40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log, Page 43 of 341  Not logged in ELOG logo
ID Date Author Type Category Subjectdown
  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)

  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
 

 

  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.

  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
  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.
 

 

  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

  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.

 

  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;

  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 

  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 &"
  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.

 

  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.
  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.

  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.

  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

  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.

 

  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.

  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.

  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.

  9209   Sun Oct 6 22:52:09 2013 Jenne, RanaUpdateIOOinput beam to PMC aligned again

pmcr.pngafter

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

  588   Sat Jun 28 14:56:44 2008 JohnUpdateComputersini files
In short, I was editing the ini files yesterday evening, I didn't e-log it and after some investigation this afternoon it apears
that I am to blame for all the computer problems which followed.


I wanted to edit C0EDCU.ini and C1IOOF.ini to change C1: PSL-FSS_FAST to a fast channel as C1: PSL-FSS_FAST_F
was dead.

I opened these files and made backups. It appears this is where it all went awry. My backup for C1IOOF
is called C1IOO.ini.090627 i.e. missing the F.

Later c1susvme2 and c1iovme crashed. After failing to bring c1iovme back I wondered if my edits had
caused the problems so I restored the back up files. It appears that here I wrote over C1IOO with my backup of
C1IOOF (presumably because I had made a typo in the name).

To remedy the situation we could restore C1IOO from e.g. chans/archive/C1IOO_080618_160028.ini

No excuses for not e-logging this activity.
  3909   Fri Nov 12 13:12:55 2010 kiwamuUpdatePSLincreased NPRO power

I maximized the laser power by rotating the HWP after the NPRO.

If someone works on the MC locking, one should decrease it again.

 

  11580   Mon Sep 7 16:30:56 2015 ranaHowToComputer Scripts / Programsincrease of window border size on Rossa

Frustrated by the single pixel width of the windows and how hard that makes it to drag things around, I explored StackExchange:

which showed how there is a .xml file which can be edited to increase this. I've changed the border size to 4 pixels on Rossa - its nice.devil

  4105   Tue Jan 4 13:57:48 2011 kiwamuUpdateIOOincident mirror changed from 45deg to 0 deg

I replaced the final steering mirror (Y1-1037-45-S) in the zig-zag path on the PSL table by a 0 deg mirror Y1-1037-0.

With a sensor card I confirmed the transmission reduced a lot after the replacement.

As we expected, the replacement of the mirror caused a mis-alignment of the incident beam axis to the MC, so I compensated it by touching the angle of the mirror a little bit.

After the alignment of the mirror, the MC is still resonating at TEM00.

We will check the spot positions more accurately by A2L technique.

Quote:

- Y1-45S has 4% of transmission. Definitively we like to use Y1-0 or anything else. There must be the replaced mirror. 

I think Suresh replaced it. So he must remember wher it is.

  5478   Tue Sep 20 13:57:44 2011 kiwamuUpdateIOOincident beam to MC aligned

Since the MC wasn't able to capture the 00 mode in this morning I aligned the incident beam going to MC.

As a result C1:IOO-RFPD_DCMON went down to 0.6. However the beam on IPPOS is almost falling off from the QPD.

  8328   Thu Mar 21 13:50:08 2013 JamieUpdateLockingincident angles

Is there a reason to use non-45 degree incident angles on the steering mirrors between the laser and the PD?  I would always use 45 degree incident angles unless there is a really good reason not to.

  8329   Thu Mar 21 14:02:45 2013 AnnalisaUpdateLockingincident angles

Quote:

Is there a reason to use non-45 degree incident angles on the steering mirrors between the laser and the PD?  I would always use 45 degree incident angles unless there is a really good reason not to.

 Actually not, it is a mistake! It is one of the things I'm going to modify, in addition to add more BS to reduce the power. 

  10874   Wed Jan 7 21:13:35 2015 ranaUpdateGeneralinane LSCoffsets script removed

Quote:

 A few things that I have neglected to ELOG yet:

  • scripts/offsets/LSCoffsets is a new script that uses ezcaservo to set FM offsets of our LSC PDs. It still warns about large changes, and lets you revert. It reads the FM gain to pick the right gain for the ezcaservo call. 

 We never, ever want to use ezcaservo to do this. IN fact, we twice have already deleted scripts where people have implemented these (sometimes) unstable servos. Also, since this change had never been committed to the SVN, I just deleted it and updated from the SVN to get back the script that doesn't use any servos.

I'm going to periodically delete locking scripts that are not committed to the SVN since anyone who is too lazy to use the SVN probably can't write code worth using.

