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ID Date Author Type Category Subject
  2911   Tue May 11 16:38:16 2010 josephb,rana,rolfUpdateCDSCDS questions and thoughts

1) What is c1asc doing?  What is ascaux used for?  What are the cables labeled "C1:ASC_QPD" in the 1X2 rack really going to?

2) Put the 4600 machine (megatron) in the 1Y3 (away from the analog electronics)  This can be used as an OAF/IO machine.  We need a dolphin fiber link from this machine to the IO chassis which will presumably be in 1Y1, 1Y2 (we do not currently have this fiber at the 40m, although I think Rolf said something about having one).

3) Merge the PSL and IOOVME crates in 1Y1/1Y2 to make room for the IO chassis.

4) Put the LSC and SUS machines into 1Y4 and/or 1Y5 along with the SUS IO chassis.  The dolphin switch would also go here.

5) Figure out space in 1X3 for the LSC chassis.  Most likely option is pulling asc or ascaux stuff, assuming its not really being used.

6) Are we going to move the OMC computer out from under the beam tube and into an actual rack?  If so, where?

 

Rolf will likely be back Friday, when we aim to start working on the "New" Y end and possibly the 1X3 rack for the LSC chassis.

 

  2910   Tue May 11 14:39:17 2010 AidanUpdateGreen LockingGreen Laser Beam Profile

 

 Here's a photo of the set-up used. The beam profile is measured relative to the f=-100mm lens.

Attachment 1: P5110057_beams.jpg
P5110057_beams.jpg
  2909   Mon May 10 22:25:03 2010 KojiUpdateGreen LockingGreen Laser Beam Profile

Hey, what a quick work!

But, wait...

1) The radius of the beam was measured by the razor blade.

2) The diameter of the beam (13.5% full-width) at each point was measured by Beam Scan. The one at z=~7cm was consistent with 1)

3) The data 2) was fitted by a function w = sqrt(w0^2+lambda^2*(x-x0)^2/(pi*w0)^2). This is defined for the radius, isn't it?

So the fitting must be recalculated with correct radius.
Make sure that you always use radius and write with a explicit word "radius" in the record.

Quote:

Kiwamu and Kevin measured the beam profile of the green laser by the south arm ETM.

The following measurements were made with 1.984A injection current and 39.65°C laser crystal temperature.

 

Two vertical scans (one up and one down) were taken with a razor blocking light entering a photodiode with the razor 7.2cm from the center of the lens. This data was fit to

b + a*erf(sqrt(2)*(x-x0)/w) with the following results:

scan down: w = (0.908 ± 0.030)mm  chi^2 = 3.8

scan up:      w = (0.853 ± 0.025)mm   chi^2 = 2.9

giving a weighted value of w = (0.876 ± 0.019)mm at this distance.

 

The beam widths for the profile fits were measured with the beam scanner. The widths are measured as the full width at 13.5% of the maximum. Each measurement was averaged over 100 samples. The distance is measured from the back of the lens mount to the front face of the beam scanner.

distance (cm) vertical w (µm) horizontal w (µm)
3.2 ± 0.1 1231 ± 8 1186 ± 7
4.7 ± 0.1 1400 ± 4 1363 ± 6
7.4 ± 0.1 1656 ± 5 1625 ± 9
9.6 ± 0.1 1910 ± 10 1863 ± 9
12.5 ± 0.1 2197 ± 8 2176 ± 8
14.6 ± 0.1 2450 ± 12 2416 ± 10
17.5 ± 0.1 2717 ± 12 2694 ± 14
20.0 ± 0.1 2973 ± 16 2959 ± 8
22.4 ± 0.1 3234 ± 12 3193 ± 14

This data was fit to w = sqrt(w0^2+lambda^2*(x-x0)^2/(pi*w0)^2) with lambda = 532nm with the following results:

For the vertical beam profile:

reduced chi^2 = 3.29

x0 = (-87 ± 1)mm

w0 = (16.30 ± 0.14)µm

For the horizontal beam profile:

reduced chi^2 = 2.01

x0 = (-82 ± 1)mm

w0 = (16.12 ± 0.10)µm

 

  2908   Mon May 10 20:33:29 2010 KojiSummaryCDSFinished

This IPC stuff looks really a nice improvement of CDS.

Please just maintain the wiki updated so that we can keep the latest procedures and scripts to build the models.

Quote:

So I finished writing a script which takes an .ipc file (the one which defines channel names and numbers for use with the RCG code generator),  parses it, checks for duplicate channel names and ipcNums, and then parses and .mdl file looking for channel names, and outputs a new .ipc file with all the new channels added (without modifying existing channels). 

The script is written in python, and for the moment can be found in /home/controls/advLigoRTS/src/epics/simLink/parse_mdl.py

I still need to add all the nice command line interface stuff, but the basic core works.   And already found an error in my previous .ipc file, where I used the channel number 21 twice, apparently.

Right now its hard coded to read in C1.ipc and spy.mdl, and outputs to H1.ipc, but I should have that fixed tonight.

 

  2907   Mon May 10 20:03:22 2010 KevinUpdateGreen LockingGreen Laser Beam Profile

Kiwamu and Kevin measured the beam profile of the green laser by the south arm ETM.

The following measurements were made with 1.984A injection current and 39.65°C laser crystal temperature.

