installed optics.

Red letters represent the incomplete states which still need further adjustment.

Blue letters represent the complete status which don't need any further adjustment.

 

name on the drawing

(see the wiki ) 

status
BS tower BS well aligned by a caliper
PRM tower PRM approximately aligned. LL OSEM
TIp-TIlt PR3 approximately aligned
Pick off Window (wedged) IPPO

wedge is correctly set (fat part is on the left).

 approximately aligned

steering mirror IPPOSSM1 mirror is correctly flipped. approximately aligned
steering mirror IPANGSM1 mirror is correctly flipped. approximately aligned
steering mirror IPANGSM2 approximately aligned
pzt mirror SM2 approximately aligned

 

Attachment 1: DSC_2284.JPG
DSC_2284.JPG
Attachment 2: DSC_2291.JPG
DSC_2291.JPG
  3313   Wed Jul 28 17:32:37 2010 kiwamuUpdateSUSinstallation of in-vac optics

[Jenne, Koji and Kiwamu]

We have installed two steering mirrors and the green periscope.

Also we took the tip-tilt out from the chamber for characterization.


1. installed two steering mirrors

     - We installed IPPOSSM2 and IPPOSSM3.

    - Because IPPOSSM2 is a new 0 deg mirror so we newly engraved "Y1-LW1-2037-1064-0-AR" on the mount and deleted  the previous enegravement.

      For the 0 deg mirror itself, it had already been engraved by Koji. The wedge was horizontally aligned.

      Now IPPOSSM2 is off from the right place by 5 inch for convenience because it may touch our stomachs when we try to lean further into the chamber.

    - IPPOSSM3 is a 45 deg mirror which used to be in the chamber and had been already correctly engraved, so we didn't have to newly engrave on it. Now it's on the right place approximately.

 2. put three oplev mirrors

      - Two of them are approximately on the place, but one which is going to be on the center of the table is not on the place because there is a cable distributer sitting exactly there.

 3. installed the green periscope

      - Both the mirrors and the periscope were correctly engraved.

     - Now it's sitting on the right place approximately.

 4. removed the tip-tilt 

      -  This tip-tilt is now in the clean room and the mechanical mode will be characterized. 

 


 The next things to be done

* Cross-coupling evaluation of the PRM OSEMs

* Rearrangement of the cable distributer panel.

   - In order to do this we have to pull its cables which are attached to the stack.

* Installation of three green steering mirrors

   - All of them need to be engraved.

* Installation of two tip-tilt

  - One for the SRC and the other for the PRC

  3310   Wed Jul 28 14:34:29 2010 channaUpdateComputersinstallation on allegra

I have done the following on allegra and rosalba:

[root@allegra caltech]# yum install glade2

On rosalba the matplotlib was out of date with respect to allegra.  I have no idea how the version 0.98 on allegra got there, but I left it.  However I updated rosalba to the epel version

  1 yum remove python-numpy
  2 yum install python-matplotlib numpy scipy --enablerepo=epel --disablerepo=rpmforge

 

This is all to support the LIGO data listener which now has a shortcut on rosalba and allegra's desktop.  It seems to work for (live mode) right now.
 

 

  15921   Mon Mar 15 20:40:01 2021 ranaConfigurationComputersinstalled QTgrace on donatella for dataviewer

I installed QTgrace using yum on donatella.angel Both Grace and XMgrace are broken due to some boring fight between the Fedora package maintainers and the (non existent) Grace support team. So I have symlinked it:

controls@donatella|bin> sudo mv xmgrace xmgrace_bak
controls@donatella|bin> sudo ln -s qtgrace xmgrace
controls@donatella|bin> pwd
/usr/bin

I checked that dataviewer works now for realtime and playback.cool Although the middle click paste on the mouse doesn't work yet.angry

Attachment 1: cutiegrace.png
cutiegrace.png
  6354   Mon Mar 5 13:11:06 2012 kiwamuUpdateLSCinstalled a long BNC cable for REFL OSA

A long BNC cable was installed and now the REFL OSA signal is happily shown on an oscilloscope in the control room.

Quote from #6352

The OSA for the REFL beam is now fully functional.

The only thing we need is a long BNC cable going from the AP table to the control room so that we can monitor the OSA signal with an oscilloscope.

