40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
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ID Date Author Type Category Subjectup
  63   Mon Nov 5 14:44:39 2007 waldmanUpdateOMCPZT response functions and De-whitening
The PZT has two control paths: a DC coupled path with gain of 20, range of 0 to 300 V, and a pair of 1:10 whitening filters, and an AC path capacitively coupled to the PZT via a 0.1 uF cap through a 2nd order, 2 kHz high pass filter. There are two monitors for the PZT, a DC monitor which sniffs the DC directly with a gain of 0.02 and one which sniffs the dither input with a gain of 10.

There are two plots included below. The first measures the transfer function of the AC monitor / AC drive. It shows the expected 2 kHz 2d order filter and an AC gain of 100 dB, which seems a bit high but may be because of a filter I am forgetting. The high frequency rolloff is the AA and AI filters kicking in which are 3rd order butters at 10 kHz.

The second plot is the DC path. The two traces show the transfer function of DC monitor / DC drive with and with an Anti-dewhitening filter engaged in the DC drive. I fit the antidewhite using a least squares routine in matlab constrained to match 2 poles, 2 zeros, and a delay to the measured complex filter response. The resulting filter is (1.21, 0.72) : (12.61, 8.67) and the delay was f_pi = 912 Hz. The delay is a bit lower than expected for the f_pi = 3 kHz delay of the AA, AI, decimate combination, but not totally unreasonable. Without the delay, the filter is (1.3, 0.7) : (8.2, 13.2) - basically the same - so I use the results of the fit with delay. As you can see, the response of the combined digital AntiDW, analog DW path is flat to +/- 0.3 dB and +/- 3 degrees of phase.

Note the -44 dB of DC mon / DC drive is because the DC mon is calibrated in PZT Volts so the TF is PZT Volts / DAC cts. To calculate this value: there are (20 DAC V / 65536 DAC cts)* ( 20 PZT V / 1 DAC V) = -44.2 dB. Perfect!

I measured the high frequency response of the loop DC monitor / DC drive to be flat.
Attachment 1: 07110_DithertoVmonAC_sweep2-0.png
Attachment 2: 071105_LSCtoVmonDC_sweep4-0.png
Attachment 3: 07110_DithertoVmonAC_sweep2.pdf
07110_DithertoVmonAC_sweep2.pdf 07110_DithertoVmonAC_sweep2.pdf
Attachment 4: 071105_LSCtoVmonDC_sweep4.pdf
071105_LSCtoVmonDC_sweep4.pdf 071105_LSCtoVmonDC_sweep4.pdf
  5149   Tue Aug 9 02:34:26 2011 JennyUpdatePSLPZT transfer function measurement

Using a PDA255 on the PSL table, I measured the amplitude response of the NPRO PZT, sweeping from 10kHz to 5 MHz.

I took a run with the laser beam blocked. I then took three runs with the beam unblocked, changing the temperature of the laser by 10 mK between the first two runs and by 100mK between the second and third runs.

At the end of the night I turned off the network analyzer and unplugged the inputs. I'm leaving it near the PSL table, because I'd like to take more measurements tomorrow, probing a narrow bandwidth where the amplitude response is low.

On the PSL table, I'm still monitoring the reflected light from the cavity and the transmitted light through the cavity on the oscilloscope. I'm no longer driving the NPRO temperature with the lock-in.

I closed the shutter on the NPRO laser at the end of the night.

I'll log more details on the data tomorrow morning.

  179   Fri Dec 7 11:33:24 2007 waldmanOmnistructureOMCPZT wiring
The 2 pin LEMO connector has got an unmarked pin and a pin marked by a white half-circle.
The unmarked pin is connected to the side of the PZT attached to the mirror.
The marked pin is connected to the side of the PZT attached to the tombstone.
  6351   Mon Mar 5 03:50:49 2012 kiwamuUpdateIOOPZT1 PITCH railing

PZT1 started railing in the pitch direction and because of this TRY doesn't go more than 0.7. I will leave it as it is for tonight.

Tomorrow I will shift the alignment of the MC to make the PZT1 happier.

Quote from #6300

PZT1, the one with Koji's custom mid-HV driver (#5447), is getting degraded.


  7323   Thu Aug 30 20:31:35 2012 JenneUpdateIOOPZT1 and PZT2 set to center of their ranges

[Koji, Jenne]

Jamie and Koji pointed out that we need to be doing the in-vac alignment with the PZTs at the center of their ranges.  Also, we confirmed that they were set to "closed loop off", so the strain gauges were not supplying any feedback.

PZT1 was set to 0 for both pitch and yaw, since it has a very limited range of motion right now, so 0 is close enough.

For PZT2, Koji and I moved the slider in pitch and yaw, and watched the LCD output monitor on the PZT driver at the bottom of 1Y3.  We saw the value on the LCD change between slider values +4 to -6 for PZT2 yaw, so it is set to -1 as the center.  We saw the value on the LCD change between slider values -4 to +5 for PZT2 pitch, so it is set to +0.5 as the center.   Beyond these slider values (the sliders all go -10 to +10), the LCD value didn't change, either at 0, or at the maximum. 

Since PZT1 doesn't really move, this shouldn't affect any of the alignment work that Suresh and I did last night, although we should quickly confirm tomorrow. On the agenda for tomorrow is adjusting PZT2 such that we hit the center of PR2 (and hopefully that will also put us through the center of the PRM target, if the alignment was done well enough last time), so it's okay that we have only now set it to the center of its range.

  6410   Wed Mar 14 04:03:37 2012 kiwamuUpdateIOOPZT1 and associate extra works

As the PZT1 has not been functional, I have been aligning the Y arm to the input beam instead of aligning the beam to the Y arm.

It turned out that this procedure leads to two extra works everytime after alignments of the Y arm:

  1. The Y green beam must be always aligned to the Y arm
    • The amount of the misalignment was found to be relatively big compared with how it used to be.
  2. The PSL beat note setup must be always realigned because the Y green path is determined by the orientation of the Y arm.
    • In the past I didn't often realign the beat note path, but currently it needs to be pay more attentions.

Sad ..

Quote from #6357

   The polarity for controlling the PZT1 PITCH seems to have flipped for some reason.


  5368   Fri Sep 9 11:59:58 2011 kiwamuUpdateIOOPZT1 doesn't work

Last night I noticed that PZT1 didn't work properly

I am not sure what is going on. Today I will try localizing the cause of the problem.

