 Wed May 19 14:36:46 2010, Aidan, HowTo, Phase Camera, Phase Camera algorithm and stuff 
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I had a think about the algorithm we might use for the phase camera measurement. MATLAB has an fft function that will allow us to extract the data
that we need with a single command.
We record a series of images from a camera and put them into a 3D array or movie, image_arr, where |
 Thu May 20 10:06:56 2010, Aidan, HowTo, Phase Camera, Phase Camera- raw data video
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Wed May 26 18:54:55 2010, Aidan, Summary, Green Locking, Mounted Crystal 724 in the Doubling Oven
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Andri and I mounted the Raicol Crystal #724 in one of the new Covesion Ovens. The procedure was the same as before - see
elog entry here.
There was one issue - the glass plate that goes on top of the crystal is coated on one side with ITO (Indium-Tin |
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Thu May 27 08:22:57 2010, Aidan, Update, Computers, Restarted the elog this morning
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Wed Jun 16 18:14:13 2010, Aidan, Update, General, Glass cover from overhead light smashed on PSL table
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I was giving a tour of the 40m yesterday. We were looking at the PSL table. About 30 seconds after I turned the lights on a glass cover from one of the
lights (NW corner) popped out of its holder and smashed on the table.
I've cleaned up all the broken glass I could see but there may be some small shards there. Please use caution |
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Thu Jun 24 06:49:29 2010, Aidan, Update, Green Locking, a channel for PPKTP temperature
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Is this a setpoint temperature that we can change by writing to the channel or is it a readout of the actual temperature of the oven?
kiwamu:
This is a readout channel just to monitor the actual temperature. |
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Fri Aug 13 15:29:35 2010, Aidan, Frogs, Photos, Here's the 40m team
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Thu Oct 21 19:10:39 2010, Aidan, Update, PSL, Found the beat at 1064nm
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Fri Oct 22 21:28:27 2010, Aidan, Update, Locking, Green era: found a green beat note finally
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Nice work!
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Fri Nov 12 11:36:06 2010, Aidan, Configuration, Computers, Fixed the PERL PATH errors from the scripts directory change
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I've been trying to get a PID loop running for the green locking and I've discovered that some of the directories in the path for the Perl Modules
are now obselete. Specifically, since the scripts directory has been moved from /cvs/cds/caltech/scripts to /cvs/cds/rtcds/caltech/c1/scripts
the following locations in the Perl @INC path list need to be changed: |
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Fri Nov 12 12:06:11 2010, Aidan, Configuration, Green Locking, PID script working - now it needs to be tuned
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I've set up a PID script that senses the EX-PSL Green Beat note (from the frequency counter) and actuates on the temperature of the end laser to
drive the beat note to a given setpoint.
I've added the necessary EPICS channels to c1iscaux and rebooted it so that the channels are live. They are listed |
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Mon Nov 15 14:42:01 2010, Aidan, Update, PSL, C1PSL rebooted?
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Yeah. Joe and I rebooted c1psl a couple of times this morning. I didn't realize the burtrestore wasn't automatic.
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Tue Nov 16 09:02:54 2010, Aidan, Update, Green Locking, PID loop - calibration of SR620 output
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[Aidan, Kiwamu]
Kiwamu and I roughly calibrated the analogue output from the SR620 frequency counter yesterday. The input channel, intuitively named C1:PSL-126MOPA_126MON,
now reads the measured frequency in MHz with an error of about 0.1MHz - this is, I think, due to the bit noise on the D/A conversion that Kiwamu discovered |
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Tue Nov 16 10:47:45 2010, Aidan, Update, Green Locking, Rebooted c1psl - added new GRNBEAT_FREQ channel
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I restored C1:PSL-126MOPA_126MON to its original settings (EGUF = -410, EGUL = 410) and added a new calc channel called C1:LSC-EX_GRNBEAT_FREQ that is
derived from C1:PSL-126MOPA_126MON. The calibration in the new channel converts the input to MHz.
