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  ATF eLog, Page 3 of 56  Not logged in ELOG logo
ID Date Authorup Type Category Subject
  538   Tue Jan 19 18:16:53 2010 AidanLaserFiberDouble passed stabilization - mark II - hmmm

I was very dubious of the previous measurement - there was something about the way the stabilization just suddenly engaged when I passed a threshold level in the gain that was very suspect. None of the DC channels were changing so I decided to have a look at the size of the 10MHz AC output from the OUT of LOOP PD on a spectrum analyzer. When the loop is open this peak is around -24dBm. When I close the loop with high gain it drops to -70dBm, then when I lower the gain by 10x this signal increases back to -24dBm. There's definitely something screwy going on.

 

  540   Thu Jan 21 23:02:36 2010 AidanLaserFiberCharacterizing fiber stabilization measurement - sidebands and mode-matching

 I'm in the process of completely characterizing the fiber stabilization setup before we pull it all apart. I discovered the following things:

  1. The 10MHz RF level on the out-of-loop sensor was really low. I'm not sure if it's always been like this or has drifted over time but I tuned up the alignment of the two beams on that sensor and increased the RF level by approximately 30dB.
  2. Looking at the 20MHz in-loop RF output on a spectrum analyzer (with the loop open) I noticed some pretty large sidebands at +/- 570kHz around the 20MHz signal. (I recorded a spectra which I will plot later on). I suspected these were due to a saturation in one of the amplifiers for the AOMs. I lowered the drive signal to the amplifier of the 70MHz AOM (far side of the fiber) from +2dBm to -2dBm and the sidebands completely disappeared. I also lowered the drive signal to the 80MHz near-side AOM by 4dB as a precaution.

I've closed the loop again and it looks to be more stable than it was, at least by watching a time series of the out of loop sensor, but I think we could definitely improve it in a rebuilt version. I'll post some spectra tomorrow.

  541   Fri Jan 22 11:09:45 2010 AidanLaserFiberWhitening filter and RF spectra data
Attachment 1: FS_20M_3.zip
  542   Fri Jan 22 11:59:57 2010 AidanLaserFiberWhitening filter in Pomona box data from SR785
Attachment 1: SCRN0007.TXT
+2.000000e-002	   -9.966553e+001
+2.799996e-002	   -9.964724e+001
+3.919989e-002	   -9.961172e+001
+5.487977e-002	   -9.954261e+001
+7.683157e-002	   -9.942007e+001
+1.075641e-001	   -9.919257e+001
+1.505895e-001	   -9.878689e+001
+2.108250e-001	   -9.809244e+001
+2.951545e-001	   -9.700558e+001
+4.132158e-001	   -9.545834e+001
... 31 more lines ...
Attachment 2: SCRN0008.TXT
+2.000000e-002	   +3.576504e+000
+2.799996e-002	   +4.984181e+000
+3.919989e-002	   +6.964202e+000
+5.487977e-002	   +9.687648e+000
+7.683157e-002	   +1.338145e+001
+1.075641e-001	   +1.832598e+001
+1.505895e-001	   +2.476780e+001
+2.108250e-001	   +3.269450e+001
+2.951545e-001	   +4.171112e+001
+4.132158e-001	   +5.098363e+001
... 31 more lines ...
  543   Fri Jan 22 15:08:50 2010 AidanLaserFiberCharacterizing fiber stabilization measurement - sidebands and mode-matching

Quote:

 I'm in the process of completely characterizing the fiber stabilization setup before we pull it all apart. I discovered the following things:

  1. The 10MHz RF level on the out-of-loop sensor was really low. I'm not sure if it's always been like this or has drifted over time but I tuned up the alignment of the two beams on that sensor and increased the RF level by approximately 30dB.
  2. Looking at the 20MHz in-loop RF output on a spectrum analyzer (with the loop open) I noticed some pretty large sidebands at +/- 570kHz around the 20MHz signal. (I recorded a spectra which I will plot later on). I suspected these were due to a saturation in one of the amplifiers for the AOMs. I lowered the drive signal to the amplifier of the 70MHz AOM (far side of the fiber) from +2dBm to -2dBm and the sidebands completely disappeared. I also lowered the drive signal to the 80MHz near-side AOM by 4dB as a precaution.

I've closed the loop again and it looks to be more stable than it was, at least by watching a time series of the out of loop sensor, but I think we could definitely improve it in a rebuilt version. I'll post some spectra tomorrow.

 The attached plot shows the 570kHz sidebands on the in-loop signal that appear when I drive the 70MHz AOM close to the limit of the amplifier it is driving.

Attachment 1: RF_signals_with_sidebands.png
RF_signals_with_sidebands.png
  544   Fri Jan 22 15:10:35 2010 AidanLaserFiberWhitening filter in Pomona box data from SR785

Here is the transfer function of the passive whitening filter I am using.

