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ID Date Author Typeup Category Subject
  2473   Mon Jan 4 17:21:30 2010 JenneConfigurationIOOElusive Mode Matching Solution found!

I think I have finally found a Mode Matching solution for our new Input Mode Matching Telescope!  And after looking at the layout diagram with Koji and Raffaele, it seems like all of the optics will fit into the chambers / onto the tables (not true as of last week). 

3. RoCMMT1 is -5m
   RoCMMT2 is 8m,
   with the MMTs 1.89m apart.
   This is a 1.6x telescope.
   MMT2 is 2.2641m from the PRM
   MMT1 is 2m from MC3.
   The Condition Number for this optical chain is 89219047.5781.

This layout is very similar to the one that Koji posted on the wiki yesterday:  Upgrade09/Optical Layout.  The difference is that I want to move MMT1 ~20cm closer to the MC13 table, so just on the other side of the main red beam that goes directly to PRM.  There is plenty of space there, so it should be all good.  The tricky bit is that the flat steering mirrors fit into things now while they are piezos, but they will be trickier to fit if we make them into Tip Tilts.  But I have full faith in Koji's amazing optical table layout skills, that he can make it happen. 

Unless there are major objections, I think this is the MMT that we're going to go with. (So speak now or forever hold your peace.)  The angle between tilt and translation isn't quite what we'd like it to be (at ~18deg), but it's not too terrible.  And we still have 99.5% overlap which is very important.

Attachment 1: Awesome_MM_Solution.png
Awesome_MM_Solution.png
  2481   Wed Jan 6 03:44:41 2010 KojiConfigurationIOOElusive Mode Matching Solution found!

I am in the way to get a reasonable optical layout.
Please calculate the final results with the following conditions.

"Result" =
- mode overlapping with astigmatism
- alignment matrix (m/rad, rad/rad) for Pitch and Yaw
- alignment orthogonality
- sensitivity of the mode overlapping to the perturbations
  * histgram
  * individual scan of the optic positions

Optics chain: MC3 - SM1(flat) - MMT1(f=-5m) - MMT2(f=+8m) - SM2(flat) - PRM

Incident angles: SM1 24deg, MMT1 3deg, MMT2 1deg, SM2 44.5deg

Distances:
MC3 HR - SM1: 884mm
SM1 - MMT1: 1058.2mm
MMT1 - MMT2: 1890mm
MMT2 - SM2: 2007.9mm
SM2 - PRM HR: 495.6mm

It has ~200mm deviation from the solution. I can move only MMT1 for final optimization.
Give us the numbers if it can improve the performance.
Note that this move changes SM1-MMT1 and MMT1-MMT2 simultaneously.

Quote:

I think I have finally found a Mode Matching solution for our new Input Mode Matching Telescope!  And after looking at the layout diagram with Koji and Raffaele, it seems like all of the optics will fit into the chambers / onto the tables (not true as of last week). 

3. RoCMMT1 is -5m
   RoCMMT2 is 8m,
   with the MMTs 1.89m apart.
   This is a 1.6x telescope.
   MMT2 is 2.2641m from the PRM
   MMT1 is 2m from MC3.
   The Condition Number for this optical chain is 89219047.5781.

This layout is very similar to the one that Koji posted on the wiki yesterday:  Upgrade09/Optical Layout.  The difference is that I want to move MMT1 ~20cm closer to the MC13 table, so just on the other side of the main red beam that goes directly to PRM.  There is plenty of space there, so it should be all good.  The tricky bit is that the flat steering mirrors fit into things now while they are piezos, but they will be trickier to fit if we make them into Tip Tilts.  But I have full faith in Koji's amazing optical table layout skills, that he can make it happen. 

Unless there are major objections, I think this is the MMT that we're going to go with. (So speak now or forever hold your peace.)  The angle between tilt and translation isn't quite what we'd like it to be (at ~18deg), but it's not too terrible.  And we still have 99.5% overlap which is very important.

 

  2490   Fri Jan 8 20:13:49 2010 Alberto, JoBConfigurationComputersThe 40m Kaiser Permanent Reboot Marathon
This morning after Alex and Jo's tinkering with Megatron the RFM network crashed and it brought down also some computers. The effect was that it was not possible to lock the mode cleaner anymore.
A few computers crashed and things didn't come back to their origianl state.
After an endless day of rebooting and fixing problems with the single front ends (in particular with c1susvme1), eventually the mode cleaner got locked again.
Among my weapons I also used the Nuclear Option (TM).
Maybe I'll include more details in a future elog entry.
Anyway, in the end I burtrestored everything to Jan 8 2009 at 9:00.

pasadena_marathon.JPG

  2518   Sun Jan 17 05:22:42 2010 ranaConfigurationComputersELOG script change

With Dave Barker's help, I changed the elog startup script. Instead of running as a Daemon with the -D option,

it now runs in the background with the unix "&". I think that the stdout and stderr are now redirected to a log file called elog.log.