  10880   Thu Jan 8 19:41:50 2015 ericqUpdateGeneralinane LSCoffsets script removed

The restored offset script used old tdsavg calls that our workstations can't do, and didn't include things like the transmon QPDs. I've written yet another offset script that uses cdsutils averaging to do the thing, and committed to the svn. 

  5258   Wed Aug 17 20:14:49 2011 jamie, kiwamu, suresh, jenne, keiko, anamariaUpdateGeneralin-vacuum work status, prep for pump

This afternoon's work:

  • OSEMs were adjusted on all suspended optics.
  • X and Y-arms were aligned to green.
  • Once that was done, the input pointing was adjusted with the PZTs to get the IR beam centered on ITMY and ETMY.
  • Once the input pointing was ok we extracted IPANG and IPPOS.
  • BS, ITMY, PRM, SRM optical levers (oplevs) were extracted.
  • Prepared rails and stops for TMs for morning drag wiping.

TODO before drag wiping:

  • Check full IFO alignment.
  • Readjust OSEMs if needed.
  • Extract ITMX oplev.
  5152   Tue Aug 9 10:15:25 2011 kiwamuUpdateGeneralin-vac work plan today

We will move on to the vertex region today.

The goal of the vertex region work is to get the pick-off beams out the chambers, including POX/Y and POP.

The work will be in parallel to the ETM woks.

The first step will be : lock and align MC with the IR beam.

  5155   Tue Aug 9 15:14:46 2011 KojiUpdateGeneralin-vac work plan today

This morning Kiwamu and I have aligned the MC. Kiwamu aligned the last steering (on the OMC table) to recover the touch last week.
Then I have aligned the MC with MC1 and MC3 as the last steering did not help to get TEM00.

Before

C1:SUS-MC1_PIT_COMM = 2.6587
C1:SUS-MC1_YAW_COMM = 2.7471
C1:SUS-MC2_PIT_COMM = 3.486
C1:SUS-MC2_YAW_COMM = -1.1592
C1:SUS-MC3_PIT_COMM = -1.876
C1:SUS-MC3_YAW_COMM = 1.2829

After

C1:SUS-MC1_PIT_COMM = 2.7596
C1:SUS-MC1_YAW_COMM = 2.6627

C1:SUS-MC2_PIT_COMM = 3.486
C1:SUS-MC2_YAW_COMM = -1.1592
C1:SUS-MC3_PIT_COMM = -1.697
C1:SUS-MC3_YAW_COMM = 1.2901

Quote:

We will move on to the vertex region today.

The goal of the vertex region work is to get the pick-off beams out the chambers, including POX/Y and POP.

The work will be in parallel to the ETM woks.

The first step will be : lock and align MC with the IR beam.

 

  5253   Wed Aug 17 06:42:38 2011 kiwamuUpdateGeneralin-vac work : the end is near

We will pump down the chambers on Thursday morning.

Today will be a day of the OSEM and oplev party.

 

 -- to do list for today --

 + OSEM mid-range adjustment

 + oplev realignment

 + placement of beam traps

 + extraction of IPPOS

 + table leveling

 + interferometer alignment

 + AM-PM mystery

 + preparation for drag and wipe

  5256   Wed Aug 17 15:55:01 2011 JenneUpdateGeneralin-vac work : the end is near

Quote:

We will pump down the chambers on Thursday Friday morning.

 All hands on deck at 9am Thursday for drag wiping and doors.  We'll do the 5 doors first (including drag wiping), then put on the access connector last.  Steve will then begin pumping early Friday morning.

  5275   Mon Aug 22 02:43:28 2011 kiwamuUpdateGeneralin-vac work

[Kieko / Kiwamu]

 The AS beam shows a little bit of clipping and right now this is the only concern for the alignment of the interferometer.

Other than that everything is okay including :

  + Beam centering on all the suspended optics

  + Arm cavity alignments. The Fabry-Perot fringes from both arm cavity were found on the AS camera.

  + POX/POY/POP, they are still successfully coming out from the chambers

  + IPPOS/ANG

  + Alignment of the green beams and the associated optics. Both green are reaching to the PSL table

 

We need to check/fix the AS beam clipping and once it's done we will readjust the OSEM mid range and the oplevs.

Then it will be ready for the drag/wipe and door closing.