As far as I remember it was perfectly working at the time just after we readjusted the OSEMs on MC1 and MC3 (Aug 23th)


The symptoms are :

  + No response to both pitch and yaw control from EPICS (i.e. C1:LSC-PZT1_X and C1:LSC-PZT1_Y)

  + When a big value (-3 or so) from EPICS was applied, the PZT1 mirror suddenly jumped.

     However it turned out it just corresponded to a state where OOR (Out Of Range) LED lights up.


I did some brief checks :

  + checked the voltage going into the HV amplifiers' "MOD" input. Those are the voltage coming out from DACs and controlled from EPICS.

   --> looked healthy. They went from -10 to 10 V as expected (although the HV amp takes up to only +/-5V).

  + swapped the ''MOD" input cables such that C1:LSC-PZT1 controls the PZT2 HV and vice versa.

    --> The PZT2 mirror was still controlable, but the PZT1 mirror still didn't move. So the DAC and EPICS are innocent.

  + swapped the D-dub cables, which are directly going into the feedthroughs, such that the PZT1 HV drives the PZT2 mirrors and vice versa.

    --> the PZT2 mirror became unable to be controlled. For the PZT1 mirror, only PITCH worked smoothly.

  5447   Sat Sep 17 14:04:45 2011 KojiUpdateIOOPZT1 driver in place

The PZT driver is now in place. The actual PZTs are not connected yet!

It is accommodated on Ben's connector adapter board.

The panel has additional connectors now: two inputs and a power supply connector.

The supply voltage is +/-30V (actual maximum +/-40V), and the input range is +/-10V
which yields the output range of -5V to 30V. The gain of the amplifier is +2.

It is confirmed that the HV outputs react to the epics sliders although the PZT connector is not connected yet
so as not to disturb the locking activity.

When we engage the PZT connector, we should check the HV outputs with an oscilloscope to confirm they
have no oscillation with the capacitances of the PZTs together with the long cable.

Attachment 1: P9171579.JPG
Attachment 2: P9171580.JPG
  7857   Wed Dec 19 18:40:00 2012 JenneUpdateIOOPZT1 removed, TT1 in place

[Manasa, Jamie, Jenne]

PZT1 has been removed, and is wrapped in foil and stored in a (labeled) plastic box.

We beeped the cable between the cable holder bracket on the in-vac table, and the outside of the feedthrough.  Things are mirrored, so pins 1,14 (one edge on the feedthrough) go to pins 13,25 on the in-vac cable bracket.

Tip Tilt, serial number ### (Manasa will get the serial number and put it in the elog) was taken out of the cleanroom, for use as TT1.

We checked the epics controls from the TT screen that Jamie made a while back (accessible from the ASC tab on the sitemap) to the output of the AI board.  Things were very weird, but Jamie fixed them up in the model, then rebuilt and restarted the ASS model so that now the epics channel corresponding to, say, UL actually actuates on the UL output of the boards.

We tested the cables from the rack to the feedthrough, and discovered that they are also mirrored, to undo the mirroring between the feedthrough and the in-vac bracket.

Jamie made an adapter cable to take the pinout of the coil driver boards correctly to the pinout of the quadrupus cable, through this double-mirroring (i.e. no net mirror effect).

We set up a laser pointer on a tripod outside the door of the MC chamber (where the access connector usually is), and pointed it at the back of the TT.  Den or whomever put the cable on the TT didn't follow the diagram (or something got messed up somewhere), because when we actuate in pitch (+ on the uppers, - on the lowers), we see the TT move in yaw, and vice versa. 

We are in the process of removing the quadrupus from the TT, figuring out which connector goes where, putting it on correctly, and re-testing.

Depending on how far things get tonight, Jamie and Manasa may ask Steve to help them remove the BS door, so they can get started on replacing PZT2 with TT2.

  7858   Wed Dec 19 19:28:12 2012 ManasaUpdateIOOPZT1 removed, TT1 in place


Tip Tilt, serial number ### (Manasa will get the serial number and put it in the elog) was taken out of the cleanroom, for use as TT1.


Depending on how far things get tonight, Jamie and Manasa may ask Steve to help them remove the BS door, so they can get started on replacing PZT2 with TT2.

Tip-Tilt TT1


I have fixed TT1 close to what it's position looks like in the CAD drawing. Only 2/3 of TT1 rests on the table...so we need to be extra careful when we will move it for alignment.

Serial Number:  SN 027

dcc number: D1001450-V2

 We are still in the process of removing the quadrupus from the TT, figuring out which connector goes where, putting it on correctly, and re-testing.

We closed the IMC chamber with light doors calling it a day!


  5431   Fri Sep 16 11:15:12 2011 KojiUpdateIOOPZT1 situation

[Koji Kiwamu]

- We have checked the situation of the broken Piezo Jenna PZT (called PZT1)

- Tested PZT1 by applying a dc voltage on the cables. Found that pitch and yaw reasonably moving and the motions are well separated each other.
  The pitch requires +20V to set the IPPOS spot on the QPD center.

- Made a high-voltage (actually middle voltage) amp to convert +/-10V EPICS control signal into -5 to +30V PZTout. It is working on the prototype board and will be put into the actual setup soon.


- The Piezo Jenna driver box has 4 modules. From the left-hand side, the HV module, Yaw controller, Pitch controller, and Ben abbot's connector converter.

- We checked the voltage on Ben's converter board. (Photo1)
  It turned out that the red cable is the one have the driving voltage while the others stays zero.

- We hooked a 30V DC power supply between the red cable and the shield which is actually connected to the board ground.

- Applying +/-10V, we confirmed the strain gauge is reacting. If we actuated the pitch cable, we only saw the pitch strain gauge reacted. Same situation for yaw too.

- Kiwamu went to IPPOS QPD to see the spot position, while I change the voltage. We found that applying +20V to the pitch cable aligns the spot on the QPD center.


- I started to make a small amplifier boards which converts +/-10V EPICS signals into -5V to +30V PZT outs.

- The OPAMP is OPA452 which can deal with the supply voltages upto +/-40V. We will supply +/-30V. The noninerting amp has the gain of +2.

- It uses a 15V zener diode to produce -15V reference voltage from -30V. This results the output voltage swing from -5V to +35V.
The actual maximum output is +30V because of the supply voltage.

- On the circut test bench, I have applied +/-5V sinusoidal to the input and successfully obtained +5V to +25V swing.

- The board will be put on Ben's board today.