  4354   Thu Feb 24 21:46:30 2011 kiwamuUpdateGreen Lockinginstalled a summing box

In this past weekend I replaced a summing amplifier for the end green PDH locking by a home-made summing circuit box in order to increase the control range.

It's been working well so far.

However due to this circuit box, the demodulation phase of the PDH locking is now somewhat different from the past, so we have to readjust it at some point.

 

(background)

    At the X end station, the voltage going to the NPRO PZT had been limited up +/- 4 V because of the summing amplifier : SR560.

Therefore the laser was following the cavity motion only up to ~ +/- 4 MHz, which is not wide enough. (it's okay for night time)

So we decided to put a passive circuit instead of SR560 to have a wider range.

 

(summing box)

   We made a passive summing circuit and put it into a Pomona box.

The circuit diagram is shown below. Note that we assume the capacitance of the 1W Innolight has the same capacitance as that of the PSL Innolight (see #3640).

summing_box.png

The feedback signal from a PDH box goes into the feedback input of the circuit.

Then the signal will be low passed with the corner frequency of 200 kHz because of the combination of RC (where R is 681 Ohm and C is capacitance of the PZT).

Because of this low pass filter, we don't drive the PZT unnecessarily at high frequency.

On the other hand the modulation signal from a function generator goes into the other input and will be high passed by 50 pF mica capacitor with the corner frequency of 200 kHz.

This high pass filter will cut off noise coming from the function generator at low frequency.

In addition to it, the 50 pF capacitor gives a sufficient amount of attenuation for the modulation because we don't want have too big modulation depth.

 

Here is a plot for the expected transfer functions.

You can see that the modulation transfer function (blue curve) has non-zero phase at 216 kHz, which is our modulation frequency.

transfer_func.png
 

 

  6330   Tue Feb 28 12:00:54 2012 kiwamuUpdateLSCinstalled anti-whitening filters

I found that none of the filter banks in the LSC input signals have the precise anti-whitening filters.

I installed the precise filters on REFL11, REFL33, REFL55 and AS55 based on Jenne's measurement (#4955)

After installing them I briefly checked the REFL11 sensing matrix with the PRMI locked, but it didn't change so much from what I got (#6283).

But I felt that the PRMI became more robust after that ... I just felt so ...

 


(Background)

The lock of the PRMI doesn't look healthy, especially the sensing matrix doesn't make sense at all (#6283).
A very staring thing in the sensing matrix is that the REFL11 and REFL55 didn't show the 90 degree separation between MICH and PRCL.
So I suspected some electronics, particularly the demodulation boards.
 

(What I did)

I checked the anti-whitening filters shape to see if they are ok or not.
I found that they all had the default filters of two zeros at 150 Hz and two poles at 15 Hz. So they weren't quite tuned.
I thought this could be a problem when I measure the sensing matrix because I usually excite the length DOFs at a high frequency of 283.1 Hz
and the mismatches between the anti-whitening and whitening filters may lead to something funny at such a high frequency.
 
So I installed the precise filters on REFL11, REFL33, REFL55 and AS55.
After that I did a orthogonality test on each I-Q pair of the demod signals to correct the D-phases and the relative gain between I and Q.

 

(Next ?)

 Rana and I discussed the plan and decided to go back to a simple Michelson which should be easy enough to understand what is going on and should allow us a complete set of measurements.
Our big concern behind it is that we maybe locking the PRMI at a funny operation point.
In order to assess the issue I will do the following actions on the Michelson at first and then apply the same things on the PRMI later :
  • Check  the amount of of the sidebands using the OSA
  • Check the amount of the DC light
  • Check the sensing matrix to see if the absolute values in watt / meter make sense or not
    • This work needs calibrations on all the demodulated board (this is equivalent to measuring the conversion losses of the mixers in the demod boards).
  • Measure the contribution from the RAMs (it must be measurable by some means)
  6331   Tue Feb 28 15:48:32 2012 kiwamuUpdateLSCinstalled anti-whitening filters

I installed the rest of the precise anti-whitening filters. Now all of the LSC sensors have the right filters.

Quote from #6330

I found that none of the filter banks in the LSC input signals have the precise anti-whitening filters.

I installed the precise filters on REFL11, REFL33, REFL55 and AS55 based on Jenne's measurement (#4955)

  4093   Thu Dec 23 12:19:43 2010 kiwamuUpdateGreen Lockinginstalled doubling oven base at PSL table

I gave a christmas present to a doubling oven who has been sitting on the PSL table.

