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ID Date Author Type Category Subjectup
  10166   Wed Jul 9 17:34:11 2014 NichinUpdateElectronicsPDFR: Beam pointing adjustments and DC measurements

 [Nichin, Manasa]

AIM: Taking DC output readings with multimeter for each PD to create a database (required for transimpedance calculations), by taking off the table tops. Also, making sure each PD is illuminated properly.

What we did:

  • In rack 1Y1: Diode laser controller was set to 150.0 mA at all times. This gave powers in the neighbourhood of 1mW at the end of fibers illuminating all PDs. The laser outputs light of 1064nm wavelength. The laser was switched off in the end.
  • Checked the collimation of the fiber for each PD. In some cases they were not focused to give a sharp spot, so we had to unmount the fibers and fix it and mount them back. Manasa did it initially and I learnt how it was done properly. Eventually I got better and did it myself (under her supervision)
  • Set the mount alignment for maximum illumination of the PD.
  • Record the power falling on the laser and also the DC voltage output. Any light that did not come from my fiber was blocked when taking the readings and then unblocked. I also took care of offset voltage present when taking the DC readings.

Recorded measurements:

REFL11:   Pinc = 0.91 mW         VDC = 34.9 mV 

REFL33:   Pinc = 0.83 mW         VDC = 33.2 mV 

REFL55:   Pinc = 1.08 mW         VDC = 42.7 mV 

REFL165: Pinc = 0.79 mW         VDC = 115.3 mV

AS55:         Pinc = 0.78 mW         VDC = 31.3 mV

POX11:      Pinc = 0.83 mW         VDC = 34.7 mV

POP22**:   Pinc = 1.08 mW         VDC = 5.82 mV

POY11:      Not illuminated; there was no optical fiber mount. Although, there was a fiber near it with a cap on the end. It also looks like there is no space to put in a new mount near the PD. 

REF PD:    Pinc = 1.19 mW         VDC = 8.2 V     (REF PD = New focus 1611)

**Note: The current POP 22 PD does not have 2 different outputs for DC and RF signals. I unplugged the RF cable from the output, took readings with the multimeter and then plugged back the RF cable.

Further work:

I will calculate the responsivity for each PD and compare it to the expected values. 

  10183   Fri Jul 11 11:51:03 2014 NichinUpdateElectronicsPDFR: List of DC transimpedances

The following values are going to be entered in the param_[PDname].yml file for each PD. I am elogging them for future reference.

I got the values from combing schematics and old Elog entries. Please let me know if you believe the values are different.

  • AS55: 66.2 ohms
  • REFL11 : 66.2 ohms 
  • REFL33 : 50.2 ohms
  • REFL55: 50 ohms (Elog 4605)
  • REFL165: 50.2 ohms
  • POY11: 66.2 ohms
  • POX11: 50.2 ohms
  • REF (NF1611): 700 ohms
  • POP22: ?? (This is currently a Thorlab BBPD )
  2432   Sat Dec 19 14:33:25 2009 KojiConfigurationComputersPDFlib lite / gnuplot 4.2.6 on Rosalba/Allegra

In order to enable 'set terminal pdf' in gnuplot on Rosalba/Allegra, I installed PDFlib lite and gnuplot v4.2.6. to them.
(PDFlib lite is required to build the pdf-available version of gnuplot)


Installation of PDFlib lite:

  • Building has been done at rosalba
  • Download the latest distribution of PDFlib lite from http://www.pdflib.com/products/pdflib-7-family/pdflib-lite/
  • Expand the archive. Go into the expanded directory
          tar zxvf PDFlib-Lite-7.0.4p4.tar.gz
          cd ./PDFlib-Lite-7.0.4p4
  • configure & make
          ./configure
          make
  • install the files to the system / configure the dinamic linker
          sudo make install
          sudo ldconfig

Installation of gnuplot:

  • Building has been done at rosalba
  • Download the latest distribution of gnuplot form http://www.gnuplot.info/
  • Expand the archive. Go into the expanded directory
          tar zxvf gnuplot-4.2.6.tar.gz
          cd ./gnuplot-4.2.6.tar.gz
  • configure & make
          ./configure --prefix=/cvs/cds/caltech/apps/linux/gnuplot
          make
          make install
  • Create symbolic links of the executable at
          /cvs/cds/caltech/apps/linux/bin
          /cvs/cds/caltech/apps/linux64/bin
  • Note: Although the original (non-PDF) gnuplot is still at
          /usr/bin/gnuplot
    new one is active because of the path setting
          rosalba:linux>which gnuplot
          /cvs/cds/caltech/apps/linux64/bin/gnuplot

 

  11498   Wed Aug 12 14:35:46 2015 ericqUpdateComputer Scripts / ProgramsPDFs in ELOG

I've tweaked the ELOG code to allow uploading of PDFs by drag-and-drop into the main editor window. Once again we can bask in the glory of 

(You may have to clear your browser's cache to load the new javascript)

Attachment 1: smooth.pdf
smooth.pdf
  5808   Fri Nov 4 13:13:25 2011 ZachUpdateGreen LockingPDH box #17 modified, too

I also modified the Y-Arm PDH box itself slightly. Previously, there was a flying 10k resistor from the SWEEP input to TP2. I don't see the point of this, so I moved it from TP2 across R19 (to the same point where it is on the gyro PDH boxes) to allow for excitation signals to be injected with the loop closed (i.e., with the SWEEP switch off). This is useful for OLTF measurements.

  15218   Fri Feb 21 10:59:08 2020 shrutiUpdateALSPDH error signals?
Here are a few PDH error signals measured without changing the servo gain or phase from that optimized for 231.25 kHz. This was done by keeping the X arm cavity and laser unlocked but keeping the shutter for green open; so I did not force a frequency sweep but saw the unhindered motion of cavity wrt the laser using the PDH servo error monitor channel from the box (not sure if this is the best way to do it?).
 
