This week I've got all TT stuff baked and today was testing eddy current damping and electronics.

In the beginning everything was good: ring magnets fit mirror holder holes and their interaction with actuation magnets is strong enough to keep damping magnets in the wholes. I've put the frame horizontally and kicked it, magnets were still in the whole. Brackets also fit to the TT frame.  

I've tested eddy current dumping during ring down measurements, it was strong enough.

Then I started to test electronics. I've provided signal to TT1 channels and could see it in the clean room. But then things went terrible. I just could not connect TT cables to OSEMS, there is not enough space in the OSEM for the connector to plug in.

Connector should be machines to be more narrow. There is actually no reason for a connector to have this shape. I think it was designed to fit perfectly the OSEM frame but turned out to be ~0.5 mm wider then it should be.

False alarm - the mistake was mine. Looking at the schematic diagram, the AI/Dewhite board, D000316, accepts the inputs from the DAC on the P2 connector. While restoring the connections at 1Y2, I had plugged the outputs of the DAC interface board into the P1 connectors of the AI boards. Having rectified this problem, I am now able to move the beam on the AS camera in both PIT and YAW using TT1 or TT2. So to zero-th order, this subsystem appears to work. A more in-depth analysis of the angular stability of the TTs can only be done once we re-align the arms and lock some cavities.

Summary:

The custom ribbon cables piping the coil driver board outputs to the eLIGO (?) TTs (a.k.a. TT1 and TT2) are damaged. They need to be re-made. I can't find any pin-mapping for them.

Details:

While waiting for the LSC photodiode whitening switching cross-connect work to be done, I thought I'd re-align the IFO a bit. However, I was unable to find any beam making it to the REFL/AS ports despite some TT steering. I remembered that Chub had undone the TT connections at 1Y2 as well, and thought I'd check the cabling to make sure all was in order. On going to the rack, however, I found that these connections were damaged at the coil-driver end (see Attachment #1), presumably during the cable extraction. These need to be re-made...😔 

While debugging this problem, c1lsc models crashed. I ran the reboot script this morning to bring the models back. There was a 0x4000 error on the DC indicators for the c1lsc models (mx_stream error which couldn't be fixed by restarting the mx service) the first time I ran the script so I did it again, now the indicator lights are in their nominal state.

To debug the issue of the suspected drifting TTs further, I temporarily hijacked CH0-CH8 of ADC1 in the c1lsc expansion chassis, and connected the "MON" outputs of the coil drivers (D010001) to them via some DB9 breakouts. The idea is to see if the problem is electrical. We should see some  slow drift in the voltage to the TTs correlated with the spot walking off the IPPOS QPD. From the wiring diagram, it doesn't look like there is any monitoring (slow or fast) of the control voltages to the TT coils, this should be factored into the Acromag upgrade of c1iscaux/c1iscaux2. EPICS monitoring should be sufficient for this purpose so I didn't setup any new DQ channels, I'll just look at the EPICS from the IOP model.

Atm1,  TT 1.5" high adaptor base will be back from the shop in 10 days.

Atm2,  There is no PITCH damping, YAW edie current damping works well at 0.5 mm gap

Atm3,  Adjustable Al -disc that contains a small magnet is purely designed.

We have to come up with a solution to have damping in PITCH

[Koji, Rana, Nic, Steve]

We went to the 25-pin D cable which connects to the TT1 quadropus and succeeded eventually in swapping pins 12/24 into the 13/25 positions.

1. The D-sub connector is a custom made LIGO part and so it doesn't at all work to use the standard pin extractor tools to move the pins out; we should have investigated this before spending all this time poking at and possibly damaging the existing connector.
2. To move the pins, we have to partially dis-assemble the connector and fish the pins/wires through the appropriate holes. Unfortunately, the design is such that we nearly lose all of the pins when trying to do this. Pictures describe the story better than words.
3. After the swap we tried to test the TT, but again wasted some time because the vac feedthrough was incorrectly labeled. The 25-pin feedthrough labeled as "PZT1" does not, in fact, connect to the TT. Instead, its the one slightly above it that is labeled "Pico". I have moved the PZT1 sticker up to match the actual connector. In order to discover this, we beeped through several stages of the coil driver, cable system. WE need to order some in-line D-sub breakouts for 25pin, 37pin, and 9pin which are similar to the ones we have now for 15pin. These are better than the green terminal block breakouts.
4. After this, we were able to see the TT move, but elected to leave the final piece of the work (determining which microD goes with which coil) to when Jamie gets back.
5. The TT screen is not good: it needs to be just like the usual sus screen so that we can put in offsets, excitations, etc. Perhaps also the ASC-TT screen can link to the TT:SUS screens. We can just copy the eLIGO TT screens to get going.