Attachment 1: P9151574.JPG
Attachment 2: P9161576.JPG
Attachment 3: P9161577.JPG
  7440   Wed Sep 26 01:10:34 2012 JenneUpdateIOOPZT2 not working?!?! MC back to normal

[Jenne, Evan, Den]

MC REFL beam is back on the PD, and the mode cleaner locks.  It looks like we're a little high on the MC Refl camera, but the MC spots were measured, and don't look like they changed from Friday (or maybe Monday?), the last time they were measured. We took this to be acceptable MC alignment, and did not touch the PSL table's pointing.

The laser power reduction optics were removed, and placed out of the way on the PSL table (where do they belong?).  PSL-POS and PSL-ANG aren't quite perfectly centered, but a beam dump had been in the way of that path, so I don't know if they drifted bad, or if it was a sudden thing.  The beam is still hitting the QPDs though.  After removing the beam power reducing optics, we recentered the MC REFL beam on the REFL PD, still not touching any PSL alignment.  MC mirrors were aligned (Den did this work while I showed Evan around, so I don't know by how much), and MC Trans was maximized (really MC Refl was minimized, making sure that the unlocked MC Refl was the usual 4.something units on the EPICS readback.

We turned on the PZT high voltage supplies for the output steering PZTs and for the input steering PZTs.  We left the OMC locking PZT supplies off, since we're still not using the OMC.  Sadly, the beam coming out of the AS port looks clipped somewhere.  [SELF: attach the videocapture shot when you get to work tomorrow] We tried moving PZT2's sliders, but nothing happened!!! I can move BS and the ITMs to get the beam mostly unclipped, but I really need to be able to move the PZTs, or at least one of them.  IPPOS and IPANG beams are hitting the QPDs (although they're not centered perfectly), so the PZTs came back mostly to the same positions, but not exactly.  Evan and I sat next to the input steering PZT controllers in 1Y3, and moved the sliders around.  For most of the range, nothing changes on the LCD screen for either PZT2 pitch or yaw.  Yaw can make 2 small steps near the far negative side of the slider, but nothing happens for most of the slider.  Pitch really doesn't do anything for any part of the slider.  We ensured that the LED labeled "CL ON" was not illuminated, next to the button labeled "closed loop", for all 4 controllers (PZT1 and 2, pitch and yaw).  Sad!!   I don't know if the LCD screen on the front panel of the PZT controllers is a readback of signal supplied to the PZTs, or of the strain gauges.  I really hope it's the controller that's not working, rather than the PZTs themselves.  The PZTs were fine before we vented, and Koji and I did our centering of the PZT range check during the vent, so they were fine then.  What happened???  All PZT high voltage supplies were off during the pump-down.  I turned them off yesterday, and Evan and I turned them back on tonight around 9:30pm or 10pm.  What else could make them bad?

Without being able to move PZT2, just using BS and / or ITMs, I was unable to completely make the beam look nice on the AS camera.  I came close, but it still seems a little bit funny, and I had to move the suspended optics quite a bit to find that place.  This is not good. 

  7509   Tue Oct 9 00:25:33 2012 JenneUpdateIOOPZTs - hacky solution in place!!

[Evan, Jenne]

We applied some volts across both the pitch and yaw pin sets of the ribbon cable that goes to PZT2.  We ended up with ~40V yaw and ~14.5V pitch.  That was the nice happy center of the clipping that we can see on the AS camera.  Once we found the center of the PZT clipping range with the ITMY beam, we recentered the AS camera (actually, this took a few iterations, but now it's good). 

We then aligned MICH, but aren't able to get it to lock.  Before falling asleep, we have decided to align the PRM and SRM, so right now we have a flashing DRMI.  Both the SRMI and PRMI look a little funny the closer you get to 'good' alignment, so I'll investigate a little more tomorrow, and include pictures.  (The video capture script has barfed again, and I'm not in the mood to deal with it today.)

  4108   Tue Jan 4 21:21:57 2011 kiwamuUpdateIOOPZTs are connected to c1iscaux

I connected PZT1 and PZT2 to a slow front end machine c1iscaux.

Now we are able to align these PZTs from the control room via epics.


   Since we removed C1ASC that was controlling the voltage applied on the PZTs, we didn't have the controls for them for a long time.

So Rana and I decided to hook them up to an existing slow front end machine temporarily.

(probably the best solution is to connect them to C1LSC, which is fast enough to dither them.)

We actually found that c1iscaux is the proper machine, because it looked like it used to control the PZTs a long long time ago.

Moreover, c1iscaux still has DAC channels named like C1:LSC-PZT1_X, and so on.


  Below shows a screen shot of the medm screen for controlling the PZTs, invoked from a button on sitemap.adl ( pointed by a black arrow in the picture below)

The current default values are all zero at the right top sliders.


  5589   Fri Sep 30 18:06:24 2011 kiwamuSummaryIOOPZTs straing guage


  12139   Fri May 27 11:54:22 2016 VarunUpdateGeneralPackage delivery

A package labelled 'UPS Ground' has arrived.


  4986   Mon Jul 18 22:26:43 2011 NicoleUpdateSAFETYPainful Voltage Regulator and Circuit-Testing Lessons

Today I learned some important circuit-building lessons while testing my photosensor circuit box (i.e. how NOT to test a circuit and, conversely, things that should be done instead). 

I blew my first circuit today. The victim is in the photo below (bottom 7805 voltage regulator). The plastic covering fell off after I removed the fried regulator.  After checking various components, I figured out that I blew the circuit because I had forgotten to ground the regulator.  Although this was very unfortunate, I did make an important discovery. While testing the voltage output of the 7805 voltage regulator (I put a new one), I discovered that contrary to the claims of the datasheet, an input voltage of 5V will not produce a steady 5V supply. I found that at 5V, my regulator was only producing 4.117 V. I was using a 5 V supply because I wanted to use only 1 power supply (I was using a two-channel power supply that had a fixed 5V output to produce the +15, -15, ground, and 5 V I need for my photosensor circuit box).  After seeing this, I got a second power supply and am now using 10V to as an input for the regulator to produce 4.961V. I found that from a voltage range of 10V to 15 V, the regulator produced a steady  4.961 V supply. I have decided to use 10V as an input. My newly-grounded voltage regulator did not smoke or get hot at 10V.

