40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log, Page 136 of 344  Not logged in ELOG logo
ID Date Authorup Type Category Subject
  6004   Thu Nov 24 20:22:42 2011 MirkoUpdateIOOF2A filter for MC

I calculated the F2A filters for the input mode cleaner optics as described in T010140-01-D eq (4). On Ranas recommendation I added an s/ ( w_0 * Q ) term to the numerator.

The used values are:

w_0 = 2pi / s
h= 0.0009
D= 2.46957E-2
Q=10

UpperCoils.pdf

LowerCoils.pdf

I put theses filters into C1:SUS-MC1_TO_COIL_1_1 to _4_1 . For convenience split in Z and P. Well it doesn't work. After a few seconds the optic begins to swing wildly.

  6005   Fri Nov 25 12:46:13 2011 MirkoUpdateWienerFilteringWiener filtering tryout

Tried the wiener filter with the TF from p.5900

Tried it out with the TFs from p.5900:

WienerFiltering.pdf

Adding a filter element that compensates the acutator TF makes the MC lose lock.

  6011   Fri Nov 25 22:11:12 2011 MirkoUpdateCDSBeware of fancy filter modules

[Rana, Den, Mirko]

It seems you can shoot yourself in the foot if your filter modules are too complex.

Den discovered this when looking into the C1:SUS-MC?_SUSPOS filter module named Cheby, consisting of cheby1("LowPass",6,1,12)cheby1("LowPass",2,0.1,3)gain(1.13501) by noticing that the coherence between input and output of the filter is low.

Cheby filter:

Cheby.png

CoherenceCheby.pdf

This is most likely due to the filter spanning more than the 16 orders of precision that the double data type spans.

The coherence is fine when one splits the filter in two, giving every cheby1 filter its own module. The coherence is also fine when you use the Cheby filter in a 2kHz system, although the freq. response looks very odd

Black: 16kHz, Red 2kHz (yes the filter was converted correctly, no text file editing there)

ChebyAt16kHzBlackand2kHzRed.png

The problem occurs on c1lsc as well as c1sus computer.

 

Looking into the foton files actually points to a precision problem, with the huge range of scale covered in there:

C1:MCS 16kHz (Cheby: Original filter with low coherence. CHbyTST & ChebyTST: Original filter split amongst two filter modules)
################################################################################
### SUS_MC3_LSC                                                              ###
################################################################################
# DESIGN   SUS_MC3_LSC 0 zpk([0],[30],0.333333,"n")
# DESIGN   SUS_MC3_LSC 1 cheby1("LowPass",6,1,12)
# DESIGN   SUS_MC3_LSC 2 cheby1("LowPass",2,0.1,3)gain(1.13501) \
#                       
# DESIGN   SUS_MC3_LSC 3 cheby1("LowPass",2,0.1,3)gain(1.13501)cheby1("LowPass",6,1,12)
# DESIGN   SUS_MC3_LSC 4 ellip("BandStop",4,1,40,16.1,16.9)ellip("BandStop",4,1,40,23.7,24.5)gain(1.25871)
###                                                                          ###
SUS_MC3_LSC 0 12 1  32768      0 30:0.0          9.942903833923793  -0.9885608209680459   0.0000000000000000  -1.0000000000000000   0.0000000000000000
SUS_MC3_LSC 1 21 3      0      0 CHbyTST     9.095012702673064e-18  -1.9978637592754149   0.9978663974923444   2.0000000000000000   1.0000000000000000
                                                                 -1.9984258494490537   0.9984376515442090   2.0000000000000000   1.0000000000000000
                                                                 -1.9994068831713223   0.9994278587363880   2.0000000000000000   1.0000000000000000
SUS_MC3_LSC 2 12 1  32768      0 ChebyTST    1.228759186937126e-06  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000
SUS_MC3_LSC 3 12 4  32768      0 Cheby       1.117558041371939e-23  -1.9972699801052749   0.9972743606395355   2.0000000000000000   1.0000000000000000
                                                                 -1.9978637592754149   0.9978663974923444   2.0000000000000000   1.0000000000000000
                                                                 -1.9984258494490537   0.9984376515442090   2.0000000000000000   1.0000000000000000
                                                                 -1.9994068831713223   0.9994278587363880   2.0000000000000000   1.0000000000000000
SUS_MC3_LSC 4 12 8  32768      0 BounceRoll     0.9991466189294013  -1.9996634951844035   0.9997010181703262  -1.9999611719719754   0.9999999999999997
                                                                 -1.9999303040590390   0.9999684339228864  -1.9999605309876360   0.9999999999999999
                                                                 -1.9999248796830529   0.9999668732412945  -1.9999594299327190   1.0000000000000002
                                                                 -1.9996385459838455   0.9996812069238987  -1.9999587601905868   1.0000000000000000
                                                                 -1.9996161812709703   0.9996978939989944  -1.9999163485656493   0.9999999999999999
                                                                 -1.9998855694973159   0.9999681878303275  -1.9999154056705493   0.9999999999999998
                                                                 -1.9998788577090287   0.9999671193335300  -1.9999137972442669   1.0000000000000000
                                                                 -1.9995951159123118   0.9996843310430819  -1.9999128255920269   1.0000000000000000

C1:OAF 2kHz
###############################################################################
### YARM_IN                                                                  ###
################################################################################
# DESIGN   YARM_IN 0 zpk([0],[30],0.333333,"n")
# DESIGN   YARM_IN 3 cheby1("LowPass",6,1,12)cheby1("LowPass",2,0.1,3)gain(1.13501)
# DESIGN   YARM_IN 4 ellip("BandStop",4,1,40,16.1,16.9)ellip("BandStop",4,1,40,23.7,24.5)gain(1.25871)
# DESIGN   YARM_IN 8 cheby1("LowPass",6,1,12)cheby1("LowPass",2,0.1,3)gain(1.13501)zpk([],[10],1,"n")
###                                                                          ###
YARM_IN  0 12 1   4096      0 30:0.0           9.56649943398763  -0.9119509539166185   0.0000000000000000  -1.0000000000000000   0.0000000000000000
YARM_IN  3 12 4   4096      0 Cheby       1.829878084970283e-16  -1.9828889048300398   0.9830565293861987   2.0000000000000000   1.0000000000000000
                                                                 -1.9868188576622443   0.9875701115261976   2.0000000000000000   1.0000000000000000
                                                                 -1.9940934073784453   0.9954330165532327   2.0000000000000000   1.0000000000000000
                                                                 -1.9781245722853238   0.9784022621062476   2.0000000000000000   1.0000000000000000

  6012   Fri Nov 25 23:25:24 2011 MirkoUpdateIOOF2A filter for MC

Quote:

Woo. Pretty crazy. The numerators should only be ~10% larger than the denominator below 1 Hz. Let's try again.