Z = 0.35Hz, P = 84.7Hz

Attachment 1: pomona_box_WF_transfer_fn.png
pomona_box_WF_transfer_fn.png
  545   Mon Jan 25 11:35:15 2010 AidanLaserFiberFiber layout - before dismantling

 Here is a schematic of the fiber stabilization layout before the dismantling due today. I have measured all the relevant powers and voltages and will append them shortly:

Attachment 1: FS_table_layout_JAN_2010.pdf
FS_table_layout_JAN_2010.pdf
Attachment 2: FS_table_layout_JAN_2010.jpg
FS_table_layout_JAN_2010.jpg
  551   Tue Jan 26 11:00:45 2010 AidanLaserFiberFiber stabilization loop transfer function measurements & calculation

There was an additional 200x gain (~46dB) between V_B and V_A, where the measured transfer function below is V_B/V_A. Hence the loop transfer function is 200x the measured transfer function. See the experiment layout for an illustration of this.

  • SCRN0009.txt - transfer function - magnitude [10mV source drive amplitude]
  • SCRN0010.txt - transfer function - phase [10mV source drive amplitude]

 

  • SCRN0011.txt - transfer function - magnitude [100mV source drive amplitude]
  • SCRN0012.txt - transfer function - phase [100mV source drive amplitude]

Calculation of Loop transfer function:

  1. The amplitude of the 20MHz RF signal on the in-loop PD was measured and is equal to -0.93dBm.
  2. This is fed into a mixer (ZAD-1-1+). When the loop is locked the amplitude of the output of the mixer, V_e, is approximately (a_mixer*(-0.93dBm)*delta_phi), where a_mixer is the attenuation of the mixer at 20MHz (a_mixer = -5dB) and delta_phi is the phase difference between the RF signal and the local oscillator. This phase difference is the error signal.
  3. This goes into an SR560 and is amplified by F(s) = 200x
  4. The output of the SR560 goes into the Marconi and is amplified by the FM deviation, K = 100Hz/Vrms
  5. The phase at the output of the Marconi, phi_out, (ignoring the 80MHz signal) = 2*Pi*integrate(K*F(s)*V_e, dt)
  6. = 2*pi*[K*F(s)*V_e]/(i*2*pi*f)
  7. = K*F(s)*V_e/(i*f)
  8. The in-loop laser beam is double passed through the AOM, so the above phase is added twice to that beam (x2)

Therefore, the loop gain, phi_out/delta_phi, = 2*K*F(s)*a_mixer*(-0.93dBm)/(i*f) ~= 2*(100Hz/Vrms)*(200)*(0.113Vrms)/(i*f) = 4520 Hz/f

This loop gain is plotted in the attached figure. It is within 10% of the measured value.

 

 

 

 

Attachment 1: SCRN0012.zip
Attachment 2: FS__measured_transfer_fn.pdf
FS__measured_transfer_fn.pdf
  552   Tue Jan 26 13:52:44 2010 AidanLaserFiberFiber setup - voltages and power levels throughout the experiment

 The following values were measured on the fiber setup - see experiment setup for diagram of the experiment.

 

OUT-OF-LOOP PD

Ref beam DC = 0.601 mW +/- 0.1uW (DAQ - PD calibration: assumed 770 V/W)

Ref beam DC = 0.504 mW (ThorLabs power meter)

 

Trans Beam DC = 1.67 uW +/- 0.02 uW (DAQ –  PD calibration: assumed 770 V/W)

Trans Beam DC = 0.001 mW +/- 0.001mW (ThorLabs power meter)

 

RF Level = +6.36 dBm

 

IN-LOOP PD

Ref beam DC = 0.614 mW +/- 1uW (DAQ : PD calibration: assumed 770 V/W)

Ref beam DC = 0.468 mW (ThorLabs Power Meter)

 (Re-calibrated PDs slightly at this point - multiplied DAQ input by 468/614)

Double-Trans Beam DC = 0.66uW +/- 0.03 uW (DAQ  PD calibration: assumed 587 V/W)

Double-Trans Beam DC = 0.34uW +/- 0.04 uW (DAQ PD calibration: assumed 587 V/W) – with 70MHz AOM off, therefore this is scatter

 

RF Level = -0.93 dBm

 

  553   Tue Jan 26 15:57:01 2010 AidanLaserFiberFS - phase noise measurements

 The phase and frequency noise measurements for the fiber stabilization experiment. Includes open & closed loop, as well as relative sizes of contributions from intensity noise, shot noise and electronics noise. I think we need to build a better reference arm to stabilize the fiber against.

Attachment 1: 2010-01-22_fiber_stabilization_phase_noise.pdf
2010-01-22_fiber_stabilization_phase_noise.pdf
  675   Wed Mar 17 08:48:32 2010 AidanLaserGYROGYRO CAVITY LOCKED IN BOTH DIRECTIONS

Boffo! Nice work lads.