[Koji, Rana, Nic, Steve]

I recalled that we used an optical lever to check if the TT is moving or not.
We used a laser pointer on a tripod, which was prepared by Steve.

I should also note that we stepped back the eddy current dampers from the magnets
in order to enhance the motion of the suspension. They should be restored in the end.

The mini-D connectors on the OSEMs are loosened so that we can plug the cables in.
This requires a specific metric allen key that is stored in a clean tool box with an aluminum foil.

 I had asked Q to write this down on a piece of paper, but then I forgot to transcribe it into the elog....

The TT screen matrix, at least for TT1, is flipped or something.  When Eric moved the pit slider, the optic moved in yaw, and vice versa. 

We need to fix this, but for now, here's the situation when TT1 was pointed correctly at MMT1:

                       PIT    YAW

TT1 Pit slider     |  1000   1000  | --->   700 UL


     0             | -1000   1000  | --->   700 LL


TT1 Yaw slider     |  1000  -1000  | --->  -700 UR


    0.7            | -1000  -1000  | --->  -700 LR

The confusing thing is that Koji and I confirmed (by plugging in the correct cable to the correct sensor) that "UL" on the screen goes to the UL coil, and the same for the other 3 coils.  This needs investigation / fixing.


Tip Tilt pitch adjustment on existing-in vacuum suspension. This can be added by a simple installation of a 1.25" long 2-56 threaded rod with nuts.

Arnaud has taken 1 TT suspension from the 40m clean lab to Downs for modal testing. Estimated time of return is tomorrow evening.

[Jamie,Manasa]

We've been trying to figure out the connector for the TTs. Since, we found the cables were plugged in wrong in TT1; when triggered in pitch, the mirror moves in yaw and viceversa.

Referring to the cabling diagram, D1000234-v10, we infer that connectors go as J2 - LR, J3 - UR, J4 - LL, J5 - UL and the connections are made looking at the mirror from behind.

 The view looking at the optic from the back:  

UL    UR

LL    LR

Update

TT1 was moved in pitch to restore flashing in the arms on Wednesday (Mar 20) so that it doesn't drift too far off making it difficult to lock again. Since then, the arms have been flashing without any drifting and TTs have remained untouched. The hysteresis has disappeared.

 I doubt that it has truly disappeared. Can you please make a measurement of it and quantify the hysteresis using some angle sensor?

I'm running a script that moves TT1 and TT2 randomly in some restricted P/Y space to try and find an alignment that gets some light onto the TRY PD. Test started at gpstime 1228967990, should be done in a few hours. The IMC has to remain locked for the duration of this test. I will close the PSL shutter once the test is done. Not sure if the light level transmitted through the ITM, which I estimate to be ~30uW, will be enough to show up on the TRY PD, but worth a shot I figure.

Test was completed and PSL shutter was closed at 1228977122.

I removed the ND filter from the ETMYT camera to facilitate searching for a TRY beam. This should be replaced before we go back to high power.

 Manasa, Jenne

We started off to try and get TT2 working. We used the cables Jamie had already prepared while working on TT1 and used them to connect TT to the channels in 1Y3.

There were sma cable connectors already running between the channels 5-8 on the board to the UL,LL,UR and LR. Triggering the UL LL UR LR matrix on epics did not show any analog voltage at the output analog channels on the board. Talking to Jamie over phone, we inferred  that the  SMA cables that were already left connected corresponded to channels assigned for TT4 in epics.  So we set the connections right and could see analog voltage outputs corresponding to epics triggers.

We connected the ribbon cables running from the board to the TT. But changing pitch and yaw did not do anything to the TT2 mirror. We opened the BS door and checked if  the tt cables were connected to the post. We beeped the cable running from the board to TT (we also traced the cable's trail through the cable rack pile from 1Y3 to BSC). Using a function generator at the board end of the cable, we could not observe anything at the TT end of the cable.

We ran out of options on what can be done next and closed the doors. We hope Jamie can fix the problem once he returns next week.