 [Rana, Mirko]

I redid this calculation. The idea behind it is to get rid on any pitch that is introduced by applying longitudinal feedback to the mirrors. This coupling happens because the center of percussion for pitch , which is identical with the point where the wires lift off of the mirror, is above the center of mass.

With the same values as before, just less faulty math and Q = 2 instead of 10 we end up with the following filters:

For the lower coils (red), compared to corresponding preexisting BS filters (black):

F2aForMCcomparedToBS.pdf

The upper coils' TF is just mirrored at the 0dB magnitude axis, and have a corresponding frequency response.

I switched the F2a filters on for all MC mirrors. For convenience they are split into F2aZeros and F2aPoles. Everything seems fine. The F2a filters seem to be off for ( all ?) other mirrors.

  6013   Sat Nov 26 02:05:43 2011 MirkoUpdateCDSBeware of fancy filter modules

 

We replaced the complicated Cheby filter module with three separate filter modules. Probably the filter doesn't need to be so complicated, but rather not change too many things at once. The new filter modules are called:
Ch1, Ch2, Ch3 and are in filter module 3,9, and 10 of the C1:SUS-MC?_SUSPOS filters. The coherence with these filters is fine. Someone should look into the possibility of simplifying these filters.

It would be good to check for numerical problems in other filters!

  6014   Sat Nov 26 02:15:42 2011 MirkoUpdateSUSNot adaptive, still cool

[Rana, Mirko]

I tried out the virtual pendulum idea today. The idea is to compensate the physical pendulum via the control system, and then add a virtual pendulum formed in the control system. We know the actuator TF from p. 5900 and apply its inverse to the C1:SUS-MC?_SUSPOS filters. Also we add an pendulum Q=3 with a resonance frequency of 0.1Hz to the POS control loops.

The result is pretty awesome!

1. Black: Standard config. Wfs on. New Cheby filter in place ( p. 6031 )
2. Red: With virtual pendulum. Extra eliptic LP filter @ 2.5Hz

PendulumQ0.1HzWithElip2comma5HzLpWfsOnCorrectedShape.pdf

Filter shape:

VirtualPendulumFilterShape.pdf

This is stable for 5-10minutes, at which point it falls out of lock, swinging in yaw.

 

 

  6057   Thu Dec 1 03:27:39 2011 MirkoUpdateSUSNot adaptive, still cool

Quote:

[Rana, Mirko]

I tried out the virtual pendulum idea today. The idea is to compensate the physical pendulum via the control system, and then add a virtual pendulum formed in the control system. We know the actuator TF from p. 5900 and apply its inverse to the C1:SUS-MC?_SUSPOS filters. Also we add an pendulum Q=3 with a resonance frequency of 0.1Hz to the POS control loops.

The result is pretty awesome!

1. Black: Standard config. Wfs on. New Cheby filter in place ( p. 6031 )
2. Red: With virtual pendulum. Extra eliptic LP filter @ 2.5Hz

PendulumQ0.1HzWithElip2comma5HzLpWfsOnCorrectedShape.pdf

Filter shape:

VirtualPendulumFilterShape.pdf

This is stable for 5-10minutes, at which point it falls out of lock, swinging in yaw.

 

 

In the above entry MC_f  signal is improved off of resonance by the implementation of the pendulum compensation. It should be checked if this is actually due to the implementation of the virtual pendulum at 0.1Hz. A way to check that might be to implement a simple double LP at 0.1Hz instead and look at the resulting MC_f signal. A projection of the OSEM FB noises with the compensation active might be interesting.
The physical resonance at 1Hz is clearly not compensated correctly, which is probably the reason for the lock losses after a few minutes. It might be a good start to measure the residual resonance with the compensation in place. The filters in bank 7 of C1:SUS-MC?_SUSPOS have both the compensation of the 1Hz resonance( really the inverse actuator TF ) and the virtual pendulum in them. The ‘pure’ compensation can be found in the InvTF module in the C1:OAF-ADAPT_MCL_CORR filter.
The fact that the beam swings in yaw at lock loss indicates that the separation of the DOFs might not be perfect. One should have a look into the yaw and pitch DOFs with the compensation active.

  2091   Wed Oct 14 15:48:26 2009 MottHowToGeneralPhase Noise measurement

I have gotten the hang of the procedure for measuring phase noise on the AOMs. 

Koji suggested I right up a short guide (wiki page?) on how to do this. 

I will finish up here, then go measure the AOMs at the other lab (may have to be tomorrow, after laser safety), and then write up the instructions.

  2117   Mon Oct 19 13:00:53 2009 MottUpdateGeneralPhase Noise Measurement

Here is the result for the measurement of the phase noise.  We used the marconi function generator and compared it with an Isomet AOM driver (model 232A-1), so this is really a measure of the relative phase between them.  We used a 5x gain and a frequency response of 13 Hz/V for the modulation.  In all the attached plots, the blue is the data and the red is the measurement limit (as determined by the noise in the SRS785).  Also note that the units on the yaxis of the Phase noise plot are incorrect, they should be dB/Sqrt(Hz), I will fix this and edit as soon as possible.

  2362   Mon Dec 7 19:02:22 2009 MottUpdateGeneralReflectivity Measurements

I have made some measurements of the R value for some coatings we are interested in.  The plots have statistical error bars from repeated measurements, but I would suspect that these do not dominate the noise, and would guess these should be trusted to plus or minus 5% or so.  They still should give some indication of how useful these coatings will be for the green light.  I plan to measure for the ITM as soon as possible, but with the venting and finals this may not be until late this week.

 

EDIT (12/9/09): I fixed the label on the y axis of the plots, and changed them to png format.

  2392   Thu Dec 10 18:27:48 2009 MottUpdateGeneralUpdated R & T Measurements

Attached are updated plots of the T&R Measurements for a variety of mirrors, and diagrams for the setup used to make the measurements.

T is plotted for the 1064 nm measurement, since these mirrors are highly reflective at 1064, and either R or R&T are plotted for the 532 nm measurement, depending on how larger the R signal is.

As with the previous set of plots, the error bars here are purely statistical, and there are certainly other sources of error not accounted for in these plots.  In general, the T measurement was quite stable, and the additional errors
are probably not enormous, perhaps a few percent.

The mirrors are:

Y1-1037-00.50CC

Y1-2037-45S

Y1-2037-45P

Y1S-1025-0

Y1S-1025-45

 

  2474   Mon Jan 4 17:26:01 2010 MottUpdateGeneralT & R plots for Y1 and Y1S mirrors

The most up-to-date T and R plots for the Y1 and Y1S mirrors, as well as a T measurement for the ETM, can be found on:

http://lhocds.ligo-wa.caltech.edu:8000/40m/Upgrade_09/Optics/RTmeasurement

 

  2696   Mon Mar 22 22:11:26 2010 MottUpdateABSLPLL reconstructed

 

 It looks like the PLL drifted alot over the weekend, and we couldn't get it back to 9 dBm.  We switched back to the new focus wideband PD to make it easier to find the beat signal.  I replaced all the electronics with the newly fixed UPDH box (#17) and we aligned it to the biggest beat frequency we could get, which ended up being -27 dBm with a -6.3V DC signal from the PD.  