 

Two vertical scans (one up and one down) were taken with a razor blocking light entering a photodiode with the razor 7.2cm from the center of the lens. This data was fit to

b + a*erf(sqrt(2)*(x-x0)/w) with the following results:

scan down: w = (0.908 ± 0.030)mm  chi^2 = 3.8

scan up:      w = (0.853 ± 0.025)mm   chi^2 = 2.9

giving a weighted value of w = (0.876 ± 0.019)mm at this distance.

 

The beam widths for the profile fits were measured with the beam scanner. The widths are measured as the full width at 13.5% of the maximum. Each measurement was averaged over 100 samples. The distance is measured from the back of the lens mount to the front face of the beam scanner.

distance (cm) vertical w (µm) horizontal w (µm)
3.2 ± 0.1 1231 ± 8 1186 ± 7
4.7 ± 0.1 1400 ± 4 1363 ± 6
7.4 ± 0.1 1656 ± 5 1625 ± 9
9.6 ± 0.1 1910 ± 10 1863 ± 9
12.5 ± 0.1 2197 ± 8 2176 ± 8
14.6 ± 0.1 2450 ± 12 2416 ± 10
17.5 ± 0.1 2717 ± 12 2694 ± 14
20.0 ± 0.1 2973 ± 16 2959 ± 8
22.4 ± 0.1 3234 ± 12 3193 ± 14

This data was fit to w = sqrt(w0^2+lambda^2*(x-x0)^2/(pi*w0)^2) with lambda = 532nm with the following results:

For the vertical beam profile:

reduced chi^2 = 3.29

x0 = (-87   ± 1)    mm

w0 = (16.30 ± 0.14) µm

For the horizontal beam profile:

reduced chi^2 = 2.01

x0 = (-82   ± 1)    mm

w0 = (16.12 ± 0.10) µm

Note: These fits were done with the beam diameter instead of the beam radius. The correct fits to the beam radius are here: http://nodus.ligo.caltech.edu:8080/40m/2912

Attachment 1: vbp.jpg
vbp.jpg
Attachment 2: vbp_residuals.jpg
vbp_residuals.jpg
Attachment 3: hbp.jpg
hbp.jpg
Attachment 4: hbp_residuals.jpg
hbp_residuals.jpg
  2906   Mon May 10 19:29:33 2010 AlbertoHowToElectronicsNew Focus 1811 PD calibrated against New Focus 1611 PD
I measured the output impedance of the New Focus 1611 PD (the 1GHz one) and it is 50 Ohm for both the DC and the AC output. It turns out that the transimpedance values listed on the datasheet are the following:
T1611_dc = 1e4 V/A (1MOhm referred)
T1611_ac = 700 V/A (50 Ohm)
The listed transimpedances for the 1811 PD (the 125 MHz PD) are the following:
T_dc = 1e3 V/A (??)
T1811_ac = 4e4 V/A (50 Ohm)
I measured the output impedances of the 1811 and they are: 50 Ohm for the AC output, ~10 Ohm for the DC output.
It's not clear which input impedance the DC transimpedance should be intended referred to.
So I measured the transimpedance of the 1811 using the 1611 as a (trusted) reference. It turns out that for the AC transimpedance to match the listed value, the DC transimpedance has to be the following:
T1811_dc = 1.7e3 V/A (1MOhm)
  2905   Mon May 10 19:09:45 2010 ranaUpdateElectronicsUnexpected oscilaltionin the POY11 PD

Quote:

Where did you get the 55nH based notch from? I don't remember anything like that from the other LSC PD schematics. This is certainly a bad idea. You should remove it and put the notch back over by the other notch.

 Why is it a bad idea?

You mean putting both the 2-omega and the 55MHz notches next to each other right after the photodiode?

  2904   Mon May 10 18:56:53 2010 ranaUpdateElectronicsUnexpected oscilaltionin the POY11 PD

Where did you get the 55nH based notch from? I don't remember anything like that from the other LSC PD schematics. This is certainly a bad idea. You should remove it and put the notch back over by the other notch.

  2903   Mon May 10 17:47:16 2010 josephbSummaryCDSFinished

So I finished writing a script which takes an .ipc file (the one which defines channel names and numbers for use with the RCG code generator),  parses it, checks for duplicate channel names and ipcNums, and then parses and .mdl file looking for channel names, and outputs a new .ipc file with all the new channels added (without modifying existing channels). 

The script is written in python, and for the moment can be found in /home/controls/advLigoRTS/src/epics/simLink/parse_mdl.py

I still need to add all the nice command line interface stuff, but the basic core works.   And already found an error in my previous .ipc file, where I used the channel number 21 twice, apparently.

Right now its hard coded to read in C1.ipc and spy.mdl, and outputs to H1.ipc, but I should have that fixed tonight.

  2902   Mon May 10 16:59:35 2010 AlbertoUpdate40m UpgradingUnexpected oscilaltionin the POY11 PD

The measured transimpedance of the latest POY11 PD matches my model very well up to 100 MHz. But at about ~216MHz I have a resonance that I can't really explain.

2010-05-10_POY11_CalibratedOpticalResponse0-500MHz.png

 

 The following is a simplified illustration of the resonant circuit:

POX11.png

 

Perhaps my model misses that resonance because it doesn't include stray capacitances.

While I was tinkering with it, i noticed a couple of things:

- the frequency of that  oscillation changes by grasping with finger the last inductor of the circuit (the 55n above); that is adding inductance

- the RF probe of the scope clearly shows me the oscillation only after the 0.1u series capacitor

- adding a small capacitor in parallel to the feedback resistor of the output amplifier increases the frequency of the oscilaltion

  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.