Was the connection between the feedthrough (atmosphere side) and the connector on the optical table confirmed to be OK?

We had a similar situation for the TT1. We found that we were using the wrong feedthrough connector (see TT1 elog).

 The major problem that Manasa and I found was that we weren't getting voltage along the cable between the rack and the chamber (all out-of-vac stuff).  We used a function generator to put voltage across 2 pins, then a DMM to try to measure that voltage on the other end of the cable.  No go.  Jamie and I will look at it again today.

Everything was fine.  Apparently these guys just forgot that the cable from the rack to the chamber flips it's pins.  There was also a small problem with the patch cable from the coil driver that had flipped pins.  This was fixed.  The coil driver signals are now getting to the TTs.

Investigating why the pitch/yaw seems to be flipped...

[Jenne, Manasa]

PZT2 was removed from the BS table, and packed away in a foil-lined plastic box.

PRM oplev path has been altered, including installation of a 3rd mirror, to accommodate TT2, which is larger than PZT2.

      * Unfortunately, PR3 is a few mm more north than is indicated in the CAD drawing, so I wasn't able to place the oplev mirrors exactly as Manasa indicated in elog 7815. 

      * We came up with a different layout. Photos were taken.  We will need to confirm that the IPPOS, AS, and GreenX beams all clear past the oplev mirrors, but by imagining straight lines between mirrors for those beams, I think we should be okay.  but we must confirm when we have real beams.

TT2 was installed, according to the placement in the diagram.   Dogged down just as TT1 - one dog for the riser, 3 dogs for the TT base which also squish the riser.  You should be able to see this in the photos. Without having installed the PRM target, it looks like the input beam is hitting pretty close to the PRM's center.  Tomorrow Jamie The Tall can install the PRM target for us so we can confirm.

Photos - I'm posting them on Picasa here.  The new camera, and the fact that you can rotate the viewfinder, is amazing for overhead in-chamber photos.  Seriously, it's much easier to take useful photos.  It's great.

Tomorrow:

We remove the ITMX door first thing.  If Steve isn't here, we'll ask Koji or Bob to help us with the crane. 

First thing on the alignment list is to finalize TT2's pointing.  Put a target in front of PR2, put on the PRM target, etc, etc.  We're basically back to the same alignment procedure as we've been doing the last few vents.

Item for meditation:

Do we trust ourselves, or do we want to think about installing a 'bathroom mirror' so we can see the face of PR3 while we are pumped down?

[Bob, Manasa, Jenne]

We opened the ITMX heavy door.  Before getting too far, we realized that we had to do the fancy pin swapping before we can activate TT2.  So....

[Nic, Jenne]

We followed the instructions in elog 7869, and the associated Picasa album, and swapped the pins for the in-vac connector that will go to TT2.  Pretty easy, since the procedure was already well documented.

We then looked at the beam location on PR2, and the beam is ~2 inches up and to the left (as viewed from the front) from the center of the optic.  This is very easily correctable with the actuators, so we're leaving TT2 as it is.

We replaced GE81 by PZT2907A (PNP transistor) in TTFSS #7, it's working fine.

  Last time I broke Q4 transistor, which is used in the low noise power module for TTFSS, (see the schematic) and could not find another PZT2907A, so GE81 was used temporarily. Now we changed it back to PZT2907A as designed.  I tested it by checking the voltage outputs of the board. It works fine, all voltage outputs are correct. I labeled one of the slot on the blue cabinet tower and kept the rest of the transistors there.

[Den, Jenne]

Den noticed that the -15V LED on the TTFSS board was not illuminated.  A further symptom of the FSS being funny was that the PC RMS Drive was constantly high (3.6 ish) and the FAST Monitor was very high, often saturated. 

We took the TTFSS board out, and put an extender card in, and it looked like all of the correct power is being supplied to the board (the +\- 24V LEDs on the extender card were illuminated).  Just to check, we put the board back in, and this time both +\- 15V LEDs came on.  So it looks like the board is fine, it just wasn't seated in there all the way.

Now the readbacks on the FSS screen look good (PC RMS Drive is less than 1, FAST Mon is 5ish), the MC is locked, and I think we're back in business. 

I keep a set of new TTFSS for 40m in electronic cabinet along the North arm.

The set number is #6. It is working and has not been modified by me.