Locking was still elusive, so we calculated the loop gain and found the UGF is about 45 kHz, which is too high.  We added a 20 dB attenuator to the RF input to suppress the gain and we think we may have locked at 0 gain.  I am going to add another attenuator (~6 dB) so that we can tune the gain using the gain knob on the UPDH box.  

Finally, attached is a picture of the cable that served as the smb - BNC adaptor for the DC output of the PD.  The signal was dependent on the angle of the cable into the scope or multimeter.  It has been destroyed so that it can never harm another innocent experiment again!

  2697   Mon Mar 22 23:37:32 2010 MottUpdateABSLPLL reconstructed

 

We have managed to lock the PLL to reasonable stability. The RF input is attenuated by 26 dBm and the beat signal locks very close to the carrier of the marconi (the steps on the markers of the spectrum analyzer are coarse).  We can use the marconi and the local boost of the pdh box to catch the lock at 0 gain.  Once the lock is on, the gain can be increased to stabilize the lock.  The locked signals are shown in the first photo (the yellow is the output of the mixer and the blue is the output to the fast input of the laser.  If the gain is increased too high, the error signal enters an oscillatory regime, which probably indicates we are overloading the piezo.  This is shown in the second photo, the gain is being increased in time and we enter the non-constant regime around mid-way through.

Tomorrow I will use this locked system to measure the PZT response (finally!).

  2703   Tue Mar 23 18:44:46 2010 MottUpdateABSLPLL reconstructed

 

 After realigning and getting the lock today, I tried to add in the SR785 to measure the transfer function.  As soon as I turn on the piezo input on the PDH box, however, the lock breaks and I cannot reacquire it.  We are using an SR650 to add in the signal from the network analyzer and that has worked. We also swapped the 20 dB attenuator for a box which mimics the boost functionality (-20 dB above 100 Hz, 0 dB below 6Hz).  I took some spectra with the SR750, and will get some more with the network analyzer once Alberto has finished with it. 

The SR750 spectra is posted below.  The SR750 only goes up to 100 kHz, so I will have to use the network analyzer to get the full range. 

  2729   Mon Mar 29 15:26:47 2010 MottHowToComputersNew script for controlling the AG4395A

I just put a script in the /cvs/cds/caltech/scripts/general/netgpibdata/ directory to control the network analyzer called AG4395A_Run.py .   A section has been added to the wiki with the other GPIB script sections (http://lhocds.ligo-wa.caltech.edu:8000/40m/netgpib_package#AG4395A_Run.py)

  2738   Wed Mar 31 03:45:49 2010 MottHowToComputersNew script for controlling the AG4395A

 

I took data for the 2 NPRO PLL using the script I wrote for the AG4395, but it is very noisy above about 1 MHz.  I assume this is something to do with the script (since I am fairly confident we don't have 600 dB response in the PZT), so I will go in tomorrow to more carefully understand what is going on, I may need to include a bit more latency in the script to allow the NA to settle a bit more.  I am attaching the spectrum just to show the incredibly high noise level, 

  2746   Thu Apr 1 00:43:33 2010 MottUpdateGeneralPZT response for the innolight

Kiwamu and I measure the PZT response of the Innolight this evening from 24 kHz to 2MHz.  

We locked the PLL at ~50 MHz offset using the Lightwave NPRO and and swept the Innolight with the network analyzer (using the script I made; it has one peculiar property, but it does work correctly).  

We will post the plot of the Lightwave PZT response tomorrow morning.

 

**EDIT**: As Koji pointed out, the calibration factor on this plot is WRONG.  See my more recent update for the correctly calibrated plot.

  2748   Thu Apr 1 10:21:58 2010 MottUpdateGeneralPZT response for the innolight

Quote:

The shape of the TF looks nice but the calibration must be wrong.

Suppose 1/f slope with 10^-4 rad/V at 10kHz. i.e. m_pm = 1/f rad/V
This means m_fm = 1 Hz/V. This is 10^7 times smaller than that of LWE NPRO.

Quote:

Kiwamu and I measure the PZT response of the Innolight this evening from 24 kHz to 2MHz.  

We locked the PLL at ~50 MHz offset using the Lightwave NPRO and and swept the Innolight with the network analyzer (using the script I made; it has one peculiar property, but it does work correctly).  

We will post the plot of the Lightwave PZT response tomorrow morning.

 

 Koji is absolutely right.  I just double checked my matlab code, and saw that I divided when I should have multiplied.  The correctly calibrated plots are attached here for the Innolight and the lightwave.  Kiwamu and I will measure the amplitude and the jitter today.

  2754   Thu Apr 1 18:05:29 2010 MottUpdateGeneralPZT response for the innolight

 

 We realized that we had measured the wrong calibration value; we were using the free-running error signal with the marconi far from the beat frequency, which was very small.  When we put the Marconi right at the beat, the signal increased by a factor of ~12 (turning our original calibration of 10 mV/rad into 120 mV/rad).  The re-calibrated plots are attached. 

  2756   Thu Apr 1 19:59:32 2010 MottUpdateGeneralPZT response for the innolight

 

 We measured the Amplitude Modulation response of the PZTs, to find regions with large phase modulation but small amplitude modulation.

We did this by blocking 1 arm of the PLL, feeding the source output of the Network Analyzer into the PZT input of the laser in question, and reading the output of the PD on the NA.  We calibrated by dividing by the DC voltage of the PD (scaled by the ratio of the AC gain to DC gain of the New Focus PD).

The AM response of the Innolight looks fairly smooth up to ~1MHz, and it is significantly below the PM response for most of its range.  The region between 20 and 30 kHz shows very good separation of about 10^3 rad/RIN (and up to 10^5 rad/RIN at ~21.88 kHz, where there is the negative spike in the AM response). The region between 1.5 MHz and 2MHz also looks viable if it is desirable to actuate at higher frequencies.

The Lightwave offers very good AM/PM separation up to about 500 kHz, but becomes quite noisy about 1MHz.

  2799   Tue Apr 13 19:53:06 2010 MottUpdateGreen LockingPZT response for the innolight and lightwave

 

 I redid the PZT Phase Modulation measurement out to 5 MHz for both the Innolight and the Lightwave.  The previous measurement stopped at 2MHz, and we wanted to see if there were any sweet spots above 2MHz.  I also reduced the sweep bandwidth and increased the source amplitude at high frequency to reduce the noise (the Lighwave measurement, especially, was noise dominated above 1MHz).  I also plotted the ratio of PM/AM in rad/RIN, since this is the ultimate criterion on which we want to make a determination.