The below is a picture of the present I gave. It's a base plate for the doubling oven, made from a block of aluminum, and black-anodized.

The size and the shape are nicely tailored for the combination of the Newfocus kinematic mount and the Covesion oven.

The design had been done by using Solid Works 2010

 

DSC_2820_ss.jpg

 

Here is a picture before he got the present.

DSC_2814_ss.jpg

 

Now he looks pretty happy.

DSC_2815_ss.jpg

  4095   Thu Dec 23 18:51:37 2010 ranaUpdateGreen Lockinginstalled doubling oven base at PSL table

This is not such a bad base design, but remember that we have to get a couple of parts with the purple anodize to see if there is a difference between black and purple in terms of the 532 nm reflectivity.

  3990   Mon Nov 29 18:05:17 2010 Leo SingerConfigurationComputersinstalled graphviz on Rosalba

I installed the following packages on Graphviz in order to support visualization of GStreamer pipeline graphs:

graphviz

  4779   Thu Jun 2 10:19:37 2011 Alex IvanovSummaryDAQinstalled new daqd (frame builder) program on fb (target/fb/daqd)

I hope that new daqd code will fix the problem with non-aligned at 16 seconds frame file GPS times.

I have compiled new daqd program under /opt/rtcds/caltech/c1/core/release/build/mx and installed it under

target/fb/daqd, then restarted daqd process on "fb" computer. It was installed with the ownership of user root

and I did chmod +s on it (set UID on execution bit). This was done in order to turn on some code to renice daqd process

to the value of -20 on the startup. Currently it runs as the lowest nice value (high priority).

 

controls@fb /opt/rtcds/caltech/c1/target/fb $ ls -alt daqd
-rwsr-sr-x 1 root controls 6592694 Jun  2 10:00 daqd

 

Backup daqd is here:

 

controls@fb /opt/rtcds/caltech/c1/target/fb $ ls -alt daqd.02jun11
-rwxr-xr-x 1 controls controls 6768158 Feb 21 11:30 daqd.02jun11

 

 

  4055   Tue Dec 14 22:42:56 2010 kiwamuUpdateSUSinstalled the last TT . And some more progresses

  [Koji, Oasmu and Kiwamu]

We made the following progresses :

   (1) installation of the last TT called SR2.

 (2) fixing an earthquake stop issue on the BS

  (3) fixing a clipping of beams at the dark port


(earthquake stops on the BS)

 - When we were aligning the BS, we found that the BS showed funny behaviors.

For example a kick on LR didn't shake LRSEN, and a big DC angular offset (~ 8 in the medm screen ) was needed to keep a horizontal beam axis in the reflection.

We checked all the earthquake stops and found two suspicious earthquake stops at right bottom side.

They looked like slightly touching the BS. So we moved them further away from the BS.

Then the problem had gone.  We doublechecked the health by kicking, applying an angular offset  and so on.

 

(beam clipping)

We found transmitted/reflected beams from the BS to the dark port was clipped at the BS tower.

We moved the BS tower by ~1cm and realigned the rotation of the BS tower.

We also found the beam spots on the two TTs, PR2 and PR3, were offcentered. Especially the beam spot on PR3 was almost on the edge of the mirror.

Probably this was because we touched PZT1 when aligning the beam to the Y end.

So it means, it is not a good idea to align the beam to the end only by steering PZT1. We should use PR2 and PR3 as well when we align the beam to the Y end.

We realigned them such that the beam hits the center of PR2, PR3 and ETMY.

  7613   Wed Oct 24 20:09:41 2012 jamieUpdate installing the new dirchoic mirros in PR3/SR3

When installing the dichroics we need to pay attention to the wedge angle.  I didn't, so the ghost beam is currently point up and to the right (when facing the optic).  We should think carefully about where we want the ghost beams to go.

I also was using TT SN003, which I believe was being used for PR2.  However, I don't think we want to install dichroics in the PR2, and we might want to put all the tip-tilts back in the same spots they were in before.  We therefore may want to put the old optic back in SN003, and put the dichroics in SN005 (PR3) and SN001 (SR3) (see 7601).

  8946   Wed Jul 31 10:27:00 2013 SteveUpdateVACinstrument grade air is discontinoued

We have been using Air Liquide Instrument Grade Air for venting the 40m vacuum envelope. It is no longer available.