  7338   Tue Sep 4 20:03:38 2012 JenneUpdateGeneralin-vac progress

Opened ETMY, beam was high and to the right (if you look at the face of ETMY).  Tried walking beam up, since just doing PZT2 caused clipping at the BS before we got to the correct spot on ETMY.  Moved PZT1, then PZT2, to translate beam, but we couldn't get far enough without starting to fall off of PZT2.  Put PZT1 approx. back where it was. Jamie tapped on the top of PR3 (tip tilt just before BS), and then did some compensation with PZT2 to get the beam through the BS target to the center of ETMY.

The beam is very dim at ETMY.  We ended up holding the big IR card with holes such that one of the holes was near the center of the optic, in front of the cage.  Then one person turned off all the room lights so we could see the beam, another person moved PZT2 and PR3, then lights person turned on and off the lights so we could compare beam position with hole position.  A total pain, but it ended up working better than just trying to follow the beam with a card.

We clearly need a better plan for adjusting the tip tilts in pitch, because utilizing their hysteresis is ridiculous.  Koji and Steve are thinking up a set of options, but so far it seems as though all of those options should wait for our next "big" vent.  So for now, we have just done alignment by poking the tip tilt.

Tomorrow, we want to open up the MC doors, open up ETMY, and look to see where the beam is on the optic.  I am concerned that the hysteresis will relax over a long ( >1hour ) time scale, and we'll loose our pointing.  After that, we should touch the table enough to trip the BS, PRM optics, since Koji is concerned that perhaps the tip tilt will move in an earthquake.  Jamie mentioned that he had to poke the tip tilt a pretty reasonable amount to get it to change a noticeable amount at ETMY, so we suspect that an earthquake won't be a problem, but we will check anyway.

After doing all of that, we adjusted IPANG so that the beam gets out of the vacuum envelope.  The beam must squeeze between the wall of the black beam tube and a lens for the oplev, so there is a very, very limited amount of space.  The eventual new tables will be very helpful for alleviating this, but for now we must live with it.  Even though it is pretty squishy right at the edge of the table, with the new layout we should think about giving IPANG a little more space.  Basically, if there is any Yaw motion, the beam going to the QPD will be clipped, and we may get confusing info.  We moved some of the IPANG optics that are on the end transmission table so the beam is centered on the optics while it just makes it through the space between the wall and the lens.  The spot was centered on the IPANG QPD. 

We still need to check on IPPOS, but it is always easier than IPANG.

General notes:

We discovered that the 45deg SOS beam targets are awesome, especially the ones with the irises.  The plain hole ones have very small holes relative to our beam size, so they are much more useful for the MC optics (which they were designed for).  The 45deg targets were made such that the target holes do not line up with the mounting holes.  This is good, since the mounting holes are lower than the center of the optic.  I don't think ericQ and I realized that on Friday, so it's probable that we had installed the target upside-down.  We still need to remake the 0deg targets for the next vent.

Jamie dogged down the new 'bathroom mirror' that lets us see BS and PRM on the same camera view.  He also adjusted some of the masses on the BS table to relevel the table. We need to (at some point) rename the AS_SPARE camera to something like BS_PRM, since we plugged the new camera into the AS_SPARE port on the videoswitch.

tl;dr: Input beam adjusted so we're hitting center of ETMY.  IPANG coming out of vacuum, QPD centered. Need better tip tilt in-situ adjustment capability.

  7865   Thu Dec 20 18:33:52 2012 JamieUpdateGeneralin-vac adapter cables for TTs

We need short cables that mirror the pins:

invac-adapter-cable.pdf

The male side will plug into the 25-pin female on the stack-top bracket.  The tip-tilt quadrapus cable will plug into the female side. This will match up pin 1 on the tip-tilt cable, which is connected to it's shield, to pin 13 on the bracket, which is the shield of the cable that runs to the stack.

They need to be vacuum compatible.  Shorter length is preferred, and there is no minimum length (something like an all-in-one gender changer would be ideal, but probably expensive to have made).


 

  7868   Fri Dec 21 09:55:23 2012 SteveUpdateGeneralin-vac adapter cables for TTs

 

 Accu-Glass is closed till Jan 2, 2013

Atm2 would be the ideal solution Gender Adaptor Special with male - female sides and vented D-sub. How many are we getting 2 or 6 ?

Attachment 1: extensioncable.pdf
extensioncable.pdf
Attachment 2: genderchanger.pdf
genderchanger.pdf
  4352   Thu Feb 24 18:21:24 2011 kiwamuUpdateGreen Lockingin-loop and out-of-loop measurements

Two different measurement have been performed for a test of the green locking last night.