We can 'tail -f' this file to see what its up to and debug any future crashing.

  2549   Tue Jan 26 20:18:32 2010 ranaConfigurationALARMop540m: alarms and BLRMS and StripTool restored

I turned the StripTool and ALARMS and BLRMS back on on op540m. Looks like it has been rebooted 5 days ago and no one turned these back on. Also, there was a bunch of junk strewn around its keyboard which I restrained myself from throwing in the trash.

The BLRMS trends should be active now.

  2551   Thu Jan 28 09:14:51 2010 AlbertoConfigurationComputersc1iscey, c1iscex, c1lsc, c1asc rebooted

This morning the LSC scripts wheren't running properly. I had to reboot c1iscey, c1iscex, c1lsc, c1asc .

I burtrestored to Monday January 25 at 12:00. 

  2568   Wed Feb 3 11:13:15 2010 steveConfigurationGeneralplaned power outage for Sat. Feb 20

The electrical shop has to connect the new power transformer at CES. This means we will have no AC power for ~8 hrs on Saturday, February 20

Is this date good for us to power down ALL equipment in the lab?

Rana:  Yes

  2573   Fri Feb 5 11:01:49 2010 steveConfigurationVACslow pumpdown valve

I have installed a slow start throttle valve in front of V3  This spring loaded valve will cut down on the flow at high pressures. There will be no more sand storme

and static built-up during pump down.

Attachment 1: slow.JPG
slow.JPG
  2585   Wed Feb 10 16:27:47 2010 steveConfigurationGeneral IFO beam heights

IN VACUUM beam heights are ALL 5.5"  This is measured from the top of the optical table to the center of all TMs, mirrors and other optical components. This beam is ~36" above the floor.

PSL (inside of enclosure) main-output  beam: PMC, MZ, RC and ISS  are at 3" heights. IOO Angle & Position, MC-Trans and RFAM qpds are at 4"

ALL OTHER beam heights at atmosphere and  different ISCT (interferrometer sensing, control optical table)s are at 4"

 

 

  2589   Thu Feb 11 15:53:59 2010 steveConfigurationVACPSL output shutter is closed

Joe and Alex are working on the computers. Our vacuum system is temporary "All off" condition: meaning all valves are closed, so there is no pumping. cc1 = 1.6e-6 Torr

  2592   Thu Feb 11 18:53:57 2010 steveConfigurationVACVAC NORMAL is back

Quote:

Joe and Alex are working on the computers. Our vacuum system is temporary "All off" condition: meaning all valves are closed, so there is no pumping. cc1 = 1.6e-6 Torr

 Designated vacuum control lap top is trouble some to use. Joe finally fixed it and I switched valve configuration back to vacuum normal. Shutter is open

  2605   Tue Feb 16 10:01:16 2010 AlbertoConfigurationLSCArms and PRC not locking

Since last Friday either the arms or the PRC can't lock.

The montors show the beam flashing on the end mirrors, but the cavity can't get locked. The error signal looks fine. I suspect a computer problem.

Also PRC can't lock. SPOB is suspiciously stuck at about -95. Although that's not a fixed number, but covering the by hand the SPOB PD on the ITMY table doesn't change the number. I check the DC output of the photodetector and it is actually seen the beam.

Suspecting computer problems started after last Thursday's IP switch, I rebooted the frame builder, c1dcuepics, c1daqctrl and all the front ends. I then burtrestored to February 1st at 1:00 am.

Before I burtrestored c1iscepics, SPOB had gone back to more typical numbers around 0, as it usually read when PRC wasn't locked.

But burtrestoring c1iscepics, return it to the -95 of earlier.

Burterestoring to other times or dates didn't solve the problems.

  2607   Tue Feb 16 14:10:06 2010 josephb, rob, kojiConfigurationLSCArms and PRC not locking

Quote:

Since last Friday either the arms or the PRC can't lock.

The montors show the beam flashing on the end mirrors, but the cavity can't get locked. The error signal looks fine. I suspect a computer problem.

Also PRC can't lock. SPOB is suspiciously stuck at about -95. Although that's not a fixed number, but covering the by hand the SPOB PD on the ITMY table doesn't change the number. I check the DC output of the photodetector and it is actually seen the beam.

Suspecting computer problems started after last Thursday's IP switch, I rebooted the frame builder, c1dcuepics, c1daqctrl and all the front ends. I then burtrestored to February 1st at 1:00 am.

Before I burtrestored c1iscepics, SPOB had gone back to more typical numbers around 0, as it usually read when PRC wasn't locked.

But burtrestoring c1iscepics, return it to the -95 of earlier.

Burterestoring to other times or dates didn't solve the problems.

 Koji and I started poking around, trying to understand what was going on.  At first, we thought it might be related to a computer error, as it seemed.

Fortunately, Rob stopped by and explained that the boost stage of the filter comes under c1lsc control, and will be turned on or off depending on the power in the arms.  Although if you turn it off, it will remain off, it just if its manually selected on, it may go on or off.