  736   Wed Apr 28 09:24:01 2010 AidanComputingfubarelog craziness - test to try and crash elog

 - apparently PDFs work okay. Frank is reporting continual crashes from last night when uploading a graph of the particle counter in different formats from Firefox in Windows.

Attachment 1: 40m_figure_ETM.pdf
40m_figure_ETM.pdf
  753   Fri May 7 07:42:09 2010 AidanLab InfrastructureHVACRe-sealing and laser keys

The guys are back this morning to reseal the vents. There are some green marks around the place but also what looks like new red ones over the top of the silicon they laid down two weeks ago.

I shutdown the 35W laser using the 'System Off' option on the touch-screen and then turned off the NPRO and removed the key. That key is now in the second drawer down in the first desk. The key for the Gyro NPRO was not in the laser.

  777   Tue May 18 09:43:55 2010 AidanComputingDAQKilled the DAQD process. It restarted automatically.

I added some EPICS channels to the Hartmann sensor softIoc and then added these to be recorded in the frames.

I then killed the daqd process on fb1 so it would start afresh.

  • /cvs/cds/caltech/target/softIoc/HWS.db      - the file with the HWS EPICS channels
  • /cvs/cds/caltech/chans/daq/C4TCS.ini            - the .ini file telling the frame builder what channels to record.
  786   Mon May 24 17:35:41 2010 AidanLaserGeneralLasers powered down

The 35W laser and the Gryo NPRO have been shutdown in preparation for tomorrow's conduit installation work. The key for the 35W laser in the lower draw in the first desk attached to a Thorlabs USB flash-driver. The key for the Gyro laser wasn't in the driver. The laser was in use this afternoon and since then someone has completely powered it down and removed the key, I'm assuming in prep for tomorrow morning.

  788   Wed May 26 17:13:07 2010 AidanLab Infrastructurestuff happensMoved a New Focus 9071 4-axis stage to 40m for doubling
  805   Tue Jun 8 10:35:16 2010 AidanMiscstuff happensMoved some equipment to 40m

I've taken the following items to the 40m.

  1. 40MHz AOM
  2. Thorlabs Broadband EOM
  3. 2x New Focus 9071 4-axis stages
  4. ZHL-1A RF amplifier
  5. ZHL-2A RF amplifier

They're all marked "Adhikari Lab".

  830   Wed Jun 23 18:15:59 2010 AidanLab InfrastructureHVACNew temperature controllers

We now have two temperature controllers in the lab:

A couple of weeks ago they installed a second temperature controller on the South Wall. This drives the HVAC heater that is above the stereo.

The original temperature controller (West Wall) was also upgraded to have a fancy new 1960's-style mechanical display of the setpoint-needle on the front type. Maybe in 50 or 60 years we can get a digital controller in here.

At the moment the second controller has not been calibrated to match the original controller.

  1. 00001.jpg - new controller on South Wall
  2. 00002.jpg - close up of South Wall controller
  3. 00003.jpg - upgraded West Wall controller
Attachment 1: 00001.jpg
00001.jpg
Attachment 2: 00002.jpg
00002.jpg
Attachment 3: 00003.jpg
00003.jpg
  836   Mon Jun 28 16:13:21 2010 AidanComputingGeneralcurrently no access to ATF from outside

 

Done.


Quote:

the network connection is down again, so our router has to be restarted ...

whoever will go to the lab on Monday first plz powercycle the linksys router...

 

  859   Tue Jul 20 15:44:07 2010 AidanComputingGeneralFixed two new static IP addresses for TCS machines

I fixed two machines in the TCS lab to have static IP addresses on the local network.

The Athena DAQ CentOS box: 'tcs_daq' 10.0.1.34

The CentOS workstation: 'tcs_ws' 10.0.1.25

Frank, please add these to the network topology diagram you have ...

  860   Tue Jul 20 18:12:02 2010 AidanComputingDAQKilled the DAQD process. It restarted automatically.

I killed and restarted the daqd process because I wanted to add some 16Hz TCS channels to the frame builder. These are from the Athena DAQ box.

I edited the following files:

  • on fb1: /cvs/cds/caltech/chans/daq/C4TCS.ini    -the .ini file telling the frame builder what channels to record
  • on tcs_daq: /target/TCS_westbridge.db  - added the names for the ADC inputs and DAC outputs for the Athena box

 

Quote:

I added some EPICS channels to the Hartmann sensor softIoc and then added these to be recorded in the frames.

I then killed the daqd process on fb1 so it would start afresh.

  • /cvs/cds/caltech/target/softIoc/HWS.db      - the file with the HWS EPICS channels
  • /cvs/cds/caltech/chans/daq/C4TCS.ini            - the .ini file telling the frame builder what channels to record.

 

  910   Fri Aug 6 16:56:58 2010 AidanLab InfrastructureGeneralWHERE IS THE WINCAMD?

Looks like Hurricane Dmass.