Koji mentioned that there is a low pass filter with a cutoff frequency probably lower than 700 kHz which at the moment would hinder the efficacy of the locking at higher frequencies. The transfer function on the wiki suggests the same, although we are yet to investigate the circuit.
 
I measured the maximum range in the linear region of the signal, and here are the results:
  • Attachment 1: 231.25 kHz (current PDH sideband mod freq): 1.7 V
  • Attachment 2: 225.642 kHz: 1.2 V
  • Attachment 3: 100 kHz: 900 mV
  • Attachment 4: 763.673 kHz: 220 mV
Right now we have only inverted the phase to try locking at different frequencies (no finer adjustments were performed so elog 15216 cannot be an accurate representation of the true performance)
 
Ideas from the 40m meeting for adjusting the phase:
  1. Delay line for adding extra phase (would require over 40m of cable for 90 deg phase shift)
  2. Using two function generators for generating the sideband, clocked to each other, so that one can be sent to the PZT and the other to the mixer for demodulation.
  3. Use a different LPF (does not seem very useful for investigating multiple possible frequencies)

Once we adjust the phase we may be able to increase the servo gain for optimal locking. Unless it may be a good idea to increase the gain without optimizing the phase?

Attachment 1: IMG_0082.jpg
IMG_0082.jpg
Attachment 2: IMG_0083.jpg
IMG_0083.jpg
Attachment 3: IMG_0084.jpg
IMG_0084.jpg
Attachment 4: IMG_0085.jpg
IMG_0085.jpg
  15219   Fri Feb 21 13:02:53 2020 KojiUpdateALSPDH error signals?

Check out this elog: ELOG 4354

If this summing box is still used as is, it is probably giving the demod phase adjustment.

  5179   Wed Aug 10 20:40:17 2011 JennyUpdatePSLPDH locking: got an error signal

I ended up choosing a different dither frequency for driving the NPRO PZT: 230 kHz, because the phase modulation response in that region is higher according to other data taken on an NPRO laser (see this entry). At 230 there is a dip in the AM response of the PZT.

I am driving the PZT at 230 kHz and 13 dBm using a function generator. I am then monitoring the RF output of a PD that is detecting light reflected off the cavity. (The dither frequency was below the RF cutoff frequency of the PD, but it was appearing in the "DC output", so I am actually taking the "DC output" of the PD, which has my RF signal in it, blocking the real DC part of it with a DC block, and then mixing the signal with the 230kHz sine wave being sent to the PZT.

I am monitoring the mixer output on an oscilloscope, as well as the transmission through the cavity. I am sweeping the laser temperature using a lock in as a function generator sending out a sine wave at 0.2 V and 5 mHz. When there is a peak in the transmission, the error signal coming from the mixer passes through zero.

My next step is to find or build a low pass filter with a pole somewhere less than 100 kHz to cut out the unwanted higher frequency signal so that I have a demodulated error signal that I can use to lock the laser to the cavity.

 

  11959   Fri Jan 29 08:18:13 2016 SteveUpdatePEMPEM

 

Quote:

Air condition maintenance is happening. It should be done by 10am

 

Attachment 1: PEM.png
PEM.png
  17   Fri Oct 26 09:10:17 2007 steveRoutinePEMPEM &PSL trend
The fires are out, lab particle counts are up.
Psl HEPAs are at 100% and mobel HEPAs are just turned on
20 days plot and 5 hrs plot below
Attachment 1: counts&psl.jpg
counts&psl.jpg
Attachment 2: 5dcounts.jpg
5dcounts.jpg
  7230   Sun Aug 19 19:02:47 2012 DenUpdateCDSPEM -> RFM -> OAF

Data from PEM now goes directly to OAF without using RFM. Transmission RFM -> OAF errors are gone as RFM has to read 30 channels less now.

Again kernel "protection error" occured as before with PEM model so OAF model could not start. I changed optimization flag to -02, this fixed the problem.

  4825   Wed Jun 15 16:37:56 2011 JenneUpdatePEMPEM AA Board has been diagnosed and fixed

[Jenne, Steve]

After talking with Steve, I had a look at the PEM's AA board, to see what the problem was. 

Steve said the symptom he had noticed was that the Kepco power supplies which supply the +\- 5 V to the AA board were railing at their current limits as soon as he plugged the board in.  Also, he smelled smoke. 

I started with the power supplies, and saw that the 2 individual supplies each had a dV=5V, and that the one labeled +5V had the red wire on the + output of the power supply, and the black wire on the - output.  The supply labeled -5V had the orange wire on the -output of the power suppy, and the black wire on the + output.  Normally, you would expect that the 2 black wires are also connected together, and perhaps also to ground.  But at least together, so that they share a common voltage, and you get +\- 5V.  However these 2 power supplies are not connected together at all. 

This implies that the connection must be made on the AA boards, which I found to be true.  It seems a little weird to me to have that common ground set at the board, and not at the power supplies, but whatever.  That's how it is.

The problem I found is this:  The keyed connectors were made backward, so that if you put them in "correctly" according to the key, you end up shorting the +5V to the -5V, and the 2 black wires are not connected together.  You have to put the keyed connectors in *backwards* in order to get the correct wires to the correct pins on the board.  See the attached pdf figure.

Since these are internal board connections, and they should not ever be changed now that Steve has put in the adapter thing for the SCSI cable, I'm just leaving them as-is.  Steve is going to write in huge letters in sharpie on the board how they're meant to be connected, although since this problem wasn't caught for many many years, maybe it won't ever be an issue again.  Also, we're going to move over to the new Cymac system soon-ish.  However, whomever made the power cable connector from the box to the board for this AA board was lazy and dumb.

