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IDdown Date Author Type Category Subject
  81   Sat Aug 13 11:17:17 2016 GabrieleFacilityDaily ProgressSpot the differences

  80   Fri Aug 12 10:33:14 2016 GabrieleElectronicsConfigurationStorage added to cymac3

Installed two new 2TB disks into the cymac3. Also, the main disk has a 1TB partition with the operating system, so I created a new 1TB partition. I created a logic volume that spans the three partitions, for a total of about 5TB. This partition is mounted in /mnt/data and linked to the /frames folder. Frames are written to this new logic volume.

  79   Thu Aug 11 10:59:39 2016 GabrieleElectronicsConfigurationQuadrant calibration

I cross checked the calibration of the sum channel with a  power meter. Now all quadnant signals X3:Q?_OUT and the sum signal X3:CR1-SUM_OUT are correctly calibrated in microwatts.

  78   Thu Aug 11 09:10:01 2016 GabrieleElectronicsConfigurationReal time model

Compiled and installed an updated real time model. It acquires the four QPD segments, compute sum and differences, and normalize. I also added three experimental peak tracking components, that will be used to track in real time the amplitude and frequency of the disk modes.

I also created a summary medm screen that can be used to control all the QPD readout. It can be opened from any terminal with the command 'cr1'. I haven't added the peak tracking parts yet.

The X_NORM_OUT and Y_NORM_OUT signals are high passed at 500 Hz, to get rid of low frequency stuff that can affect the peak tracking.

 

  77   Thu Aug 11 08:45:19 2016 GabrieleGeneralGeneralQPD signals with dielectric filter

I installed a dielectric laser line filter (Thorlabs FLH05633-5, center wavelength 633 nm, FWHM 5 nm) in front of the QPD. In this way we are no more affected by the room light. In the plot below blue is without filter, red with filter. A lot of peaks at high frequency are eliminated by the filter.

The plot below shows the QPD signal quadrant signals in a few different configurations: blue with the room light on and laser off, red with the room light off and laser off, green with the laser on. With the filter installed, when the laser is on we are dominated by its intensity noise, which shows a lot of peaks at high frequency. Those peaks are not completely eliminated by the difference of the quadrants.

  76   Wed Aug 10 10:04:35 2016 GabrieleMechanicsDaily ProgressThe prototype of the disk retain system is here

Yesterday we received the prototype of the disk suspension and retain system. Everything looks good. I checked that the disk fits in the holder, and all dimensions are good. The coil holders are out for winding, so I couldn't test the movimentation yet.

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  75   Wed Aug 10 09:39:38 2016 GabrieleElectronicsDaily ProgressAnnuntio vobis gaudium magnum: habemus Cymac

Yesterday I cloned the cymac2 disk and installed it into the cymac3.

Jamie tweaked a few things (I can't really give more details) and now cymac3 is up an running with the same software as cymac2.

I compiled and installed the CR1 model, to readout the QPD. No more jumps in the signals!

To be able to access testpoints and have AWG working I had to follow the hack explained here: Cryo_Lab/781

I tested the following features:

  • the model is running and signals look good
  • I can access test points and DQ channels in real time with both dataviewer and DTT
  • I can access old data with dataviewer, using NDS
  • awggui is working and I can inject noise, that is properly going to the DAC channel (I check with a scope in the analog world)
  • I can upload filters using foton

The plot below shows the spectrum of the QPD. For the moment being I'm just sending a straight HeNe beam into the QPD, since the test setup with the disk is no more available. Units are arbitrary

  74   Mon Aug 8 10:42:46 2016 GabrieleGeneralGeneralDependency of eigenmode frequencies on thickness and diameter

I ran a set of COMSOL simulations to determine the dependency of the frequency of each eigenmode on the disk thickness and diameter, within the tolerances. I chose wide ranges: diameter 75.0 +- 0.1 mm and thickness 1.0 +- 0.1 mm, much more than the expected tolerances. It turns out that the frequencies depends almost exactly linearly on both variables: mostly on the thickness and negligibly on the diameter. The following plots shows: the mode shape and frequency (left), the frequency dependency on the two variables (center), the residual of a linear fit and the functional form of the fit (right).

I'm including only the modes that will be measurable by our system (no motion in the center, frequency below 32kHz. Since the disks in my simulation is completely round, I'm showing only one mode for each doublet.

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  73   Tue Aug 2 16:00:32 2016 GabrieleElectronicsCharacterizationMore on the signal jumps

So I’m sending a 1.123 Hz sinusoid into the ADC, and generating 3.123 Hz sines and cosines in the model. Frequencies are reasonably incommensurable with one second.

The plots below shows all three signals. In the top panels, I just separate the two segments in each second: the “normal” segment in blue, and the “jumped” segment in orange.
In the bottom panels, I took the jumped segments (orange) and shifted them “in the future” by exactly one second. The signals are perfect!
 