Quote:

Quote:

I was trying to understand why the mode matching through the PMC was so bad (I got 30 mW transmitted with 120 mW input).

  • I looked at the mode on the PMC REFL camera, and it did not look very guassian.
  • I changed the laser current from 2 A to 2.2 A (what Rick said they ran it at at LHO) and saw no change in the mode
  • I tried to take a beamscan...but could not find the WINCAMD and its computer (again.) I checked the usual suspects (PSL/TCS) and didn't see it.

So. Who knows where the wincamD is?

added: pics of PMC REFL before and after locking, in order

Totally possible that my mode matching is just that crappy? Maybe.

I did take beam scans of the mode going into the PMC just before aligning to it for the final time. I can do so again to get real profiles and characterize the H1NPRO

 Here are some scans of the beam with the winCAMD. I had a reflective ND filter on for these (hence some of the fringing).

  1. 5-10 inches in front of NPRO (through mirror transmission)
  2. 21 inches in front of NPRO (maybe junk b/c of ND filter? Maybe not?)
  3. Downstream of: HWP and PBS to get 120 mW total (about 8% power), and some focusing lenses (this was at PMC waist). I think this is the "junk light" you get from an NPRO. Maybe this is a lot of power to have in junk, maybe not?

 

  966   Sat Aug 21 14:28:14 2010 AidanComputingCDSFront end rebuilt ----- BURT notes

Quote:
 1) User directories have been moved into /users. There is now the awesome /users/abrooks/aidan/Aidan/ directory.

Pure awesomeness.

  1101   Tue Oct 5 12:53:26 2010 AidanComputingGeneralAdded link to the users directory in the root directory on ws1

/users links to /cvs/users

(syntax to do this was "ln -s /cvs/users /users")

  1325   Mon Feb 28 17:47:33 2011 AidanComputingDAQRestarted DAQD on fb1

I added some Hartmann Sensor channels to the frames and restarted DAQD on fb1 to include them.

See here for details ...

  1356   Thu Mar 17 15:09:18 2011 AidanMiscstuff happensLVC Lab Tour

Visitors to the lab ...

Attachment 1: P1000411.JPG
P1000411.JPG
Attachment 2: P1000412.JPG
P1000412.JPG
Attachment 3: P1000413.JPG
P1000413.JPG
  1389   Tue Apr 12 22:47:38 2011 AidanComputingDAQAdded TCS channels and restarted daqd

http://nodus.ligo.caltech.edu:8080/TCS_Lab/135

  1397   Fri Apr 22 20:17:42 2011 AidanMiscANTS!They're heeeerrrree

The ants are back again and it's only going to get worse over summer.

We have ant poison in the TCS lab. Feel free to use it.

  1583   Tue Jan 3 15:59:07 2012 AidanComputingComputingDirectory clean up

 I've moved all the old medm directories into an archive directory. (/caltech/medm/archive)

I've also gone into the /cvs/cds/advLigo/fe/ and moved all the old models into an archive directory (/cvs/cds/advLigo/fe/archive).

 

  1780   Sat Nov 3 13:20:27 2012 AidanComputingComputingRe-compiled Real Time Model with TCS channels

 I saved the existing ATF model as atf.mdl.ctrl and built a modified version for some temporary TCS real-time work for aLIGO. The new ATF model is saved as atf.mdl.tcs (and currently as atf.mdl).

The new model compiled and was installed. It still runs all the GYRO stuff (which was all unaltered) but I replaced the defunct CTRL block from the doubling experiment with a new TCS block.

- should the old model need to be replaced, this can be done by copying aft.mdl.ctrl to atf.mdl and compiling with fb0:/cvs/cds/advLigo$ make atf install-atf

 

Attachment 1: Screen_Shot_2012-11-02_at_11.51.42_AM.png
Screen_Shot_2012-11-02_at_11.51.42_AM.png
  1781   Mon Nov 5 13:12:53 2012 AidanComputingComputingTCS aLIGO Real-Time model

The C2ATF model with aLIGO TCS controls is now running correctly on fb0

I followed the standard troubleshooting instructions in ATF eLog 124 to get the model to run. All the channels can be access from the C2ATF_TCS_MASTER.adl medm screen in /cvs/cds/caltech/medm/c2/atf/

We're now saving 14 channels of data to frame builder. They are:

[C2:ATF-TCS_AOM_OUT_OUT_DAQ] - 4096Hz

[C2:ATF-TCS_AOM_SET_OUT_DAQ] - 16Hz

[C2:ATF-TCS_CHILLER_SLOW_GAIN_OUT_DAQ] - 16Hz

[C2:ATF-TCS_CHILLER_TEMP_SET_OUT_DAQ] - 16Hz

[C2:ATF-TCS_ISS_IN_AC_OUT_DAQ] - 4096Hz (in-loop ISS PD)