After several more debugging trials (my LED was still not lighting up, according to the infared viewer), I learned another painful lesson. I learned DO NOT USE CLIP LEADS TO TEST CIRCUITS!!!! Initally, I was powering my circuit and making all of my connections between the photosensor head (2 photodiodes and 1 LED) with clip leads. This was a BAD IDEA BECAUSE CLIP LEADS ARE UNSTABLE AND IT IS VERY EASY TO SHORT A CIRCUIT IF THEY ACCIDENTALLY TOUCH! I did not realize this important lesson until my photosensor circuit was once again burning. Confused as to why my circuit was once again burning, I foolishly touched the voltage regulator. As you can see on the top voltage regulator in the photo below, my finger left its mark on the smoldering voltage regulator. As you cannot see the wincing on my face as I try to type this long elog, I will painfully type that the voltage regulator left its own mark on my finger (an ugly sore little welt).  Suresh has taught me a valuable lesson: WHEN DEALING WITH SOMETHING OF QUESTIONABLE/UNKNOWN TEMPERATURE, USE YOUR NOSE, NOT YOUR FINGER TO DETERMINE IF THAT COMPONENT IS HOT!!!! 



To make my circuit-testing safer, upon the suggestion of Suresh, I have since removed the clip leads and inserted a 12 pin IDC component (pictured below). There are 12 pins for the 6 inputs I will get from each of the 2 photosensor heads. I have requested orders for a 16 pin IDC connector, 15 pin Dsub male part, 15 pin Dsub feed-thru, 9 pin Dsub male part (2), and 9 pin Dsub feed-thru (2). After receiving these components, I should be able to safely test my circuit.


 In the meanwhile, I can explore SimMechanics and try to figure out how to use the accelerometer

  4990   Tue Jul 19 13:45:22 2011 SureshUpdateSAFETYPainful Voltage Regulator and Circuit-Testing Lessons

There is should be a few IDC connectors in the lab (and some ribbon cable) using which you can proceed with the testing of the circuit, if you prefer.  If not we can get them from our ever helpful electronics division at Downs.  In any case there is no need to lose time waiting for parts to arrive.


  14172   Tue Aug 21 03:09:59 2018 johannesOmnistructureDAQPanels for Acromag DAQ chassis

I expanded the previous panels to 6U height for the new DAQ chassis we're buying for the upgrade. I figure it's best if we stick to the modular design, so I'm showing a panel for 8 BNC connectors as an example. The front panel has 12 slots, the back has 10 plus power connectors, switches, and the ethernet plug.

I moved the power switch to the rear because it's a waste of space to put it in the front, and it's not like we're power cycling this thing all the time. Note that the unit only requires +24V (for general operation, +20V also does the trick, as is the situation for ETMX) and +15V (excitation field for the binary I/O modules). While these could fit into a single CONEC power connector, it's probably for the better if we don't make a version that supplies a large positive voltage where negative is expected, so I put in two CONEC plugs for +/- 15 and +/- 24.

I want to order 5-6 of these as soon as possible, so if anyone wants anything changed or sees a problem, please do tell!

Attachment 1: auxdaq_40m_6U_front.pdf
Attachment 2: auxdaq_40m_6U_rear.pdf
Attachment 3: auxdaq_40m_6U_BNC.pdf
  14283   Wed Nov 7 19:20:53 2018 gautamUpdateComputersPaola Battery Error

The VEA vertex laptop, paola, has a flashing orange indicator which I take to mean some kind of battery issue. When the laptop is disconnected from its AC power adaptor, it immediately shuts down. So this machine is kind of useless for its intended purpose of being a portable computer we can work at optical tables withno. The actual battery diagnostics (using upower) don't report any errors. 

  14672   Thu Jun 13 22:21:44 2019 KojiConfigurationCDSPaola wireless connected to martian

SURFs had trouble connecting paola to martian via wireless.
Of course, it requires a fixed IP but it had not it yet. So I went to chiara and gave as "paolawl". Note that the wired connection has .111 and it is "paola".

Followed the instruction on http://nodus.ligo.caltech.edu:8080/40m/14121

  1482   Tue Apr 14 17:20:36 2009 YoichiUpdateComputer Scripts / ProgramsParallel Optickle
I wrote a parallel version of tickle() function for Optickle.
The attached ptickle.m, which provides ptickle() command, can be used as a drop-in replacement of tickle() command.
Just download it and place it in the @Optickle directory.
This command will run multiple instances of Matlab to calculate the frequency responses in parallel.
The speed gain is roughly proportional to the number of CPU cores you use.

To use multiple cores, you have to run matlabpool() command first. See the comment at the beginning of ptickle.m for more detail.
The progress bar is disabled at this moment because it is not clear for me how to make a single progress bar from multiple instances of Matlab.

I sent the code to Matt, so this may be included in the next release of Optickle.
Attachment 1: ptickle.m
% Compute DC fields, and DC signals, and AC transfer functions
% This is a parallelized version of tickle. You have to run matlabpool(n)
% command before using this command. matlabpool(n) will invoke n instances
% of matlab workers in your computer. Once you have started those workers,
% you can reuse them many times (i.e. you don't have to run matlabpoo(n)
% every time you use ptickle). Usually n should be equal to the number of
% CPU cores in your computer, but the Matlab parallel computing toolbox has
% the limit of maximum 4 workers for a local computer. If you use a cluster 
% of computers across a network, this limit does not apply. But I haven't
... 393 more lines ...
  16429   Tue Oct 26 16:56:22 2021 PacoSummaryBHDPart I of BHR upgrade - Locked PMC and IMC

[Paco, Ian]

We opened the laser head shutter. Then, we scanned around the PMC resonance and locked it. We then opened the PSL shutter, touched the MC1, MC2 and MC3 alignment (mostly yaw) and managed to lock the IMC. The transmission peaked at ~ 1070 counts (typical is 14000 counts, so at 10% of PSL power we would expect a peak transmission of 1400 counts, so there might still be some room for improvement). The lock was engaged at ~ 16:53, we'll see for how long it lasts.

There should be IR light entering the BSC!!! Be alert and wear laser safety goggles when working there.

We should be ready to move forward into the TT2 + PR3 alignment.

  16425   Mon Oct 25 17:37:42 2021 AnchalSummaryBHDPart I of BHR upgrade - Removed optics from BSC

[Anchal, Paco, Ian]

Clean room etiquettes

  • Two people in coverall suits, head covers, masks and AccuTech ultra clean gloves.
  • One person in just booties to interact with outside "dirty" world.
  • Anything that comes in chamber, first cleaned outside with clean cloth and IPA. Then cleaned by the "clean" folks. We followed this for allen keys, camera and beam finder card.
  • Once the chamber cover has been removed, cover the annulus with donut. We forgot to do this :(

Optics removal and changes

We removed the following optics from the BSC table and stored them in X-end flowbench with fan on. See attachment 1 and 2.