I think we could explain this if the order of the samples in each second is scrambled, like we have a circular buffer but we point to the wrong starting point…
 
 
  72   Tue Aug 2 15:58:12 2016 GabrieleElectronicsDaily ProgressSix QPD functional and tested

I finished populating the new four QPD boards, and fixed the first one I populated weeks ago. I tested all five new boards: the output of the transimpendance respond correctly to the ambient light; the output of the whitening also respond correctly and has increased high frequency noise; the differential driver stages are all functional and balanced.

In summary, we have six QPD circuits ready: serial 02 is installed into the box and it has been used for the previous tests. Serial number 01, 03, 04, 05, 06 are not yet into a box, but fully functional. Boxes are ready.

For testing purposed, I also built another ADC interface board: it's complete with the exception of the connector that goes to the ADC.

  71   Mon Aug 1 16:56:57 2016 GabrieleElectronicsDaily ProgressPopulated four new QPD boards

Today I populated four more QPD boards. All components are installed, except for the QPD themselves.

  70   Fri Jul 29 14:08:31 2016 GabrieleGeneralDaily ProgressPeak tracking code for real time model

Summary

I wrote a C function to reconstruct the amlplitude and frequency of a line. It can be added as a block into a real time monitor. The idea is to use it to track in real time the frequency and amplitude of the disk modes, during the ring down. I did some tests and finally managed to get the function to compile and run on the cymac2 (the crackling lab cymac).

The following plot shows a simulation, since I can't run the code on the new cymac and I don't have the disk installed anymore. The top panel gives the amplitude of a decaying line, and the bottom panel the frequency offset from a reference local oscillator (more below). The nominal values are an initial amplitude of 1, frequency of 1109.375 Hz to be compared to a 1109.0 local oscillator. The fitted decay time is 10.005 seconds, to be comapred with 10 seconds nominal. There is some additive gaussian noise, that causes the ring down to be unmesurable after about 70 seconds of data.

This code will be used for real time estimation of the disk modes, once theot frequency has been roughly estimated with FFTs. The estimation of the frequency work remarkably well. In the first 20 seconds the mean value is 0.3747 Hz, with a standard deviation of 1.5 mHz. When the SNR gets worse (between t=30s and t=50s) the mean value is 0.3745 with a standard deviation of 20 mHz. 

Because of the way it's built (see below) the code is sensitive to DC offsets, so the input signal must be high-passed.  

Details on the implementation

The code is based on demodulation of the input signal with a reference local oscillator thta must have a frequency as close as possible to the line we want to track.  The inputs to the block are: the signal to be monitored, sine of the local oscillator, cosine of the local oscillator. The outputs are: amplitude squared of the peak, frequency offset in Hz from the local oscillator.

Here's the math. Let's assume that the signal is

x(t)=A \sin (2\pi f t + \phi)

and the local oscillator has a frequency f0:

s(t)= \sin (2\pi f_0 t) \qquad c(t)= \cos (2\pi f_0 t)

The code multiply the signal by the two local oscillators and average the result over 65kHz / 8 Hz samples. Therefore we get two output streams at 8 Hz which are

\left< x(t) s(t) \right> = -\frac{A}{2} \sin\left[2\pi(f-f_0)t + \phi \right]

\left< x(t) c(t) \right> = \frac{A}{2} \sin\left[2\pi(f-f_0)t + \phi \right]

Then the sum of the two squared 8 Hz streams give an estimate of the amplitude squared. The code computes this every second

\hat A = 4 \left[ \left<x(t) s(t)\right>^2+\left<x(t) c(t)\right>^2\right]

while the arctangent of the ratio gives a phase that varies linearly with time.

\arctan \frac{\left< x(t) c(t)\right>}{\left< x(t) s(t)\right>} = \phi + 2\pi(f-f_0)t

For each of the 8Hz samples the code computes the arctangent (using a home-brewed function based on a lookup table, since we can't import math.h in the RCG). It unwraps it, and then every second fit a line to the unwrapped arctangent, to estimate the frequency offset with respect to the local oscillator.

The C function has some parameters hard coded: the main sampling frequency (65536 Hz), the number of points per second to use for the frequency estimation (8 Hz), the fact that the output is computed every second. The first two parameters can be changed, the third one cannot for the moment being.

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  69   Thu Jul 28 17:15:22 2016 GabrieleElectronicsDaily ProgressADC/DAC interfaces upgrade

Installed the ADC and DAC boards into a proper box. Also, swapped the temporary DAC board (with cale hack) with the final one. Schematics and PCB are in the DCC: D1600196 and D1600301

The box is sitting on top of the cymac computer, on the back, since I don't have any long cable to connect the ADC. 

  68   Thu Jul 28 14:01:27 2016 AlenaGeneralDaily ProgressClean room

Ordered the clean room (hardware+hepa filters) and vacuum gauges

  67   Thu Jul 28 13:58:48 2016 Alena, GabrieleCleanDaily ProgressThe old chamber is now being cleaned and baked

Cleaned the chamber in the washing machine at 40m and started 48 baking at 120 C

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  66   Wed Jul 27 15:43:02 2016 GabrieleFacilityDaily ProgressVacuum chamber dismantled and ready for cleaning

[Alena, Gabriele]

As decided at out Red Door meeting, we're going to clean the vacuum chamber and move it to the large table, which will be enclosed in a clean room.