The replacement is Alphagas 1, total hydrocarbon <0.1% ppm

LINK TO Alphagaz

 

A- A+ Imprimer Partager

ALPHAGAZ™ Specifications

ALPHAGAZ™ range of Pure Gases for Analysis: two purity levels tailored to cover all your analytical needs.

Because each analytical application is sensitive to critical impurities that can affect your results, tests in our research center and analyzer manufacturers' studies confirm that the main impurities are moisture, oxygen and hydrocarbons.

Based on these critical impurities, Air Liquide has developed ALPHAGAZ™ brand with a Maximum Impurity Level (H2O, O2, CnHm).

  • The Maximum Impurity Level is the same across the whole product range. This constitutes a guarantee of quality with regard to major critical impurities and contamination tracers. ALPHAGAZ™ 2 offers an even greater guarantee in terms of purity (CO, CO2, H2).
  • The Minimum Total Purity is a prerequisite for product quality, but we do not stop there: Air Liquide selects and controls its gas sources by defining specifications regarding impurities that are critical for your analysis or application.

 

ALPHAGAZ™ 1 ALPHAGAZ™ 1 ALPHAGAZ™ 2 ALPHAGAZ™ 2 ALPHAGAZ™ AUTO IV ALPHAGAZ™ CO2 SFC
He, N2, H2,
Ar, O2
Air He, N2, H2,
Ar, O2
Air Air*, N2, O2 CO2
Specifications (ppm vol):
H2O < 3 ppm
O2 < 2 ppm
CnHm < 0.5 ppm
H2O< 3 ppm
CnHm< 0.1 ppm
CO2 < 1 ppm
CO < 1 ppm
H2O < 0.5 ppm
O2 < 0.1 ppm
CO2 < 0.1 ppm
CO < 0.1 ppm
CnHm < 0.1 ppm
H2 < 0.1 ppm
H2O < 0,5 ppm
CnHm < 50 ppb
CO2 < 0,1 ppm
CO < 0,1 ppm
NOx < 10 ppb *
SO2 < 10 ppb*
CnHm < 0.2 ppm
CO2 < 0.5 ppm
CO < 0.5 ppm
NO/NOx < 0.1 ppm
H2O < 5 ppm
O2 < 2 ppm
CnHm < 2 ppm
NVOC* < 2 ppm
CO < 5 ppm
NO + NO2 < 2 ppm
S Total < 1 ppm
H2 < 0.5 ppm
  20 ± 1 % O2 (Europe)
21 ± 1% O2 (North America)
  20,9 ± 1 % O2
*: Detection limit
*20 ± 1 % O2 *NVOC: Non Volatile Organic Compounds
Minimum Total Purity

 

 

  4181   Fri Jan 21 02:45:43 2011 kiwamuUpdateGreen Lockinginterface for PLL to ADC

 [Suresh, Kiwamu]

  We did the following things:

     - installed a 1/10 voltage divider such that the signal won't be saturated at the AA board (see here)

     - put a Ithaco preamplifier 1201 as a whitening filter

     - checked the entire beat detection system without using the real beat note

Here are some items to be done before the sun goes down tomorrow:

       - calibration of ADC and the interfaces including the voltage divider and the whitening filter.

     - fine matching of unwhitening filter at the digital side

         - PLL response measurement ( freq to voltage response ) over the frequency range of interest

         - plotting an well calibrated spectrum of the PLL output 


(whitening filter)

The Ithaco 1201 was setup to have a zero at 0 Hz and two poles at 0.1 Hz and 10 Hz in order to emphasize the signal over the frequency range of interest.

Around 1Hz it is supposed to have a gain of 1000. These settings have done by tweaking the knobs on the front panel of the Ithaco 1201.

In addition to that, we made an unwhitening filter in digital filter banks. This filter was designed to cancel the analog whitening filter.

(system check) 

 To check the entire beat detection system, we phase-locked the VCO to a Marconi running at 80 MHz, which is the center frequency of the VCO.

Then we imposed a frequency modulation on the Marconi to see if the signal is acquired to ADC successfully or not. It's quite healthy.

According to the spectra corrected by the unwhitening filter, we confirmed that the noise floor at 1Hz is order of 1Hz/sqrt Hz, which is already quite good.