Everything is getting better. yes. yes.

green_lock_setup.png

 


[ measurement 1 : IR locking]

The X arm was locked by using the IR PDH signal as usual (#4239#4268) .

The in-loop signal at from the IR path and the out-of-loop signal at from the green beat note path were measured.

measurement1.png

Let us look at the purple curve. This is an out-of-loop measurement by looking at the green beat note fluctuation.

The rms down to 0.1 Hz used to be something like 60 kHz (see here), but now it went down to approximately 2 kHz. Good.

This rms corresponds to displacement of about 260 pm of the X arm. This is barely within the line width. The line width is about 1 nm.

 

 


[ measurement 2 : green locking]

The motion of the X arm was suppressed by using the green beat signal and feeding it back to ETMX.

After engaging the ALS servo, I brought the cavity length to the resonance by changing the feedback offset from epics.

Then took the spectra of the in-loop signal at the beat path and the out-of-loop signal at the IR PDH path.

 

 Here is a time series of TRX after I brought it to the resonance.

TRX_REFL11.png

TRX was hovering around at the maximum power, which is 144 counts.

measurement2.png

Since I put one more 10:1 filter to suppress the noise around 3 Hz, the rms of the in-loop beat spectrum went to about 1 kHz, which used to be 2 kHz (see #4341).

But the out-of-loop (IR PDH signal) showed bigger noise by a factor of 2 approximately over frequency range of from 2 Hz to 2 Hz. The resultant rms is 2.7 kHz.

The rms is primarily dominated by a peak at 22 Hz (roll mode ?).

I calibrated the IR PDH signal by taking the peak to peak signal assuming the finesse of the cavity is 450 for IR. May need a cooler calibration.

  12560   Thu Oct 13 19:28:14 2016 gautamUpdateGeneralin-air alignment

I did the following today to prepare for taking the doors off tomorrow.

  • Locked MC at low power
    • low power autolocker used during the last vent isn't working so well now
    • so I manually locked the IMC - locks are holding for ~30 mins and MC transmission was maximized by tweaking MC1 and MC2 alignments. The transmission is now ~1150 which is what I remember it being from the last vent
    • I had to restart c1aux to run LSCoffsets
  • Aligned arms to green using bias sliders on IFO align
    • X green transmission is ~0.4 and Y green transmission is ~0.5 which is what I remember it being before this vent
  • Removed ND filters from end Transmon QPDs since there is so little light now
  • Locked Y arm, ran the dither
    • Some tip tilt beam walking was required before any flashes were seen
    • I had to tweak the LSC gain for this to work
    • TRY is ~0.3 - in the previous vent, in air low power locking yielded TRY of ~0.6 but the 50-50 BS that splits the light between the high gain PD and the QPD was removed back then so these numbers are consistent
  • Tried locking X arm
    • For some reason, I can't get the triggering to work well - the trigger in monitor channel (LSC-XARM_TRIG_IN) and LSC-TRX_OUT_DQ are not the same, should they not be?
    • Tried using both QPD and high gain PD to lock, no luck. I also checked the error signal for DC offsets and that the demod phase was okay
    • In any case, there are TRX flashes of ~0.3 as well, this plus the reasonable green transmission makes me think the X arm alignment is alright
  • All the oplev spots are on their QPDs in the +/- 100 range. I didn't bother centering them for now

I am leaving all shutters closed overnight.

So I think we are ready to take the doors off at 8am tomorrow morning, unless anyone thinks there are any further checks to be done first.


Vent objectives:

  1. Fix AS beam clipping issues (elog1, elog2)
  2. Look into the green scatter situation (elog)

Should we look to do anything else now? One thing that comes to mind is should we install ITM baffles? Or would this be more invasive than necessary for this vent?


Steve reported to me that he was unable to ssh into the control room machines from the laptops at the Xend and near the vacuum rack. The problem was with pianosa being frozen up. I did a manual reboot of pianosa and was able to ssh into it from both laptops just now.

  679   Wed Jul 16 11:00:15 2008 MashaUpdateAuxiliary lockingimproving ADC input for the mach zehnder setup and completely unrelated happenings
For most of last week, the SURFs + Jenne were helping Mike and Ken with "stray light control for
Enhanced LIGO", i.e. cleaning and baking many many baffles which will catch scattered light in the
interferometer.