After putting the connectors on the way they needed to be, Steve and I powered up the board, hooked up the SCSI cable in the back, and put a constant voltage (~1.3VDC battery) across various different channels, and confirmed that we could see this voltage offset in Dataviewer. (Kiwamu is hoarding both of our SRS function generators, so we couldn't put in a low freq sine wave like I normally would). Everything looked okie dokie, so I'll check the regular PEM channels tomorrow.

Steve will re-install the board in the rack in the morning.

Attachment 1: 1X7_AAboard_connector_fix.pdf
1X7_AAboard_connector_fix.pdf
  4826   Thu Jun 16 00:39:08 2011 KojiUpdatePEMPEM AA Board has been diagnosed and fixed

As seen in the photo, the board has a strange bulge on the board,
and
the color of the internal line around the bulge got darkened.

I don't trust this board any more. We should switch to the alternative one.

Quote:

Steve will re-install the board in the rack in the morning.

 

  13788   Wed Apr 25 17:44:39 2018 ArnoldUpdatePEMPEM Anti-Alias wiring

Related image

 

  13790   Thu Apr 26 09:35:49 2018 KevinUpdatePEMPEM Anti-Alias wiring

I wired all 32 channels going to the AA board directly to the ADC as described in the previous log. However, instead of using the old AA board and bypassing the whole circuit, I just used a breakout board as is shown in the first attachment. I put the board back in the rack and reconnected all of the cables.

The seismic BLRMs appear to be working again. A PSD of the BS seismometers is shown in attachment 2. Tomorrow I'll look at how much the ADC alone is suppressing the common mode 60 Hz noise on each of the channels.

Steve: 5 of ADC DAC In Line Test Boards [ D060124 ] ordered. They should be here within 10 days.

Attachment 1: board.jpg
board.jpg
Attachment 2: SeismometerPSD.pdf
SeismometerPSD.pdf
  14949   Tue Oct 8 08:08:18 2019 gautamUpdatePEMPEM BLRMS anomaly

Yesterday, Koji and I noticed (from the wall StripTool traces) that the vertex seismometer RMS between 0.1-0.3 Hz in the X-direction increased abruptly around 6pm PDT. This morning, when I came in, I noticed that the level had settled back to the normal level. Trending the BLRMS channels over the last 24 hours, I  see that the 0.3-1 Hz band in the Z direction shows some anomalous behaviour almost in the exact same time-band. Hard to believe that any physical noise was so well aligned to the seismometer axes, I'm inclined to think this is indicative of some electronics issues with the Trillium interface unit, which has been known to be flaky in the past.

Attachment 1: PEManomaly.png
PEManomaly.png
  14989   Wed Oct 23 11:49:21 2019 gautamUpdatePEMPEM BLRMS anomaly

I looked into the seismometer situation a bit more today. Here is the story so far - I think more investigation is required:

  1. There is an abrupt change in the PEM BLRMS channels around 6pm PDT every day. This has been consistently seen for the last two weeks.
  2. The seismometer spectra look normal - see Attachment #1. The reference traces are from some months ago. There is elevated activity between 0.1-0.3 Hz, but this is seen in all the seismometers in all 3 DoFs.
  3. I looked at the minute trend of the raw seismometer outputs (before being BLRMSed) for the last 200 days and don't see any abrupt change in characteristics (the data gap is due to the issue in this thread).
  4. All the correct BLRMS filters seem to be engaged in the respective filter banks.

Attachment #2 has some spectrograms (they are rather large files). They suggest that the increase in noise in the 0.1-0.3 Hz band in the BS seismometer X channel is real - but there isn't a corresponding increase in the other two seismometers, so the problem could still be electronics related.

Quote:

Yesterday, Koji and I noticed (from the wall StripTool traces) that the vertex seismometer RMS between 0.1-0.3 Hz in the X-direction increased abruptly around 6pm PDT. This morning, when I came in, I noticed that the level had settled back to the normal level. Trending the BLRMS channels over the last 24 hours, I  see that the 0.3-1 Hz band in the Z direction shows some anomalous behaviour almost in the exact same time-band. Hard to believe that any physical noise was so well aligned to the seismometer axes, I'm inclined to think this is indicative of some electronics issues with the Trillium interface unit, which has been known to be flaky in the past.

Attachment 1: seisAll_20191021.pdf
seisAll_20191021.pdf
Attachment 2: specGrams.zip
  3977   Tue Nov 23 14:52:28 2010 JenneUpdatePEMPEM Model Started

Joe showed me what was what with adding DAQ channels, and I have begun building a simulink model to acquire the PEM channels. 

My models is in: /cvs/cds/rtcds/caltech/c1/core/advLigoRTS/src/epics/simLink/c1pem.mdl

Next on the to do list in this category: test which input connector goes with which channel (hopefully it's linear, exactly as one would think), and give the channels appropriate names. 

  11265   Fri May 1 13:22:08 2015 ericqUpdateDAQPEM Slow channels added to saved frames

Rana asked me to include add slow outputs (OUT16) of the seismometer BLRMS channels to the frames. 

All of the PEM slow channels are already set up in c1/chans/daq/C1EDCU_PEM.ini, but up to this point, daqd had no knowledge of this file, since it wasn't included in c1/target/fb/master, which defines all the places to look for files describing channels to be written to disk. This file already includes lines for C1EDCU_LSC.ini and such, which from old elogs, looks like was set up by hand for subsystems we care about. 

Hence, since we now care about slow trends for the PEM subsystem, I have added a line to the daqd master file to tell it to save the PEM slow channels. This looks to have increased the size of the individual 16 second frame files from 57MB to 59MB, which isn't so bad.