Similarly, the output from the Xarm filter bank to the ETMX  filter input will be turned on or off depending on the power in the arm.

Anyways, the locking trouble turns out to be due to no RF sidebands at 33 MHz.  The output of the Marconi was unplugged.  I don't know who, or why did it, but I've plugged it in for now, so we can lock the arms.  Let us know if you need in unplugged.  Thanks.

  2608   Tue Feb 16 15:25:00 2010 AlbertoConfigurationLSCArms and PRC not locking

 

 shock.jpg

  2612   Thu Feb 18 10:10:43 2010 steveConfigurationGeneral480 V AC power turned off

Only the 40m cranes are running on 480VAC The electricians are rewiring this transformer on the mezzanine so it was shut down.

I tested all three cranes before the 480V power was turned off. The last thing to do with the cranes to wipe them down before use.

It will happen on next Tuesday morning.

  2613   Thu Feb 18 15:39:16 2010 Koji and SteveConfigurationVACvalve condition: ALL OFF

As preparation for the upcoming planned power outage we turned turbos, RGA off and closed valves.

IFO chamber is not pumped now. Small leaks and out gassing will push the pressure up slowly. At 3 mTorr of P1 the PSL output shutter

will be closed by the interlock.

It is OK to use light in the IFO up to this point.

  2615   Fri Feb 19 02:38:32 2010 KojiConfigurationoplevsIntsant green oplevs for ITMs shooting from the ends

I set up instant green oplevs for ITMs.

A green laser pointer has been set on each end table. It illuminates the ITM center. The beam goea through the ETM substrate.
The reflected green beam returns to the ETM if the ITMs are aligned. Even though the reflected beam to the end is too big, this can
be a rough reference for each ITM.

Note: The green laser pointer at the ETMX were borrowed from Frank. We must return it to him when we finish the work.

  2624   Mon Feb 22 11:38:05 2010 joe, jenne and steveConfigurationVACvacuum is back to normal

Morning condition: vacuum rack power is still off, no MEDM screen reading.....meaning unknown vacuum pressure.We closed PSL shutter immediately.

Joe restored c1iscepis and Jenne powered up the vac-rack UPS. Now the rest of the vac-rack power were restored from starting at the top to bottom.

P1 was reading 15 mTorr.  We restarted pumps and  set vacuum valve positions. V1 opening required Rob's recipe of elog # 1863 to defeat interlock that

has a non communicating gauge: PTP1

CC1 pressure just reached 1e-6 Torr at VAC NORMAL configuration.

  2631   Tue Feb 23 13:37:04 2010 kiwamu and steveConfigurationVACventing the 40m vac envelope

Kiwamu and Steve have started venting the 40m vacuum envelope.

Preparation:

centered oplevs at resonating cavities,

ITM references were set by green pointer from the ends by Koji,

closed  PSL shutter and placed manual block into beam path,

checked  jamnuts in locked positions on bellows,

turned  HV off at PZT-Jena "steering mirror" power supply and OMC HV ps

checked  particle counts,

switched oplev servos off,

set up N2 cylinder to start vent from 1e-6 Torr to 25 Torr,

have ~ 6 cylinders of instrument grade compressed air to bring envelope from 25 Torr to 760 Torr

 

All three cranes were wiped off today.

 

  2633   Tue Feb 23 16:20:44 2010 steveConfigurationVACoutgassing + leak

Quote:

As preparation for the upcoming planned power outage we turned turbos, RGA off and closed valves.

IFO chamber is not pumped now. Small leaks and out gassing will push the pressure up slowly. At 3 mTorr of P1 the PSL output shutter

will be closed by the interlock.

It is OK to use light in the IFO up to this point.

 Our vacuum was not pumped for 4 days. The computers were not up when we started pumping again. The manual reading on P1 was 15 mTorr.

This means that our outgassing plus leakrate is  ~3.8 mTorr /day 

3-5 mTorr / day is normal

Attachment 1: outgleak.jpg
outgleak.jpg
  2634   Tue Feb 23 16:42:02 2010 ranaConfigurationComputer Scripts / ProgramsSVN restarted on NODUS

I ran the start Apache script as described by Yoichi in the WIki. SVN back up.

  2635   Tue Feb 23 19:00:45 2010 kiwamuConfigurationVACvent finished

The vent has been finished.

Now the pressure inside the chamber is 760 torr, and it's getting equilibrium with the atmospheric pressure.

Therefore we are ready and can open the door of the chamber tomorrow.

  2636   Tue Feb 23 19:07:43 2010 kiwamu and steveConfigurationVACvent is completed

Quote:

Kiwamu and Steve have started venting the 40m vacuum envelope.