Other two sets,# 5 and #7, are kept at PSL lab.

I brought TTFSS set #7 to 40m and kept it in the electronic cabinet.

note that Q4 transistor has not been replaced back to PZT2907A yet. It's still GE82.

Q3 is now pzt3904, not PZT2222A.

 Using instructions from Bram and Suresh, I was able to plug in connectors to BOSEMs. Today I've tested electronics, everything works good. Jamie made an medm screen and channels for TTs. Sliders for pitch and yaw go from -100 to 100 counts. Calibration to angle is 1e-5 rad / count.

TTs are in the clean room waiting for installation.

Please leave here what was the instruction by Bran and Suresh so that the other people can redo it sometime later!

 The connectors can be plugged into the BOSEMs if we loosen the two screws which hold down the mini-D connector and the flex circuit.  Tighten the screws after the connector is pluged in.

[Yoichi, Jenne]

Hooray!!! The Tip Tilts are completely done!  The only things remaining are (1) Install 4 TTs in chambers sometime in September and (2) do shake tests / take TFs of the spare.

Today we balanced and characterized #'s 1 and 5.  All 5 TTs are waiting happily on the flow bench in the cleanroom for installation.

[Jenne, Manasa]

2 colors 2 arms realized!

1. Spot centering:

We spot centered the IR in both arms.
- Use TT1 and TT2 to center in Y arm (I visually center the spots on the ITM and ETM and then use TTs iteratively)
- Use BS-ETM to center in X arm

Spot positions after centering
               X arm            Y arm
         itmx    etmx        itmy    etmy
pitch    -0.86    0.37        1.51    0.05
yaw      0.01    -0.1        0.08    0.10

2. TT1 drifting in pitch (Bistable)
During the arm alignment routine for spot centering, we observed that TRY dropped (from TRY = 0.9 until the arm lost lock) every 40minutes or so. The arm was relocked by moving TT1 in pitch. The (locking - unlocking due to drift - relocking) cycle was monitored and we observed that it was bistable i.e. if TT1 was moved up in pitch (0.2 on the slider) to relock for the first time ; the next time it lost lock, TT1 had to be moved down by nearly the same distance to relock the arm.
Moving TT2 or the testmasses did not help with relocking the arms; so TT1 seems to be the one causing all th trouble atleast for today.

3. ALS - green alignment

We then moved on to Ygreen.  We used the out of vac steering mirrors to center the beam on the 2 irises that are in place on the table, which was a good starting place.  After doing that, and tweaking a small amount to overlap the incident and reflected beams on the green steering mirrors, we saw some mode lock.  We adjusted the end table steering mirrors until the Ygreen locked on TEM00.  We then followed Rana's suggestion of locking the IR to keep the cavity rigid while we optimized the green transmission.  Yuta, while adjusting ITMY and ETMY (rather than the out of vac mirrors) had been able to achieve a green transmission for the Yarm of ~2700 counts using the GTRX DC PD that's on the table. We were only able to get ~2200, with brief flashes up to 2500.

After that, we moved on to the X arm.  Since there are no irises on the table, we used the shutter as a reference, and the ETM optic itself.  Jenne looked through the viewport at the back of the ETM, while Manasa steered mirrors such that we were on the center of the ETM and the shutter.  After some tweaking, we saw some higher order modes lock.  We had a very hard time getting TEM00 to stay locked for more than ~1 second, even if the IR beam was locked.  It looks like we need to translate the beam up in pitch.  The leakage of the locked cavity mode is not overlapped with the incident beam or the promptly reflected beam.  This indicates that we're pretty far from optimally aligned.  Manasa was able to get up to ~2000 counts using the same GTRX PD though (with the Ygreen shutter closed, to avoid confusion).  Tomorrow we will get the Xarm resonating green in the 00 mode.

We need to do a little cleanup on the PSL green setup.  Yuta installed a shutter (I forget which unused one he took, but it was already connected to the computers.), so we can use it to block the PSL green beam.  The idea here is to use the 4th port of the combining beam splitters that are just before each beat PD, and place a PD and camera for each arm.  We already have 2 PDs on the table connected to channels, and one camera, so we're almost there. Jenne will work on this tommorrow during the day, so that we can try to get some beat signals and do some handoffs in the evening.

- I took the shutter from AS table to use it for the PSL green. It was sitting near MC REFL path unused (elog #8259).