  1. IPPOS SM2
  2. GRX SM2
  3. PRM OL1
  4. PRMOL4
  5. IPPOS SM3
  6. IPANG SM1
  7. PRM OL2
  8. Unidentified optic inbetween IPPOS45P and IPPOS SM3
  9. Beam block behing PR3
  10. Beam block behind GR PBS
  11. GR PBS
  12. GRPERI1L (Periscope)
  13. PRMOL3
  14. IPPOS45P
  15. Cylindrical counterweight on North-west end of table.
  16. Cheap rectangular mirror on South west end of table (probably used for some camera, but not in use anymore)
  17. IPANGSM2

We also changed the direction of clamp of MMT1 to move it away from the center of the able (where PRM will be placed)

We screwed in the earthquake stops on PRM and BS from front face and top.

We unscrewed the cable post for BS and PRM oplevs and loved it in between SR3 and BS and screwed it lightly.

We moved the PRM, turned it anti-clockwise 90 degrees and brought it in between TT2 and BS. Now there is a clear line of sight between TT2 and PR2 on ITMY table.

Some next steps:

  • We align the input beam to TT2 by opening the "Injection Chamber" (formerly known as OMC chamber). While doing so, we'll clear unwanted optics from this table as well.
  • We open ITMX chamber, clear some POP optics. If SOS are ready, we would replace PR2 with SOS and put it in a new position.
  • Then we'll replace PR3 with an SOS and align the beam to BS.

These are next few days of work. We need atleast one SOS ready by Thursday.

Photos after today's work: https://photos.app.goo.gl/EE7Mvhw5CjgZrQpG6

Attachment 1: rn_image_picker_lib_temp_44cb790a-c3b4-42aa-8907-2f9787a02acd.jpg
Attachment 2: rn_image_picker_lib_temp_0fd8f4fd-64ae-4ccd-8422-cfe929d4eeee.jpg
  16431   Wed Oct 27 16:27:16 2021 AnchalSummaryBHDPart II of BHR upgrade - Prep

[Anchal, Paco, Ian]

Before we could start working on Part II, which is to relocate TT2 to new location, we had to clear space in front of injection chamber door and clean the floor which was very dusty. This required us to disconnect everything we could safely from OMC North short electronics rack, remove 10-15 BNC cables, 4-5 power cords and relocate some fiber optic cables. We didn't had caps for fiber optic cables handy, so we did not remove them from the rack mounted unit and just turned it away. At the end, we mopped the floor and dried it with a dry cloth. Before and after photos in attachments.


Attachment 1: OMCNorthBefore.jpeg
Attachment 2: OMCNorthAfter.jpeg
  16433   Wed Oct 27 16:38:02 2021 AnchalSummaryBHDPart II of BHR upgrade - Relocation of TT2 and MMT1/2 alignment

[Anchal, Paco]

We opened BSC and Injection Chamber doors. We removed two stacked counterweights from near the center of the BS table, from behind TT2 and placed them in the Xend flow bench. Then we unscrewed TT2 and relocated it to the new BHR layout position. This provided us with the target for the alignment of MMT1 and MMT2 mirrors.

While aligning MMT1 and MMT2, we realized that the BHR layout underestimated the clearance of the beam from MMT2 to TT2, from the TT1 suspension unit. The TT1 suspension stage was clipping our beam going to TT2. To rectify this, we decided to move the MMT2 mirror mount about a cm South and retry. We were able to align the beam to the TT2 optic, but it is a bit off-center. The reflection of TT2 now is going in the general direction of the ITMX chamber. We stopped our work here as fatigue was setting in. Following are some thoughts and future directions:

  • We realized that the output beam from the mode cleaner moves a lot (by more than a cm at MMT2) between different locks. Maybe that's just because of our presence. But we wonder how much clearance all beams must have from MC3 to TT2.
  • Currently, we think the Faraday Isolator might be less than 2 cm away from the beam between MMT1 and MMT2 and the TT1 suspension is less than 2 cm away from MMT2 and TT2.
  • Maybe we can fix these by simply changing the alignment on TT1 which was fixed for our purposes.
  • We definitely need to discuss the robustness of our path a bit more before we proceed to the next part of the upgrade.

Thu Oct 28 17:00:52 2021 After Photos: https://photos.app.goo.gl/wNL4dxPyEgYTKQFG9

  16434   Wed Oct 27 18:11:37 2021 KojiSummaryBHDPart II of BHR upgrade - Relocation of TT2 and MMT1/2 alignment

Closed the PSL shutter @18:11
During the vent, we want to keep the cavity unlocked if not necessary.


  16435   Wed Oct 27 18:16:45 2021 KojiSummaryBHDPart II of BHR upgrade - Relocation of TT2 and MMT1/2 alignment

- Moving the MMT2 south by a cm is fine. This will give you ~0.5cm at TT1 without changing the other alignment much.
- IMC mode is moving because of your presence + HEPA blow.
- 2cm at Faraday is plenty for the beam diameter of a few mm.


  16438   Thu Oct 28 17:01:54 2021 AnchalSummaryBHDPart III of BHR upgrade - Adding temp fixed flat mirror for PR2

[Anchal, Paco, Ian]

  • We added a Y1-2037-0 mirror (former IPPOS SM2 mirror) on a fixed mount in the position of where PR2 is supposed to be in new BHR layout.
  • After turning out all lights in the lab, we were able to see a transmitted beam on our beam finder card.
  • We aligned the mirror so that it relfects the beam off to PR3 clearly and the reflection from PR3 hits BS in the center.
  • We were able to see clear gaussian beams splitted from BS going towards ITMX and ITMY.

Photos: https://photos.app.goo.gl/cKdbtLGa9NtkwqQ68

  16628   Thu Jan 27 18:03:36 2022 PacoSummaryBHDPart III of BHR upgrade - Install PR2, balance, and attempt OSEM tuning

[Paco, Anchal, Tega]

After installing the short OSEMs into PR2, we moved it into ITMX Chamber. While Tega loaded some of the damping filters and other settings, we took time to balance the heavily tilted ITMX chamber. After running out of counterweigths, Anchal had to go into the cleanroom and bring the SOS stands, two of which had to be stacked near the edge of the breadoard. Finally, we connected the OSEMs following the canonical order

LL -> UR-> UL

LR -> SD

But found that UR was reading -14000 counts. So, we did a quick swap of the UR and UL sensors and verified that the OSEM itself is working, just in a different channel... So it's time to debug the electronics (probably PR2 Sat Amp?)...