 

[C2:ATF-TCS_ISS_IN_DC_OUT_DAQ] - 16Hz (in-loop ISS PD)

[C2:ATF-TCS_ISS_OUT_AC_OUT_DAQ] - 4096Hz (in-loop ISS PD)

[C2:ATF-TCS_ISS_OUT_DC_OUT_DAQ] - 16Hz (in-loop ISS PD)

[C2:ATF-TCS_LSR_HD_PD_OUT_DAQ] - 16Hz

[C2:ATF-TCS_LSR_SLOW_GAIN_OUT_DAQ] - 16Hz

[C2:ATF-TCS_LSR_TCS_LSR_TEMP_OUT_DAQ] - 16Hz

 

[C2:ATF-TCS_LSR_PWR_MTR_OUT_DAQ] - 16Hz

[C2:ATF-TCS_PZT_CTRL_SENS_OUT_DAQ] - 16Hz

[C2:ATF-TCS_PZT_OUT_OUT_DAQ] - 4096Hz

 

 

 

 

Attachment 1: Screen_Shot_2012-11-05_at_1.08.55_PM.png
Screen_Shot_2012-11-05_at_1.08.55_PM.png
  1841   Sat Jun 8 10:40:15 2013 AidanComputingGeneralHow to make high quality plots in Matlab

Another (incredibly) useful suggestion:

Always add the filename used to generate plots to your plot ... so when you post/print it, you can easily determine the source file at later date.

text(0, -0.12, [mfilename('fullpath'), '.m'], 'FontSize', 6, 'Interpreter', 'none', 'Units', 'normalized')

Depending on the orientation and margins of the plot, you may have to play around with the Y coordinate of the text command (= -0.12 in this example) to get the text to fit on the image without interfering with the X-axis plot label.

RXA: Use IDfig.m instead.

Attachment 1: IDfig.m
function tt = IDfig(varargin)
% IDfig puts the name of the calling function and the date on the right side of a figure
% there must be a current axis, and it must be called from an m-file
% replaces IDplot, which has a name conflict with something in the sys-ID
% toolbox. BTL July 17, 2007.
%
% if called with an input string, that string will be appended to the message,
% eg IDfig('data from tf_120104_1.mat')
%
% if called with an output argument, it returns the handle to the text object it created
... 61 more lines ...
  1993   Tue Aug 4 10:43:21 2015 AidanComputingGeneralFB0 unresponsive. Rebooting.

FB0 was unresponsive from the network. I am trying a hard reboot of it.

  2056   Sun Jul 31 09:06:43 2016 AidanComputingTempCtrlTemplate PID servo script from eLIGO days

I've attached a template PID servo Perl script that we used during the eLIGO days for temperature control of the TCS chillers. We can adapt this to offload the PZT voltage offset to the temperature of the NPRO lasers.

Attachment 1: PIDChillerServo.pl
#!/usr/bin/perl -w

# Chiller PID Servo
# Adapted by Danny Atkinson 2009-05-20 from:
# PID Servo for PSL-FSS (Slow)
# Tobin Fricke 2007-01-09
#
# Current SVN version
# $Id: PIDChillerServo.pl 937 2010-05-04 16:42:01Z daniel.atkinson@LIGO.ORG $
#
... 303 more lines ...
  2057   Mon Aug 1 15:33:25 2016 AidanMiscANTS!It's summer. The ants are back. I have laid down some ant bait

One in the TCS Lab. One by the ATF door. I have more ant bait available in the TCS Lab.

  2066   Thu Sep 29 08:21:07 2016 AidanLaser2micronLasersTwo micron fiber set-up (dry run)
I set up most of the two micron fiber optics as described in T1600146. I discovered that (a) our 90:10 splitters were accidentally ordered with 
FC/PC connectors, not FC/APC connectors [but Iíve already spoken to Thorlabs to arrange a swap] and (b) we definitely need fiber trays to 
handle spools of extra fiber.

Other than that, the basic layout looks good.
Attachment 1: PastedGraphic-1.pdf
PastedGraphic-1.pdf
Attachment 2: IMG_7260.JPG
IMG_7260.JPG
Attachment 3: IMG_7259.JPG
IMG_7259.JPG
  2079   Tue Jan 3 16:27:41 2017 AidanLaserTMTFTwo micron test facility - v1: mocked up and locked

Two micron test facility set up.

Before the holiday break, I set up the first stage of the TMTF. The basic concept is to use a fiber Mach-Zender with unequal path lengths as a ruler for the frequency noise of the laser diode.

The existing set up is as follows in the block diagram. The actual set up is shown in the attached photo.

The output from the laser diode is sent into an isolator. This is then passed to a 90/10 splitter. The 90% port is dumped and the 10% port is sent into COUPLER A (nominally a 50/50 BS for the input into a MZ). One path of is connected directly into COUPLER B. The other is first connected into a 2m long patch cable and then into COUPLER B. One output from the coupler is sent into a Thorlabs S148C InGaAs photodiode based power meter.