So today we disassembled and packaged the vacuum chamber, which is now ready to be trasnspoted to be cleaned and baked.

  65   Wed Jul 27 11:27:11 2016 GabrieleFacilityGeneralPumps stopped and venting

11:25am LT: closed valve between roughing and turbo pumps, switched off both pumps. Turbo pump is slowing down

After lunch I opened the chamber and removed everything from the inside.

The chamber around the vacuum gauge is really dirty now, see picture:

In addition, the electrostatic driver shows some signs of "burn" even though it was still working quite well. Unfortunately, whatever happened contaminated our sample:

  64   Wed Jul 27 10:19:36 2016 GabrieleElectronicsConfigurationLast finding in the signal jump saga

This plot shows a signal which is generated purely digitally inside a code that I was testing.

Jumps are present even in this case.

Another addition: I was testing some simple code I was writing. Forget about OUT1 and OUT2, but OUT3 and OUT4 should be simple counters. Here's what I get by running the code on cymac3:

Since it didn't make any sense, I ran the same code on cymac2. Here's the (correct) result:

So there's something wrong even when all-digital signals are generated.

  63   Wed Jul 27 08:59:12 2016 GabrieleElectronicsGeneralPressure now in torr

The old channel X3:CR1-PRESSURE_LOGTORR does not exist anymore. The new channel is now directly in torr and it is called X3:CR1-PRESSURE_TORR.

I had to write a C function to compute the 10^x operation, since it is not included in the RCG routines. Also it's not possible to include library functions, so I had to write an ad-hoc function, which first compute the integer part of the exponent, and then approximate the fractional part with linear interpolation and a look-up table. Code is in /opt/rtcds/userapps/release/models/pow10.c

  62   Tue Jul 26 11:45:03 2016 GabrieleElectronicsCharacterizationHigh frequency noise budget

Just to confirm that my noise estimates make sense, here's a plot of the not-normalized QPD signal that gives the X motion (sum and difference of all four quadrants):

This is the signal after compensating for the whitening filter. If I remove this compensation, the following plot gives the noises in terms of the voltage directly in input to the ADC (or in output of the analog board):

So the total "dark" electronic noise is about 13 uV/rHz.

I did a roughly estimate of the sources of electronic noise:

  • QPD dark current noise, from datasheet, at the peak sensitivity is equivalent to 2e-14 W/rHz, or 2 nV/rHz at the output of the TI stage
  • First stage: Johnson-Nyquist noise of the TI resistor: 58 nV/rHz
  • First stage: output voltage noise of the LT1124: 3 nV/rHz
  • First stage: input curent noise of the LT1124, converted to the output: 60 nV/rHz

So the total noise at the outoput of the first stage is about 84 nV/rHz. The second stage adds a gain of 30 at high frequency, and negligible noise. So at the output of the whitening we have 2.5 uV/rHz. The DRV135 adds another gain of 2 and a neglegible output noise. 

So the total electronic noise at the output of each quadrant is 5 uV/rHz. Since we are combining four of them, the total expected electronic noise is 10 uV/rHz, which is not too far from the measured value. 

We are basically dominated equally by the Johnson-Nyquist noise of the TI resistor and by the input current noise of the LT1124. No gain to be obtained by changing the whitening.

Quote:

I measured the noise sources limiting the QPD sensitivity. Unfortunately, I had to do some MATLAB tricks to get rid of the glitches: basically I load the data directly from the raw frames (NDS access to data is not working yet) and remove all jumps in the signals that happen in one single sample and are larger than a manually tuned threshold. This is not perfect, but it's enough to give us a rough idea of the spectrum of the QPD signal. The following plot shows the QPD_X signal (in units of disk motion, radians) in a few situations:

  • Blue: normal (laser on, room lights on)
  • Orange: laser on, room lights off (including the vacuum gauge)
  • Yellow: laser and room light off
  • Purple: same as above, but I switched off the PC monitors too
  • Green: QPD electronics off (this is the ADC noise)

The total power on the QPD is 30 uW, which correspond to a shot noise limited sensitivity of 4.3e-12 W/rHz. Considering that the signal is the quadrant asymmetry normalized by the total power, the shot noise limited sensitivity is sqrt(2) * SN / Power which once calibrated corresponds to 1.1e-10 rad/rHz.

The following plot shows that shot noise is the dominant source, followed closely by the electronics dark noise. The total agrees perfectly with the measured background noise above 2 kHz. Below that we have some leakage due to the large turbopump peak: this is due to FFT limitations but mostly to unsuppressed glitches.

From the QPD datasheet (Hamamatsu S5981) I learn that the noise equivalent power should be of the order of 2e-14 W/rHz at the sensitivity peak, so probably a factor of two or so worse at the HeNe frequency. It's still much lower than the measured dark noise. 