  11266   Fri May 1 16:42:42 2015 ranaUpdateDAQPEM Slow channels added to saved frames

Still processing, but I think it should work fine once we have a day of data. Until then, here's the summary pages so far, including Vac channels:

http://www.ligo.caltech.edu/~misi/summary/day/20150501/pem/

  1987   Tue Sep 15 15:46:05 2009 steveUpdatePEMPEM and VAC

FSS_RMTEMP is moving up and  daily fluctuations  are  less . 120 and 16 days plots are below.

Attachment 1: 120dpem.jpg
120dpem.jpg
Attachment 2: 16dpem.jpg
16dpem.jpg
  1615   Thu May 21 12:58:32 2009 robConfigurationALARMPEM count-half disabled

I've disabled the alarm for PEM_count_half, using the mask in the 40m.alhConfig file.  We can't do anything about it, and it's just annoying.

  6935   Sat Jul 7 16:34:41 2012 MashaUpdatePEMPEM no longer freaking out (as much).

Hi everybody,

Sorry for flooding the ELOG about the PEM channels. Today I

- Changed all of the GUR1 and GUR2 filters to elliptic, and lowered the orders of their low-pass filters.

- Lowered the order of the low-pass filters on the STS channels

- Changed the parameters in seismic.strip, which I saved as MashaTemplate2.

 

Attached is the most recent status of the channels as seen with StripTools:

Attachment 1: Masha.png
Masha.png
  6936   Sat Jul 7 17:28:11 2012 MashaUpdatePEMPEM no longer freaking out (as much).

Quote:

Hi everybody,

Sorry for flooding the ELOG about the PEM channels. Today I

- Changed all of the GUR1 and GUR2 filters to elliptic, and lowered the orders of their low-pass filters.

- Lowered the order of the low-pass filters on the STS channels

- Changed the parameters in seismic.strip, which I saved as MashaTemplate2.

 

Attached is the most recent status of the channels as seen with StripTools:

I'm not currently sure how to apply my template to seismic.strip shown on the wall (I saved it as seismic.strip on Pianossa and copied the old file to seismic.stripOld). I understand the job is being run on Megatron. I'll play around with this later tomorrow. (In other words, the display currently on the wall, while it does not have the Nan spikes like yesterday and this morning does not currently display the template I made).

  303   Fri Feb 8 17:55:53 2008 joshConfigurationPEMPEM-AS_MIC now in PSL enclosure
I have moved the microphone to the PSL enclosure, hanging near the south (Y) side from a support rod for the overhanging storage area so that it's reasonably close to the PMC. I've fastened it in many places using cable ties to make sure that it won't fall.

Alberto helped me solder together a female BNC-female 3.5 mm stereo adapter so that I can use the DAQ to output through BNC to PC speakers. My plan is do sweep sine output through PC speakers to find the transfer function of sound from outside the enclosure to inside the enclosure and by moving the microphone more centrally over the PSL table, check if there are any strong resonances. Hopefully I can use this technique at other places around the interferometer or measure the effect of installing acoustic foam.
  298   Tue Feb 5 17:39:05 2008 jweinerConfigurationPEMPEM-AS_MIC taken down from AS table, will put in PSL enclosure soon
I took down the microphone that Andrey hung above the AS table his first week in lab. I want to hang the microphone above the PMC to check the effect of acoustic noise on the PMC. The cables were a little more tangled than I thought so I've only taken the microphone down and haven't hung it back up yet, but on Thursday I'll have enough time to carefully put it up inside the PSL and see what I can find out about acoustic noise inside the PSL. I think the microphone should be sensitive enough for the frequencies we're interested in, and I'll hopefully find out if it's sufficient once I put it up in the PSL. The microphone cable and microphone are on top of the PSL for now.
  3449   Fri Aug 20 16:17:35 2010 steveUpdatePEMPEM-count channels are not working

C1: PEM-count channels are dead since August 12, 2010

  6468   Thu Mar 29 20:13:21 2012 jamieConfigurationPEMPEM_SLOW (i.e. seismic RMS) channels added to fb master

I've added the PEM_SLOW.ini file to the fb master file, which should give us the slow seismic RMS channels when the framebuilder is restarted. Example channels:

[C1:PEM-RMS_ACC6_1_3]
[C1:PEM-RMS_GUR2Y_0p3_1]
[C1:PEM-RMS_STS1X_3_10]
etc.

I also updated the path to the other _SLOW.ini files.

I DID NOT RESTART FB.

I will do it first thing in the am tomorrow, when Kiwamu is not busy getting real work done.

Here's is a the diff for /opt/rtcds/caltech/c1/target/fb/master:h

controls@pianosa:/opt/rtcds/caltech/c1/target/fb 1$ diff -u master~ master
--- master~	2011-09-15 17:32:24.000000000 -0700
+++ master	2012-03-29 19:51:52.000000000 -0700
@@ -7,11 +7,12 @@
 /opt/rtcds/caltech/c1/chans/daq/C0EDCU.ini
 /opt/rtcds/caltech/c1/chans/daq/C1MCS.ini
 /opt/rtcds/caltech/c1/target/gds/param/tpchn_c1mcs.par
-/cvs/cds/rtcds/caltech/c1/chans/daq/SUS_SLOW.ini
-/cvs/cds/rtcds/caltech/c1/chans/daq/MCS_SLOW.ini
-/cvs/cds/rtcds/caltech/c1/chans/daq/RMS_SLOW.ini
-/cvs/cds/rtcds/caltech/c1/chans/daq/IOP_SLOW.ini
-/cvs/cds/rtcds/caltech/c1/chans/daq/IOO_SLOW.ini
+/opt/rtcds/caltech/c1/chans/daq/SUS_SLOW.ini
+/opt/rtcds/caltech/c1/chans/daq/MCS_SLOW.ini
+/opt/rtcds/caltech/c1/chans/daq/RMS_SLOW.ini
+/opt/rtcds/caltech/c1/chans/daq/IOP_SLOW.ini
+/opt/rtcds/caltech/c1/chans/daq/IOO_SLOW.ini
+/opt/rtcds/caltech/c1/chans/daq/PEM_SLOW.ini
 /opt/rtcds/caltech/c1/target/gds/param/tpchn_c1rfm.par
 /opt/rtcds/caltech/c1/chans/daq/C1RFM.ini
 /opt/rtcds/caltech/c1/chans/daq/C1IOO.ini
controls@pianosa:/opt/rtcds/caltech/c1/target/fb 1$