PR2 Sat Amp preliminary investigation:

  • The UR channel (CH1 or CH4, on PR2 Sat Amp)  gives negative value as soon as an OSEM is connected.
  • Without anything connected, the channel reports the usual 0V output.
  • With the PDA inputs of PR2 Sat Amp shorted, we again see 0V output.
  • So it seems like when non-zero photodiode current goes, the circuit sees a reversal of gain polarity and the gain is roughly half in magnitude as the correct one.
  16629   Thu Jan 27 20:46:38 2022 KojiSummaryBHDPart III of BHR upgrade - Install PR2, balance, and attempt OSEM tuning
  • Started debugging D1002818 / S2100737 (8:30PM)
  • Confirmed the issue of the negative output of the UR sensor with the dummy OSEM connected at the air side of the ITMY chamber. Both PD Out and PD Mon have negative outputs.
  • The same issue remains when the dummy OSEM box is connected to the chassis with a short DB25M/F cable at the rack.
  • Started debugging the setup at the workbench.
    • CH1 TIA Output=-3.0V / CH2 (in question) TIA Output =-2.7V => No Problem
    • CH1 Whitening Out=+3.0V / CH2 Whitening Out=-1.4V => Problem
    • Resolder the components around whitening CH2 => no change
    • Remove AD822 and replace with a new one => CH2 Whitening OUt = +2.7V ==> Problem solved
    • PD1~3 channels of the left and right PCBs tested with the OSEM box ==> nearly +3V/-3V differential output (All Clear)
    • Chassis closing
  • Chassis restored in Rack 1Y1 and the normal output with the dummy OSEM box confirmed
  • Mission Completed (9:30PM)
  • Elog finished (9:40PM)
  • Case closed
Attachment 1: Screen_Shot_2022-01-27_at_20.33.56.png
Attachment 2: Screen_Shot_2022-01-27_at_21.30.16.png
  16630   Fri Jan 28 10:37:59 2022 PacoSummaryBHDPart III of BHR upgrade - PR2 OSEM finalized, reinsall LO1 OSEMs


Thanks to Koji's hotfix on the PR2 SatAmp box last evening, this morning I was able to finish the OSEM installation for PR2. PR2 is now fully damped. Then, I realized that with the extreme rebalancing done in ITMX chamber, LO1 needed to be reinstalled, so I proceeded to do that. I verified all the degrees of freedom remained damped.

I think all SOS are nominally damped, so we are 90% done with suspension installation!


  16631   Fri Jan 28 11:30:52 2022 KojiSummaryBHDPart III of BHR upgrade - PR2 OSEM finalized, reinsall LO1 OSEMs

All green! Great work, Team!

  16637   Wed Feb 2 16:22:00 2022 AnchalSummaryBHDPart III of BHR upgrade - PR2 inpute matrix diagonalized

The free swinging test was successful. I ran the input matrix diagonalization code (/opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/sus_diagonalization.py) on the PR2 free-swinging data collected last night. The logfile and results are stored in /opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/PR2 directory. Attachment 1 shows the power spectral density of the DOF basis data (POS, PIT, YAW, SIDE) before and after the diagonalization. Attachment 2 shows the fitted peaks. I chose to not type out the matrix values now. One can find them in teh repo links above.


Attachment 1: PR2_FreeSwingData_PeakFitting_20220125.pdf
Attachment 2: PR2_SUS_InpMat_Diagnolization_20220202.pdf
  16638   Wed Feb 2 16:27:57 2022 AnchalSummaryBHDPart III of BHR upgrade - PR3 inpute matrix diagonalized

The free swinging test was successful. I ran the input matrix diagonalization code (/opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/sus_diagonalization.py) on the PR3 free-swinging data collected last night. The logfile and results are stored in /opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/PR3 directory. Attachment 1 shows the power spectral density of the DOF basis data (POS, PIT, YAW, SIDE) before and after the diagonalization. Attachment 2 shows the fitted peaks. I chose to not type out the matrix values now. One can find them in teh repo links above.


Attachment 1: PR3_FreeSwingData_PeakFitting_20220125.pdf
Attachment 2: PR3_SUS_InpMat_Diagnolization_20220202.pdf
  16432   Wed Oct 27 16:31:35 2021 AnchalSummaryBHDPart III of BHR upgrade - Removal of PR2 Small Suspension

I went inside the ITMX Chamber to read off specs from PR2 edge. This was required to confirm our calculations of LO power for BHR later. The numbers that I could read from the edge were kind of meaningless "0.5 088 or 2.0 088". To make it more worthwhile this opening of the chamber, we decided to remove the PR2 suspension unit so that the optic can be removed and installed on an SOS in the cleanroom. We covered the optic in clean aluminum foil inside the chamber, then placed in on another aluminum foil to cover completely. Then I traveled slowly to the C&B room, where I placed it on a flow bench.

Later on, we decided to use a dummy fixed mount mirror for PR2 initially with the same substrate thickness, so that we get enough LO power in transmission for alignment. In the very end, we'll swap that with the PR2 mounted on an SOS unit.

  16627   Thu Jan 27 17:57:35 2022 AnchalSummaryBHDPart III of BHR upgrade - Replaced small suspended PR3 with new SOS PR3 and OSEM tuning

[Anchal, Paco]

We removed the old PR3 housed in a tip-tilt style suspension and put it on the North flow bench in the cleanroom. I put PR3 in an accessible position near the North West edge of the BS chamber and balanced the table again with many weights. The OSEM tuning was very uneventful and easy. Following are the full brightness ADC counts for the OSEMs:
UL 25693. -> 12846
UR 24905. -> 12452
LL 23298. -> 11649
LR 24991. -> 12495
SD 26357. -> 13178

I was able to damp the optic easily after the OSEM installation with no issues.

Photos: https://photos.app.goo.gl/jcAqwFJoboeUuR7F9

  16733   Thu Mar 17 17:23:22 2022 AnchalSummaryBHDPart IIa of BHR upgrade - Green laser alignment

[Anchal, Yehonathan] (on Y Arm)

We first checked if the PZT mirrors M1 and M2 can be controlled. They indeed show no motion even after being connected with a power supply. So green injection path can not be aligned using cds controls right now.

We also noticed that all ETMY slow controls and monitors are offline. That's because the electronics upgrade did not include acromag chassis. This means that the DC bias adjustment is not accessible for ETMY.