This sensitivity is already pretty good, but we can improve it by increasing the power on the diode. Indeed, 30 uW corresponds to about 2.7 V after the transimpedance, so we could increase the power by a factor 4 and win a factor 2 in the shot noise to dark noise ratio. Probably not worth it, since it will give us only a 30% gain in high frequency noise.

 

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  61   Mon Jul 25 17:44:13 2016 GabrieleElectronicsCharacterizationHigh frequency noise budget

I measured the noise sources limiting the QPD sensitivity. Unfortunately, I had to do some MATLAB tricks to get rid of the glitches: basically I load the data directly from the raw frames (NDS access to data is not working yet) and remove all jumps in the signals that happen in one single sample and are larger than a manually tuned threshold. This is not perfect, but it's enough to give us a rough idea of the spectrum of the QPD signal. The following plot shows the QPD_X signal (in units of disk motion, radians) in a few situations:

  • Blue: normal (laser on, room lights on)
  • Orange: laser on, room lights off (including the vacuum gauge)
  • Yellow: laser and room light off
  • Purple: same as above, but I switched off the PC monitors too
  • Green: QPD electronics off (this is the ADC noise)

The total power on the QPD is 30 uW, which correspond to a shot noise limited sensitivity of 4.3e-12 W/rHz. Considering that the signal is the quadrant asymmetry normalized by the total power, the shot noise limited sensitivity is sqrt(2) * SN / Power which once calibrated corresponds to 1.1e-10 rad/rHz.

The following plot shows that shot noise is the dominant source, followed closely by the electronics dark noise. The total agrees perfectly with the measured background noise above 2 kHz. Below that we have some leakage due to the large turbopump peak: this is due to FFT limitations but mostly to unsuppressed glitches.

From the QPD datasheet (Hamamatsu S5981) I learn that the noise equivalent power should be of the order of 2e-14 W/rHz at the sensitivity peak, so probably a factor of two or so worse at the HeNe frequency. It's still much lower than the measured dark noise. 

This sensitivity is already pretty good, but we can improve it by increasing the power on the diode. Indeed, 30 uW corresponds to about 2.7 V after the transimpedance, so we could increase the power by a factor 4 and win a factor 2 in the shot noise to dark noise ratio. Probably not worth it, since it will give us only a 30% gain in high frequency noise.

  60   Mon Jul 25 15:35:31 2016 GabrieleOpticsCharacterizationCalibration of the QPD in physical units

The equations below are wrong. Please refer to https://nodus.ligo.caltech.edu:8081/CRIME_Lab/116 for the correct results

I measured the properties of the beam on the QPD. The total power is 31 uW. The beam shape is not gaussian, since we are seeing the interference of the reflection from the two surfaces:

The X and Y diameters are 1400 and 1300 microns, so I take the average of the two as an estimate of the beam size: 1300 +- 100 um. I also estimated the lever arm length to be 1.03 +- 0.02 m.

This allows me to esitmate the response of the normalized QPD signal to a tilt of the disk surface:

\frac{s}{P_0}=\frac{4}{\pi w^2} \cdot 2L \cdot \theta_{disk}

Plugging in the numbers gives a gain of (1900 +- 300) /rad for the normalized signals. I implemented those numbers in the filter banks: now X_NORM and Y_NORM have units of radians, and measure the disk surface angular motion. I also calibrated the SUM channel in microwatts, using the nominal responsivity of 0.45 A/W and the transimpedance of 200k (gain 11.1 uW/V)

Here's teh calibrated spectrum: note that the background noise is much larger than the real one because of the signal jumps.

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  59   Mon Jul 25 12:24:06 2016 GabrieleElectronicsConfigurationMore on the signal jumps

Here are two more tests I did this morning

  • removed the DAC card from the cymac and the models, and restarted everything: signal jumps are still there
  • move the cymac2 from the crackling noise lab to the CRIME lab, ans set it up with all the same hardware I was using with the cymac3: there are no jumps, signals look perfect (see plots at the end)

So in conclusion: the problem is in the cymac3 computer, either software or hardware. I tend to excluse an I/O hardware problem, since I used two different ADCs and removed the DAC, without improving the situation.

  58   Fri Jul 22 14:22:10 2016 GabrieleElectronicsConfigurationInvestigations on the signal jumps

[Rolf, Ben, Rich, Gabriele]

Rolf couldn't find any good explanation on the software side for the signals jumps. He investigated a bit the reason why IOP takes a long execution time, without success. It's still mysterious why it ran with low time for a while.

One effect of Rolf activity is that now the signal jumps happen at ~0.8 seconds (after the start of each second) instead that ~0.45. This is suspiciously pointing to a software issue...

Ben and I spent a few hours trying to better understand the origin of the glitches. Finally, we plugged in a function generator to the four ADC channels, and we could find the glitches again, at the expected time. So we could rule out completely that it's a problem of the QPD analog electronics.