grecord(calc, "C1:LSC-EX_GRNBEAT_FREQ") |
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Tue Nov 16 12:47:30 2010, Aidan, Update, Green Locking, PID loop but no green
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The PID loop is ready to be run on the green beat note but, since the tanks are open, there is no green transmission from the end getting to the PSL
table. Nevertheless, here's the screen for the PID loop. The loop script is still in my directory /cvs/cds/caltech/users/abrooks/GRNXSlowServo
The medm screen is attached. It shows the current beat note frequency in MHz () |
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Tue Nov 16 16:00:26 2010, Aidan, Update, Green Locking, PID loop but no green
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Quote:
RA: All MEDM screens must be in the proper MEDM directory!! Also, all perl scripts must have a .pl extension!!! Also, all scripts must be |
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Fri Dec 10 09:58:57 2010, Aidan, Update, SUS, beam pointing has been done
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Good news. I feel multi-chromatic-locking success is just around the corner.
By the way, there's a new presentation on the DCC from the ANU group where they've locked a short single cavity with both colors - G1000735:
https://dcc.ligo.org/cgi-bin/private/DocDB/ShowDocument?docid=14040 |
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Thu Jan 20 15:39:59 2011, Aidan, Update, Locking, Upper limit on frequency noise of ADC
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[Aidan, Kiwamu]
Kiwamu and I plugged the output from a DS3456 function generator into the ADC and started recording the data. The func. generator output a 237.8Hz,
1Vpp sine wave. We chose this value because it corresponds to the FSR of a 38.5m cavity (=3.896MHz) divided by 2^14, the frequency divider amount we intend |
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Thu Jan 20 17:00:39 2011, Aidan, Configuration, Locking, Ballpark figures for Green Locking PLLs (Digital vs Analogue)
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If we use a digital PLL for locking the frequency of the PSL and END green lasers then we can expect a UGF of around 1kHz (assuming a sampling rate of
16kHz). Let's assume a simple 1/f loop giving a loop gain of ~1000x at 1Hz. If the free-swinging ETM pendulum motion at 1Hz is of the order of 1 micron,
then the residual motion at 1Hz, once we lock the digital PLL by actuating on the ETM position, will be of the order of 1nm. This is bordering on too high. |
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Fri Jan 21 11:45:01 2011, Aidan, Configuration, Locking, Ballpark figures for Green Locking PLLs (Digital vs Analogue)
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Quote:
If we use a digital PLL for locking the frequency of the PSL and END green lasers then we can expect a UGF of around 1kHz (assuming a sampling |
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Wed Jan 26 10:11:47 2011, Aidan, Update, Green Locking, cavity scan
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Quote:
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Wed Jan 26 14:49:48 2011, Aidan, Update, Environment, Turned on Control room AC
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| 80 degrees is too uncomfortable in the control room so I turned on the AC. The set point is 74F. |
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Fri Jan 28 09:03:38 2011, Aidan, Summary, Green Locking, Digital Frequency Discriminator
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Quote:
That's some pretty fast work! I thought we would be taking up to a week to get that happening. I wonder what's the right way to measure |
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Sun Jan 30 17:15:09 2011, Aidan, Summary, Green Locking, Digital Frequency discriminator - frequency noise
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I've had a go at trying to estimate the frequency noise of the digital frequency discriminator (DFD). I input a 234.5Hz (0.5Vpp) signal from a 30MHz
function generator into the ADC. The LP output of the DFD measured 234.5Hz. However, this signal is clearly modulated by roughly +/- 0.2Hz at harmonics
of 234.5Hz (as you can see in the top plot in the dataviewer screenshot below). So the frequency noise can be estimated as rms of approximately 0.2Hz. |
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Mon Jan 31 07:03:59 2011, Aidan, Summary, Green Locking, DFD - noise spectra
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Quote:
I've had a go at trying to estimate the frequency noise of the digital frequency discriminator (DFD). I input a 234.5Hz |
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Mon Jan 31 07:41:23 2011, Aidan, Update, Green Locking, DFD - medm screen
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I added an MEDM screen for the DFD to the GREEN screen. It is displayed in the attached screen shot.