Preparation:

centered oplevs at resonating cavities,

ITM references were set by green pointer from the ends by Koji,

closed  PSL shutter and placed manual block into beam path,

checked  jamnuts in locked positions on bellows,

turned  HV off at PZT-Jena "steering mirror" power supply and OMC HV ps

checked  particle counts,

switched oplev servos off,

set up N2 cylinder to start vent from 1e-6 Torr to 25 Torr,

have ~ 6 cylinders of instrument grade compressed air to bring envelope from 25 Torr to 760 Torr

 

All three cranes were wiped off today.

 

 Kiwamu has completed the vent.

Attachment 1: vent2010feb23.jpg
vent2010feb23.jpg
  2641   Thu Feb 25 19:59:50 2010 KojiConfigurationSUSITMX OSEMs

Koji, Steve

ITMX OSEM CONFIGURATION

 

Attachment 1: osem_config_ITMX.png
osem_config_ITMX.png
  2644   Fri Feb 26 15:32:13 2010 steveConfigurationVACpreparation for power outage: vacuum all off

There is a planned power outage tomorrow, Saturday from 7am till midnight.

I vented all annulies and switched to ALL OFF configuration. The small region of the RGA is still under vacuum.

The vac-rack: gauges, c1vac1 and UPS turned off.

Attachment 1: ventd3.jpg
ventd3.jpg
  2648   Mon Mar 1 11:21:50 2010 steveConfigurationVACvacuum contoller is back to normal

Quote:

There is a planned power outage tomorrow, Saturday from 7am till midnight.

I vented all annulies and switched to ALL OFF configuration. The small region of the RGA is still under vacuum.

The vac-rack: gauges, c1vac1 and UPS turned off.

 Vac- rack is powered back up.  UPS first, than all other power switches from top to bottom of the rack, except Maglev

Manually started one by one TP2 and TP3  to accelerate to 50 KRPM

Brought up vac.control screen on lap-top at /cvs/cds/caltech/medm/c0/ve/VacControl_BAK.adl

V5 and VM3 were opened so TP3 can pump on the RGA

V4 was opened so TP2 can pump on the Maglev-TP1. The Maglev power was  turned on and started acceleration.

The vac control screen positions indicators were checked for true position and annulies vent valves were opened.

RGA manual on/off switch was turned at the top of the RGA-head. Ubuntu copmuter was started at cc4 1.1e-6 Torr

The RGA communication was started with:  ssh c0rga from control room

The rga-script was started ./RGAset.py     This script turns on the filament, rs-232 and scan parameters etc

 

Vac -configuration: IFO-P1 at atm, RGA is pumped and running in background mode, all annulos at atm

 

  2670   Fri Mar 12 17:08:22 2010 steveConfigurationVACbg-RGAscan at d18

RGA scan of rga-region only at day 18   This is the back ground of the rga with some calibration gas.

Attachment 1: bg-d18_20100312scan.png
bg-d18_20100312scan.png
  2695   Mon Mar 22 16:57:45 2010 josephb,daisuke, alexConfigurationComputersMegatron test points working again

We changed the pointer on /cvs/cds/caltech/target/gds/bin/awgtpman from

/opt/gds/awgtpman    to

/cvs/cds/caltech/target/gds/bin/awgtpman.091215.

Then killed the megatron framebuilder and testpoint manager (daqd, awgtpman), restarted, hit the daq reload button from the GDS_TP screen. 

This did not fix everything. However, it did seem to fix the problem where it needed a rtl_epics under the root directory which did not exist.  Alex continued to poke around.  When next he spoke, he claimed to have found a problem in the daqdrc file.  Specifically, the cvs/cds/caltech/target/fb/ daqdrc file.

set gds_server = "megatron" "megatron" 10 "megatron" 11;

He said this need to be:

set gds_server = "megatron" "megatron"  11 "megatron" 12;


However, during this, I had looked file, and found dataviewer working, while still with the 10 and 11.  Doing a diff on a backup of daqdrc, shows that Alex also changed

set controller_dcu=10  to set controller_dcu=12, and commented the previous line. 

He also changed set debug=2 to set debug=0.

In a quick test, we changed the 11 and 12 back to 10 and 11, and everything seemed to work fine.  So I'm not sure what that line actually does.  However, the set controller_dcu line seems to be important, and probably needs  to be set to the dcu id of an actually running module (it probably doesn't matter which one, but at least one that is up).  Anyways, I set the gds_server line back to 11 and 12, just in case there's numerology going on.

I'll add this information to the wiki.

  2708   Wed Mar 24 12:38:17 2010 HartmutConfigurationGreen LockingBroadband PD for green PLL

Modified one of the PD assemblies carrying a large SI-Diode (~10mm diameter).

Removed elements used for resonant operation and changed PD readout to transimpedance

configuration. The opamp is a CLC409 with 240 Ohm feedback (i.e. transimpedance) resistor.

To prevent noise peaking at very high frequencies and get some decoupling of the PD,

I added a small series resistor in line with the PD and the inverting opamp input.

It was chosen as 13 Ohm, and still allows for operation up to ~100MHz.

Perhaps it could be smaller, but much more bandwith seems not possible with this opamp anyway.