Then we took several spectra while putting a modulation on the Marconi at a different frequency in each measurement.

The peak due to the artificial modulation essentially works as a calibration peak in the spectra.

So in this way we briefly checked the flatness of the response of the system in the frequency domain.

As a result we found that the response is not perfectly flat in the range of 0.05 - 30Hz, probably due to a mismatch of the combination of the whitening and unwhitening filters.

We will check it tomorrow.

 

  5374   Sat Sep 10 01:36:15 2011 kiwamuUpdateASCinterferometer coarsely aligned

The interferometer was coarsely aligned.

Now spatially overwrapped DRMI and FP arm fringes are visible on the AS camera although the incident beam alignment was done only with PZT2.

All the DC biases were saved so that we can go back to this condition any time.

 

/***** some health checks *******/

 [FINE] IPPOS : it looks okay but the spot on the QPD is a little bit too low by a few mm.

 [NOT GOOD] IPANG : maybe hitting a post or something because the spot is vertically split into two. The spot is too low.

 [FINE] POX/POY/POP : they all are coming out. POP is visible with an IR viewer.

 [FINE] REFL :  no clipping but the beam looks a little bit too low relative to the CCD camera.

 [FINE] AS : no clipping and the spot position on the AS camera looks fine.

 [FINE] Green beams : both X and Y beams are successfully landing onto the PST table without no clipping.

 [FINE] Suspensions : all of them are reasonably quiet without the oplevs, which is good.

  8230   Tue Mar 5 06:27:14 2013 yutaUpdateLSCintra-cavity power dependence on mirror misalignment

I measured intra-cavity power dependance on mirror misalignment.
Intra-cavity power of PRC in PRMI degrates roughly 20 % when there's 0.5 mrad 5 urad misalignment. (edited by YM)
Currently, PRMI lock is not so stable, so it is hard to do this measurement and error bars are huge.

Measurement method:
  0. Align the cavity and lock.
  1. Misalign one optic and measure oplev output value and intra-cavity power.
  2. Also, dither the optic in pitch or yaw in 8.5 Hz and get demodulated amplitudes at 8.5 Hz of oplev output and intra-cavity power using tdsdmd.
  3. Misalign the optic again and do the same things.

  1. gives intra-cavity power dependence on mirror misalignment directly, but 2. should give better S/N because of dithering.


Scripts:
  /opt/rtcds/caltech/c1/scripts/dither/dithergfactor.py does these things, and ./plotgfactor.py plots the result.
  They work quite well, but it should be made better so that

  - it checks if the cavity is locked
  - automatically change the oplev calibration factor for each optic
  - automatically adjusts the region and modulation amplitude
  - read data with better error evaluation

  etc...


PRMI alignment:
  Y green looks like it drifted quite a lot somehow. If we start aligning Yarm to Y green, we get AS and POP beam at different spot on camera compared with last week. Also, TRY and TRX only goes as high as ~0.7. Since we have A2L now (elog #8229), let's start using Yarm spot positions as input pointing reference.


PRMI locking details:
  Same as in elog #8212, but I changed gains in the lock acquisition mode.

  == PRMI carrier ==
  MICH: AS55_Q_ERR, AS55_PHASE_R = -12 deg,  MICH_GAIN = -0.2, feedback to ITMX(-1),ITMY(+1)
  PRCL: REFL55_I_ERR, REFL55_PHASE_R = 70 deg, PRCL_GAIN = 1.0, feedback to PRM

  I made gainx5 in LSC_MICH filter bank so that it increases the overall gain when locked by trigger.
  I also made gainx0.3 in LSC_PRCL filter bank so that it reduces the overall gain when locked by trigger.


Result for PRC in PRMI:
  For PRMI, I couldn't done dithering method because dithering takes time to measure and I could not hold PRMI locking during the measurement.
  Below is the result when reading just the DC values. Mirror angle is calibrated by oplev (elog #8221). Error bars are huge because of beam motion mainly in yaw.


PRM in pitch: PRM_PIT_20130305a.png    PRM in yaw:PRM_YAW_20130305b.png


Results for the arms:
  For the arms, I could do both in DC and dithering. Below are the results, but ITMs misalignments are not calibrated because we don't have calibrated oplev yet.
  Results for the arms can be used to verify this method because we know g-factors of the arms from mode scan.