- If X green lock is not tight, maybe temporarily increasing loop gain helps. This can be done by increasing the amplitude of the frequency modulation or increasing green refl PD gain. Also, if X green beam spot is too wiggly compared with Y green, it is maybe because of air flow from the air conditioner (elog #6849). I temporarily turned it off when I did X green steering last summer.

- X green transmission on PSL table reached ~270 uW last summer (elog #6849, elog #6914). Y green transmission is now ~240 uW and ~2700 counts at maximum. So, X green transmission should reach ~3000 in counts.

- Did you have to re-align TRX path? We moved the harmonic separator on X end table horizontally to avoid IR TRX clipping before beam centering on X arm (elog #8162). I wonder what is the current situation after the beam centering.

 - We tried locking with the air conditioning switched off at the X-end

- TRX path is unaltered (IR still goes through the center of the harmonic separator.

During the vent we have tried to measure the distances of the optical tables for BS-ITMX and BS-ITMY.
We need to take into account the difference between the AutoCAD drawing and the reality.

X direction distance of the table center for BS and ITMX:
84.086" (= 2135.8mm)
(This is 84.0000" in AutoCAD drawing)

Y direction distance of the table center for BS and ITMX:
83.9685" (= 2132.8mm)
(This is 83.5397" in AutoCAD drawing)

We used two scales attached each other in order to measure the distance of the certain holes on the tables.

We got more numbers that were estimated from several separated measurements.
I think they were not so accurate, but just as a record, I also put the figure as an attachment 2.

I think this table will help us to fix the scanning range of the Marconi frequency. This will also help in predicting the position of the resonance peak corresponding to the injected frequency.

f_diff = f_m ±80 MHz ;                     f_diff = N*FSR_y ;              FSR_y = 3.893 MHz.

Too many cavity poles! It should be just a single pole. Please show us your OLG Bode plot on the same plot as each of the individual pieces of the loop, so we can see what contributes to the TF.

Here are the transfer functions of the individual components along with the OLTF.

RXA: please spend some time trying to make the plot more useful: grid lines, distinguishable colors, zoom into important range, some text descriptions of each trace, comments on differences between theory and reality, etc., etc., etc

While modelling the system, I had no way of knowing the gain of each individual component. The individual transfer function of the PDH box and overall open loop is known, so I combined the Cavity, PZT, Low Pass filter, and Photodiode into one block, and fitted its overall gain to match with the overall OLTF of the system. 

Using this setup, with the pole values taken from Gautam’s thesis, and the fitted PDH zpk values; I was able to get the OLTF of the model to agree with the OLTF experimentally taken. I now use the model as a base for the setup, to test controller designs, impulse response, and stability margins. There is some deviation from the experimental value (~10dB in magnitude in the low frequency range, ~20 deg phase). 

We can see that at lower frequencies, the PDH box influences the transfer function while at higher frequencies the other components contribute. This is a good sign as we primarily want to increase the stability and performance of the system in the 10Hz to 20kHz range (Which is where the AUX laser noise is suspected to dominate in the ALS beat note) and this can be easily adjusted by changing the PDH box parameters. 

 I tried to simulate this block using the SR560, I tested with both a single and double pole at 30kHz. The 2-pole setup seemed to be the closest to the combined cavity, pzt, photodiode, low pass filter and summer combo (plant).  

With two poles at 30kHz and the fitted PDH controller implemented on the Moku: Go, I took an OLTF, and it was deviating ~20 dB from the model (in hindsight, I could've increased the gain in sr560 (but I dismantled the setup to use the SR560 to take OLTF at with digital controller at XEND) will take another reading if I get time, but still the phase is way off).  

I have moved onto implementing the digital PDH box on the actual system, I have not been able to design an optimal controller, but using the fitted values, and increasing gain on the Moku, I was able to achieve similar (not necessarily better in terms of open loop characteristics as that of the original PDH box. I will get some more data and post the comparisons of OLTFs and noises when locked.
 

I wrote a Python code to simulate the AUX laser stabilisation system. It takes the poles and zeroes of the individual components (cavity, pzt, summer, low pass filter, pdh controller) and combines them, and shows the stability margins and impulse responses. Now any PDH controller designed can be easily plugged into the code and the stability and perfomance of the loop can be tested.