  2900   Sat May 8 03:09:15 2010 KojiUpdateIOOSteering around MC

After the MZ-removal work:

- I found that the input steering (IM1) was right handed. This was different from the CAD layout. This was the main reason why the MC trans was kicked by the mount.
- Removed the mount from the post and converted it to a keft handed.
- Align IM1 so that we can get TEM00 lock. Align IM1 further.

- After the IM1 was optimized for the TEM00, move the periscope mirrors to have best alignment.

- Checked the beam spot positions. They looks quite good (MC2 is not the matter now).

C1:SUS-MC1_ULPIT_GAIN = 0.998053
C1:SUS-MC1_ULYAW_GAIN = 0.992942
C1:SUS-MC2_ULPIT_GAIN = 1.00856
C1:SUS-MC2_ULYAW_GAIN = 1.04443
C1:SUS-MC3_ULPIT_GAIN = 0.99868
C1:SUS-MC3_ULYAW_GAIN = 1.00041

  2899   Sat May 8 02:38:08 2010 KojiSummaryIOOMC incident power

As per Steve's request I checked the MC incident power as a function of time.

The output is negative: the lower voltage, the higher power.

Before I put the attenuator the incident power was 1.1W. It appear as -5V.

Now the output is -0.1V. This corresponds to 22mW.

 

Attachment 1: MC_input.png
MC_input.png
  2898   Fri May 7 21:55:59 2010 kiwamuUpdatePSLremove Mach-Zehnder

[Koji, Kiwamu]

The Mach-Zehnder on the PSL table was removed.

A path for 166 MHz modulation in the Mach-Zehnder (MZ) was completely removed, the setup for another path remains the same as before.

Also the photo detector and the CCD for the PMC transmittion were moved to behind the PZT mirror of PMC. 

 


Before removing them, we put an aperture in front of the PD for MC REFL so that we can recover the alignment toward MC by using the aperture.

After the removal we tried to re-align the EOM which imposes the sideband of 29MHz for MC.

We eventually got good alignment of 97% transmissivity at the EOM ( the power of the incident beam is 1.193W and trans was 1.160W )

And then we aligned the beam going to MC by guiding the reflected beam to the aperture we put. This was done by using the steering mirrors on the periscope on the corner of the PSL table.

Now MC got locked and is successfully resonating with TEM00.

Attachment 1: NO_MachZehnder_s.jpg
NO_MachZehnder_s.jpg
  2897   Fri May 7 19:02:27 2010 ranaUpdate40m UpgradingNew improved design for the 11MHz photodiode

To measure the width of a resonance, the standard method is to state the center frequency and the Q. Use the definition of Q from the Wikipedia.

As far as how much phase is OK, you should use the method that we discussed - think about the full closed loop system and try to write down how many things are effected by there being a phase slope around the modulation frequency. You should be able to calculate how this effects the error signal, noise, the loop shape, etc. Then consider what this RFPD will be used for and come up with some requirements.

  2896   Fri May 7 18:18:02 2010 AlbertoUpdate40m UpgradingNew improved design for the 11MHz photodiode

Quote:

How much is the width?

Quote:

 This should be better. It should also have larger resonance width.

 

 The transfer function phase drops by 180 degrees in about 2MHz. Is that a good way to measure the width?

  2895   Fri May 7 14:51:04 2010 josephbUpdateCDSWorking on meta .mdl file scripts

I'm currently working on a set of scripts which will be able to parse a "template" mdl file, replacing certain key words, with other key words, and save it to a new .mdl file.

For example  you pass it the "template" file of scx.mdl file (suspension controller ETMX), and the keyword ETMX, followed by an output list of scy.mdl ETMY,  bs.mdl BS, itmx.mdl  ITMX, itmy.mdl ITMY, prm.mdl PRM, srm.mdl SRM.  It produces these new files, with the keyword replaced, and a few other minor tweaks to get the new file to work (gds_node, specific_cpu, etc).  You can then do a couple of copy paste actions to produce a combined sus.mdl file with all the BS, ITM, PRM, SRM controls (there might be a way to handle this better so it automatically merges into a single file, but I'd have to do something fancy with the positioning of the modules - something to look into).

I also have plans for a script which gets passed a mdl file, and updates the C1.ipc file, by adding any new channels and incrementing the ipcNum appropriately.  So when you make a change you want to propagate to all the suspensions, you run the two scripts, and have an already up to date copy of memory locations - no additional typing required.

Similar scripts could be written for the DAQ screens as well, so as to have all the suspension screens look the same after changing one set.

  2894   Fri May 7 11:21:49 2010 kojiUpdate40m UpgradingNew improved design for the 11MHz photodiode

How much is the width?

Quote:

 This should be better. It should also have larger resonance width.

 

  2893   Thu May 6 19:57:26 2010 AlbertoUpdate40m UpgradingNew improved design for the 11MHz photodiode

Quote:

After munching analytical models, simulations, measurements of photodiodes I think I got a better grasp of what we want from them, and how to get it. For instance I now know that we need a transimpedance of about 5000 V/A if we want them to be shot noise limited for ~mW of light power.

Adding 2-omega and f1/f2 notch filters complicates the issue, forcing to make trade-offs in the choice of the components (i.e., the Q of the notches)

Here's a better improved design of the 11Mhz PD.

 This should be better. It should also have larger resonance width.