Changes are marked in the schematic, and I list affected components here.

(Numbers refer to version 'PD327.SCH' from 30-April-1997):

-removed L4

-connected L3 (now open pad) via 100 Ohm to RF opamp output. This restores the DC sognal output.

-removed c17

-connected pin 3 of opamp via 25 Ohm to GND

-connected kathode of PD via 13 Ohm to pin 2 of opamp

-removed L6, C26, L5, C18, and C27

-shorted C27 pad to get signal to the RF output

 

Measured the optical TF with the test laser setup.

(Note that this is at 1064nm, although the PD is meant to work with green light at 532nm!)

Essentially it looks usable out to 100MHz, where the gain dropped only by about

6dB compared to 10MHz.

Beyond 100MHz the TF falls pretty steeply then, probably dominated by the opamp.

 

The maximal bias used is -150V.

If the bias is 'reduced' from -150V to -50V, the response goes down by 4dB at 10MHz and

by 9dB at 100MHz.

 The average output was 30mV at the RF output, corresponding to 60mV at the opamp output (50Ohm divider chain).

With 240 Ohm transimpedance this yields 250µA photo-current used for these transfer functions.

SiAmpl.png

 

SiPhase.png

 

 

  2709   Wed Mar 24 12:40:25 2010 daisukeConfigurationGeneralPeriscope for green laser delivery from the BSC to PSL table

The periscope design for beam elevation of the green beams is posted. The design for the 90 deg steering version is also coming.

(2010-03-29: update drawings by daisuke)

90deg version: http://nodus.ligo.caltech.edu:8080/40m/2725

40m_periscope.png

Attachment 2: 40m_periscope_A_100329.pdf
40m_periscope_A_100329.pdf 40m_periscope_A_100329.pdf 40m_periscope_A_100329.pdf 40m_periscope_A_100329.pdf
Attachment 3: 40m_periscope_A_dwg_100329.zip
  2725   Mon Mar 29 01:45:26 2010 daisukeConfigurationGeneralPeriscope version B for green laser ...

Here the design of the periscope for the 90 deg steering version is posted.

straight version http://nodus.ligo.caltech.edu:8080/40m/2709

Attachment 1: 40m_periscope_B.png
40m_periscope_B.png
Attachment 2: 40m_periscope_B_100329.pdf
40m_periscope_B_100329.pdf 40m_periscope_B_100329.pdf 40m_periscope_B_100329.pdf 40m_periscope_B_100329.pdf
Attachment 3: 40m_periscope_B_dwg_100329.zip
  2730   Mon Mar 29 18:41:34 2010 KojiConfigurationSUSStarted to build TTs

Steve and Koji

WE started to build 5 TTs. 4 of them are used in the recycling cavities. One is the spare.

We built the structure and are building the cantilever springs.

Attachment 1: IMG_2348.jpg
IMG_2348.jpg
  2732   Mon Mar 29 21:43:27 2010 AlbertoConfigurationPSLReference Cavity PD Noise Spectrum

[Rana, Alberto]

This evening we measured the noise spectrum of the reference cavity PD used in the FSS loop. From that we estimated the transimpedance and found that the PD is shot-noise limited. We also found a big AM oscillation in correspondence of the FSS modulation sideband which we later attenuated at least in part.

This plot shows the spectrum noise from the RF output of the photodetector.
 
 (here you should be able to see an attached figure, if not it's probably becasue imagemagic has having problems with displaying png files)
2010-03-29_FSS_PD_shotnoise_and_darknoise.png
 
The tall peak at 21.5 MHz is the AM modulation introduced by the EOM. It seems to be caused by a misalignment of the EOM which might be somehow modulating the polarization.
The mount in which the EOM sits is not very solid. We should change it with something similar to that of the other two EOMs in the Mach Zehnder.
By tightening down the plastic screws of the mount Rana reduced the amplitude of the AM modulation by 20dB.
 
The bump in both the dark and shot noise are in corrispondence of the resonance of the PD's electronics. As it appears, the electronics is not well tuned: the bump should coincide with the AM peak.
 
In the case of the dark noise spectrum, the bump is due to the thermal noise of the electronics. It's a good sign: it means that the electronics is good enough to be sensitive to it.
 
Transimpedance Estimate
As a "sanity check" we made an approximate estimate of the transimpedance to make sure that the PD is dominated by shot noise rather than other noises, ie electronic's noise.
 