Trying to make a tabletop simulation of the setup, using an SR560 preamplifier with a second order pole at 30kHz to model the arm cavity and other ocmponents. The Moku:Go will be the digital PDH controller, and transfer of the setup will be taken with another Moku:Pro (not enough Gos). The individial and combined OLTF of the setup is taken and compared to the similar data. 

I loaded the same digital filter into both the Moku:Pro and Moku:Go, to see if there was any difference. I used the multi instrument mode, with Digital Filter and Frequency Response analyser. To my surprise, every configuration else exactly same, the transfer function was different for both Go an Pro. I also ran the Filter on the Go, and took the frequency response using the Pro, the transfer function was identical to the Go taken internally.The Pro is giving the expected transfer function. Idk if i am missing something here.

I will be testing out the digital controller on the Xend AUX setup today, replacing the anlaogue PDH box with the Moku:Go fitted with, see if i can get a lock with the digital version, see any problems that might come up.

Summary:

I have written a code(a basic one which needs a lot of improvements, but still does the job) for taking multiple measurements from the AG4395A. I have also written a separate code for plotting the data taken from the previoius code along with the error bars upto 1 standard deviation.

Details on How To Operate AG4395A:

1. Under 'Measurement' tab, press the 'Meas' button and select the Analyzer Type (Network Analyzer or Spectrum Analyzer).
2. Then under the same options select which 'ratio' needs to be measured (A/R, B/R or A/B).
3. Then press the 'Format' button to select what needs to be measured (Eg - Log|Mag|, Phase, etc.).
4. In order to measure and see two channels at the same time (Eg - Log|Mag| and Phase), press the 'Display' button and select 'Dual Channel'.
5. Using the 'Scale' button we can set the scale/div or use autoscale and also set the attenuator values of the different channels.
6. The 'Bw/Avg' option gives us an averaging option which averages few sets of data to produce the result. In doing this we lose quiet a lot of data and the resulting plot isn't able to give us the information on the statistical errors.
7. This option also allows us to set the 'Intermediate Frequency' Bandwidth. This basically dictates the sampling rate of the Analyzer. The lower the IF bw, the higher is lesser is the noise (due to less uncertainty in Frequency).
8. The 'Cal' button helps us calibrate the Analyzer to the current connections and signals. This is done because there is usually a difference in the 'cable lengths' for the two channels which introduces an extra phase term depnding upon the rf frequency. The calibration can be simply done by removing the Device Under Test (DUT) and diectly connecting the coaxial cables to the channels. After this the 'Calibrate Menu' allows us to calibrate the response using the short, open and thru methods.
9. Now, under the 'Sweep' tab, the 'Sweep' button allows us to select various sweep options such as 'Sweep Time' (Auto, or set a time), 'Number of Points' (b/w 201-801) and 'Sweep Type' (Linear, Log, List Freq. etc.).
10. Using the 'Source' button we can set the source power in dBm units (Usually kept as -20 to -10 dBm).
11. The Scan Range can be set in a few ways such as using the start and end points or using the center and span range/width.
12. After setting up all of the above, we can take the measurement either from the analyzer itself or using one of the control PCs. The command to download the data from AG4395A is netgpibdata -i 192.168.113.105 -d AG4395A -a 10 -f [filename].

Brief Details on How the 'AGmeasure' command works:

AGmeasure is a python script developed by some of the people who work at 40m. It is set as a global command and can be used from within any directory. The source code is in the scripts folder on the network, or else it can also be found in Eric Quintero's git repository. This command accepts at the very least a parameter file. This is supposed to be a .yml file. A template (TFAG4395Atemplate.yml) can be found in the scripts folder or in Eric's repo. There are some other options that can be passed to this command, see the help for more details.

The Multi_Measurement Script:

This script calls the 'AGmeasure' command repetitively and keeps storing the data files in a folder. Right now, the script needs to be fed in th template file manually at prompt.

The Test_Plotting Script:

This script plots the a set of data files obtained from the above mentioned script and produces a plot along with the errors bands upto 1 standard deviation of the data. The format (names) and total number of text files need to be explicitly known, for now at least.

Attachments:​

1. The output test files and the two scripts.
2. This is the 'Bode Plot' for a data set made using the above two scripts.