It looks like there is nothing extremely useful above 2MHz for either laser.  There are several candidates for the lightwave at about 140 kHz and again at about 1.4 MHz.  The most compelling peak, however, is in the innolight at 216 kHz, where the peak is about 2.3e5 rad/RIN.

Below about 30kHz, the loop suppresses the measurement, so one should focus on the region above there.

  3233   Thu Jul 15 23:51:47 2010 Mr. MaricHowToSUSLevitate me if you can

You guys must work harder.

mag_lev.jpg


  8742   Tue Jun 25 10:18:34 2013 Mystery ManUpdateLSCArm Cavity scan with X-ALS after ALS servo upgrade

Quote:

RMS is now less than 1 kHz or ~50 pm. (in your face, Kiwamu!)

 Isn't this still a factor of 2 away from the limit in the paper?

  3027   Tue Jun 1 18:39:59 2010 NancyUpdate Lead spheres for the seismographs

 

the lead spheres that were placed below the granite slab have been flattened by hammering to have lesser degree of wobbling of the slab.

the height of each piece, and the flatness of their surfaces was checked by placing another slab over them and checking by the spirit level.

P6010170.JPG

P6010166.JPG

P6010164.JPG

 

  3386   Mon Aug 9 12:46:24 2010 NancyUpdateIOOMode Cleaner WFS


 Yesterday , I put in the Output Matrix, and changed the gain sliders for the 4 WFS loops.

From how much to how much have you chnged the gain?

I changed the gains from all 4 0.01 to o.27, 0.23, 0.32 and 0.11 and the main alignment gain to be 0.8

 

 

Next we stepped to putting in the gains for the MC2 oplev servo.

I like to put the credit to Aidan for teaching Nancy how to use FOTON.

 Yes, I am sorry for not mentioning this.

Thanks Aidan

 

 

  13080   Mon Jun 26 09:39:15 2017 NaomiSummaryGeneralMeasure transfer functions of Mini-Circuits filters

I have spent my first few days as a SURF getting experience working with the Network/Spectrum Analyzer (AG 4395A). After an introduction to the 40m by Koji, I was tasked with using the AG4395A to measure the transfer function of several filters (for example, Mini-Circuits Low Pass Filter SLP-30). I am now familiar with configuring the AG 4395A, taking a single set of data using a command from one of the control computers, and plotting the dataset as a Bode plot (separate plots for magnitude and phase) using Python.

To Do:

  • Use AGmeasure to take multiple datasets with a single command.
  • Plot multiple datasets for each filter on a single Bode plot and perform some statistical analysis. 

To experiment with plotting multiple datasets on a single Bode plot, I used a single dataset from the Network Analyzer using the SLP-30 filter and added random noise to create ten datasets to plot. I am attaching the resulting Bode plot, which has the ten generated sets of data plotted along with their average.

We discussed with Rana and Koji how to interpret this type of dataset from the Network Analyzer. Instead of considering the magnitude and phase as separate quantities, we should consider them together as a single complex number in the form H(f) = M exp(iπP/180), where M is the magnitude and P is the phase in degrees. We can then find the average value of the measured quantity in its complex number form (x + iy), as opposed to just taking the average of the magnitude and phase separately.  

  13131   Fri Jul 21 19:44:58 2017 NaomiSummaryComputer Scripts / ProgramsUsing PyKat to run Finesse

I have been working on using PyKat to run Finesse. There appear to be several ways to run an equivalent simulation using Finesse:

1: .kat only

Run a .kat file directly from the terminal. For example, if in the directory containing the Finesse kat.ini file, run the command ‘./kat file.kat’. This method does not use PyKat.

To edit the simulation using this method, one must directly edit the .kat file. This is not ideal, as all parameters must be hard-coded, and there is no looping method for duplicate commands.


Both of the following methods use PyKat in some manner. To run Finesse using PyKat from a .py file, the command ‘from pykat import finesse’ should be included. In addition, two environment variables must be defined:

  • FINESSE_DIR': directory containing ‘kat’ executable
  • KATINI’: location and name of kat.ini file

Within a .py file running PyKat, the kat object contains all of the optical components and their states. To create a kat object, we use the command:

kat = finesse.kat()


2: .kat + .py

To load Finesse commands from a .kat file, we can use the command loadKatFile(). For example, using the kat object as defined above:

kat.loadKatFile(‘file.kat’)

The kat object now contains any components defined in the .kat file. The states of these components can be altered using PyKat. For example, if in the .kat file, we defined a mirror named ‘ITM’, with R = 0.9, T = 0.1, phi = 0, and with nodes 1 and 2 to its left and right, respectively, using the Finesse command

m ITM 0.9 0.1 0 n1 n2

we can now alter the state of the mirror using a PyKat command such as

kat.ITM.phi = 30

which changes the ‘phi’ property of the mirror to 30 degrees. Once all alterations to objects are made, we can run Finesse using the command

out = kat.run()

which stores the output of the Finesse simulation in the variable out.


3: .py only

We can also run a Finesse simulation without any .kat file. There are two ways to define Finesse objects within a .py file.

- Parse a string containing Finesse commands, as would be found in a .kat file, using the command parseCommands(). For example,

            kat.parseCommands(‘m ITM 0.9 0.1 0 n1 n2’)

defines the same mirror as above. This object can now be altered using pyKat in the same manner as above.

- Define an object using the classes defined in PyKat. For example, to define the same ITM mirror, we can use:

ITM = mirror(‘ITM’, ‘n1’, ‘n2’, 0.9, 0.1, 0)

kat.add(ITM)

The syntax for these classes can be found in the files included in the PyKat package named ‘commands.py’, ‘detectors.py’, and ‘components.py’.

We can also run Finesse commands (rather than just defining components) using their respective classes. These must also be added to the kat object. For example:

x = xaxis(‘lin’, [‘-4M’, ‘4M’], ‘f’, 1000, ‘laser’)

kat.add(x)

This runs the command ‘xaxis’, which sets the x-axis of the output data to run from freq = -4 MHz to 4 MHz, in 1000 steps. This is equivalent to the following Finesse command:

xaxis laser f lin -4M 4M 1000

In theory, we should be able to use PyKat to run any Finesse command. However, not all Finesse commands appear to be defined in PyKat; one example is the Finesse command ‘yaxis’, which I cannot locate in PyKat. In addition, I have had difficulty running some commands such as ‘cav’ and ‘pd’, despite following their class definitions in the PyKat files. However, these commands can still be easily run in PyKat using parseCommands().

  9376   Wed Nov 13 18:32:04 2013 Nic, EvanUpdateISSSR560 ISS loop

We have implemented an SR560-based ISS loop using the AOM on the PSL table. This is a continuation of the work in 40m:9328.

We dumped the diffracted beam from the AOM onto a stack of razor blades. This beam is not terribly well separated from the main beam, so the razor blades are at a very severe angle. Any alternatives would have involved either moving the AOM or attempting to dump the diffracted beam somewhere on the PMC refl path. We trimmed the RF power potentiometer on the driver so that with 0.5 V dc applied to the AM input, about 10% of the power is diverted from the main beam.