Some more ivnestigations:

  • swapped the SR DS345 with an Agilent 33210A for the timing signal. No change: jumps are still there
  • rebooted and powered off the cymac many time, this never changed the glitches or the position in time
  • swapped the ADC interface board (D1600196) with a new one similar to that of the crackle lab (D1500402): no change, jumps are still there
  • switched off the roughin pump to reduce ambient acoustic noise. Not surprisingly, no change, still jumps
  • according to the motherboad manual, PCIe slots 4 and 6 are PCI-EX16, while the other are PCI-EX8. I moved the ADC and DAC to those those slots. Guess what? No change, still jumps

On a bright side, Rolf recompiled the awgman software, and now excitation channels are working.

  57   Thu Jul 21 14:58:26 2016 GabrieleElectronicsGeneralGlitches are of digital origin

So here's the final proof that the glitches I see are digital:

  • There is a positive jump (of random size) every second, every time 0.45s after the beginning of the second. There is a negative jump at a less constant time, but between 0.65s and 0.8s after the beginning of each second
  • I moved my whole setup to the crackle lab. This included: HeNe laser with power supply, QPD with cable, interface board and power supply. I don't see any glitch there

I swapped the ADC board with a second one in the new cymac, but no change: glitches are still there.

 

  56   Thu Jul 21 12:10:14 2016 GabrieleGeneralDaily ProgressGlitch hunting

Yesterday I could clearly see the glitches as jumps in the time domain plot of X and Y signals, and trace them to somewhat harder to see jumps in the quadrant signals. 

  • I tried to catch them with an oscilloscope looking at the analog signals, but couldn't see any. However, for a brief period I had a persistent square wave oscillation in all transimpedance stages
  • I hooked the single ended output of the whitening filter to an ADC, and I could see the jumps there too. So I can exclude it's a problem of the differential drivers

One suspect was an intermittend oscillation of the transimpendance amplifier, so I looked into the schematics (D1600196) to see what could be the optimal value of the compensating capacitor C7. Following some useful notes online I computed the optimal value of C7 to be close to 2pF (instead of 10pF). I used 30-35 pF as the QPD capacitance, and 10 MHz has the gain-bandwidth product of the opamp. I swapped all 10pF capacitors with 2pF. After this I can still see the glitches in the spectra, but I can't find them anymore in the time domain. So things seem to have improved, although I still have annoying glitches.

Rich suggested to test the stability of the transimpendance stage by driving the output with a square wave and looking for the signal ringing. Here's his note:

I tried this for both the TI stage and the whitening stage, using 1k and 1uF and a square wave at 10 kHz. Here are the results, which look reasonable to me (firts is the TI, ringing at about 0.5 MHz, second is the whitening, almost no ringing):

So now I'm quite confident that the electronics is working. In the first trace you can see some intermittend background noise, due to the ambient light leaking into the QPD.

More investigations will follow.

  55   Wed Jul 20 10:26:40 2016 GabrieleElectronicsConfigurationAre glitches a digital artifact?

Not so sure anymore...

  • those glitches do not happen at regular times
  • I tried to send a sinusoid into another ADC channel, and I couldn't see any jump
  • using DTT and zooming into the jumps, they don't seem a clean one-sample jump anymore... There might be a bit of ringing before and/or after the jump
  • The jumps have different sizes and directions, and they seems to happen at the same time in all four quadrants, but not in the same direction or with the same amplitude

I was suspecting dust crossing the beam, so I build a very rough enclosure, that should help with dust. I don't think I saw any change in the glitches. 

Also:

  • glitches are there even with the HeNe off, with ambient light only. So it's not the laser.
  • I tried sending a sinusoid into one of the same ADC channels used to acquire the QPD signals. I couldn't see any glitch

So one might conclude that the glictches are produced by the analog QPD electronics. However, I plugged in a scope and I couldn't see any in the analog signal. But I checked only before the DRV135 stages. I'll need some sort of breakout board to test the output of the DRV135.

Quote:

The glitches I saw in the data happens roughly every second, even though not exactly on the second. They are suddend jumps on the signal values over one sample, so of clear digital origin

 

 

  54   Tue Jul 19 20:19:38 2016 GabrieleElectronicsConfigurationGlitches are a digital artifact

The glitches I saw in the data happens roughly every second, even though not exactly on the second. They are suddend jumps on the signal values over one sample, so of clear digital origin

 

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  53   Tue Jul 19 17:21:48 2016 GabrieleGeneralDaily ProgressFirst modes excited!

We can't generate any arbitary signal with the real time model, since awg is not working properly yet. For the moment being I added a uniform random number generator in the model (only option I found for noise) and send it into the ESD filter bank. In this way I can generate band-passed noise.

I plugged in the DAC output to the HV amplifier input, and I could send white noise to the electrostatic drive. Behold: I was able to excite quite a few modes. In the following trace blue is a reference and red is right after I sent white noise (3 V peak to peak) to the disk for a while (less than 1 minute). Excitation stopped at 4:56pm LT.

Using COMSOL and tuning the disk thickness at 1.018 mm I could hit the frequency of the first butterfly mode (1109 Hz) and get a reasobly good estimate of the other modes.