ITMX in yaw: ITMX_YAW_20130305.png    ITMY in yaw: ITMY_YAW_20130305.png



By the way:
  I found C1:SUS-ITMY_LSC_GAIN is somehow set to be 2.895 recently. I think this should be 1.0. Maybe this is why we had actuation imbalance in ITMs(elog #8212).


Next:
 - more stable lock
 - calibrate ITM oplevs to apply this method to the arms
 - derive g-factor from these measurements
 - measure PRM angular motion spectra using calibrated oplev

  2098   Thu Oct 15 12:35:09 2009 ZachUpdatePSLinventory

I'm at the PSL table taking inventory of the elements I don't have down yet.

  2099   Thu Oct 15 12:57:23 2009 ZachUpdatePSLinventory

Quote:

I'm at the PSL table taking inventory of the elements I don't have down yet.

 OK, I'm out--hopefully for good. HEPAs back at 20%.

  5597   Sun Oct 2 18:33:36 2011 kiwamuUpdateSUSinversion of the input matrix on ETMX, ITMX and PRM

The input matrices of ETMX, ITMX and PRM have been newly inverted.

Those were the ones having some troubles (see #5444, #5547).

After a coarse adjustment of the damping Q factors, they look damping happily.

 

    optic                    spectra    inverted matrix   BADNESS
ETMX ETMX.png       pit     yaw     pos     side    butt
UL    0.848   0.108   1.578   0.431   1.025 
UR    0.182  -1.892   1.841  -0.128  -1.172 
LR   -1.818  -1.948   0.422  -0.122   0.939 
LL   -1.152   0.052   0.159   0.438  -0.864 
SD    1.756  -3.794  -0.787   1.000  -0.132 
  5.37028
ITMX ITMX.png     pit     yaw     pos     side    butt
UL    0.510   0.584   1.228   0.458   0.203 
UR    0.783  -1.350   0.348  -0.050   0.555 
LR   -1.217   0.065   0.772   0.264   0.312 
LL   -1.490   2.000   1.652   0.772  -2.930 
SD   -0.635   0.853  -1.799   1.000  -1.597  
 7.5125
PRM PRM.png       pit     yaw     pos     side    butt
UL    0.695   1.422   1.774  -0.333   0.954 
UR    1.291  -0.578   0.674  -0.068  -0.939 
LR   -0.709  -1.022   0.226   0.014   0.867 
LL   -1.305   0.978   1.326  -0.251  -1.240 
SD    0.392  -0.437  -0.500   1.000   0.420
 5.09674

 

(some notes)

 Before running the peakFit scripts, I woke up the nds2 sever process on Mafalda because it hasn't been recovered from the power outage.

To start the nds2 process I followed the instruction by Jamie (#5094).

Then I started requesting the data of the last night's free swinging test (#5594)

However the NDS2_GetData command failed everytime when data with long duration were requested.

It maybe because some of the data are missing in sometimes, but I haven't seriously checked the data stored in fb.

So for the reason, I had to use a short duration of 1200 sec (default is 3600 sec). That's why spectra look noisier than usual.

  12038   Fri Mar 18 11:04:56 2016 SteveUpdateSUSinverted pendulum

Kate Dooley picked up this item today.

Attachment 1: invPeng.jpg
invPeng.jpg
  2812   Tue Apr 20 07:48:42 2010 steveUpdatePSLion pump HV turned on

We found ref-cavity HV was off yesterday afternoon. It was turned back on.

  3873   Fri Nov 5 23:05:43 2010 ranaConfigurationIOOioo.db file changed in c1iool0 to get back MC TRANS

 

We like to have the MC TRANS channels so that we can run all of our old scripts and trends on it. This is the usual BROWN

channel that's on the LockMC screen. Its also the thing that we use for thresholding to activate the MC Autolocker Daemon.

I modified the ioo.db file in the target/c1iool0/ directory so that the MC_TRANS_SUM, _P, and _Y channels are all now just

CALC records of the MC2 OL channels (where the calculation is MC_TRANS_SUM = MC2 OL_SUM + 0.001, etc.). I then

rebooted c1iool0 a few times to get the syntax right. It SEEMS to be working now. I'm sure that this won't effect anything.
I've committed the new file to the SVN repo. Once Suresh is done hacking the QPD circuit, we can set the threshold in the Autolocker.