None of the fibers are polarization maintaining.

After connecting everything and turning on the diode, the power meter showed an output power than ranged from 11.25uW to 14.8uW. I could clearly see the output fluctuate through a sine wave as made one up longer by gently heating the patch cable. Additionally, changing the diode temperature induces a wavelength change. By adjusting the temperature set point, I could make the output go through fringes.

 

Given a 2m long path length difference (DeltaL) with a refractive index of 1.43, the accumulated phase difference is:

Phi = 2 Pi DeltaL/Lambda

The change in phase difference with changing wavelength is:

Dphi = -2 Pi DeltaL/Lambda^2 * DeltaLambda

= -2 Pi DeltaL/Lambda^2 * (DeltaLambda/DeltaT) * DeltaT

= 450 radians/K

 

For the 10K thermistor, one degree corresponds to 462 Ohms, so we expect around 6.5 Ohms to correspond to 2 Pi radians (or 3.25Ohms corresponding to a peak-peak value of 3.55uW or 0.31V from the power meter analog output). Very gently changing the thermistor set point showed the output of the MZ going through fringes at roughly this rate.

The output of the MZ slowly drifts between maximum and minimum over the course of twenty or thirty seconds. I decided to try to lock the output of the MZ at low frequencies using the analog output of the power meter, a crude analog integrator and the input to the temperature controller as an actuator. I also used a DC voltage source to lock to a point half way up the fringe.

The integrator used 1.68MOhm resistance with 10uF capacitor to yield a transfer function of 9.5mHz/f. The total loop gain, including the 2kOhm/V response of the temperature controller input and the 0.31V/3.25Ohm response of the power meter readout of the MZ to a thermistor set point change was estimated as 1.8Hz/f.

This was enough to lock the MZ output to a steady-state point about half-way up a fringe. Without a proper photodiode, there was no real spectrum to be measured.

The next step is to set up some proper photodiodes to do the readout out and locking.

Attachment 1: IMG_8458.JPG
IMG_8458.JPG
Attachment 2: IMG_8459.JPG
IMG_8459.JPG
Attachment 3: TMTF_rev1.png
TMTF_rev1.png
  2082   Wed Jan 25 11:41:55 2017 AidanComputingCymacsPulled old IO chassis and FB0

We want to set up a new Cymacs in the ATF. It would be much cheaper if we don't have to order new ADC and DAC cards.

I pulled the old IO chassis (which contained the old ATF ADC and DAC cards). Unfortunately. they are PCI-X (we think) which will not fit in the PCI-E slots in the new Cymacs. 

We figured we might be able to leave the DAQ cards in the old chassis and continue to it if we can hook it up to a new Cymacs. So we pulled FB0 and extracted the board that expands the BUS out to the IO Chassis (see below). At the moment, we're investigating if this board will work in the new Cymacs. It is, at least, PCI-E.

 

Attachment 1: IMG_8643.JPG
IMG_8643.JPG
  2083   Fri Jan 27 13:36:04 2017 AidanLab InfrastructurePEMGot old PEM sensors running with Windows 7 OPC server

I have set up a dedicated Windows 7 machine in the TCS lab to be the OPC server for the Newport Temperature sensors. 

The OPC server is now running and broadcasting the EPICS channels for the temperature, humidity and pressure for these sensors. Currently, the channel names have the prefixes listed below, but we'll likely change them to actual lab names.

C4:PEM = TCS Lab

C3:PEM = CTN Lab

C6:PEM = CRIME Lab

Installation guide:

https://nodus.ligo.caltech.edu:30889/ATFWiki/doku.php?id=main:experiments:psl:install_newport_zed-bth_environmental_sensors​

See also:

https://nodus.ligo.caltech.edu:8081/PSL_Lab/1815​

 

  2085   Wed Apr 5 11:54:31 2017 AidanComputingPEMTemperature data being written to file

I forgot to note this last Friday. The temperature data from the labs is now being written to file in a somewhat brute force fashion:

camonitor [channel_name] > file.dat

This is still running, so at the very least we should be getting a coarse record of the lab temperatures. Eventually we want to set up a DAQD and framebuilder for this. We should be able to convert the current data into GWF frame files when that happens.

Attachment 1: IMG_9115.JPG
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  2088   Wed Apr 19 14:34:10 2017 AidanLaserTMTFEblana laser diode intensity noise spectra

I measured the intensity noise of the Eblana EP2004-D laser diode. I confirmed that the intensity noise is above the dark noise of the photodiode but I have not, as yet, made any attempt to optimize the photodiode response (or analytically determine its expected noise floor).