After about half a hour of ring down, most of the modes are gone but the two lowest are still going strong.

Note that the flattish background noise seems to be generated by some sort of glitches. I tried to swap the laser and the power supply, without change. More investigations are needed.

Note that the roughing pump was still on during the test.

  52   Tue Jul 19 17:15:37 2016 GabrieleFacilityDaily ProgressVacuum pressure acquired

[Alena, Gabriele]

We connected the analog output of the vacuum gauge controller to one of the ADC channels. The signal is calibrated so that the pressure is 10^(X3:CR1-PRESSURE_LOGTORR_OUT). Unfortunately the RTG does not know how to compute 10^x...

  51   Mon Jul 18 18:05:46 2016 GabrieleOpticsDaily ProgressOptical setup

Small modifications to the optical setup:

  • added a 1m focal lenght lens (AR coated for 1064nm...) right before the beam enters the viewport, to reduce the beam spot size on the QPD
  • added a 0.3 ND right after the laser, to avoid saturation of the QPD (about 75 microwatts total on the QPD)

  50   Mon Jul 18 17:48:58 2016 GabrieleElectronicsConfigurationStatus of real time system and workstation

[EricQ, Gabriele]

The real time system seems to be working properly, except for the excitations: we can't activate any excitation using awggui or diaggui

Eric rebuilt the workstation from scratch installing Debian 8.5. All CDS software seem to be working. We setup a ssh-key for ssh'ing into cymac3 and configured the automatic mount of the remote /opt/rtcds.

  49   Mon Jul 18 17:46:04 2016 GabrieleGeneralDaily ProgressFirst look at QPD signals

Here's the first spectrum of the QPD X and Y signals, acquired with the digital system. Roughing and turbo pumps are still on.

The noise floor seems quite non stationary. To be investigated.

  48   Mon Jul 18 14:29:07 2016 GabrieleGeneralDaily ProgressStatus of the test setup

I checked that the QPD electronics works as expected, and that I can acquire the signals using the ADCs. A new model (x3cr1) is up and running. It acquires the four quadrants, convert them from counts to volts, and compensate for the analog whitening filter. The four quadrant signals are X3:CR1-Q1_OUT, X3:CR1-Q2_OUT, X3:CR1-Q3_OUT, X3:CR1-Q4_OUT.

A matrix is used to compute the X and Y signals, defined as X = (Q1+Q4-Q2-Q3) and Y = (Q2+Q4-Q1-Q3). The SUM signal is also computed as SUM = (Q1+Q2+Q3+Q4).

Finally, the X and Y signals are normalized with the sum to produce X3:CR1-X_NORM_OUT and X3:CR2-Y_NORM_OUT.

A filter bank (ESD) is connected to the DAC channel #0 to produce the excitation that will be sent to the high voltage amplifier. I checked that the DAC is working properly (adding offsets). The input to the ESD filter bank is in volts.

The normalized X and Y signals, the sum of all four quadrants and the output of the ESD driver filter bank are saved to frames. The model runs at 65kHz.

  47   Mon Jul 18 13:42:46 2016 GabrieleElectronicsCharacterizationQPD signal convention

The QPD quadrants are wired accoridng to the following convention

  46   Mon Jul 18 13:39:45 2016 GabrieleFacilityDaily ProgressPump down started

Today at 1:40pm pressure is 8.5e-7 Torr

Quote:

Following Alena's procedure, at about 1:30pm LT I started the chamber pump down. At 14:15pm LT the pressure was still 240 mTorr

At 6:20pm the pressure was about 70 mTorr, so I started the turbo pump.

 

  45   Sat Jul 16 14:15:44 2016 GabrieleFacilityDaily ProgressPump down started

Following Alena's procedure, at about 1:30pm LT I started the chamber pump down. At 14:15pm LT the pressure was still 240 mTorr

At 6:20pm the pressure was about 70 mTorr, so I started the turbo pump.

  44   Fri Jul 15 17:56:50 2016 GabrieleGeneralDaily ProgressQPD connected to digital system

I connected the QPD to the ADC interface with a temporary cable running on the floor.

I could get signals. I still have a problem with the digital system: I can't access test points with dataviewer, but I get them with DTT. This will have to be fixed.

 

  43   Fri Jul 15 16:05:07 2016 GabrieleElectronicsDaily ProgressElectrostatic actuator installed

Using the already installed high voltage feedthrough, I cabled one of the electrostatic actuators (1mm gap between electrodes) and installed it into the chamber. One of the electrodes is connected to the feedthrough cenral pin, the other is grounded on the bottom of the chamber.

The electrostatic actuator is mounted at about 1 mm above the disk, see pictures.

As a preliminary test, I checked that switching the HV amplifier on and off with about 1.5kV produces a visible motion (~2-3 mm) of the optical lever beam. So the actuator is working.