To Do:

• Improve upon the two scripts to be as compatible as the AGmeasure function itself.
• Try and incorporate the whole script into AGmeasure itself along with improving upon the templates.
• The above details, with some edits perhaps, can go into the 40m wiki too(?).

Update: Increased the font size in the plot. Added a few comments to the two scripts

To Do: Need to consider the transfer function as a single physical quantity (both the magnitude and phase) and then take the averages and calculate the standard deviation and then plot these results. 

EDIT:

The attachment with the test files and the code now also contains a pdf with all the relations/equations I have used to calculate the averages and errors.

I copied the netgpibdata folder onto rossa (under the directory ~/Agilent/), which contains all the necessary scripts and templates you'll need to remotely set up, run, and download the results of measurements taken on the AG4395A network analyzer. The computer will communicate with the network analyzer through the GPIB device (plugged into the back of the Agilent, and whose communication protocol is found in the AG4395A.py file in the directory ~/Agilent/netgpibdata/).

The parameter template file you'll be concerned with is TFAG4395Atemplate.yml (again, under ~/Agilent/netgpibdata/), which you can edit to fit your measurement needs. (The parameters you can change are all helpfully commented, so it's pretty straightforward to use! Note: this template file should remain in the same directory as AGmeasure, which is the executable python script you'll be using). Then, to actually set up, run, and download your measurement, you'll want to navigate to the ~/Agilent/netgpibdata/ directory, where you can run on the command line the following: python AGmeasure TFAG4395Atemplate.yml

The above command will run the measurement defined in your template file and then save a .txt file of your measured data points to the directory specified in your parameters. If you set up the template file such that the data is also plotted and saved after the measurement, a .pdf of the plot will be saved along with your .txt file.

Now if you want to just download the data currently on the instrument display, you can run: python AGmeasure -i 192.168.113.105 -a 10 --getdata

Those are the big points, but you can also run python AGmeasure --help to learn about all the other functions of AGmeasure (alternatively, you can read through the actual python script).

Happy remote measuring! :)

I've modified the lsc.mdl and lsp.mdl files back to an older configuration, where we do not use an IO processor.  This seems to let things work for the time being on megatron while I try to figure out what the is wrong with the "correct" setup which includes the IO processor.

Basically I removed the adcSlave = 1 line in the cdsParameters block.

I've attached a screen shot of the desktop showing one filter bank in the LSP model passing its output correctly to a filter block in the LSC.  I also put in a quick test filter (an integrator) and you can see it got to 80 before I turned off the offset.

So far this is only running on megatron, not the new machine in the new Y end.

The models being use for this are located in /cvs/cds/caltech/cds/advLigoRTS/src/epics/simLink

Took finer measurements of the x-arm aux laser actuator tranfer function (10 kHz - 1 MHz, 1024 pts/decade) using the Moku.

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I took finer measurements using the moku by splitting the measurement into 4 sections (10 - 32 (~10^4.5) kHz, 32 - 100 kHz, 100 - 320 kHz, 320 - 1000 kHz) and then grouping them together. I took 25 measurements of each ( + a bonus in case my counting was off), plotted them in the attached notebook, and calculated/plotted the standard deviation of the magnitude (normalized for DC offset). Could not upload to the ELOG as .pdf, but the pdf's are in the .zip file.

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Next steps are to do the same stdev calculation for phase, which shouldn't take long, and to use the vectfit of this better data to create a PZT inversion filter.

(Tuesday, Jun 20, 2023)

While the X end hardware was being updated, I decided to take an open loop transfer function of the green laser locking system at the Y end. It was already set up to measure the frequency response using the SR785, and i just had to take the inputs to it and just directly plug it into the Moku:Go. I was trying to test the 'Dynamic amplitude' mode of the Moku:Go's frequency response analyser, which "Increases the measurment dynamic range by reducing output signal amplitude when stauration is detected at input". There was no noticeable difference from a normal measurment without that feature and from that of the X arm measurment taken earlier. I wanted to take measurments of individual components, but didnt as I did not want to disturb the setup at the Y too much. I carefully replugged the bnc cables back into the SR785 and returned it to the way it was.

Took the backup (snapshot) of nodus' /home/export as of Aug 25, 2023

controls@nodus> cd /cvs/cds/caltech/nodus_backup
controls@nodus> rsync -ah --progress --delete /home/export ./export_230825 >rsync.log&

After finishing my last elog entry, I monitored the digital loop's error signal (the control signal for the fast loop) and the output to the laser heater remotely, (from West Bridge), using dataviewer. The ref cav surrounding can temperature was set to 36 degrees C.