Otherwise, the two channels of the Mach Zehnder which will be used to measure fibre noise were
balanced, which should reduce the effect of laser amplitude noise in phase noise detection. I have
set up two digital channels to collect time series data from the two photodiodes and took some
preliminary noise measurements. I will be using Matlab to combine the signals as to directly measure
the phase noise, and I wrote some Matlab code to speed up this process: loading the files,
manipulating time series data, and converting into frequency domain. Currently I am building a
filter that will attenuate the signal at frequencies below 1Hz and amplify at higher frequencies in
order to whiten the spectra and reduce ADC noise.
  6776   Thu Jun 7 02:25:27 2012 yutaUpdateGreen Lockingimproved Y arm green alignment - even more

[Koji, Yuta]

Summary:
  We improved the Y arm green transmission to the PSL table. It is now 197 uW.
  The improvement was done mainly by adjusting the Y arm green servo gain.

What we did:
  1. Fine-adjusted steering mirrors after the faraday on Y end table by monitoring Y arm green transmission (used Thorlabs PDA36A as a PD, C1:GCV-GREEN_TRY as a channel). We decided which way to adjust the mirrors by just pushing/pulling its mount.

  2. The output of the reflection PD on the oscilloscope seemed like the Y end frequency servo was oscillating. So, we reduced the amplitude of the frequency modulation from 2.83 V to 0.13 V.

  3. We noticed there were two TEM00, one is brighter and the other is dim. We thought this came from a mode-hopping or something. So, we changed the Y end laser temperature from 34.68 deg C to 34.13 deg C (measured). This reduced dim TEM00 and the main one got brighter. C1:GCY-SLOW_SERVO2_OFFSET was changed from 29425 to 29845.

  4. Fine-adjusted the position of the mode-matching lens by reduing LG modes.

Current green power:
  Current measured green power values are as follows.

beatygreenpower20120607.png

  Calculated value for the Y arm green transmission is ~ 600 uW, but we think we are almost at the maximum we can get. So, we have about 70% loss from the Y end table to the PSL table. There may be large loss in windows. The beam shape of the transmitted beam seems OK, but there may be some clipping.

To do:
  - Fine tune the Y end frequency servo loop. Reducing the amplitude of the frequency modulation for reducing the gain is not a very good idea.

  6780   Thu Jun 7 07:27:27 2012 KojiUpdateGreen Lockingimproved Y arm green alignment - even more

Yes. The end PDH servo should be checked more carefully.

The end PDH seems to have insufficient gain at around 100Hz.
The attached is the ALS noise budget calculated with the simulink model for the green locking paper.

The residual error of the end AUX laser (green) is contributing to the final ALS signal (black).
In particular, the residual AUX frequency noise, which is shown as the blue, is contributing to the noise above 100Hz.

In the model I also confirmed that the servo still has a room for improvement.

By having more suppression of the AUX frequency noise, we will be able to increase the ALS servo bandwidth
without increasing the ALS residual RMS by a servo bump. This will give us the improvement of the seismic
noise suppression at 10Hz (i.e. more suppression of red).

Attachment 1: freq_noise_AUX.pdf
freq_noise_AUX.pdf
  6771   Wed Jun 6 21:11:45 2012 yutaUpdateGreen Lockingimproved Y arm green alignment

Summary:
  Y arm green transmission to the PSL table improved from ~ 20 uW to 61 uW. Improvement was done by adjusting steering mirrors before and after the faraday on the Y end table.
  But 61 uW is not enough!

What I did:
  1. The incident power to the faraday for the green beam on the Y end table was 1.4 mW, but the transmission was 1.2 mW. So, I adjusted the steering mirrors and the transmission increased to 1.4 mW.

  2. I found that adjusting the steering mirrors to the faraday also increased alignment of the green beam to the Y arm. We always adjusted only the steering mirrors after the faraday for the alignment. I adjusted the alignment using both steering mirrors this time. Reflection of the green beam on the ETMYT camera seems more reasonable now and more frequently lock to TEM00 when closing and opening the Y end green servo loop.

  3. For the adjustment, I tried to utilize PD at the reflection port, or the transmission port. However, I couldn't do that because they fluctuates too much. I don't know why.

  4. Measured the green transmission to the PSL table, The transmitted power was ~20 uW, but after the aligning, it improved to 61 uW.

Current green power:
  I measured the green beam power at various places using Newport power meter (Model 840) with its filter on.

beatygreenpower20120606.png

  Incident green power to the Y arm is ~ 1 mW (more than 1 mW because the aparture of the power meter was smaller than the beam size) and Y arm transmission is designed to be 55%. So, if the alignment and mode matching are perfect, the transmission to the PSL table should be ~ 600 uW. The measured value 61 uW seems too small. Kiwamu says it was 140 uW when he did Y arm.