  42   Thu Jul 14 17:06:47 2016 GabrieleElectronicsConfigurationNetworking

The laboratory workstation is coatings.ligo.caltech.edu

The RTS is cymac3.ligo.caltech.edu

I set up a ssh-mount of the /opt/rtcds/userapps folder in the workstation. I also created shared ssh keys for the controls user, so we can ssh into the cymac3 without password

  41   Thu Jul 14 16:56:00 2016 AlenaFacilityDaily Progresstest vacuum system

Please see prosidures for pumping down and venting with air for the test vacuum chamber here https://dcc.ligo.org/T1600304

  40   Thu Jul 14 15:30:48 2016 ericqElectronicsConfigurationCymac RTS configuration

We played around a bit with the cymac, in efforts to make things better.

  • We disabled some more fancy-sounding options in the machine's BIOS
  • I created safe.snap files for the x3iop and x3tst models 
    • x3iop's was created by booting the model while mashing the EPICS command to set the burt restore bit, and then saving the EPICS database to file via the SDF screen
    • x3tst's was created by copying an existing .snap file 
  • I gave the controls user ownership of /frames via sudo chown controls:controls /frames
  • I then created the following folders (which the daqd log was complaining about not finding_
    • /frames/full
    • /frames/trend/minute
    • /frames/trend/minute_raw
    • /frames/trend/second
  • I also created the folder /opt/rtcds/tst/x3/target/fb, since that is listed in the daqd config as the nds job dir. (However nds does not seem to be running. Is it needed? I couldn't compile it in the rtbuild directory)

As I see it, the main problems that persist are:

  • daqd crashes over and over again every few seconds
    • The logs seem to be complaining about EPICS server problems. Is the related to whatever situation made the epics-env script neccessary?
  • The IOP seems to be taking too much time: 8-9 usec
    • This is especially problematic as Gabriele actually wants to run the IOP at an even faster rate than the current 64k, which isn't possible with the current timing
  39   Tue Jul 12 17:19:07 2016 GabrieleElectronicsDaily ProgressADC and DAC cabling

This afternoon I completed the assembly of the electronics boards to interface the ADC and DAC. The ADC is interfaced with a new custom board, which accepts up to eight QPD inputs, the syncronization signal, and it's connected to the ADC:

For the DAC I used one spare board from the Crackle experiment. However, that board had a wrong pinout for the DAC side connector, so I had to implemented again the same hack I did for the crackling noise experiment. 

All boards are connected to the ADC and DACs, and to the syncronization signal generated with a SR DS345. No boxes for the moment being, I'll figure out a better organization of the boards in the future if needed. I still haven't tested if the real time system is able to communicate properly with the new interfaces.

  38   Mon Jul 11 17:04:06 2016 AlenaFacilityDaily ProgressVacuum chamber tests

At 5pm the pressure was 6.5e-6 torr.

Checked again at:

  • 9am, pressure was 2e-6 torr
  • 11:30am, pressure was 1.5e-6 torr
  • 5pm, pressure was 1.4e-6 torr
Quote:

Installed a gate valve between the roughing and tubbo pump. See below a pump down curve. The convection gauge is not calibrated. the turbo started at 14th min (at about 3 torr)

 

  37   Mon Jul 11 15:21:12 2016 GabrieleGeneralDaily ProgressOne disk installed into the chamber

[Alena, Gabriele]

We attached one of the silicon lenses to a 1" optical post using some kapton tape, and installed it into the vacuum chamber. We built a simple periscope using standard optical component, and managed to send the optical level beam into the disk and back out.

To set a reference for the horizontal position of the disk we used the LMA method: we put a small container with water in place of the disk, and mark on a reference where the reflected beam hits out of the chamber:

We then put back the disk, and aligned it to have the beam hitting the same position. During pumdown we couldn't see any shift of the disk, judging from the position of the optical lever beam.

  36   Mon Jul 11 14:56:45 2016 AlenaFacilityDaily ProgressVacuum chamber tests

Installed a gate valve between the roughing and tubbo pump. See below a pump down curve. The convection gauge is not calibrated. the turbo started at 14th min (at about 3 torr)

Attachment 1: 20160711.png
20160711.png
  35   Mon Jul 11 08:49:25 2016 GabrieleElectronicsConfigurationCymac RTS configuration

I copy here parts of an email from Jamie with instructions on how to run the RTS on the cymac:

I had to change the site/ifo to be "caltech/x3" to avoid EPICS
collisions with other cymacs.  You'll need to update your models to
reflect this change (change names, site/ifo parameters in the model,
etc.).  So for instance, change x1iop -> x3iop, and update the params
block inside.

daqd is installed and running, although I haven't really stress tested
it yet (no models/channels/etc).  It's running under systemd, which is
the Debian service management system.  You can control daqd with the
following commands:

# systemctl restart daqd
# systemctl stop daqd
# systemctl start daqd
# systemctl status daqd
# journalctl --unit=daqd

controls@cymac3:~ 0$ systemctl status daqd
● daqd.service - Advanced LIGO RTS daqd service
  Loaded: loaded (/etc/systemd/system/daqd.service; enabled)
  Active: active (running) since Sat 2016-07-09 11:22:38 PDT; 23h ago
Main PID: 20827 (daqd-standiop)
  CGroup: /system.slice/daqd.service
          └─20827 /usr/bin/daqd-standiop -c /etc/advligorts/daqdrc
controls@cymac3:~ 0$ sudo journalctl --unit=daqd
...