  1. Supposing that the laser beam hitting the PD was shot noise limited, we measured 1.1V at the DC output. That let us estimate the photocurrent at DC of 20mA, for a 50Ohm output impedance.
  2. The shot noise for 20mA is 80 pA/rtHz
  3. From the nosie spectrum, we measured 3e-7 v/rtHz at 21.5MHz
  4. The impedance at RF is then Z_rf = 3e-7 V/rtHz / 80e-12 pA ~ 4000 Ohm
  5. Since the RF path inside the PD has a gain of 10, the transimpedance is ~400Ohm, which is about as we (ie Rana) remembered it to be.
  6. The PD seems to be working fine.
Attachment 2: 2010-03-29_FSS_PD_shotnoise_and_darknoise.png
2010-03-29_FSS_PD_shotnoise_and_darknoise.png
  2733   Tue Mar 30 06:37:32 2010 ranaConfigurationPSLReference Cavity PD Noise Spectrum

Some more words about the RFAM: I noticed that there was an excess RFAM by unlocking the RC and just looking at the RF out with the 50 Ohm input of the scope. It was ~100 mVp-p! In the end our method to minimize the AM was not so sensible - we aligned the waveplate before the EOM so as to minimize the p-pol light transmitted by the PBS cube just ahead of the AOM. At first, this did not minimize the RFAM. But after I got angry at the bad plastic mounting of the EOM and re-aligned it, the AM seemed to be small with the polarization aligned to the cube. It was too small to measure on the scope and on the spectrum analyzer, the peak was hopping around by ~10-20 dB on a few second timescale. Further reduction would require some kind of active temperature stabilization of the EOM housing (maybe a good SURF project!).

For the EOM mount we (meaning Steve) should replace the lame 2-post system that's in there with one of the mounts of the type that is used in the Mach-Zucker EOMs. I think we have spare in the cabinet next to one of the arms.

After the RFAM monkeying, I aligned the beam to the RC using the standard, 2-mirror, beam-walking approach. You can see from the attached plot that the transmission went up by ~20% ! And the reflection went down by ~30%. I doubt that I have developed any new alignment technique beyond what Yoichi and I already did last time. Most likely there was some beam shape corruption in the EOM, or the RFAM was causing us to lock far off the fringe. Now the reflected beam from the reference cavity is a nice donut shape and we could even make it better by doing some mode matching! This finally solves the eternal mystery of the bad REFL beam (or at least sweeps it under the rug).

At the end, I also fixed the alignment of the RFPD. It should be set so the incident angle of the beam is ~20-40 deg, but it was instead set to be near normal incidence ?! Its also on flimsy plastic legs. Steve, can you please replace this with the new brass ones?

Attachment 1: rc.png
rc.png
  2759   Sat Apr 3 11:35:47 2010 ranaConfigurationPSLReference Cavity PD Noise Spectrum

The units on this plot are completely bogus - we know that the thermal noise from the resonant part of the circuit is just V = sqrt(4*k*T*Z) ~ 3nV/rHz. Then the gain of the MAX4107 stage is 10. The output resistor is 50 Ohms, which forms a divide by 2 with the input impedance of the spectrum analyzer and so the bump in the dark noise should only be 15 nV/rHz and not microVolts.

Quote:

[Rana, Alberto]

This evening we measured the noise spectrum of the reference cavity PD used in the FSS loop. From that we estimated the transimpedance and found that the PD is shot-noise limited. We also found a big AM oscillation in correspondence of the FSS modulation sideband which we later attenuated at least in part.

This plot shows the spectrum noise from the RF output of the photodetector.

  2760   Sat Apr 3 16:07:40 2010 AlbertoConfigurationPSLReference Cavity PD Noise Spectrum

 I was aware of a problem on those units since I acquired the data. Then it wasn't totally clear to me which were the units of the data as downloaded from the Agilent 4395A, and, in part, still isn't.

It's clear that the data was in units of spectrum, an not spectral density: in between the two there is a division by the bandwidth (100KHz, in this case). Correcting for that, one gets the following plot for the FSS PD:

2010-03-29_FSS_PD_shotnoise_and_darknoise.png

Although the reason why I was hesitating to elog this other plot is that it looks like there's still a discrepancy of about 0.5dBm between what one reads on the display of the spectrum analyzer and the data values downloaded from it.

However I well know that, I should have just posted it, including my reserves about that possible offset (as I'm doing now).

Quote:

The units on this plot are completely bogus - we know that the thermal noise from the resonant part of the circuit is just V = sqrt(4*k*T*Z) ~ 3nV/rHz. Then the gain of the MAX4107 stage is 10. The output resistor is 50 Ohms, which forms a divide by 2 with the input impedance of the spectrum analyzer and so the bump in the dark noise should only be 15 nV/rHz and not microVolts.

Quote:

[Rana, Alberto]

This evening we measured the noise spectrum of the reference cavity PD used in the FSS loop. From that we estimated the transimpedance and found that the PD is shot-noise limited. We also found a big AM oscillation in correspondence of the FSS modulation sideband which we later attenuated at least in part.

This plot shows the spectrum noise from the RF output of the photodetector.

  2789   Mon Apr 12 16:20:05 2010 AlbertoConfiguration40m UpgradingREFL55 improved
During the commissioning of the AS55 PD, I learned how to get a much better rejection of the 11MHz modulation.
So I went back to REFL55 and I modified it using the same strategy. (Basically I added another notch to the circuit).
After a few days of continuous back and forth between modeling, measuring, soldering, tuning I got a much better transfer function.