With the loop closed and a gain of 0.008, after seeing the output voltage to the laser heater (TMP_OUTPUT) remain fairly constant and the error signal (TMP_INMON) stay close to zero for ~3 hours, I tried to step the temperature. (This was at 2am last night). I was working remotely from West Bridge. To step the temperature I used the following command:

ezcawrite C1:PSL-FSS_RCPID_SETPOINT 35.5

Rather than change the can temperature to 35.5 C, it outputted:

C1:PSL-FSS_RCPID_SETPOINT=0.

It had set the setpoint to 0 degrees C, which was essentially turning the heater off. I tried resetting it back to 36 and had no luck. I tried changing the syntax slightly.: ezcawrite C1:PSL-FSS_RCPID_SETPOINT=36 and ezcawrite C1:PSL-FSS_RCPID_SETPOINT (36). No success.

I ran over to the 40m and changed the temperature back to 36 manually. The in-loop temp sensor had decreased to 31.5 degrees C before I was able to step the setpoint back up. The system seems to have recovered from this large impulse though, and the laser has remained locked.

(5 hours of minute-trend data)

From left to right: 

Top: Out-of-loop can temp sensor; Voltage sent to heat can

Middle: signal sent to heat the laser (TMP_OUTPUT); room temp

Bottom: Error signal for slow loop (sampled control signal from fast loop); In-loop can temp sensor

At 9:30 this morning (7 and a half hours after accidentally setting the setpoint to zero), I came in to the 40m. TMP_OUTPUT was still decreasing but was slowing somewhat, so I decided to step the can temperature up half a decree to 36.5 C.

TMP_OUTPUT responded to the step, but it is also oscillating slowly with room-temperature changes, and these oscillations are on the same order as the step response. The oscillations look like the room-temp oscilations, but inverted. (TMP_OUTPUT reaches maxima when RMTEMP reaches minima). Oddly, there does not appear to be much of a time delay between the room temperature and TMP_OUTPUT signals. I would expect a time delay since there's a time constant for a room-temperature change to propagate into the cavity. Perhaps the laser itself is susceptible to room-temperature changes and those propagate into the laser cavity on a much faster time scale. I don't know the thermal coupling of ambient temperature changes into the laser.

(24-hours of second-trend data)

Options are:

--If the system can handle it, do a larger temperature step (3 degrees, say), so that I can more clearly distinguish the oscillations with room temp from the step response.

--Insulate the cavity with foam (will in principle make the temperature over the can surrounding the ref cav more uniform and less affected by room temperature changes).

--Insulate the laser? Is this possible?

--Leave the system as is and, as a first approximation, fit the room-temp data to a sine wave and subtract it off somehow from my data to just see the step response.

--Don't bother with steps and just try to get the transfer function from out-of-loop temperature (RCTEMP, which is affected by temperature noise from the room) to TMP_OUTPUT via taking the Fourier transforms of both signals.

I'm flying out tomorrow morning, so I'll either need to figure out how to step the temperature set point of the can remotely, successfully, or I'll need someone to manually enter in the temperature steps for me in the control room.

[Jenne Kiwamu Joe Osamu Steve Koji]

Yesterday (21st), we closed the BSC and the four testmass chambers.

We splitted the team into three.

- Wiping team (Jenne/Kiwamu)
- Suspension team (Osamu/Koji)
- Door closing team (Joe/Steve)

While the wiping team was working, the suspension team prepared the next suspension.
Once the mirror was wiped, the suspension team restored that suspension at the position of the markings on the table.

After the wipe of the first mirror, the wiping team got experienced and they were the fastest among the teams.
So the wiping team worked as the second suspension team when necessary.

All of us became the closing team after the last suspension has been restored.

We checked that we still have the Michelson fringes and the oplev pointings.

In total, the work was very efficient such that we only took four hours for the entire process.

We left the suspension marking on the optical tables because they are quite useful.

[Steve, Bob, Joe, Zach, Alberto, Kiwamu, Koji]

We opened the OMC-IMC access connector, ITMX North door, and ITMY West door.
We worked from 9:30-11:00.
The work was quite smooth thanks to the nice preparation of Steve as usual.

Thank the team for the great work!