Attachment 1: pox11.pdf
pox11.pdf
  2892   Thu May 6 19:51:22 2010 JenneUpdatePEMNew 'Seismic Spectrum of the 40m'

For reasons unknown, the seismic spectra posted above Rosalba has been wrong since ~January when it was first posted.  The noise that we were claiming was waaaay lower than is really possible.

Rana and I checked the calibrations, and the numbers in DTT for the Ranger and the Guralp are correct (it's unknown what was being used at the time of the bad plot) - Cal for the Guralp is 3.8e-9 m/s, and for the Ranger is 1.77e-9 m/s.

Something is funny with the accelerometer calibration.  Hopefully Kevin's investigation will sort it out.  Their calibration used to be 1.2e-7 m/s^2 , but it was changed to be 7e-7 m/s^2 to match the noise level of the accelerometers with the seismometers at ~10Hz. We need to go through the calibration carefully and figure out why this is!

Posted above Rosalba for easy reference, and attached below, is the new seismic spectra.  The black trace is when the Ranger's mass is locked down, and the teal circle markers indicate the Guralp Spec-Sheet Noise Floor.

** Rana says> the y-axis in Jenne's plot is (m/s)/sqrt(Hz). The Guralp has a velocity readout bandwidth of 0.03-40 Hz, so we would have to modify the calibration to make it right in those frequencies. I believe the Ranger cal has the correct poles in it. The huge rise at low frequencies is because of the 1/f noise of the SR560.

Attachment 1: SeisRef_6May2010_AccelCalFudged.png
SeisRef_6May2010_AccelCalFudged.png
  2891   Thu May 6 19:23:54 2010 FrankSummaryComputerssvn problems

i tried to commit something this afternoon and got the following error message:

Command: Commit 
Adding: C:\Caltech\Documents\40m-svn\nodus\frank 
Error: Commit failed (details follow): 
Error: Server sent unexpected return value (405 Method Not Allowed) in response to  
Error: MKCOL request for '/svn/!svn/wrk/d2523f8e-eda2-d847-b8e5-59c020170cec/trunk/frank' 
Finished!:  

anyone had this before? what's wrong?

  2890   Thu May 6 18:43:58 2010 ranaUpdatePEMNoise floor of the Ranger Seismometer

I added a noise model of the SR560 to the LISO opamp.lib. This assumes you're using it in G=100, low-noise mode. The voltage noise is correct, but I had to guess on the current noise because I didn't measure it before. Lame.

This can be compared with the noise that we measure when locking it down...

Attachment 1: ranger.pdf
ranger.pdf
  2889   Thu May 6 18:25:20 2010 JenneUpdatePEMAcc power supply turned on

The accelerometer power supply / preamp board has been OFF because of exciting new accelerometer measurements.  It's now on, so watch out and make sure to turn it back off before plugging / unplugging accelerometers.

  2888   Thu May 6 17:54:44 2010 Zach Korth -- Committee Oversight (Fun Division)OmnistructureTMIMinutes from the Lab Organization Commitee meeting

Where are we going to put the tiki bar? The ice cream machine? I am disappointed in the details that appear to have been glossed over..

Quote:

Today we met and we finally come up with a lot of cool, clever, brilliant, outstanding ideas to organize the lab.

You can find them on the Wiki page created for the occasion.

http://lhocds.ligo-wa.caltech.edu:8000/40m/40m_Internals/Lab_Organization

Enjoy!

 

  2887   Thu May 6 17:47:01 2010 Alberto, kiwamu, Jc The 3rd (aka The Drigg)OmnistructureTMIMinutes from the Lab Organization Commitee meeting

Today we met and we finally come up with a lot of cool, clever, brilliant, outstanding ideas to organize the lab.

You can find them on the Wiki page created for the occasion.

http://lhocds.ligo-wa.caltech.edu:8000/40m/40m_Internals/Lab_Organization

Enjoy!

  2886   Thu May 6 16:18:37 2010 AlbertoUpdate40m UpgradingNew improved design for the 11MHz photodiode

After munching analytical models, simulations, measurements of photodiodes I think I got a better grasp of what we want from them, and how to get it. For instance I now know that we need a transimpedance of about 5000 V/A if we want them to be shot noise limited for ~mW of light power.

Adding 2-omega and f1/f2 notch filters complicates the issue, forcing to make trade-offs in the choice of the components (i.e., the Q of the notches)

Here's a better improved design of the 11Mhz PD.

Attachment 1: pox11.pdf
pox11.pdf
  2885   Thu May 6 11:34:35 2010 robUpdateCDSlsc.mdl and ifo.mdl to build (with caveats)

Quote:

I got around to actually try building the LSC and IFO models on megatron.  Turns out "ifo" can't be used as a model name and breaks when trying to build it.  Has something to do with the find and replace routines I have a feeling (ifo is used for the C1, H1, etc type replacements throughout the code).  If you change the model name to something like ifa, it builds fine though.  This does mean we need a new name for the ifo model.

Also learned the model likes to have the cdsIPCx memory locations terminated on the inputs if its being used in a input role (I.e. its bringing the channel into the model).  However when the same part is being used in an output role (i.e. its transmitting from the model to some other model), if you terminate the output side, it gives errors when you try to make.

Its using the C1.ipc file (in /cvs/cds/caltech/chans/ipc/) just fine.  If you have missing memory locations in the C1.ipc file (i.e. you forgot to define something) it gives a readable error message at compile time, which is good.  The file seems to be being parsed properly, so the era of writing "0x20fc" for block names is officially over.

 I suggest "ITF" for the model name.