We ran the PMC trans PD into an AC-coupled SR560. To shape the loop, we set SR560 to have a single-pole low- pass at 300 Hz and an overall gain of 5×104. We take the 600 Ω output and send it into a 50 Ω feed-through terminator; this attenuates the voltage by a factor of 10 or so and thereby ensures that the AOM driver is not overdriven.

The AOM driver's AM input accepts 0 to 1 V, so we add an offset to bias the control signal. The output of the 50 Ω feedthrough is sent into the 'A' input of a second SR560 (DC coupled, A − B setting, gain 1, no filtering). Using a DS345 function generator, a 500 mV offset is put into the 'B' input (the function generator reads −0.250 V because it expects 50 Ω input). The 50 Ω output of this SR560 is sent into the AOM driver's AM input.

A measurement of suppressed and unsuppressed RIN is attached. We have achieved a loop with a bandwidth of a few kilohertz and with an in-loop noise suppression factor of 50 from 100 Hz to 1 kHz. This measurement was done using the PMC trans PD, so this spectrum may underestimate the true RIN.

  9380   Wed Nov 13 20:02:12 2013 Nic, EvanUpdateISSSR560 ISS loop

Quote:

We have implemented an SR560-based ISS loop using the AOM on the PSL table. This is a continuation of the work in 40m:9328.

We dumped the diffracted beam from the AOM onto a stack of razor blades. This beam is not terribly well separated from the main beam, so the razor blades are at a very severe angle. Any alternatives would have involved either moving the AOM or attempting to dump the diffracted beam somewhere on the PMC refl path. We trimmed the RF power potentiometer on the driver so that with 0.5 V dc applied to the AM input, about 10% of the power is diverted from the main beam.

We ran the PMC trans PD into an AC-coupled SR560. To shape the loop, we set SR560 to have a single-pole low- pass at 300 Hz and an overall gain of 5×104. We take the 600 Ω output and send it into a 50 Ω feed-through terminator; this attenuates the voltage by a factor of 10 or so and thereby ensures that the AOM driver is not overdriven.

The AOM driver's AM input accepts 0 to 1 V, so we add an offset to bias the control signal. The output of the 50 Ω feedthrough is sent into the 'A' input of a second SR560 (DC coupled, A − B setting, gain 1, no filtering). Using a DS345 function generator, a 500 mV offset is put into the 'B' input (the function generator reads −0.250 V because it expects 50 Ω input). The 50 Ω output of this SR560 is sent into the AOM driver's AM input.

A measurement of suppressed and unsuppressed RIN is attached. We have achieved a loop with a bandwidth of a few kilohertz and with an in-loop noise suppression factor of 50 from 100 Hz to 1 kHz. This measurement was done using the PMC trans PD, so this spectrum may underestimate the true RIN.

 A small followup measurement. Here are spectra of the MC trans diode with and without the ISS on. The DC value of the diode (in counts) changed from 17264.2 (no ISS) to 17504.3 (with ISS), but I didn't account for this change in the plot.

There is a small inkling of benefit between 100Hz and 1kHz. Above about 100Hz, the RIN is suppressed to about the noise level of this measurement. Below 100Hz there is no change, which probably means that power fluctuations are introduced downstream of the AOM, which argues for an outer-loop ISS down the road.

Atm #2 is in units of RIN.

  8808   Tue Jul 9 01:18:48 2013 Nic, KojiUpdateASCPRMI locking / PRM ASC adjustment

[Koji, Nic]

- Locked PRMI with REFL165 I/Q

- Aligned the POP beam on the QPD. We found that the vertical motion of the beam appeared in the yaw signal, and horizontal motion in the pitch signal.
  This was fixed by swapping the cables to the ADC. Later it turned out that this was caused by the calibration setup for the QPD.
  We requested Jenne to fix the QPD on the table with the current orientation.

- Re-implemented the AC-coupled ASC servo. The filters were just copied from the previous PRM ASC servo (in the SUS ASC filter).
  The same filter was installed to the pitch and yaw filter modules for now. The gains were adjusted to have some stable lock stretches.
  C1:ASC-PRCL_YAW_GAIN: -0.01
  C1:ASC-PRCL_PIT_GAIN: -0.01

  The power spectra of C1:ASC-PRCL_YAW_IN1 and C1:ASC-PRCL_PIT_IN1 were attached.
  The reference curves are the ones with the servo on. The other two are the free-running stability of the QPD output.

- Modified the up and down scripts for the PRM ASC for the new setup.
  It first turns on the inputs of the filters and then turn on FM2/3.
  It assumes that the outputs are engaged all time.

 

  10009   Mon Jun 9 10:55:48 2014 NichinSummaryElectronicsBBPD D1002969-v8 transimpedence measurement

My SURF week-1 work...

Motivation:

To measure the transimpedence of  the Broadband photodiode (D1002969-v8), using a New focus photodiode (1611) as reference. The amplitude modulated Jenne Laser (1.2mW) was used. 

The steps involved in getting the transimpedence are as follows:

Acquiring data

  • Get 2 sets of data from Network Analyzer Agilent 4395: One set of data will be for the transfer function of Ref PD over RF out. The other set for Test PD over Ref PD.
  • The following conditions were set:

1) Frequency sweep range: 1MHz to 200 MHz.

2) Number of Points sampled in  the range: 201

3) Type of sweep: Logarithmic

  • Set the NA to give the corresponding transfer function values in dB and also Phase response in degrees.
  • Save the data into floppy disk for processing on the computer (The wireless way of acquiring data was not working when the experiment was conducted )

Plotting

  • The matlab code attached (TransimpedencePlot.m) will then give plots for the absolute values of transimpedence in V/A.
  • Logic involved in the code:
    • Transimpedence = Voltage response / (Responsivity of the photodiode * Power incident) 
    • Responsivity for BBPD is taken as 0.1 A/W and for NF1611 as 0.68 A/W as given in their datasheets.
    • Voltage response of Test PD w.r.t RF output of NA (in dB) = Voltage response of Test PD w.r.t Ref PD (in dB) + Voltage response of Ref PD w.r.t RF output of NA (in dB) 

 Results

The Plots of transimpedence obtained are attached (results.pdf) . The results obtained for BBPD is consistent with the ones obtained before, but the same method and code gives a different transimpedence for 1611.

The transimpedence of NF 1611 was obtained to be around 4-5 V/A which is very much off-track compared to the one given in the datasheet (elog: 2906).

 

The transimpedence of  Broadband photodiode (D1002969-v8) was around 1200 - 1300 V/A for most of the range, but the value started falling as the frequency approached 100 MHz. This result is consistent with DCC document: T1100467-v2.