All the details and data will be included in the wiki page (and so also the results for AS55). Here I just show the comparison of the transfer functions that I measured and that I modeled.

I applied an approximate calibration to the data so that all the measurements would refer to the transfer function of Vout / PD Photocurrent. Here's how they look like. (also the calibration will be explained in the wiki)

2010-04-12_REFL55_TF_model_to_meas_comparison.png.

The ratio between the amplitude of the 55Mhz modulation over the 11MHz is ~ 90dB

The electronics TF doesn't provide a faithful reproduction of the optical response.

  2805   Mon Apr 19 05:54:50 2010 ranaConfigurationPSLRC Temperature Servo Turned OFF temporarily

In order to measure the transfer function of the RC cavity's foam, I've turned off the servo so that the room temperature noise can excite it.

The attached plot shows a step response test from 2 weeks ago. Servo is nominally still working fine.

Attachment 1: Untitled.png
Untitled.png
  2808   Mon Apr 19 13:23:03 2010 josephbConfigurationComputersyum update fixed on control room machines

I went to Ottavia, and tried running yum update.  It was having dependancy issues with mjpegtools, which was a rpmforge provided package.  In order to get it to update, I moved the rpmforge priority above (a lower number) that of epel ( epel -> 20 from 10, rpmforge -> 10 to 20).  This resolved the problem and the updates proceeded (all 434 of them). yum update on Ottavia now reports nothing needs to be done.

I went to Rosalba and found rpmfusion repositories enabled.  The only one of the 3 repositories in each file enabled was the first one.

I then added priority listing to all the repositories on Rosalba.  I set CentOS-Base and related to priority=1.  I set CentOS-Media.repo priority to 1 (although it is disabled - just to head off future problems). I set all epel related to priorities to 20. I set all rpmforge related priorities to 10.  I set all rpmfusion related priorities to 30, and left the first repo in rpmfusion-free-updates and rpmfusion-nonfree-updates were enabled.  All other rpmfusion testing repositories were disabled by me.

I then had to by hand downgrade expat to expat-1.95.8-8.3.el5_4.2.x86_64 (the rpmforge version).  I also removed and reinstalled x264.x86_64.  Lastly I removed and reinstalled lyx. yum update was then run and completed successfully.

I installed yum-priorities on Allegra and made all CentOS-Base repositories priority 1. I similarly made the still disabled CentOS-Media priority 1.  I made all epel related repos priority 20.  I made all lscsoft repos priority=50 (not sure why its on Allegra and none of the other ones).  I made all rpmforge priorities 10.  I then ran "yum update" which updated 416 packages.

 

So basically all the Centos control room machines are now using the following order for repositories:

CentOS-Base > rpmforge > epel > (rpmfusion - rosalba only) > lscsoft (allegra only)

I'm not sure if rpmfusion and lscsoft are necessary, but I've left them for now.  This should mean "yum update" will have far fewer problems in the future.

 

  2849   Tue Apr 27 11:16:13 2010 josephbConfigurationCDSWiki page with CDS .mdl names, shared memory allocation

I've added a new page in the wiki which describes the current naming scheme for the .mdl model files used for the real time code generator.  Note, that these model names do not necessarily have to be the names of the channels contained within.  Its still possible to make all suspension related channels start with C1:SUS- for example.  I'm also allocating 1024 8 byte channels for shared memory address space for each controller and each simulated plant.

The wiki page is here

Name suggestions, other front end models that are needed long term (HEPI is listed for example, even though we don't have it here, since in the long run we'd like to port the simulated plant work to the sites) are all welcome.

  2873   Mon May 3 17:49:41 2010 ranaConfigurationPSLRC Temperature Servo Turned OFF temporarily

Quote:

In order to measure the transfer function of the RC cavity's foam, I've turned off the servo so that the room temperature noise can excite it.

The attached plot shows a step response test from 2 weeks ago. Servo is nominally still working fine.

 I've just now re-enabled the temperature control of the reference cavity can. Trend of the last 8 days is attached.

Attachment 1: rct.png
rct.png
  2875   Tue May 4 02:28:38 2010 ranaConfigurationPSLRC Temperature Servo Turned OFF temporarily

 

 My attempt to passively measure the transfer function of the foam failed fantastically.

As it turns out, the room temperature fluctuations inside the PSL box reach the 1 mK/rHz noise floor of the  AD590 (or maybe the ADC) at ~1-2 mHz. Everything at higher frequencies is noise.

So to see what the foam is doing we will have to do something smarter - we need a volunteer to disable the RC temperature servo from the EPICS screen and then cycle the PSL table lights every hour in the morning.

We'll then use our knowledge of the Laplace transform to get the TF from the step responses.

  2876   Tue May 4 06:32:58 2010 albertoConfigurationPSLRC Temperature Servo Turned OFF temporarily

Quote:

 

 My attempt to passively measure the transfer function of the foam failed fantastically.