  11723   Fri Oct 30 16:56:04 2015 gautamUpdateCDSis there a problem with the SCHMITTTRIGGER CDS library part?

Over the course of my investigations into the systematic errors in the frequency readout using digital frequency counting, I noticed that my counter variable that keeps track of the number of clock cycles between successive zero crossings was NOT oscillating between 2 values as I would have expected (because of there being a +/- 1 clock cycle difference between successive zero crossings due to the fixed sampling time of 1/16384 seconds), but that there were occassional excursions to values that were +/- 3 clock cycles away. I then checked the output of the SCHMITTTRIGGER CDS library part (which I was using to provide some noise immunity), and noticed that it wasn't triggering on every zero crossing at higher frequencies. I tested this by hooking up a digital oscillator to the SCHMITTTRIGGER part, and looked at its output for different frequencies. The parameters used were as follows:

CLKGAIN: 10000

SCHMITTTRIGGER lower threshold: -1.0

SCHMITTTRIGGER upper threshold: +1.0

I am attaching plots for two frequencies, 3000Hz and 4628Hz (Attachments #1 and #2) . I would have expected a flip in the state of the output of the schmitt trigger between every pair of horizontal red lines in this plot, but at 4628 Hz, it looks like the schmitt trigger isn't catching some of the zero crossings? Come to think of it, I am not even sure why the output of the schmitt trigger takes on any values other than 0 or 1 (could this be an artefact of some sort of interpolation in the visualization of these plots? But this would not affect the conclusion about the schmitt trigger missing some of the zero crossings?)

As an interim measure, I implemented a Schmitt trigger in my C code block - it was just a couple of extra lines anyways - I have designated the schmitt trigger output as a static variable that should hold its value in successive execution cycles, unless it is updated by comparing the input value to the thresholds (code attached for reference). Attachments #3 and #4 show the output of this implementation of a Schmitt trigger at the same two frequencies, and I am seeing the expected flip in the state between successive zero crossings as expected (though I'm still not sure why it takes on values other than 0 and 1?). Anyways this warrants further investigation. An elog regarding the implications of this on the systematic error in the frequency counter readout to follow.

Attachment 1: 3000Hz.pdf
3000Hz.pdf
Attachment 2: 4628Hz.pdf
4628Hz.pdf
Attachment 3: 3000Hz_software_SCHMITT.pdf
3000Hz_software_SCHMITT.pdf
Attachment 4: 4628Hz_software_SCHMITT.pdf
4628Hz_software_SCHMITT.pdf
  14770   Thu Jul 18 00:51:52 2019 KojiSummaryCDSiscaux electronics modifications

Along with the plan in ELOG 14744, the ISC PD interface and the whitening filter board have been modificed. The ISC PD I/Fs were restored to the crate and the cables were connected. The whitening filteres are still on the electronics bench for some more tests before being returned to the crate.

The updated schematics were uploaded as https://dcc.ligo.org/D1900318 and https://dcc.ligo.org/D1900319

- Modification of the ISC PD interface: Jumpers between DIN96 P1 and P2. Replace all AD797s with OP27. In fact only I/F #1 (the left most)  had total 12 AD797 but the other units already had OP27s.

- Modification of the whitening filter: Jumpers between DIN96 P1 and P2.

Attachment 1: LSC_whitening2.jpg
LSC_whitening2.jpg
Attachment 2: LSC_whitening.jpg
LSC_whitening.jpg
  14775   Thu Jul 18 22:34:40 2019 KojiSummaryCDSiscaux electronics modifications

The whitening filter modules have been restored to the crates. The SMA cables have been restored and fastened by a spanner. The ribbon cable to the antialiasing board was also connected. The backplane cables have not been moved from the upper DIN96 connector to the lower one.

Everything is expected to be good, but just keep eyes on the LSC signals as the boards were not quantitatvely tested yet. If you find something suspicious, report on the elog.

  10853   Mon Jan 5 18:15:18 2015 JenneUpdateCDSiscex reboot

Rana noted last week that TRX's value was stuck, not getting to the lsc from iscex.  I tried restarting the individual models scx, lsc and even scy (since scy had an extra red rfm light), to no avail.  I then did sudo shutdown -r now on iscex, and when it came back, the problem was gone.  Also, I then did a diag reset which cleared all of the unusual red rfm lights.

Things seem fine now, ready to lock all the things.