Alignment work:

  • We first aligned the green injection beam to cross two irises in the injection path to ETMY chamber.
  • Then I (Anchal) went inside the ITMY chamber to find the green light. Yehonathan controlled the injection path while I gave feedback from ITMY side. We aligned injection path to get the beam near center of ITMY.
  • Then I aligned ITMY through sitemap>IFO>Align to get counter propagating reflection near the ITMY side.
  • We were able to see reflection from ETMY hitting the beam tube.
  • Since DC alignment controls of ETMY are not accessible, we used the Alignment offset in rtcds model which puts dc offset in the coil driver to get the reflected beam from ETMY to come to ITMY table, about 1 inch above the table and about 3 inch south of ITMY SOS.
  • But we got limitted by the DAC overflow on ETMY at this point. Several back and forth attempts to relief ETMY were unsuccesful.

Possible issues:

  • We think having the HV coil driver set up for ETMY is important for this alignment work if not essential. The coil drivers of ETMY are near saturation.
  • We also think that addition of two new suspensions in ITMY table and then counter weights to balance the table, has depressed table height slightly. We need to work out how to change injection path height and angle accordingly.

[Paco, Ian] (on X Arm)


  16740   Mon Mar 21 18:24:07 2022 AnchalSummaryBHDPart IIa of BHR upgrade - Green laser alignment on Yarm

[Anchal, Tega]

We did the following alignment steps on Yarm today:

  • We aligned the green beam going into the ETMY chamber to the three irises on the path.
  • We aligned ETMY to get counter-propagating prompt reflection from ETMY.
  • We were able to see light in the reflection photodiode for the green PDH loop.
  • Then we went to ITMY chamber and checked where the beam is coming to. It was coming very low in height.
  • We walked the beam on the end to get it near the center of ITMY.
  • Then we changed the ETMY alignment again to get back the reflection beam on the reflection photodiode.
  • Then we went again to ITMY chamber and changed the ITMY alignment to get counter-propagating reflection from ITMY.

After this, we came back to the control room. One peculiar thing to note is that the C1:LS-Y_REFL_DC_OUT channel is inverted i.e. it is showing negative values for the reflection DC voltage. On this signal, we see a little bit higher-order mode flashing but it is not bright enough to be seen on the face camera of the suspension. We'll continue aligning the cavity using CDS now to get TEM00 mode.

After trying for a bit, we were able to get flash of about 2000 counts which is about 16% of the max value of 12200 counts. We adjusted the ITMY angular position using the IFO_ALIGN screen but used the OPTICAL_ALIGN offset screen to adjust the angular position of ETMY. The pitch and yaw values for ITMY are 1.0360 and -0.260 respectively whereas the pitch and yaw values for ETMY are 5664.0 and -4937.0 respectively. 

  16742   Thu Mar 24 19:20:28 2022 AnchalSummaryBHDPart IIa of BHR upgrade - Green laser alignment on Yarm

[Anchal, Paco]

Uneloged: yesterday, Paco and Ian tried locking the green laser on Yend to the Y-arm. Nothing noteworthy happened, no luck.

  • Started with aligning the green injection to the Iris on table (it was misaligned) and getting it on the ITMY center.
  • Then we realized that the beam is going through the focusing leans very offceter. This makes the beam warped and deflected inside that needs to be corrected by mirrors.
  • So we decided to adjust the lens position first.
  • We realized that lens position is hard to adjust along with keeping the beam hiting ITMY.
  • So, we decided to remove the lens first and just align the green beam directly with the Iris on the table and the ITMY center. The beam became as big as ITMY when it reached there without the lens in path. We aligned it to fall on the mirror.
  • Then we placed the lens back so that the beam goes through the center of the lens.
  • Then we aligned ETMY to get the reflection back to the reflection PD.
  • But then when we checked the beam at ITMY again, it was severely missing ITMY. The possible reason is that ETMY is a diverging lens for the beam as well and changing its position changed the beam direction in the beam tube.
  • We decided to do another iteration of lens positioning with the new ETMY position. So same steps, removed lens, aligned beam with iris and ITMY, placed back the lens, aligned ETMY again to get reflection back on the PD.
  • This time the beam was still reaching ITMY. So we were glad that our iterations converged in 2 repititions.
  • Then we aligned ITMY to get counter propagating beam.
  • At the end of this alignment:
    • We see dips in relfection photodiode counts from 12200 to 9500.
    • The ETMY oplev is partially out of range (only 1 of the quadrant seeing light) but that could be because we changed the lens position. So Oplev servo is off.
  • We confirmed that the PDH servo is properly connected and loop is on. But we see no HOM catching lock for YARM even after us doing about 10 min search with ITMY-ETMY alignments.
  • We are leaving things as it is. We'll continue trying to align the cavity tomorrow. Everyone is welcome to try as long as they restore the positions of the optics to a good state at the end.



  16744   Fri Mar 25 18:20:28 2022 AnchalSummaryBHDPart IIa of BHR upgrade - Green laser alignment on Yarm

[Anchal, Paco, Shruti]

  • Today we found out that the laser controller at the Yend had it's inputs disconnected for the FAST PZT input and the Slow temperature control input. The cables were also not labeled that were lying nearby.
  • I tracked the cables and connected the Fast input adn the slow input.
  • We then adjusted the temperature slider to go to previously marked laser crystal temperature of 40.1 degrees celsius. But we could not find the the beatnote of Y end IR with teh Main laser IR.
  • We scanned the laser crystal temeprature until we could see a beatntoe with the main IR laser and stopped in that region.
  • Then we continued looking for flashing and HOM, but no luck.
  • It was interesting that when the PDH loop was closed, we saw fluctuations in relfection photodiode DC value, but not so much when the loop was not closed.
  • We tried flipping the sign of the loop with no luck and we tried changing the gain of the loop as well, but no luck.
  • The behavior of this Yend laser and its controller is still suspicious to us. When the loop is closed, the PZT feedback signal should not cause a change in amplitude of the light so much as we see it.
  • Also the fact that when loop is clsoed we do not see signs of flashing in the reflection photodiode is interesting. If anyone has any ideas, that would be good.
  16745   Sat Mar 26 13:04:38 2022 PacoSummaryBHDPart IIa of BHR upgrade - Green laser alignment on Yarm

I came for a bit to check on the "1Y0 burning smell" reported by Koji last evening. I agree that there's a toasty smell around the 1Y0 rack, but it is hard to tell where it comes from exactly. I think we can use the FLIR heat camera, but this will have to wait for Monday when someone with an iphone is around.