 

  10034   Thu Jun 12 16:56:31 2014 NichinUpdateElectronicsPD Inspection

I and Eric Gustafson inspected the automated PD frequency response measurement system which Alex Cole built last summer. We just lifted the tops off the tables [AS table, POY table and ITMX table] and looked at the alignment checking to see if the correct optical fibers from the fiber splitter were illuminating the correct photodiodes. We did not change anything at all and put the covers back on the tables.

The PDF attached shows the state of each PD fiber pair.  The fibers labeled REFL11 and REFL55 were reversed and illuminating the wrong photodiodes.

We will do a manual measurement of REFL33 tomorrow using the network analyzer and the modulatable laser but not the RF switch.  Afterward we will check to make sure the RF cables are connected to the correct channels of the RF switch according to the switch list (/users/alex.cole/switchList).

  10037   Fri Jun 13 18:16:00 2014 NichinUpdateElectronicsChanges to the PD frequency response measurement system

 

As we had planned yesterday (ELOG 10034) I and Eric Gustafson wanted to manually measure the transimpedence for REFL33. But on closer inspection I found the RF signal cable coming from the Photodiode REF DET (mounted on the POY table), that we were supposed to plug into the network analyzer, did not have an SMA connector at the end. There was just the Teflon and metal part sticking out of the insulation. So we disconnected the cable labeled REF DET from the PD and pulled it out to fix it. (POY table and from near the 1Y1 rack)

 

 

Being unable to locate any SMA male connectors in the 40m lab [pasternack PE4025], we headed over to Downs where Rich Abbott did a quick and awesome job of soldering the SMA connector and also teaching me in the process. I will write an ELOG on how to do a clean solder of the SMA connectors to the RF cable shortly for future reference.

 

 

Coming back to the 40m we rerouted the REF DET cable from near the 1Y1 rack and into the POY table. This job was done mostly by Eric. We were also unable to locate a torque wrench to tighten the cable at the PD’s end and had to leave it finger tight. Eric is planning to buy a new torque wrench as we will need it often.

 

 

Also, I cross checked the SwithList located at /users/alex.cole/switchList with the RF switch connections at 1Y1 rack and turns out it is consistent, except that at CH2 of the first switch where MC REFL was to be connected, there is a unlabeled cable. It might belong to the correct PD, but must be made sure of. The rest of the channels that are not mentioned in the list were unconnected on the RF switch.

 

Now instead of disconnecting REFL 33 to make measurements with the NA, we had to take out AS55 from the RF switch, as the former was very hard to remove without the torque wrench. Then Eric removed the optical fiber which was illuminating the AS55 (AS table) from its mount to hook it up to the power meter. But then we were not sure of how to operate the Laser diode controller (LDC 3744C) and decided to leave stuff as it is and continue either tomorrow or on Monday. Right now we closed the optical fiber of AS55 with a cap and it remains unmounted. The RF cables of REF DET and AS55 were left hanging near the 1Y1 rack.

  10058   Wed Jun 18 15:25:06 2014 NichinUpdateElectronicsBBPD Transimepedence plot

 Motivation:

To measure the transimpedence of  the Broadband photodiode (D1002969-v8), using a New focus photodiode (1611) as reference. The amplitude modulated Jenne Laser (1.2mW) was used @20mA

The steps involved in getting the transimpedence:

Acquiring data

  • The following conditions were set on Network Analyzer Agilent 4395:

1) Frequency sweep range: 500KHz to 300 MHz.

2) Number of Points sampled in  the range: 301

3) Type of sweep: Logarithmic

  • Set the NA to give the corresponding transfer function value (output of BBPD over output of 1611) and also Phase response in degrees.
  • Save the data into floppy disk for processing on the computer.

Plotting

  • The matlab code attached (Trans_plot.m) will then give plots for the absolute values of transimpedence in V/A.
  • Logic involved in the code will be presented clearly in a separate Elog. 

 Results

The Plots of transimpedence obtained are attached. The data and matlab code used is in the zip file.

The transimpedence of  Broadband photodiode (D1002969-v8) was around 1200 - 1300 V/A for most of the range (2), but the value started falling as the frequency approached 200 MHz. 

  10062   Wed Jun 18 18:16:26 2014 NichinUpdateElectronicsChanges to the PD frequency response measurement system

[Nichin, Eric G, Koji]

Continuing out work from elog:10037, we wanted to check if the frequency response of AS55. Having figured out exactly how to use the Laser diode controller (LDC 3744C), we hooked up a fiber power meter to the optical fiber illuminating AS55 (that we disconnected from its mount last Friday ) and raised up the current to 150mA to get almost 0.8mW power reading.

When aligning the fiber to illuminate the PD, we found that the beam was pretty wide. So we pulled out the collimator and tweaked it to get a focused beam. The fiber was mounted back and was aligned to get a maximum DC reading. The multimeter readout 30mV finally. Taking the transimpedence as 200ohm approx., the hot current is about 1.5mA.

Network analyzer was now connected to the modulation input of the laser and the RF output from REF DET and AS55 (inputs to RF switch at rack 1Y1) were connected as input to measure the transfer function. We got just noise on the scope of NA. So, then we tried REFL33 as the Input and still got nothing (We were also not sure if this PD was properly illuminated, we did not check). However the REF DET was giving a nice response on the scope. Turns out all the PDs were disconnected form the Demodulator (D990511) on rack 1Y2.

On closer inspection the RF cable between domodulator and RF switch that was labelled AS55 had a loose SMA connector at the switch end. I will have to fix that tomorrow . For the time being Koji connected the cable labelled REFL33 to the AS55 demodulator and we finally got a response form the AS55 PD on the NA. However no readings were recorded. The power supply to REF DET was turned off in the end as Eric G claimed that it has been ON for almost a year now, which is not a good thing. Also, we removed the modulation input from NA to the diode laser and terminated the input with a 50ohm terminator.

We planned to pull out and check each and every RF cable (especially the SMA ends for faulty soldering and loose connections) and fix/ replace them as needed.

  10079   Fri Jun 20 11:41:18 2014 NichinUpdateElectronicsTransimpedence measurement-BBPD

EDIT: Please ignore the following data. The revised data and plot are in Elog 10089 

Yesterday evening, I conducted the same measurements done in Elog-10059 using the same REF PD (NF 1611) and the same model of BBPD, but on different piece that needed to be checked. 

I moved the NA from near rack 1Y1 to the Jenne laser table and back again after the readings were done.

 Acquiring data

  • The following conditions were set on Network Analyzer Agilent 4395:

1) Frequency sweep range: 1MHz to 300 MHz.

2) Number of Points sampled in  the range: 201

3) Type of sweep: Logarithmic

  • Set the NA to give the corresponding transfer function value (output of BBPD over output of 1611) and also Phase response in degrees.
  • Save the data into floppy disk for processing on the computer.

 Results

The Plots of transimpedence obtained are attached. The data and matlab code used is in the zip file.