  6730   Thu May 31 11:38:19 2012 DenUpdatePEMisolation system

I've put Guralps into the Steve's 2 box isolation system. Noise got better, coherence between 2 seismometers improved. We still need better performance. Probably, one device is noisy and we can not determine which one using these 2 seismometers. We need more seismometers. Sadly, STS-2 readout box is not working.

lin_box_noise2.png    lin_box_coh.png

  4906   Wed Jun 29 01:23:21 2011 haixingUpdateSUSissues in the current quad maglev system

Here I show several issues that we have encountered in the quad magnetic levitation system. It would be great if you can give
some suggestions and comments (Poor haixing is crying for help)

The current setup is shown by the figure below (I took the photo this morning):

config_2.png

Basically, we have one heavy load which is rigidly connected to a plane that we try to levitate. On corners of the
plane, there are four push-fit permanent magnets. Those magnets are attracted by four other magnets which are
mounted on the four control coils (the DC force is to counteract the DC gravity). By sensing the position of the plane
with four OSEMs (there are four flags attached on the plane), we try to apply feedback control and levitate the plane.
We have made an analog circuit to realize the feedback, but it is not successful. There are the following main issues
that need to be solved:

(1) DC magnetic force is imbalanced, and we found that one pair has a stronger DC force than others. This should
be able to solved simply by replacing them with magnets have comparable strength to others.

(2) The OSEM not only senses the vertical motion, but also the translational motion. One possible fast solution is to
cover the photodiode and only leave a very thin vertical slit so that a small translational motion is not sensed.
Maybe this is too crappy. If you have better ideas, please let me know. Koji suggested to use reflective sensing
instead of OSEM, which can also solve the issue that flags sometimes touche the hole edge of the OSEM and
screw up the sensing.

(3) Cross coupling among different degrees of freedom. Basically, even if the OSEM only senses the vertical motion,
the motion of four flags, which are rigidly connected to the plane, are not independent. In the ideal case, we only
need to control pith, yaw and vertical motion, which only has three degrees of freedom, while we have four sensing outputs
from four OSEMs. This means that we need to work out the right control matrix. Right now, we are in some kind of dilemma.
In order to obtain the control matrix, we first have to get the sensing matrix or calibrate the cross coupling; however, this is
impossible if the system is unstable. This is very different from the case of quad suspension control used in LIGO,
in which the test mass is stable suspended and it is relatively easy to measure the cross coupling by driving the test mass
with coils. Rana suggested to include a mechanical spring between the fixed plane and levitated plane, so that
we can have a stable system to start with. I tried this method today, but I did not figure out a nice way to place the spring,
as we got a hole right in the middle of the fixed plane to let the coil connectors go though. As a first trial, I plan to
replace the stop rubber band (to prevent the plane from getting stuck onto the magnets) shown in the figure with mechanical
springs. In this case, the levitated plane is held by four springs instead of one. This is not as good as one, because
of imbalance among the four, but we can use this setup, at least, to calibrate the cross coupling. Let me know if you come
up better solution.

After those issues are solved, we can then implement Jamie's Cymac digital control, which is now under construction,
to achieve levitation.

  4907   Wed Jun 29 11:13:13 2011 JenneUpdateSUSissues in the current quad maglev system

magnetQuote


(1) DC magnetic force is imbalanced, and we found that one pair has a stronger DC force than others. This should
be able to solved simply by replacing them with magnets have comparable strength to others.

 I don't know if this would work, but it might be worth a try:

You've achieved single levitation before, with fairly good stability.  Can you try taking each magnet + coil and finding the DC coil current required to hold a mass at a given position?  If you can hold the same mass at the same place with all the different magnets+coils, then you're exerting the same force against gravity, so your DC forces are balanced. 

  9828   Fri Apr 18 09:40:28 2014 SteveUpdateElectronicsit is a kick

10 days of on-off glitching?   It is a kick. The LSC is off, so it must be the ALS

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  10075   Thu Jun 19 17:11:52 2014 steveUpdatePEMit is warmer today

 The PSL HEPA was running at 30VAC-variac. It is 1 degree C warmer than usual. The HEPA fan motor turned up to 60 V

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  114   Mon Nov 19 14:19:25 2007 steveOmnistructurePEMjackhammer
The construction personal successfully jackhemmered a fence around the "Drever's parking slot"
There is no parking space available close by
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