This screen is located in: /cvs/cds/rtcds/caltech/c1/medm/c1gfd/C1GFD_DFD.adl |
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Mon Jan 31 18:25:25 2011, Aidan, Update, Green Locking, DFD - results from the new filters (and running with AWG)
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Quote:
This is a plot showing the old filters and the new ones we added this morning. |
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Thu Feb 3 16:08:06 2011, Aidan, Update, Computer Scripts / Programs, RCG VCO frequency error
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Joe and I were looking at the RCG VCO algorithm to determine if we could adapt it to run at a faster rate (you can currently change its frequency at
1Hz). I noticed that the algorithm that is used to calculated the values of sine and cosine at time T1 is a truncated Taylor series which uses the
values of sine and cosine calculated at time T1 - Delta t . I was concerned that there would be an accumulating phase error so I tested the algorithm in |
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Tue Feb 8 10:23:02 2011, Aidan, Summary, Green Locking, Digital Frequency Discriminator - reference
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Here's the reference for the self-reference frequency detection idea. See Figure 2.
http://www.phys.hawaii.edu/~anita/new/papers/militaryHandbook/mixers.pdf |
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Tue Feb 8 13:26:11 2011, Aidan, Summary, Green Locking, Temperature dependence of phase change of green on reflection
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I did a quick back of the envelope calculation of the expected green phase change on reflection from the aLIGO ITM.
The phase change per nm, K1 = delta phi/delta Lambda, around 532nm is ~1.5 degrees/nm (from the LMA data) [this number is approximately 100x smaller
at 1064nm] |
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Thu Feb 10 14:52:36 2011, Aidan, HowTo, Computers, Adding filenames in MATLAB plots
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The following code is incredibly useful when creating MATLAB plots as it adds the filename of the script to the plot itself. I think it should
be used for all MATLAB plots that go on the elog.
For example, I have no idea where |
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Thu Feb 24 17:42:00 2011, Aidan, Update, Green Locking, 15% of end laser sideband power transmitted through cavity
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I did a quick calculation to determine the amount of sideband transmission through the FP cavity.
The modulation frequency of the end PDH is 216kHz. The FSR of the cavity is about 3.9MHz. So the sidebands pick up about 0.17 radians extra phase
on one round trip in the cavity compared to the carrier. |
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Sun Feb 27 09:43:59 2011, Aidan, Update, Green Locking, sidebands on beatnote
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Can we set up a fiber-PD on the end table to look at the beat between the "end laser IR beam" and the "PSL IR beam fiber-transmitted end
beam"?
We should see the same thing on that PD that we see on the green PD (plus any fiber noise and I'm not really sure how much that'll be off the top |
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Tue Mar 1 08:42:18 2011, Aidan, Update, elog, Restarted the elog this morning
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| The elog was dead this morning. I reanimated it. It is now undead. |
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Wed Mar 2 17:19:58 2011, Aidan, Configuration, Green Locking, Moved PDH PD on end table
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As previously noted, there are multiple beams coming back from the ETM surface onto the PDH PD on the end table. They are spread out in a vertical pattern.
All the spots swing together (as the ETM moves?).
I moved the PDH Green PD on the end table so that it was further away from the Faraday and I added an iris in between the Faraday and the PD. Now |
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Wed Mar 2 18:08:43 2011, Aidan, Update, Green Locking, Ghost beams on green
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Kiwamu and I noticed that there is a ghost beam on the green beam going into the ETM. What we see is some interference fringes on the edge of the transmission
of the green beam through the dichroic beam splitter (DCBS). If we look at the reflection from the dichroic beam splitter these are much more pronounced.
The spacing of the fringes (about 2 per 10mm) indicates an angle between the fields of around 0.1 mrad. |
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Wed Mar 23 08:50:36 2011, Aidan, Update, Green Locking, servo handig off
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Nicely done!
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Wed Mar 23 19:16:17 2011, Aidan, Summary, Green Locking, Y-END green equipment is all available
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With the exception of a 2" mirror mount, I've confirmed that we have everything for the Y-end green production and mode-matching.
We need to calculate a mode-matching solution for the Lightwave laser so that it gives the correct beam size in the doubling crystal.