  2884   Thu May 6 01:06:16 2010 KojiUpdateIOOMC spot centering cont'd (Triumph)

Zach and Koji,

We finally aligned the incident beam enough close to the center of the all MC mirrors! Uraaaaah!

MC1H = -0.12mm
MC1V =
-0.13mm
MC2H = -0.15mm

MC2V = +0.14mm
MC3H = -0.14mm
MC3V = -0.11mm

The aperture right before the vacuum window has been adjusted to the beam position. This will  ensure that any misalignment on the PSL table can have the correct angle to the mode cleaner as far as it does resonate to the cavity. (This is effectively true as the small angle change produces the large displacement on the PSL table.)

If we put an aperture at the reflection, it will be perfect.

Now we can remove the MZ setup and realign the beam to the mode cleaner!


 

Method:

- The beam axis rotation has been adjusted by the method that was used yesterday.

Differential: SM2Y and IM1Y

Common: SM2Y only

- We developped scripts to shift the MC2 spot without degrading the alignment.

/cvs/cds/caltech/users/zach/MCalign/MC2_spot/MC2_spot_up
/cvs/cds/caltech/users/zach/MCalign/MC2_spot/MC2_spot_down
/cvs/cds/caltech/users/zach/MCalign/MC2_spot/MC2_spot_left
/cvs/cds/caltech/users/zach/MCalign/MC2_spot/MC2_spot_right

These scripts must be upgraded to the slow servo by the SURF students.

- These are the record of the alignment and the actuator balances

C1:SUS-MC1_PIT_COMM   =  2.4005
C1:SUS-MC1_YAW_COMM   = -4.6246
C1:SUS-MC2_PIT_COMM   =  3.4603
C1:SUS-MC2_YAW_COMM   = -1.302
C1:SUS-MC3_PIT_COMM   = -0.8094
C1:SUS-MC3_YAW_COMM   = -6.7545
C1:SUS-MC1_ULPIT_GAIN =  0.989187
C1:SUS-MC1_ULYAW_GAIN =  0.987766
C1:SUS-MC2_ULPIT_GAIN =  0.985762
C1:SUS-MC2_ULYAW_GAIN =  1.01311
C1:SUS-MC3_ULPIT_GAIN =  0.986771
C1:SUS-MC3_ULYAW_GAIN =  0.990253

  2883   Wed May 5 16:58:21 2010 KojiUpdatePSL2W hooked up to the interlock service

Ben, Steve, and Koji

Ben came to the 40m and hooked up a cable to the main interlock service.
We have tested the interlock and confirmed it's working.

[Now the laser is approved to be used by persons who signed in the SOP.]

The RC, PMC, and MZ were unlocked during the interlock maneuver.
Now they are relocked.

  2882   Wed May 5 16:32:39 2010 AlbertoUpdate40m UpgradingNew REFL55 PD, 11MHz rejection

Here's the (calibrated) transimpedance of the new REFL55 PD.

T(55.3) / T_(11.06) = 93 dB

2010-05-05_REFL55_CalibratedOpticalResponse0-60MHz.png

  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
  2880   Wed May 5 01:19:05 2010 KojiUpdateIOOMC spot centering cont"d

Koji and Zach

We improved the beam axis rotaion on the MC. We still have 3mrad to be corrected.
So far we lost the MC Trans spot on CCD as the beam is now hitting the flange of the window. We need to move the steering mirror.

To do next:

- MC2 spot is too much off. Adjust it.

- Rotate axis for 3mrad more.

- MC2 spot is too much off. Adjust it.

- Adjust Vertical spot position as a final touch.


Monday

- Incident beam had 7mrad rotation.

- Tried to rotate in-vac steering mirror (IM1) in CCW

- After the long struggle the beam from PSL table started to hit north-east side of IM1 mount.

- Moved the IM1. All of the beam (input beam, MC Trans, MC Refl) got moved. Chaotic.

- Recovered TEM00 resonance. MC Trans CCD image missing. The beam axis rotation was 8.5mrad.
  Even worse. Disappointed.

Tuesday

- We made a strategic plan after some deliberation.

- We returned to the initial alignment of Saturday only for yaw.
  Not at once, such that we don't miss the resonance.

- Adjusted SM2Y and IM1Y to get reasonable resonance. Then adjusted MC2/3 to have TEM00 lock.

- Measured the spot positions. The axis rotation was 4.8mrad.

- Moved the spot on IM1 by 7mm by rotating SM2Y in CCW - ((A) in the figure)

- Compensated the misalignment by IM1Y CCW. ((B) in the figure)
  Used a large sensor card with puch holes to see the spot distribution between the MC1 and MC3.

- Fine alignment by MC2/MC3. Lock to TEM00. The beam axis rotation was 3mrad.The beam axis translation was 3mm.

- This 3mm can be Compensated by IM1Y. But this can easily let the resonance lost.
  Put the sensor card between MC1/MC3 and compensated the misalignment by MC3 and MC1.

Note: You match the returned spot from the MC2 to the incident beam by moving the spot deviation by MC3,
the spot returns to the good position on MC1. But the angle of the returned beam is totally bad.
This angle deviation can be adjusted by MC1.

Note2: This step should be done for max 2mm (2mrad) at once. As 2mrad deviation induces the spot move on the MC2 by an inch.

- After all, what we get is

MC1H = -0.15 mm
MC1V = -0.33 mm
MC3H = +0.97 mm
MC3V = -0.33 mm

This corresponds to the axis rotation of 3mrad and the beam axis translation of 0.8mm (to north).