Remember to restart daqd ("systemctl restart daqd") after you add/change
models.

I've gotten all the RCG components working, but not without some small
kinks.  The RCG currently expects a specific EPICS install, different
than the system install we're using right now.  I've hacked a way to
make this work seemlessly for model builds, but it requires sourcing the
following file before *starting* models:

/opt/rtapps/epics/etc/epics-user-env.sh

So in the mean time, you can start/stop models via the following:

$ . /opt/rtapps/epics/etc/epics-user-env.sh
$ /opt/rtcds/caltech/x3/scripts/startx1iop

 

  34   Fri Jul 8 16:49:11 2016 GabrieleElectronicsConfigurationCyMAC

In the last days Jamie installed the patched kernel to run the real time system (RTS) on the new CyMAC. Today (with Jamie's remote advices) I managed to get a IOP (input output process) model compiled and running. There is still no timing input (to be fixed at the beginning of the netx week, I'm presently missing a connector which is on order).

Running the x1iop model gives:

controls@cymac3:/opt/rtcds/tst/x1/scripts$ ./startx1iop 

x1iopepics: no process found

Number of ADC cards on bus = 1

Number of DAC16 cards on bus = 1

Number of DAC18 cards on bus = 0

Specified filename iocX1.log does not exist.

x1iopepics X1 IOC Server started

 

controls@cymac3:/opt/rtcds/tst/x1/scripts$ awg_server Version $Id: awg_server.c 2917 2012-05-22 22:33:39Z alexander.ivanov@LIGO.ORG $

channel_client Version $Id: gdschannel.c 4170 2016-04-05 21:24:46Z jonathan.hanks@LIGO.ORG $

testpoint_server Version $Id: testpoint_server.c 3303 2013-03-05 23:33:45Z alexander.ivanov@LIGO.ORG $

/opt/rtcds/tst/x1/target/gds/bin/awgtpman -s x1iop -4 -l /opt/rtcds/tst/x1/target/gds/awgtpman_logs/x1iop.log started on host cymac3 hostid ffffffffd783d97b 

awgtpman Version $Id: awgtpman.c 4170 2016-04-05 21:24:46Z jonathan.hanks@LIGO.ORG $

 
which seems reasonable. Also, the GDT TP medm screen shows something running:
 
 
Here's what I had to do to get the models to compile and run:
 

1) install MATLAB and add to startup.m the following line

addpath(genpath('/opt/rtcds/rtscore/release/src/epics/simLink'))

 

2) copied from cymac2 the file /opt/rtcds/rtcds-user-env.sh and changed the content to match the right folders

 

3) installed readline library which was missing: apt-get install 

sudo apt-get install libreadline-dev

 

4) installed linux headers sudo apt-get install linux-headers-3.2.0-rts-amd64

 

5) created symbolic link to linux headers:

sudo ln -s /usr/src/linux-headers-3.2.0-rts-common /usr/src/linux

 

6) changed host name to cymac3

sudo vi hostname

 

7) created symbolic link to lspci 

sudo ln -s /usr/bin/lspci /usr/sbin/lspci

 

8) created a symbolic link to awgtpman

ln -s /usr/bin/awgtpman /opt/rtcds/tst/x1/target/gds/bin/awgtpman

  33   Fri Jul 8 15:26:37 2016 AlenaFacilityDaily ProgressVacuum chamber tests

Fixed the 307 gauge controller (a missing contact on the rair panel). The low pressure gauge was connected to 1G port and has measured 1.7E-6 torr. We are not sure since how long the turbo was operating (no vacuum logger yet).

 

 

Attachment 1: WP_20160708_12_25_35_Pro.jpg
WP_20160708_12_25_35_Pro.jpg
Attachment 2: WP_20160708_12_25_41_Pro.jpg
WP_20160708_12_25_41_Pro.jpg
  31   Thu Jul 7 17:44:11 2016 GabrieleFacilityDaily ProgressVacuum chamber tests

[Alena, Gabriele]

This afternoon we opened the tall belljar vacuum chamber, and took everything out of it. All the stuff that was inside the chamber is "temporarily" stored on the floor beside the optical table.

We installed a "spacer" into the chamber, made from one of the optical table legs that were sitting in the hallway. We installed one of the aluminum base plates on top of it, so that the optical components will be at the level of the viewport. Another leg and a thinner base plate are installed out of the chamber, at a similar level.

After this we closed the chamber with one of the flats used for the old chamber, and a rubber o-ring. We started the roughing pump, quickly reached a pressure below 1 mTorr and switched on the turbo pump. Unfortunately, it seems that the low pressure gauge is not working properly, so we don't know what's the pressure right now. We'll check the gauge and controller tomorrow morning and swap it out if needed.

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