As it turns out, the room temperature fluctuations inside the PSL box reach the 1 mK/rHz noise floor of the  AD590 (or maybe the ADC) at ~1-2 mHz. Everything at higher frequencies is noise.

So to see what the foam is doing we will have to do something smarter - we need a volunteer to disable the RC temperature servo from the EPICS screen and then cycle the PSL table lights every hour in the morning.

We'll then use our knowledge of the Laplace transform to get the TF from the step responses.

 more detailed instructions needed....

  2881   Wed May 5 02:37:55 2010 ranaConfigurationPSLRC Temperature Servo Turned OFF temporarily

Quote:

 more detailed instructions needed....

I showed Kiwamu and Alberto how to turn the lights on and off in the PSL. This is why Caltech is such a fine institution: most schools would have TAs delivering this kind of optics instruction.

We've turned off the RC temperature stabilization and the lights will supply the quasi-random heat input to the table and the cavity. Alberto and Kiwamu will be turning the lights on and off at random times.

The attached plot is the spectrum of temperature fluctuations of the room and the vacuum can with no stabilization from this weekend. I think the rolloff above 10 mHz is kind of fake - I had the .SMOO parameter set to 0.99 for both of these channels. I've just now set the .SMOO to 0 for both channels, so we should now see the true ADC or sensor noise level. It should be ~1 mK/rHz.

Attachment 1: Picture_7.png
Picture_7.png
  2901   Sun May 9 20:02:23 2010 ranaConfigurationSUSSUS filters deleted again to reduce CPU load on c1susvme2 again

On Friday, I deleted a bunch of filters from the c1susvme2 optics' screens (MC1,2,3 + SRM) so as to reduce the CPU load and keep it from going bonkers.

This first plot shows the CPU trend over the last 40 days and 40 nights. As you can see the CPU_LOAD has dropped by 1 us since I did the deleting.

40.png400.png

In the second plot (on the right) you can see the same trend but over 400 days and nights. Of course, we hope that we throw this away soon, but until then it will be nice to have the suspensions be working more often.

  2922   Wed May 12 12:32:04 2010 josephbConfigurationCDSModified /etc/rc.d/rc.local on megatron

I modified the /etc/rc.d/rc.local file on megatron removing a bunch of the old test module names and added the new lsc and lsp modules, as well as a couple planned suspension models and plants, to shared memory so that they'll work.  Basically I'm trying to move forward into the era of working on the actual model we're going to use in the long term as opposed to continually tweaking "test" models.

The last line in the file is now: /usr/bin/setup_shmem.rtl lsc lsp spy scy spx scx sus sup&

I removed mdp mdc mon mem grc grp aaa tst tmt.

  2923   Wed May 12 12:58:26 2010 josephbConfigurationCDSSetup fb to handle lsc, lsp models on megatron

I modified /cvs/cds/caltech/target/fb and changed the line "set controller_dcu=10" to "set controller_dcu=13" (where 13 is the lsc dcu_id number).

I also changed the set gds_server line from having 10 and 11 to 13 and 14 (lsc and lsp).

The file /cvs/cds/caltech/fb/master was modified to use C1LSC.ini and C1LSP.ini, as well as tpchn_C2.par (LSC) and tpchn_C3.par (LSP)

testpoint.par in /cvs/cds/caltech/target/gds/param was modified to use C-node1 and C-node2 (1 less then the gds_node_id for lsc and lsp respectively).

Note all the values of gds_node_id, dcu_id, and so forth are recorded at http://lhocds.ligo-wa.caltech.edu:8000/40m/Electronics/Existing_RCG_DCUID_and_gds_ids

  2938   Mon May 17 02:10:10 2010 KojiConfigurationIOOHow to lock / align the MC

Let me remind you how to lock and align the IMC

To lock

1. Open the doors for the IMC/OMC chambers. Open the manual shutter of the PSL just in front of the optical window

2. Run scripts/MC/mcloopson

3. Set the MC length path gain 0.3 / Set the MC total gain "+20"

4. If you want to avoid excitation of the mirrors by air turbulence, put a big plastic film and put three posters on the top and both the sides on the floor to block the wind go into the chamber.

To shut down

1. Run scripts/MC/mcloopsoff

2. Close the manual shutter, Remove the wind blockers, and the light door of the chambers

To align the MC

1. Tweak MC2 and MC3 to get maximum transmittion and/or minimum reflection.

  2939   Mon May 17 10:57:16 2010 steveConfigurationSUSdamping restored to ETMYs

ETMY-south sus damping was restored

  2943   Tue May 18 11:54:29 2010 steveConfigurationSAFETYpsl mechanical shutter is not working

As we learned yesterday, the PSL laser power out put mechanical shutter is not working in the remote mode. It only works in local manual mode.

Do not rely on the MEDM screen monitor readout! The position is only changing on the monitor. The main beam must be blocked before the output periscope.

ELOG V3.1.3-