Attachment 1: steering.png
steering.png
  2879   Tue May 4 18:40:27 2010 ranaHowToElectronicsMarconi phase noise measurement setup

To check the UGF, I increased the gain of the PLL by 10 and looked at how much the error point got suppressed. The green trace apparently has a UGF of ~50 Hz and so the BLUE nominal one has ~5 Hz.

The second attachment shows the noise now corrected for the loop gain. IF the two signal generators are equally noisy, then you can divide the purple spectrum by sqrt(2) to get the noise of a single source.

The .xml file is saved as /users/rana/dtt/MarconiPhaseNoise_100504.xml

Attachment 1: Untitled.png
Untitled.png
Attachment 2: ifrnoise.png
ifrnoise.png
  2878   Tue May 4 14:57:53 2010 josephbUpdateComputersOttavia has moved

Ottavia was moved this afternoon from the control room into the lab, adjacent to Mafalda in 1Y3 on the top shelf.  It has been connected to the camera hub, as well as the normal network.  Its cables are clearly labeled.  Note the camera hub cable should be plugged into the lower ethernet port. Brief tests indicate everything is connected and it can talk to the control room machines.

The space where Ottavia used to be is now temporarily available as a good place to setup a laptop, as there is keyboard, mouse, and an extra monitor available.  Hopefully this space may be filled in with a new workstation in the near future.

  2877   Tue May 4 13:14:43 2010 josephbUpdateCDSlsc.mdl and ifo.mdl to build (with caveats)

I got around to actually try building the LSC and IFO models on megatron.  Turns out "ifo" can't be used as a model name and breaks when trying to build it.  Has something to do with the find and replace routines I have a feeling (ifo is used for the C1, H1, etc type replacements throughout the code).  If you change the model name to something like ifa, it builds fine though.  This does mean we need a new name for the ifo model.

Also learned the model likes to have the cdsIPCx memory locations terminated on the inputs if its being used in a input role (I.e. its bringing the channel into the model).  However when the same part is being used in an output role (i.e. its transmitting from the model to some other model), if you terminate the output side, it gives errors when you try to make.

Its using the C1.ipc file (in /cvs/cds/caltech/chans/ipc/) just fine.  If you have missing memory locations in the C1.ipc file (i.e. you forgot to define something) it gives a readable error message at compile time, which is good.  The file seems to be being parsed properly, so the era of writing "0x20fc" for block names is officially over.

  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....

  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.

  2874   Mon May 3 19:21:43 2010 AlbertoDAQEnvironmentBoot fest

[Alberto, Koji, Rana]

The RFM network failed today. We had to reboot the frame builder anf restart all the front end following the instructions for the "Nuclear Option".

Burt-restoring to May 1st at 18:07, or April 30 18:07 made c1sosvme crash. We had to reset the front ends again and restore to April 15th at 18:07 in order to make everything work.

Everything seems fine again now.

  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
  2872   Mon May 3 16:53:27 2010 josephbUpdateCDSUpdated lsc.mdl and the ifo plant model with memory locations

I've updated the LSC and IFO models that Rana created with new shared memory locations.  I've used the C1:IFO- for the ifo.mdl file outputs, which in turn are read by the lsc.mdl file.  The LSC outputs being lsc control signals are using C1:LSC-.  Optics positions would presumably be coming from the associated suspension model, and am currently using SUP, SPX, and SPY for the suspension plant models (suspension vertex, suspension x end, suspension y end).

I've updated the web view of these models on nodus.  They can be viewed at: https://nodus.ligo.caltech.edu:30889/FE/

I've also created a C1.ipc file in /cvs/cds/caltech/chans/ipc  which assigns ipcNum to each of these new channels in shared memory.

  2871   Mon May 3 15:39:39 2010 josephbUpdateCDSDaily Downs update

Talked with Jay briefly today.  Apparently there are 3 IO chassis currently on the test stand at Downs and undergoing testing (or at least they were when Alex and Rolf were around).  They are being tested to determine which slots refer to which ADC, among other things. Apparently the numbering scheme isn't as simple as 0 on the left, and going 1,2,3,4, etc.  As Rolf and Alex are away this week, it is unlikely we'll get them before their return date.

Two other chassis (which apparently is one more than the last time I talked with Jay), are still missing cards for communicating between the computer and the IO chassis, although Gary thinks I may have taken them with me in a box.  I've done a look of all the CDS stuff I know of here at the 40m and have not seen the cards.  I'll be checking in with him tomorrow to figure out when (and if) I have the the cards needed.

  2870   Mon May 3 01:35:41 2010 KojiUpdateSUSLessons learned from MC spot centering

Lessons learned on the beam spot centering (so far)

Well-known fact:

The spot position on MC2 can be adjusted by the alignment of the mirror while maintaining the best overlapping between the beam and the cavity axes.

In general, there are two methods:

1) Use the cavity as a reference:
Move the MC mirrors such that the cavity eigenmode hits the centers of the mirrors.
-> Then adjust the incident beam to obtain the best overlapping to the cavity.

2) Use the beam as a reference:
Move the incident beam such that the aligned cavity has the spots at the centers of the mirrors.
-> Then adjust the incident beam to obtain the best spot position while the cavity mirrors keep tracking
the incident beam.

Found the method 1) is not practical.