The transimpedance of  Broadband photodiode (D1002969-v8) was around 50kV/A-70kV/A (Unusually high) for most of the range (2), but the value started falling as the frequency approached 200 MHz.

 

The high impedance might be because the PD is faulty.   

 

 

 

 

  10082   Fri Jun 20 16:36:44 2014 NichinUpdateElectronicsRF cables removed

 [Nichin, Eric G]

As mentioned in Elog 10062, we found RF cables running between demodulators in rack 1Y2 and RF switch in 1Y1 to have bad SMA connectors (No shield / bad soldering / no caps).

we pulled out all the cables belonging to PD frequency response measurement system , 8 in total, and all of them about 5.5m in length.

Their labels read :

REFL33, REFL11, REFL55, AS55, POX11, REFL165, POP22 and POP110. 

All of them are now sitting inside a plastic box in the contorl room.

On another note, instead of fixing all the cables ourselves, Steve and Eric G decided to order custom made RF cables from Pasternack as professionally soldered cables are worth it. We have placed an order for 2 cables (RG405-550CM) to check out  and test them before we order all of the cables.

  10086   Sat Jun 21 01:25:12 2014 NichinHowToElectronicsPD Trasimpedence measurement theory

 Here is the logic that I have been using to calculate the transimpedence of PDs. Please let me know if you think anything is wrong.

  10087   Sat Jun 21 01:46:28 2014 NichinUpdateElectronicsBBPD Transimepedence plot

Sorry for the late update Koji.

There was a bug in my code that was pointed out by koji and here is the revised plot of transimpedence. The correct code attached.

The transimpedence value is unusually high, about 50kV/A-70kV/A for most of the range. The same was observed when the transimpedence was calculated on another BBPD in Elog.

It is highly unlikely that both the BBPDs are faulty and might be because I am doing the calculations wrong. Must dig deeper into this. Maybe it is a good idea to try the shot noise method of calculating the transimpedence and see how the values turn out. Will do that ASAP.

  10089   Mon Jun 23 21:16:14 2014 NichinUpdateElectronicsTransimpedence measurement-BBPD

  [Nichin, Koji] 

Today evening, me and koji decided to get down to the problem of why the trasimpedence plots were not as they were supposed to be for Broadband photodiode (D1002969-v8) S1200269. There were a few problems that we encountered:

  • Turns out the REF PD was not illuminated properly, for maximum output. The DC output voltage turned out to be much higher than the previous measurement. Since I assumed that the REF PD had not been touched since the first day I took readings, I did not check this.
  • The fork holding the Test PD was a bit out of shape and only one side of it was clamping down the PD. This made the PD vulnerable swivel about that one side. We replaced it with a new one.
  • I was setting the current diving the Jenne laser to about 20mA and this resulted in nocthes at higer frequencies in the network analyzer due to over driving of the diode laser. Once we reduced this to about 12.5-13 mA they disappeared. Also, the current limit setting was set at 40mA which is way too high for the jenne laser and might have resulted in damaging it if someone had accidentally increased the current. We have now set it at 20mA.

After these changes the measurements are as follows:

I moved the NA from near rack 1Y1 to the Jenne laser table. 

 Acquiring data

  • Jenne Laser driving current: 12.8mA 
  • The following conditions were set on Network Analyzer Agilent 4395:

 

1) Frequency sweep range: 1MHz to 300 MHz.

2) Number of Points sampled in  the range: 801

3) Type of sweep: Logarithmic

  • Set the NA to give the corresponding transfer function value (output of BBPD over output of 1611) and also Phase response in degrees.
  • Save the data into floppy disk for processing on the computer.

 Results

DC output voltage of REF PD: 0.568V

DC output voltage of BBPD: 18mV

Power incident on REF PD and BBPD respectively: 0.184mW  and 0.143mW

Hence, Responsivity for REF PD and BBPD respectively:  0.315 A/W and 0.063 A/W 

Responsivity given in the Datasheet for REF PD and BBPD : 0.68 A/W and 0.1 A/W

 

 

The reason for these differences are unknown to me and must be investigated.

The Plots of transimpedence obtained are attached. The data and matlab code used is in the zip file.

The transimpedance of  Broadband photodiode (D1002969-v8) S1200269 was around 1kV/A-2kV/A for most of the range, but the value started falling as the frequency approached 100 MHz. This BBPD is best when used at 10-30 MHz.

  10093   Tue Jun 24 16:52:43 2014 NichinUpdateElectronicsAn RF cable re-installed

Quote:

 [Nichin, Eric G]

As mentioned in Elog 10062, we found RF cables running between demodulators in rack 1Y2 and RF switch in 1Y1 to have bad SMA connectors (No shield / bad soldering / no caps).

we pulled out all the cables belonging to PD frequency response measurement system , 8 in total, and all of them about 5.5m in length.

Their labels read :

REFL33, REFL11, REFL55, AS55, POX11, REFL165, POP22 and POP110. 

All of them are now sitting inside a plastic box in the contorl room.

On another note, instead of fixing all the cables ourselves, Steve and Eric G decided to order custom made RF cables from Pasternack as professionally soldered cables are worth it. We have placed an order for 2 cables (RG405-550CM) to check out  and test them before we order all of the cables.

 The new RF cables arrived. But unfortunately we did not realize that RG405 was a Semi-rigid coax cable, with a copper shielding. These are meant to be installed in setups that will not be changed / disturbed. We need to order a different set of cables. The new cables have joined the other cables in the plastic box mentioned above.

For now to check if the old setup is still working, I have installed an RF cable (that we earlier pulled out and looks like in good shape, labelled REFL33) between the AS55 Demodulator output PD RF MON in rack 1Y2 and the network analyzer input. Since Manasa and the others were busy working with the interferometer, I did not switch on the laser and did not take any readings. The power supply to REF DET remains off.

I will continue with the measurements tomorrow morning and also try to get the data wirelessly using Alex's code. 

  10097   Wed Jun 25 02:01:21 2014 NichinSummaryGeneralWeekly Report

 Attached is the weekly work plan / equipment requirement / lab expert's presence needed for the upcoming week.

  10102   Wed Jun 25 17:13:10 2014 NichinUpdateElectronicsLaser power check - PDFR system

[Nichin, Manasa]

I wanted to make sure Alex's system of Diode laser + laser controller + optical splitter was working fine and then make a manual measurement for AS55 PD. Manasa was supervising my work and helping me with unhooking the fibers and taking power meter readings. I have tuned on the power to REF DET from under the POY table.

I switched on the laser sitting in the 1Y1 rack and turned up the driving current to 240mA. On checking the laser power readings at AS55 (AS table) and REF DET (POY table) simultaneously, we got readings of 1.6mA and 2.4mA respectively. This much difference in readings was not expected and I did not continue taking the readings for transimpedence measurement.

I will rectify if this unequal splitting of power by the 1x16 optical splitter is going to cause any difficulties for the automated PDFR system measurement technique and resolve it if needed.