Next:
  I will find the beat note again tonight and check if the beat PD is working correctly and if the mode matching of the two beams at the PSL table is good.

  3054   Tue Jun 8 00:38:22 2010 Koji, KiwamuUpdateIOOimproved Gaussian beam in new IOO

The shape of the beam spot in the new input optics got much much better 

As Alberto and Kiwamu found on the last week, the beam spot after MMT1 had not been good. So far we postponed the mode measurement due to this bad beam profile.

Today after we did several things in the vacuum chamber, the beam spot became really a good Gaussian spot. See the attachment below.

There were two problems which had caused the bad profile:

(1)  a steering mirror after MMT1 with the incident angle of non 45 deg

(2) clipping at the Faraday.

 

Also MCT_QPD and MCT_CCD were recovered from misalignment  

Tomorrow we are going to restart the mode matching. 

 


(what we did)

* We started from checking the shape of the beam going out from the BS chamber. There still were some stripes which looked like an interference on the spot. 

* We found a steering mirror after MMT1 had the incident angle of non 45 deg. In fact the mirror had a large transmission. After we made the angle roughly 45 deg, the stripes disappeared.

However the spot still didn't look a good Gaussian, it looked slightly having a bump on the horizontal profile.

* Prior to moving of some optics in the vacuum, we ran the A2L_MC scripts in order to check the beam axis. And it was okay.

* To recover the MCT, we steered one of the vacuum mirrors which was located after the pick off mirror.  And after aligning some optics on the AP table, finally we got MCT recovered.

 * We rearranged MC_refl mirrors according to the new optical layout that Koji has made. At the same time the mirrors for IFO_refl was also rearranged coarsely.

 * We leveled the optical table of the MC chamber by moving some weights. Then we locked the MC again and aligned it. We again confirmed that the beam axis was still fine by running the A2L scripts.

 * We found the beam going through Faraday was off-centered by ~5mm toward the west. So we moved it so that the beam propagates on the center of it. 

 * Then looking at the beam profile after MMT1, we found that the profile became really nicer. It showed a beautiful Gaussian. 

In the attachment below, the top panel represents the horizontal profile and the bottom one represents the vertical profile.

The blue curves overlaid on the plot are fitted Gaussian profile, showing beautiful agreements with the measured profile.

Attachment 1: 2010-6-7_2.png
2010-6-7_2.png
  2450   Thu Dec 24 01:25:29 2009 kiwamuUpdateElectronicsimpedance analyzing

The validation for high impedance measurement has been well done.

The impedance measurement is one of the keys for designing the EOM circuit.

So far I was very struggling to measure the high impedance ( above several 1000 Ohm) at RF because the EOM circuit has a high impedance at its resonance.

Finally I realized that the measured impedance was suppressed by a parasitic resistance, which especially reduces the impedance at the resonance.

Also I found that we can extract the TRUE impedance data by subtracting the effect of the parasitic resistance from resultant data.

In order to confirm whether this subtraction works correctly or not,  the impedance was directly re-measured with another analyzer for crosscheck.

                The followers are details about the re-measurement.
 

 

(measurement )

The measurement has been performed with help from Peter and Frank. ( Thank you !)

By using  network analyzer AG4395A with the impedance test kit AG43961A (these are at the PSL lab.), the impedance of resonant circuit with EOM was measured.

The picture of setup is attached. This impedance test kit allows to measure typically 0.1 [Ohm]-1M [Ohm] and frequency range of 100kHz-500MHz.

 

(result)
The resultant plot is attached. In the plot the blue curve represents the impedance measured by usual analyzer at 40m.

Note this curve is already subtracted the effect of the parasitic resistance.

( the parasitic resistance is in parallel to the circuit and it has ~7.8k Ohm, which is measured while the probe of the analyzer stays open. )

The red curve is the re-measured data using the impedance test kit.

The important point is that; these two peak values at the resonance around 40MHz show good agreement in 10%.

The resonant frequencies for two data differs a little bit, which might be the effect of a stray capacitance ( ~several [pF] )

The red curve has a structure around 80MHz, I think this comes from the non-coaxial cables, which connect the circuit and analyzing kit.

You can see these cables colored black and red in the picture.

 

( conclusion )

Our measurement with the subtraction of the  parasitic resistance effect is working reliably !

Attachment 1: DSCN0421.JPG
DSCN0421.JPG
Attachment 2: EOM.png
EOM.png
ELOG V3.1.3-