 

  6484   Wed Apr 4 13:25:29 2012 jamieConfigurationPEMPEM_SLOW (i.e. seismic RMS) channels aquiring

Quote:

I've added the PEM_SLOW.ini file to the fb master file, which should give us the slow seismic RMS channels when the framebuilder is restarted. Example channels:

[C1:PEM-RMS_ACC6_1_3]
[C1:PEM-RMS_GUR2Y_0p3_1]
[C1:PEM-RMS_STS1X_3_10]
etc.

 The framebuilder seems to have been restarted, or restarted on it's own, so these channels are now being acquired.

Below is a minute trend of a smattering of the available RMS channels over the last five days.

2012-04-04-132346_1182x914_scrot.png

  10347   Thu Aug 7 14:50:43 2014 HarryUpdateGeneralPER Measurement

 Purpose

I wanted to do a more robust measurement of PER of PM fibers for FOL, so I thought up this scheme.

Methods

I put together a setup as depicted below in order to take measurements of PER.

PERFinalSetup.png

The first thing to do was to calibrate the whole setup. In order to do so, I first used the quarter and half wave plates closest to the NPRO to eliminate as much ellipticity from the output beam as possible, and then rotate the newly linearized light to be in alignment with the transmittance of the first polarizing beam splitter (P-Polarization).

I then aligned the fiber's fast axis with the P-Polarization on both the input and output sides. This was important so that no virtual ellipticity would be measured in the final measurement of PER.

I then mode matched and fiber coupled the first PBS output into the fibers, to about 30 mW (~60% coupling).

Photodiode Calibration

I wanted to measure both intensity of P and S simultaneously, so as to minimize the random little time-varying changes that would affect the measurements, so I used a powermeter and a PD, calibrated with the aformentioned powermeter.

In order to be able to compare the photodiode (PDA520) output to the powermeter (Orion) output, I fixed them each in their positions, and varied the laser power to produce the type of linear relationship we expect to see between PD Voltage and Optical Power. In this case, the conversion was P = V*2.719.

PDCalibration.png

PER Measurement

As opposed to the first method, which took only one datum, this method records P and S simultaneously, at different points through rotation of a linearly polarized beam.

Using the second HWP, I rotated the linearly polarized beam before it entered the fiber, at each point, recording the outputs of the PD and the Powermeter.

These data were then converted to be the same units, and fit to a sine wave.

Polarization_Intensity_Variation.png

As you can see, the intensities vary nearly identically, at a half wavelength phase difference, which is what one expects in this case. The PER of each polarization can be calculated by dividing the maximum value of one by the minimum of the other, and vice versa. The fact that these oscillate as we expect shows that the beam is relatively well linearized, and essentially that everything is working as it is assumed to be.

By looking at these fits, however, it is visible that they do not overlap with the actual extrema of the data. So, in order to produce more realistic values of extrema, those particular regions were fit to second order polynomials.

Extrema.png

The values of these extrema yield the following measurements:

(SMin / PMax) = 0.007 +/- .004  --->  -21.54 +/- 2.48 dB

(PMin / SMax) = 0.022 +/- .009  --->  -16.58 +/- 1.78 dB

Conclusion

The problem I find with these measurements is that they're hard to reproduce.

Plus they seem high, since non-PM fibers advertise extinction ratios around -30 dB., plus I measured it at roughly -24 dB the first time I tried.

Moving Forward

 

The next thing to do in terms of fiber characterization is to measure the frequency noise they introduce.

With respect to FOL, I just need some time to work on the PSL table, and at the Y end to couple the dumped SHG light, and then we can start using 1064nm beat notes to test//implement the feedback control system.

Attachment 5: PEReport.zip
  8669   Tue Jun 4 10:44:13 2013 SteveUpdateendtable upgradePI pzt holders are ready

The PI pzt holders are back from the shop. They are numbered 1, 2 & 3 and machined to match.

Tapered black delrin opener is to gauge the gap if it is too small to fit pzt. This is to prevent holder to be opened too much.

Attachment 1: PIpztholders.jpg
PIpztholders.jpg
  12964   Wed May 3 16:02:36 2017 SteveUpdateGeneralPI pzt inventory check

One is broken, two are ready to steer green and 3 available in un known condition

 

Attachment 1: IMG_3678.JPG
IMG_3678.JPG
Attachment 2: PIpztETMYgreen.jpg
PIpztETMYgreen.jpg
  12967   Wed May 3 16:47:45 2017 KojiUpdateGeneralPI pzt inventory check

I also have a functional one on my desk, which has one of the wires repaired.

Quote:

One is broken, two are ready to steer green and 3 available in un known condition

 

 

  13793   Thu Apr 26 19:46:26 2018 ranaUpdatePEMPID Quixote

Increased the Integral gain (from -1 to -4) on the EX temperature controller. This didn't work a few weeks ago, but now with the added P gain, it seems stable. Daily temperature swings are now ~3x smaller.