 

  10105   Wed Jun 25 20:45:04 2014 NichinUpdateElectronicsAS55 Bodeplot

 [Nichin]

I finally did carry out a measurement on the network analyzer. This proves that the previous system will work properly. Just the optical splitter problem is to be taken care of.

For this, after Elog 10102, I did not touch any of the tables or photodiodes. Only turned on the laser at 1Y1 and took readings from the NA located nearby. I switched off the laser after measurements. The power to REF PD remains on.

I plotted transimpedence plots in the usual way and got ridiculous values of 15 ohms at 55MHz. Obviously there is the problem of varying amount of power illuminating the REF PD and AS55.

So, I just plotted the bode plots of transfer function got from the NA to check if the characteristics of AS55 looks as it was supposed to be and Yes! I got a nice peak at 55MHz.

 

Acquiring data

 RACK 1Y1

  • Diode Laser driving current: 240mA 
  • The following conditions were set on Network Analyzer Agilent 4395:

 

1) Frequency sweep range: 1MHz to 100 MHz.

2) Number of Points sampled in  the range: 801

3) Type of sweep: Linear

  • Set the NA to give the corresponding transfer function value (output of AS55 over output of 1611) and also Phase response in degrees.
  • Save the data into floppy disk for processing on the computer.

 

 

The experimental values obtained were:

DC output voltage of REF PD: 7.48V

DC output voltage of AS55: 53.7mV

Power incident on REF PD and AS55 respectively: 2.4mW  and 1.6mW

Taking the DC transimpedence of AS55 as 66.2 ohms (from schematic given at D1300586-v1) and for REF PD as 1E04 ohms

Hence, Responsivity for REF PD and AS55 respectively are:  0.312 A/W and 0.51 A/W

 

The data and code used are in the zip file.

  10108   Fri Jun 27 18:07:38 2014 NichinUpdateComputer Scripts / ProgramsUpdated script for acquiring data from Agilent 4395A network analyzer

The updated script for remotely getting data from Agilent 4395A network analyzer is located at /users/nichin

This network analyzer device is located at crocetta.martian (192.168.113.108)

How to run the script:

> python NWAG4395A_modified.py [filename.yml]

  1. The script accepts sweep parameters and output options via a .yml file that is written following a template that can be found at /users/nichin/NWAG4395template.yml
  2. The data obtained is stored as a .dat file and the corresponding details regarding the acquired data is in a .par parameter file
  3. You can choose to get a plot of the data obtained by specifying it in the .yml file. The plots are automatically stored as PDF.
  4. Plots, data and parameter files are all stored in a new folder that is created with a timestamp in its name.
  5. NOTE: Plotting options are only available in computers running numpy versions of 1.6.0 or above. The plotting sections of the code worked on Chiara, which has a 1.6.1 numpy, but did not work on Rossa which only had 1.3.0 numpy. Anyway, I have added an extra function that checks the version and skips the plotting part if needed.

Test Run:

I connected a simple 2MHz Low pass filter between the modulation output and signal input of the NA and ran a scan from 0Hz to 20MHz. The script was run from Chiara.

The expected plot was obtained and is attached here.

Further work:

I now have to work on setting up the RF switch in rack 1Y1 to select between required PDs and also on the code that chooses which channel is being selected.

There is also a problem of 2 8x1 RF switches being present, instead of one 16x1. Alex's code for RF switching does not take this into account.

RXA: I've deleted your plot because it didn't meet the minimal Bode plot standards. Please look up "Bode Plot" using Google/Wikipedia and try to follow some good example. Bode plot should contain Phase as well as magnitude. Also, the axes must be labeled with some physical units.

  10111   Mon Jun 30 00:18:15 2014 NichinUpdateComputer Scripts / ProgramsUpdated script for acquiring data from Agilent 4395A network analyzer

Quote:

 

RXA: I've deleted your plot because it didn't meet the minimal Bode plot standards. Please look up "Bode Plot" using Google/Wikipedia and try to follow some good example. Bode plot should contain Phase as well as magnitude. Also, the axes must be labeled with some physical units.

Sorry Rana for not giving much attention to the plot. I will definitely change the way they are being plotted.

I was more focused on getting the data acquisition to work. Also, the current script gets only the magnitude and not the phase... I still have to work on that.

  10123   Wed Jul 2 16:16:45 2014 NichinUpdateGeneralLAN wire added

 [Nichin, Eric Q]

We added a new LAN wire from Rack 1Y4 to 1Y1 to connect the RF switch at 1Y1 to the martian network. The wire is labelled "To RF Switch (1Y1)"

The wire was run along the Y arm in the tray right next to the vaccum chamber, not the one on top.

 

  10128   Thu Jul 3 16:28:38 2014 NichinUpdateElectronicsRF cables installed

 [ Nichin, Eric G]

RF cables have been installed between deomodulator output PD RF MON and the RF switch for the following PDs:

 REFL33, AS55, REFL55,REFL165,REFL11,POX11,POP22

The cables are labelled on both ends and have been run on the overhead tray.

The cabling looks neat on 1Y2, but not so much in 1Y1(RF switch). I will better organize them later.

There were quite a few more demodulator units labelled with PD names. Do any of them need to be included in the automated frequency response measurement system? Please let me know so that I can include them to the RF switch and check them for proper illumination, which i will do for all the above PDs next week.

Test run:

I tested the RF switch selection code and then the data acquisition code for the NWAG4395A network analyzer and they both seemed to work fine. I selected the channel to which AS55 is hooked up to and then remotely got its transfer function.

There is quite some noise in the system as the plot shows. Especially the phase. Maybe my driving power was a bit too low. Have to figure out the reason behind this.

Further work:

  • Make sure all the PDs are properly illuminated.
  • Create a DC voltage reading's database for all PDs.
  • Canonical plots for each PD to compare with the current data.
  • Implement a script to fit the transfer function and extract required information about the PD.

 

 

 

  10143   Mon Jul 7 17:20:09 2014 NichinUpdateElectronicsRF PDs needed

Quote:

Quote:

 REFL33, AS55, REFL55,REFL165,REFL11,POX11,POP22

There were quite a few more demodulator units labelled with PD names. Do any of them need to be included in the automated frequency response measurement system? Please let me know so that I can include them to the RF switch and check them for proper illumination, which i will do for all the above PDs next week.

 In the order that makes more sense to me, it looks like you have:

REFL11, REFL33, REFL55, REFL165,

AS55

POX11

POP22

We don't really need POP22 right now, although we do want the facility to do both POP22 and POP110 for when we (eventually) put in a better PD there.  Also, we want cabling for POP55, so that we can illuminate it after we re-install it.  If we're working on 2f PDs, we might as well consider AS110 also, although I don't know that there was a fiber layed for it.  The big one that you're missing is POY11.

 A new RF cable has been included for POY11. Cabling for POP55 and POP110 might or might not exist. I will check and report it.

ELOG V3.1.3-