Additionally, Rana has suggested that we change the pedestals from the normal 1" |
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Fri Mar 25 08:58:38 2011, Aidan, Update, Treasure, Cleared stuff off SP table
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I tidied up some of the stuff that was on the SP table. The ISS box that has been sitting on there for months is now underneath the X-arm on top of the
spare Marconi which is stored there.
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Wed Mar 30 16:32:29 2011, Aidan, Configuration, Computer Scripts / Programs, Added a sitemap alias
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I added an alias to the sitemap MEDM screen in /cvs/cds/caltech/target/cshrc.40m
Now you can enjoy launching sitemap from a terminal.
alias sitemap 'medm -x /cvs/cds/rtcds/caltech/c1/medm/sitemap.adl' |
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Thu Mar 31 20:37:10 2011, Aidan, Summary, Green Locking, RF amplitude source
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I gutted one of the $2 red laser pointers to build a laser source whose amplitude we could modulate at RF frequencies. Basically, I cut off the
bulk of the housing from the pointer and soldered a BNC connection into the two terminals that the 2x 1.5V batteries were connected to. When I applied
3V across this BNC connector the diode still worked. So far so good. |
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Thu Mar 31 20:46:11 2011, Aidan, Summary, Green Locking, Green beat note PD DC response
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I measured the DC response of the Green PD
Power into PD at DC (green laser pointer) = 285 uW |
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Wed Apr 6 19:36:32 2011, Aidan, Summary, Green Locking, (In)sanity check of Green PD - some inconsistencies
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I moved the Hartmut Green PD to the Jenne laser bench to try to determine if the response at RF was reasonable or somehow very much smaller than it should
be. It was set up as shown in the attached diagram. The first pass at this was by comparing the ratio of the RF photocurrent of the green PD to the RF
photocurrent of the New Focus 1611 InGaAs PD. That ratio (at a sufficiently low frequency) should be the same as the ratio the DC photocurrents of the |
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Thu Apr 7 16:09:17 2011, Aidan, Summary, Green Locking, (In)sanity check of Green PD - some inconsistencies
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I think I had underestimated the responsivity of the Silicon PD at 1064nm. The previous value was based on a rough search online for the responsivity
of Silicon (I couldn't find the product number of the actual PD we are using). For instance, the PDA100A Si detector from Thorlabs has a
responsivity of 0.35-0.4A/W at 1064nm. |
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Thu Apr 7 21:58:57 2011, Aidan, Summary, Green Locking, Beat note amplitude
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Having convinced myself that the green Hartmut PD is giving an acceptable response at RF frequencies I decided to double-check the beatnote at IR (fiber
transmission from the X-end beating with the PSL). This took a while because I had to realign the beam into the fiber at the X-end (I had a PD monitoring
the output from the fiber on the PSL table and 40m of BNC cable giving me the signal from it at the X-end). |
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Wed Apr 27 20:14:16 2011, Aidan, Summary, elog, Restarted with script ...
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Thu Apr 28 22:38:38 2011, Aidan, Update, Green Locking, Electronics schematic for vertex beatbox
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With some assistance from Kiwamu and Koji, I've drawn up the electronics design for the Beat Box for the vertex green locking. The Omingraffle
schematic is posted
on the Green Locking Wiki page. It's also attached below. Some final touches are necessary before we can Altium this up. |
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Wed May 18 18:33:46 2011, Aidan, Update, elog, restarted elog with script
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Tue Jan 3 18:40:08 2012, Aidan, Summary, Computer Scripts / Programs, medm directory clean-up
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I moved the following old and obsolete MEDM directories to an archive /cvs/cds/rtcds/caltech/c1/medm
c1vga
c1vgl
c1gpt
c1gpv
c1nio
c1spy
c1spx
None
of these models were present in /cvs/cds/rtcds/caltech/c1/target |
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Sun Oct 7 12:11:00 2012, Aidan, Update, Computers, Rebooted cymac0
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I rebooted cymac0 a couple of times. When I first got here it was just frozen. I rebooted it and then ran a model (x1ios). The machine froze the second
time I ran ./killx1ios. I've rebooted it again. |