Notes for Kira on what we need to do tomorrow (Friday):

  1. add the MEDM screen EPICS values to the DAQ so that we can plot those trends DONE
  2. add the out-of-loop sensor to the EX can
  3. reboot the AUX-EX so we can pick up the new channels and the fixed spelling of the old channels DONE
  4. Re-install EX seismometer and hook up seismometer channels to PEM DAQ so we can start testing its performance.

For those who are flabbergasted by the way I calibrated the TEMP_MON channel from volts to deg C, here's how:

XMgrace->Data->Transformations->Geometric Transforms...

use the 'scale' and 'translate' fields to change the slope and offset for calibration in the obvious ways

Attachment 1: dv.pdf
dv.pdf
  13803   Tue May 1 11:15:19 2018 KiraUpdatePEMPID Quixote

I added an out of loop sensor to the can by placing the lab temperature sensor inside the can. I'm not sure which channel is logging this temperature though. I also noticed that the StripTool still had the old misspelled name for the temperature readout so I fixed that as well.

I've attached a picture of the setup.

Quote:

Increased the Integral gain (from -1 to -4) on the EX temperature controller. This didn't work a few weeks ago, but now with the added P gain, it seems stable. Daily temperature swings are now ~3x smaller.

Notes for Kira on what we need to do tomorrow (Friday):

  1. add the MEDM screen EPICS values to the DAQ so that we can plot those trends DONE
  2. add the out-of-loop sensor to the EX can
  3. reboot the AUX-EX so we can pick up the new channels and the fixed spelling of the old channels DONE
  4. Re-install EX seismometer and hook up seismometer channels to PEM DAQ so we can start testing its performance.

For those who are flabbergasted by the way I calibrated the TEMP_MON channel from volts to deg C, here's how:

XMgrace->Data->Transformations->Geometric Transforms...

use the 'scale' and 'translate' fields to change the slope and offset for calibration in the obvious ways

 

Attachment 1: IMG_20180501_154826.jpg
IMG_20180501_154826.jpg
  3930   Tue Nov 16 09:02:54 2010 AidanUpdateGreen LockingPID loop - calibration of SR620 output

 [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 earlier. That is, the output range of the SR620 corresponds to around 100MHz and is digitized at 10-bit resolution, and ...

100MHz/(10^2) ~= 0.098MHz. [Sad Face]

Calibration:

We set the EPICS range to [-100, 100] (corresponding to [-5V, 5V]), connected a Marconi to the Freq Counter, input a variety of different frequencies and measured the counts on the EPICS channel.

The linear fit to the calibration data was F = 2.006*EPICScount - 0.2942. From this we worked out the maximum and the minimum for the range settings that give the channel in MHz: EGUF = -200.8942 and EGUL = 200.3058. The previous range was [-410, 410]

 

Calibration of SR620 analogue output
Input Frequency (MHz) Measured EPICS Value
10  5.191
20  9.98
30 15.21
40 20.00
50 25.18
60 29.99
70 35.18
71 35.565
72 35.9894
73 36.3861
74 37.17
75 37.576
76 37.9669
77 38.3575
78 39.166
79 39.5691
80 39.978
   

 

  10334   Tue Aug 5 19:20:05 2014 AkhilUpdateGeneralPID loop Design for beat note stabilization

 Today I and EricQ went inside the lab and set up the cables running from the a DAC channel into  PZT input so that we can use the PID controller to tune in the PZT offset to maintain the beat note within a detectable range (This is plan B as the main plan of actuating on the laser temperature can be achieved only after the fiber setup with the PSL is ready). I obtained all the poles and zeroes of plant and started designing a PID loop to test it with the existing system.

I will put in my PID values into the already existing PERL controller code (that is used for controller design in the 40m) and run tests with the PID loop while actuating on the PZT offset. 

 

  10353   Fri Aug 8 14:42:41 2014 AkhilUpdateGeneralPID loop Design for beat note stabilization

 The attached in a zip file are the Simulink feedback loop models for the FOL for both X and Y ends. The controller PID values are estimated by setting a temperature count reference point to 5344, which corresponds to 100 MHz frequency.  The plant transfer function is as calculated in my previous elogs.

 We were not  able to test the PID loop , with the green laser by PZT actuation because of the misalignment of the arms and non-existence of the beat note since last few days. However, we have a complete idea of the design and PID parameters that will be used for the FOL with infrared laser. So we decided that it would be better to test the loop by temperature actuation after the fiber optics is installed and the coupling of infrared laser into the fiber is complete. As of now, we have planned to place the FOL box inside so that it can be used to obtain the green laser beat note on the StripTool graphs. 

Attachment 1: PID.zip
  3932   Tue Nov 16 12:47:30 2010 AidanUpdateGreen LockingPID loop but no green

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 ()

In c1auxey/ETMYaux.db I added a couple of channels. These are all displayed on the MEDM screen. I added them to autoBurt.req as well.

  • C1:LSC-EX_GRNLSR_TEMP_NOM: the zero-volt setpoint temperature of the end laser (as set on the front panel of the Mephisto controller). This must be entered manually in EPICS as there is no way to read it remotely. [Sad Face]
  • C1:LSC-EX_GRNLSR_TEMP_CALC: the sum of the zero-volt set point temperature and the offset temperature set by the input voltage from C1:LSC-EX_GREENLASER_TEMP

I rebooted c1auxey to get these to work.

Once we get the green beat back again, the PID loop should servo on the end laser temperature to drive the Beat Frequency to the Frequency Setpoint, C1:LSC-EX_GRN_PID_SETPT, which can be set by the pink slider.

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 in the scripts directory even if they are in development!!! And all scripts should use 'env' rather than have absolute pathnames for the location of perl, csh, tcsh, python, etc.