Settings:

  • Diode current: 55mA
  • Diode temperature set point (in Ohms): 10.779 kOhms

Power measurement (power meter)

Laser > isolator > 90/10 split > 90 port > Thorlabs power meter (596 microW)

Power measurement (photodiode)

Laser > isolator > 90/10 split > 90 port > DET10D > 50 Ohm terminator > SR560 [100x gain] > 3.159 V [DC]

Therefore, the voltage across the 50Ohm terminator on the photodetector is 0.0316V. The current is then 632 microAmps. The responsivity of the DET10D is 1.2A/W at 2000nm. Therefore, this is approximately 530 microWatts (about a 13% difference with the power meter measurement).

Intensity/dark noise measurement:

Laser [OFF] > isolator > 90/10 split > 90 port > DET10D > 50 Ohm terminator > SR560 [1E4 gain, high pass filter at 0.3Hz] > SR785 [DN measurement]

Laser [ON] > isolator > 90/10 split > 90 port > DET10D > 50 Ohm terminator > SR560 [1E4 gain, high pass filter at 0.3Hz] > SR785 [INT NOISE measurement]

The results from these two measurements are plotted below. The SR560 filtering was undone to refer the measurements back to the DET10D/50Ohm output and both results were divided the DC voltage at that point (31.6V).

Initial intensity noise:

1 Hz: 1E-5 per rtHz

10 Hz: 1.5E-6 per rtHz

 

Attachment 1: eblana_noise_intensity.pdf
eblana_noise_intensity.pdf
Attachment 2: 20170418_Eblana_intensity_noise.asc
Input File: ../spectra/srs003.78d
Measure Group: FFT
Measurement: FFT 1
Num of extracted Points: 801
Start Freq: -0 Hz
Span: 100 Hz
FFT Lines:  400 
Window: Hanning
Averaging Mode: RMS
Averaging Type: Linear / Fix Len
... 806 more lines ...
Attachment 3: 20170418_DET10D_dark_noise.asc
Input File: ../spectra/srs001.78d
Measure Group: FFT
Measurement: FFT 1
Num of extracted Points: 801
Start Freq: -0 Hz
Span: 100 Hz
FFT Lines:  400 
Window: Hanning
Averaging Mode: RMS
Averaging Type: Linear / Fix Len
... 806 more lines ...
  2091   Fri Apr 21 16:06:51 2017 AidanElectronicsCamerasPhosphor coated camera shows ZERO response at 2004nm

Johannes and I took the phospor coated CCD camera (from the cryo lab) down to the ATF to see the response to 2004nm. We tested it was working by shining an incandescent light onto it and confirming that we could see a signal on the monitor. Then we took the output of the 2004nm laser diode and put about 600 microWatts directly onto the CCD camera and ...

We saw no response at all. Nothing - on any of the gain settings.

 

 

  2093   Fri Apr 28 13:54:35 2017 AidanLaserPD QEDET10D QE at 2004nm measured (it was 0.79)

I set up a measurement of the DET10D QE at 2004nm. I supplied the Eblana 2004nm fiber-coupled laser diode with 45mA of current. I first measured the output with the Thorlabs power meter and then measured output with the DET10D photodiode. Both systems are fiber-coupled (although both fiber couplers are screwed on rather than glued on).

The power was 0.34mW = 3.425E15 photons per second

The photodetector output was run through a 50 Ohm resistor which was then run through a SR560 with 100x gain at DC. The measured voltage from the SR560 was 2.183V. Hence the photocurrent was 4.36E-4A  = 2.7E15 electrons per second

Therefore, the QE was 0.79 at 2004nm. This agrees with the manufacturers curve. However, I notice that there:

  • is a window over the photodiode (so we might lose a few percent there). It's not clear from the manual whether this is AR coated or not.
  • the voltage from the SR560 fluctuates a bit when I rotate the fiber coupler that is attached to the front (I measured the QE when this was maximized). This tells me that we’re not centered on the photodiode and a fraction of the fiber output isn’t getting onto the active area of the PD.  

 

 

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  2095   Tue May 2 11:11:16 2017 AidanLaserTMTFDET-10 intensity noise - round 2

I've done a more thorough examination of the Eblana 2004nm intensity noise spectrum. Unfortunately, there is something weird going on with the detector which I haven't resolved yet. The set up was:

500 micro-Watts > DET10D > 1497 Ohm transimpedance resistor (RT) > SR560 (AC measurement settings: HP filter, 6dB @ 0.1Hz, Gain = 1000x)

DC measurement: SR560 Output = 0.962V (gain = 1) > current = 6.4E-4A > 535E-6 Watts electrical > 677E-6 Watts optical (need to check this!)

Noises:

  • Shot noise (current): PD_resp*SQRT[2 * P * h * nu] = 1.2E-11 A
  • Johnson noise: 0.13E-9/SQRT[RT] = 3.3E-12 A
  • SR560 noise (curve is attached) ~ 20E-9V/RT @ 5Hz = 1.3E-11 A
  • NEP DET10D = 1E-12W * 1.2A/W = 1.2E-12A (from the manual)

However, when the intensity noise and the dark noise are measured, I find the dark noise (laser off) is way above the NEP, and well above the JN, the shot noise, the SR560 input noise (measured and from manual) and the expected NEP.