This is because we can move the eigenmode of the cavity only by very tiny amount if we try to keep the cavity locked.
How much we can move by mirror alignment is smaller than the waist radius or the divergence angle.
For the MC, the waist radius is ~2mm, the divergence angle is 0.2mrad. This means the axis
translation of ~1mm is OK, but the axis rotation of ~4mrad is impractical.

Also it turned out that adjustinig steering mirror to the 10-m class cavity is quite difficult.
A single (minimum) touch of the steering mirror knob is 0.1mrad. This already change the beam position ~0.1mm.
This is not an enough resolution.

Method 2) is also not so easy: Steering mirrors have singular matrix

Indeed! (Remember the discussion for the IMMT)

What we need is the pure angle change of 4mrad at the waist which is ~2m distant from the steering mirror.
This means that the spot at the steering mirror must be moved by 8mm (= 4mrad x 2m). This is the result of the
nearly-singular matrix of the steering mirrors.

We try to avoid this problem by moving the in-vac mirror (IM1), which has somewhat independent move.
The refl beam path also has the big beam shift.
But once the vacuum manifold is evacuated we can adjust very little angle.

This can also be a good news: once the angle is set, we hardly can change it at the PSL side.

  2869   Mon May 3 01:16:50 2010 ranaHowToElectronicsMarconi phase noise measurement setup

 To try the 3-corner hat method on the Marconis, I started to set up the measurement into the DAQ system.

I have set the bottom 2 in the PSL rack to 11.1 MHz. I use a ZP-3MH level 13 mixer as the phase detector. The top one is the LO, it has an output of +13 dBm.

The bottom one is the test unit, it has an output of +6 dBm (should be close to the right level - the IP3 point is +9 dBm). The top one has external DC FM modulation enabled with a FM dev range of 10 Hz.

Mixer output goes through a 50 Ohm in-line termination and then a BLP-5 low pass filter (Steve, please order ~7 of the BLP-1.5 or BLP-1.9 low pass filter from Mini-Circuits) and then into

the DC coupled of a SR560. After some gain and filtering that feedback goes back to the FM input of the top-Marconi to close the PLL. I adjusted the gain to be as small as possible and still stay locked and not

saturate the ADC.

The input to the SR560 is Tee'd into another SR560 with AC coupled input, G = 1000, low-noise. Its output is going directly to the ADC channel - C1:IOO-MC_DRUM1.

I calibrated the channel by opening the loop and setting the AC coupled gain to 1. This lets the Marconis beat at several Hz. The peak-peak signal is equivalent to pi radians.

 

As usual, I was befuddled by the FM input. For some reason I always forget that since its a straight FM input, we don't need any filtering to get a plain 1/f loop. The attached plot shows how we get bad gain peaking if you forget this and use a 0.03 Hz pole in the SR560.

The grey trace is the ADC signal with everything hooked up, but the RF input set to zero (via setting Carrier = OFF in the bottom Marconi). It is the measurement noise.

The BLUE trace is very close to the true phase noise beat of the two Marconis with a calibration error of ~5%. I have not corrected for the loop gain: its right now around a 1 Hz UGF and 1/f. Next, I will measure the loop and compensate for it in the DTT calibration.

Then I'll measure the relative phase noise of 3 of the signal generators to get the individual noises.

Bottom line is that the sensitivity of this approach is good and we should do this rather that use spectrum analyzers since its easy to get very long averages and high res spectra. To get 5x better sensitivity, we can just use the Rai-FET box instead of a SR560 for the readout, but just have to contend with its batteries. Also should try using BALUNs on the RF and LO signals to get rid of the ground loops.

Attachment 1: pn.png
pn.png
  2868   Mon May 3 00:36:49 2010 KojiUpdateSUSHow to steer the incident beam to the MC?

Actually, I tried some tweaks of the input steering to get the beam being more centered on the MC mirrors on Saturday evening.

I made a mistake in the direction of the IM1Y tuning, and it made the horizontal spot position worse.

But, this also means that the opposite direction will certainly improve the horizontal beam angle.

Rotate IM1Y CCW!!!


The current setting is listed below

Alignment
MC1P 3.2531
MC1Y -0.5327
MC2P 3.3778
MC2Y -1.366
MC3P -0.5534
MC3Y -2.607


Spot positions
MC1H = +1.15 mm
MC1V = -0.13 mm
MC3H = +0.80 mm
MC3V = -0.20 mm

 

Quote:

Deviations of the MC spot from the center of the mirrors were measured.

MC1H = +0.29 mm
MC1V = -0.43 mm
MC3H = +1.16 mm
MC3V = -0.68 mm

 

  2867   Sun May 2 17:16:43 2010 KojiUpdateSUSHow to steer the incident beam to the MC?

Deviations of the MC spot from the center of the mirrors were measured.

MC1H = +0.29 mm
MC1V = -0.43 mm
MC3H = +1.16 mm
MC3V = -0.68 mm

1) The vertical deviation looks easy being adjusted as they are mostly translation. They are ~0.5mm too high.
The distance from SM2 to MC is 1.8m. Thus what we have to do is
rotate SM2 Pitch in CW knob by 0.25mrad.
1 turn steers the beam in 10mrad. So 0.25mrad is 1/40 turn (9deg)

2) The horizontal deviation is more troublesome. The common component is easily being adjusted
but the differential component (i.e. axis rotation) involves large displacement of the beam
at the periscope sterring mirrors.

(MC3H - MC1H) / 0.2 m * 1.8 m = 8 mm

The beam must be moved in 8mm at the periscope. This is too big.