Attachment 1: Screenshot-C1LSC_EX_GRN_SLOW.adl.png
Screenshot-C1LSC_EX_GRN_SLOW.adl.png
  3934   Tue Nov 16 16:00:26 2010 AidanUpdateGreen LockingPID loop but no green

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 in the scripts directory even if they are in development!!! And all scripts should use 'env' rather than have absolute pathnames for the location of perl, csh, tcsh, python, etc.

 That's not unreasonable. But if we try 

 grep "perl" /cvs/cds/rtcds/caltech/c1/scripts/*/* 

you can see that we've got a fair amount of housekeeping to attend to. We might want to think about tidying up the scripts directory as part of the cds upgrade.

 

 

 

 

  13887   Thu May 24 15:18:12 2018 KiraUpdatePEMPID loop restarted

Rana said that it wasn't necessary to gather more data on the temperature fluctuations so I have reconnected the heater circuit and restarted the PID loop with the can on the seismometer.

  11189   Wed Apr 1 11:42:30 2015 manasaUpdateComputer Scripts / ProgramsPID script in python

Since none of us here are experts in pearl, I have put together a python script for a simple PID controller. This can be imported into any main scripts that will run the actual PID loop. The script, PID.py, exists in /scripts/general/

  3908   Fri Nov 12 12:06:11 2010 AidanConfigurationGreen LockingPID script working - now it needs to be tuned

 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 in a new database file slow_grnx_pid.db
  • This database was added to the list of those loaded by startup.cmd.  
  • The PID script, GRNXSlowServo, is just a modified version of FSSSlowServo.
  • The version I've been running is currently in /cvs/cds/caltech/users/abrooks/.
  • There's also an MEDM screen in this directoy, C1LSC_EX_GRN_SLOW.adl, there that shows the PID settings.

Right now the script only passes the initial sanities checks, that is:

  1. It runs.
  2. You can enable/disable it without any errors and it starts actuating.

The settings all need to be tuned up - e.g. maximum_increment, hard_stops, time_step, PID constants.

Additionally, the units in the whole thing are pretty useless - some of the channels are in VOLTS, others in WATTS. I'd like to change all these to be in Hz. 


EPICS channels added:

  • grecord(ao,"C1:LSC-EX_GRN_SLOWKD")
  • grecord(ao,"C1:LSC-EX_GRN_SLOWKP")
  • grecord(ao,"C1:LSC-EX_GRN_SLOWKI")
  • grecord(ao,"C1:LSC-EX_GRN_PID_SETPT")
  • grecord(ao,"C1:LSC-EX_GRN_TIMEOUT")
  • grecord(stringin,"C1:LSC-EX_GRN_SLOWVERSION")
  • grecord(bi,"C1:LSC-EX_GRN_SLOWLOOP")
  • grecord(bi,"C1:LSC-EX_GRN_DEBUG")
  • grecord(bi,"C1:LSC-EX_GRN_SLOWBEAT")
 

 

Attachment 1: Screen_shot_2010-11-12_at_12.05.01_PM.png
Screen_shot_2010-11-12_at_12.05.01_PM.png
  13718   Thu Mar 29 17:14:42 2018 KiraUpdatePEMPID test

[Kira, Gautam]

We closed the loop today and implemented the PID script. I have attached the StripTool graph for an integral value of 0.5 and proportional value of 20. We had some issues getting it to work properly and it would oscillate between some low values of the control voltage. The set point here was -3.20, which corresponds to about a 20 degree increase in temperature. The next step would be to find which values of Kp, Ki, and Kd would work in this case and low pass filter the signal from the temperature sensor, and also create an MEDM screen for easier PID control.

Attachment 1: PID_test.png
PID_test.png
  13722   Fri Mar 30 06:16:45 2018 ranaUpdatePEMPID test

Can't really figure out what this plot means. We need to see the sensor (in units of deg C) and the control signal (in heating power (W)). The plot should show a few step responses with the PID loop on, so that we can see the loop response time. Please zoom in on the axes so that we can see what's happening.

Quote:

[Kira, Gautam]

We closed the loop today and implemented the PID script. I have attached the StripTool graph for an integral value of 0.5 and proportional value of 20. We had some issues getting it to work properly and it would oscillate between some low values of the control voltage. The set point here was -3.20, which corresponds to about a 20 degree increase in temperature. The next step would be to find which values of Kp, Ki, and Kd would work in this case and low pass filter the signal from the temperature sensor, and also create an MEDM screen for easier PID control.

 

  13723   Fri Mar 30 16:10:46 2018 KiraUpdatePEMPID test

I created two new channels today, C1:PEM-SEIS_EX_TEMP_MON_CELCIUS, which turns the output voltage signal into degrees C, and C1:PEM-SEIS_EX_TEMP_CTRL_WATTS, which takes the input voltage from the DAC and turns it into a value of watts. I'm trying to stabilize the temperature at 35 degrees, but it's taking a lot longer than expected. Perhaps we'll need to use different values for P and I and decrease the noise in the sensor, since right now there's about a 10 degree variation between the highest and lowest values.

  13726   Wed Apr 4 16:23:10 2018 KiraUpdatePEMPID test

I did a step response for the loop from 35 degrees to 40 degrees. The PID is not properly tuned, so the signal oscillates. In the graph, the blue curve is the temperature of the can in celcius and the green curve is the heating power in watts. The x-axis is in minutes. Before, the signal was too noisy to do a proper step response, so I placed a 3.3 microF capacitor in parallel with the resistor in my temperature sensor circuit (I'll draw and attach this updated version). This created a 5 Hz low pass filter and the signal is now pretty clean.