 

Quote:

The DET-10D is an extended InGaAs photodiode which is biased either using a battery or an external supply. On the schematic you can see that the diode is directly connected to the BNC cable.

According to the datasheet, the NEP is 1 pW/rHz. The shot noise in 600 uA is sqrt(2 * 1.6e-19 * 600e-6) = 14 pA/rHz, so we should be fine if the datasheet is accurate for f < 1 kHz (which I doubt).

14 pA / 600 uA => RIN = 2.3e-8

Where is this dark noise coming from???

The input referred noise of the SR560 is ~5 nV/rHz above 5 Hz. With the 50 Ohm resistor, that gives us an equivalent current noise of 100 pA/rHz (much worse than anything else in this circuit). It is also ~5x larger than the thermal noise of the 50 Ohm resistor.

You should use a wire-wound resistor instead of a sketchy terminator, and it should be ~1-3 kOhms. To keep from saturating the SR560, you'll have to AC couple it.

 

Attachment 1: eblana_noise2_intensity.pdf
eblana_noise2_intensity.pdf
  2096   Tue May 2 11:15:41 2017 AidanLaserTMTFDET-10 intensity noise - round 2

If the diode shut resistance was really low (like 10 Ohms), then this might explain what we're seeing. Unlikely, but the detector is behaving like it has a very low resistor in parallel to the transimpedance resistor.

  2098   Tue May 2 15:31:24 2017 AidanComputingCymacsATF Cymacs FB4 built - only OS and RTSCDS package right now

I've installed Debian 8 on the new ATF Cymacs and called the machine FB4.

Following the instructions on the ATF Wiki, I've installed the ADVLIGORTS-CYMAC package. However, I've not built the framebuilder, RTS or DAQD.

 

  2117   Wed Jun 7 15:19:30 2017 AidanElectronicsCamerasTwo micron camera light-saber test of Pembroke Widy camera

I ran the 1550nm laser through the silicon piece at 11mW incident power. The laser current was set to 100mA and the output power was measured on the Thorlabs 2W power head. The camera was approximately 250mm from the silicon and I did my best to image the front surface of the silicon.

The camera exposure time was set to 200ms. The didn't seem to be any other gain settings available. 

I took 100 images with the laser on and then 100 images with the laser off. I average these and took the difference - which is shown below. You can see a faint horizontal light-saber line around Y-coordinate = 170 pixels.

The data from the averaged images is in the attached MAT file.

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IMG_9850.JPG
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Attachment 3: Widy_Data.mat
  2118   Wed Jun 7 15:30:46 2017 AidanElectronicsCamerasTwo micron camera light-saber test of Pembroke Widy camera

Some more plots of the data, including a mean of the columns in the image of the silicon. The silicon piece is about 60mm in width.

Quote:

I ran the 1550nm laser through the silicon piece at 11mW incident power. The laser current was set to 100mA and the output power was measured on the Thorlabs 2W power head. The camera was approximately 250mm from the silicon and I did my best to image the front surface of the silicon.

The camera exposure time was set to 200ms. The didn't seem to be any other gain settings available. 

I took 100 images with the laser on and then 100 images with the laser off. I average these and took the difference - which is shown below. You can see a faint horizontal light-saber line around Y-coordinate = 170 pixels.

The data from the averaged images is in the attached MAT file.

 

Attachment 1: Screen_Shot_2017-06-07_at_3.29.10_PM.png
Screen_Shot_2017-06-07_at_3.29.10_PM.png
  2170   Thu Aug 24 13:47:00 2017 AidanSafetyGeneralLeak in the ATF Lab

Yesterday the leak was worse. And there was a smell of foul effluent in the lab. And some brown water by the bottom of the rack. This was later discovered to be drain water rather than sewage.

The custodians cleaned up the clear water. I filed a Service Request and the plumbers came out and cleared up the brown water with disinfectant. They subsequently spotted a leak in the pipe itself - about 8 feet up the pipe. This is scheduled to be fixed. Eric G informs me that there is duct tape on leak right now. I spoke to the service center and they're going to do a permanent repair (replacing the pipe) sometime in the near future. If the pipe leaks again in the interim, they said to contact them and they'll expedite the replacement.

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  2177   Fri Sep 15 14:12:38 2017 AidanLab InfrastructureGeneralQIL (ATF) Lab preparation for the plumbing work

[Aidan, Gabriele, Eric]

We have wrapped the two optical tables in plastic. The flammables cabinet has been shifted away from the pipe on the West wall. The computer rack has been disconnected from several cables so that it is clear of the south wall drain pipe.

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