We need to move the in-vac steering mirror IM1. Move SM2Yaw in 7mrad. This moves the spot on IM1 by 5mm*Sqrt(2).
Then Move Im1 Yaw such that we see the resonance.

For the alignment adjustment, try to maximize the transmission by MC2 Yaw (cavity axis rotation) and SM2Y (beam axis translation)  

Actual move will be:

- Move IM1Y CCW (assuming 100TPI 1.5 turn in total...half turn at once)
- Compensate the misalignment by SM2Y CW as far as possible.
- Take alignment with MC2Y and SM2Y as far as possible

This operation will move the end spot something like 15mm. This should be compensated by the alignment of MC1Y at some point.

Attachment 1: steering.png
steering.png
  2866   Sun May 2 16:52:44 2010 KojiSummarySUSCoil Actuator Balancing and Spot Position

Yes, of course. But so far I am trusting that the coils are inheretly balanced.
Probably you are talking about the dependence of the nodal position on the frequency...I need to check if 18Hz is sufficiently high or not for 0.1mm precision.

Also I am practicing myself to understand how I can adjust them by which screws as we probably have to do this adjustement many times.
(i.e. removal of the MZ, move of the table, PSL renewal and so on)

For the actuator calibration, we may be able to calibrate actuator responses by shaking them one by one while reading the OPLEV P/Y signals.

 

Quote:

 Oh, but it gets even better: in order to trust the A2L script in this regard you have to know that the coil driver - coil - magnet gain is the same for each channel. Which you can't.

But we have these handy f2pRatio scripts that Vuk and Dan Busby worked on. They use the optical levers to balance the actuators at high frequency so that the A2L gives you a true spot readout.

But wait! We have 4 coils and the optical lever only gives us 2 signal readouts...

 

  2865   Sun May 2 15:38:12 2010 ranaSummarySUSCoil Actuator Balancing and Spot Position

 

Oh, but it gets even better: in order to trust the A2L script in this regard you have to know that the coil driver - coil - magnet gain is the same for each channel. Which you can't.

But we have these handy f2pRatio scripts that Vuk and Dan Busby worked on. They use the optical levers to balance the actuators at high frequency so that the A2L gives you a true spot readout.

But wait! We have 4 coils and the optical lever only gives us 2 signal readouts...

  2864   Sun May 2 15:28:25 2010 KojiUpdateIOOSpot Positions of MC1/MC3

Summary

The spot positions on the MC mirrors were measured with coil balance gains.
The estimated spot positions from the center of the MC1 and MC3 are as followings:

MC1H = +0.29 mm
MC1V = -0.43 mm
MC3H = +1.16 mm
MC3V = -0.68 mm

The cordinates are described in the figure

Method

As far as the cavity mirrors are aligned to the incident beam, spots on the MC1 and MC3 tell us the geometry of the incident beam.
Note that spot position on the MC2 is determined by the alignment of the MC1 and MC3, so it does not a big issue now.
The calibration between the coil balance and the spot position are described in the previous entry.

  1. Lock the MC. Align it with MC2/MC3
  2. Run A2L scripts. script/A2L/A2L_MC1 and so on.
    • The scripts run only on the solaris machines. They require "expect" in stalled some specific place which does not exist on the linux machines.
    • Excitation amplitude, excitation freq, readback channels were modified

Result

Beam powers
MC Trans: 0.18
MC Refl: 0.12-0.13

Alignment biases
MC1P 3.2531
MC1Y -1.0827
MC2P 3.4534
MC2Y -1.1747
MC3P -0.9054
MC3Y -3.1393

Coil balances
MC1H 1.02682
MC1V 0.959605
MC3H 0.936519
MC3V 1.10755

(subtract 1, then multiply 10.8mm => spot position.)

Attachment 1: spot_position.png
spot_position.png
  2863   Sun May 2 13:04:51 2010 KojiSummarySUSCoil Actuator Balancing and Spot Position

I liked to know quantitatively where the spot is on a mirror.

With an interferometer and A2L scripts, one can make the balance of the coil actuators
so that the angle actuation does not couple to the longitudinal motion.
i.e. node of the rotation is on the spot

Suppose you have actuator balancing (1+α) f and (1-α) f.

=> d = 0.016 x α [m]

Full Imbalance   α = 1      -> d = 15 [mm]
10% Imbalance α = 0.1   -> d = 1.5 [mm]
1% Imbalance   α = 0.01 -> d = 0.15 [mm]


Eq of Motion:

I ω2 θ =  2 R f 
(correction) - I ω2 θ =  D f cos(arctan(L/2/D))
(re-correction on Sep 26, 2017) - I ω2 θ =  D f

m ω2 x = 2 α f ,
(correction) - m ω2 x = 2 α f ,

where R is the radius of the mirror, and D is the distance of the magnets. (kinda D=sqrt(2) R)

d, position of the node distant from the center, is given by

d = x/θ = α I / (m R) = 2 α β / D,

where β is the ratio of I and m. Putting R=37.5 [mm], L=25 [mm], β = 4.04 10-4 [m2], D~R Sqrt(2)

i.e. d = 0.015 α [m]

Attachment 1: coil_balance.png
coil_balance.png
  2862   Fri Apr 30 23:16:51 2010 KojiUpdateSUSSRM/PRM ready for baking

Kiwamu and Koji

- Checked the SRM/PRM balancing after the gluing.

- The mirrors were removed from the suspensions for baking.

- Bob is going to bake them next week.

ELOG V3.1.3-