-----

I also added in new Epics channels so that we could log the data using Data Viewer. The channels I added were C1:PEM-SEIS_EX_TEMP_MON_CELCIUS and C1:PEM-SEIS_EX_TEMP_CTRL_WATTS. I used 13023 as a guide on how to do this.

Update: the channels work and show data in Data Viewer

-----

Edit: I've attached a photo of the circuit with the capacitor indicated. It is in parallel with the resistor below it. I've attached an updated circuit diagram as well.

Attachment 1: step_response.png
step_response.png
Attachment 2: capacitor.jpg
capacitor.jpg
Attachment 3: IMG_20180412_120427.jpg
IMG_20180412_120427.jpg
  13618   Wed Feb 7 17:01:25 2018 gautamUpdatePEMPID test plan

[kira, gautam]

We did a survey of the lab today to figure out some of the logistics for the PID control test for the seismometer can. Kira will upload sketches/photos from our survey. Kira tells me we need

  • +/- 15V for the temperature sensors
  • +/- 20V, 5A for heater circuit (to be confirmed by Kira after looking at voltage regulator datasheet for dropout voltage)
  • 2 ADC channels for temperature sensing (one inside can and one outside)
  • 1 DAC channel for controlling MOSFET

There are no DAC channels available in the c1ioo rack. In fact, there is a misleading SCSI cable labelled "c1ioo DAC0" that comes into the rack 1X3 - tracing it back to its other end, it goes into the c1ioo expansion chassis - but there are no DAC cards in there, and so this cable is not actually transporting any signals!

So I recommend moving the whole setup to the X end (which is the can's real home anyways). We plan to set it up without the seismometer inside for a start, to make sure we don't accidentally fry it. We have sufficient ADC and DAC channels available there (see Attachments #1 and #2, we also checked hardware), and also Sorensens to power the heater circuit / temperature sensing circuit. Do we want to hook up the Heater part of this setup to the Sorensens, which also power everything else in the rack? Or do we want to use the old RefCav heater power supply instead, to keep this high-current draw path isolated from the rest of our electronics?

If this looks okay (after pics are uploaded), we will implement these changes (hardware + software) tomorrow.

-----

I have attached the sketch of the whole system (attachment 3) with all the connections and inputs that we will need. Attachment 4 is the rack with the ADC and DAC channels labeled. Attachment 5 is the space where we could set up the can and have the wires go over the top and to the rack.

Attachment 1: ADC_EX.png
ADC_EX.png
Attachment 2: DAC_EX.png
DAC_EX.png
Attachment 3: IMG_20180207_170628.jpg
IMG_20180207_170628.jpg
Attachment 4: dac_adc.jpg
dac_adc.jpg
Attachment 5: IMG_20180207_165833.jpg
IMG_20180207_165833.jpg
  13619   Wed Feb 7 19:14:19 2018 ranaUpdatePEMPID test plan
  1. The heater circuit should get its own dedicated supply.
  2. We do not want to ever use the old Ref Cav heater for anything. Its unreliable and noisy.
  3. Steve should update all the sticky labels on all the power supplies in the lab to indicate what voltage they should be set at. Even if the label is correct, the date should be updated.
  13624   Thu Feb 8 12:24:37 2018 KiraUpdatePEMPID test plan

Some points before we can set up the can:

  1. Cable length and type
    • For the DAC, we can use the LEMO outputs and change it to BNC, then have a long BNC cable running over the top of the lab and to the can 
    • ADC is also LEMO, which we can convert to BNC and have a cable run from that to the temperature sensors
    • Sorensens use plain cables, so we need to find ones that can take a few amps of current and have them be long enough to reach the can and temperature sensors
  2. Making sure that there is enough space for the can
    • Can measures about 59 cm in diameter, which does fit in the space we chose
  3. Finding Sorensens that work and can provide +/-24V to the heater circuit (since Rana said we want the heater to have its own supply)
    • Found two Sorensens, but only one works for our purpose (update: found a second one that works)
    • The other can only proviide up to 20V before shorting and has been labeled
    • Grounding (see point 5) - we want to have these power supplies be independent, but we must still specify a ground
    • There is exactly enough space to fit in the two Sorensens below the ones that are currently there
  4. DIN fuses for 15V and 24V
    • 15V fuses can be easily installed since we don't need a very high current for the temperature sensors
    • the 24V fuses seem to be able to handle 6.3A according to the datasheet, but it only says 4V on the fuse itself. Not sure if this is the wrong darasheet...
  5. Connecting the crcuit to the DAC and what connectors to use
    • Using the rightmost DAC because there's less important things connected to it, and use the LEMO conncectors to provide the input
    • Connect the grounds of the DAC and the new Sorensens that we're going to install to the grounds of the rest of the Sorensens
    • *confirm that this setup will work and if not find an alternative
  6. Which channels to use for the ADC
    • channels 29, 30, 31 are available, so we can use any two of those (one for each sensor)

Also, I need to eventually remake the connections on my circuit board because they are all currently test points. I also need to find a box for the heater circuit and figure out what to do with the MOSFET and heat sink for it. This can either be done before setting everything up, or we can just change it later once we have the final setup for the can ready.

If all of this looks good then we can begin the setup.


gautam:

  1. I recommend using a DAC output from the rightmost AI board because (i) only the green steering mirror PZTs are hooked up to it while the other has ETMX suspension channels and (ii) the rightmost AI board has differential receiving from the DAC, and in light of the recent discussions about ground loops, this seems to be the way to go. Outputs 5-8 are currently unused, while outputs 1-4 are used for the EX green input steering mirror control.
  2. Converters required:
    • 2 pin LEMO to BNC --- 2pcs for each temp sensor.
    • Single pin LEMO to BNC --- 1pc for AI board to heater circuit input (readily available)
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