I also played a bit with the YAUX alignment (which is still poor) but I didn't try anything different nor did I seem to have more success. This is also an outstanding item for Monday, where maybe the next step is to install the GTRY path for a CCD.

  16749   Thu Mar 31 18:58:16 2022 Ian MacMillanSummaryBHDPart IIa of BHR upgrade - IR laser alignment on Xarm

[Ian, Paco]

We continued to try and lock the IR laser to the x-arm. Last time we adjusted TT2 PR2 and PR3 to adjust the beam to hit the center of the ITMX. Today we continued to adjust the same optics to make the beam hit the center of the beam splitter and make sure the beam is going in the direction of the ITMY. Then removed a mirror that wasn't even bolted down. I put it on the front right corner of the hood with all the other optics (right in front of a suspended mirror). With this unknown mirror removed the path was clear and hit the center of ITMX. From there we went and opened the ETMX chamber and using the IR scope we adjusted ITMX to put the beam on the center of the ETMX. We continued adjusting ETMX and ITMX until we had three reflections. We stopped here because we realized we should set up POX. We think this because any adjustment to set up the POX would mess up the work we had done on the x arm alignment.

  16757   Tue Apr 5 18:15:06 2022 AnchalSummaryBHDPart IIa of BHR upgrade - IR laser alignment on Xarm

[Paco, Anchal, Ian, JC]

We attempted the alignment of IR beam into the arm cavities. We used PR2 and PR3 (moved manually as well as using cdsutils) and got the YAW aligned pretty good on both X and Y directions. PIT alignment however turned out to be much harder to align. PR2 PR3 didn't have much range, so we zeroed there offset and tried to use TT1, TT2, MMT1, and MMT2 to align the PIT but it would get clipped before reaching BS table if we were to correct for PIT misalignment happening downstream. We concluded that the issue is that one of the PR2, PR3 mirrors have too much PIT offset in equilibrium position. We have requested Koji to change the output resistors in the coil drivers of PR2 and PR3 so that we can correct for the PIT offset in them directly using the coils and reduce load on upstream optics. We have tweaked TT1, TT2, MMT1, and MMT2 positions today, so we do not have the previous reference anymore.

  16758   Wed Apr 6 01:20:48 2022 KojiSummaryBHDPart IIa of BHR upgrade - IR laser alignment on Xarm

PR2/PR3 Output R for fame OSEMS reduced from 1.2K to 1.2K//100Ohm

I put the R=100Ohm for PR3 with the functions of the units mistakenly swapped. This affects imbalanced actuation of PR3 right now as well as too strong SD

PR2 Coil Driver 1 (UL/LL/UR) / S2100616 / PCB S2100520 / R_OUT = (1.2K // 100) for CH1/2/3

PR2 Coil Driver 2 (LR/SD) / S2100617 / PCB S2100519 / R_OUT = (1.2K // 100) for CH3

PR3 Coil Driver 1 (UL/LL/UR) / S2100619 / PCB S2100516 / R_OUT = (1.2K // 100) for CH3 only

PR3 Coil Driver 2 (LR/SD) / S2100618 / PCB S2100518 / R_OUT = (1.2K // 100) for CH1/2/3


The output R was reduced from 1.2k to 1.2k//100 = 92 Ohm.

This means that the face coil gains were increased by a factor of 13.

The original gains for PR2 Pos/Pit/Yaw were {0.7, 0.3, 0.2}. To keep the same loop gain, the new gains were supposed to be {0.054, 0.023, 0.015}.
With the new gain, the oscillations were very slowly reduced. Therefore, I increased the gains to have the gain margin of 2. (i.e. increased the gains until I have the oscillation, and then made it half.)
The new values were {0.2, 0.1, 0.05}. The side gain was 20 and unchanged

For PR3 the same operation has been done.

The original gains for PR3 Pos/Pit/Yaw were {1, 0.52, 0.2}. They were supposed to be reduced to  {0.077, 0.04, 0.015}.
The gains were increased to {0.5, 0.1, 0.1}. The side gain was also increased from 1 to 5.

Attachment 1: PXL_20220406_060846581.jpg
Attachment 2: PXL_20220406_014205726.jpg
Attachment 3: PXL_20220406_060324812.jpg
Attachment 4: PXL_20220406_015259326.jpg
  16760   Wed Apr 6 22:51:47 2022 KojiSummaryBHDPart IIa of BHR upgrade - IR laser alignment on Xarm

[Yuta Koji]

We took out the two coil driver units for PR3 and the incorrect arrangement of the output Rs were corrected. The boxes were returned to the rack.

In order to recover the alignment of the PR3 mirror, C1:SUS_PR3_SUSPOS_INMON / C1:SUS_PR3_SUSPIT_INMON / C1:SUS_PR3_SUSYAW_INMON were monitored. The previous values for them were {31150 / -31000 / -12800}. By moving the alignment sliders, the PIT and YAW values were adjusted to be {-31100 / -12700}. while this change made the POS value to be 52340.

The original gains for PR3 Pos/Pit/Yaw were {1, 0.52, 0.2}. They were supposed to be reduced to  {0.077, 0.04, 0.015}.
I ended up having the gains to be {0.15, 0.1, 0.05}. The side gain was also increased to 50.


Overall, the output R configuration for PR2/PR3 are summarized as follows. I'll update the DCC.

PR2 Coil Driver 1 (UL/LL/UR) / S2100616 / PCB S2100520 / R_OUT = (1.2K // 100) for CH1/2/3

PR2 Coil Driver 2 (LR/SD) / S2100617 / PCB S2100519 / R_OUT = (1.2K // 100) for CH3

PR3 Coil Driver 1 (UL/LL/UR) / S2100619 / PCB S2100516 / R_OUT = (1.2K // 100) for CH1/2/3

PR3 Coil Driver 2 (LR/SD) / S2100618 / PCB S2100518 / R_OUT = (1.2K // 100) for CH3

Attachment 1: PXL_20220406_213356237.MP.jpg
Attachment 2: PXL_20220406_212936502.MP.jpg
  16759   Wed Apr 6 12:03:51 2022 AnchalSummaryBHDPart IIa of BHR upgrade - IR laser alignment on Yarm

[Anchal, Paco]

After Koji reduced the output resistors on PR2/PR3 coil drivers, we got much better actuation range. We aligned TT1 TT2 again to get beam centered on PR2 and PR3. Then we used only PR2 and PR3 to do the input beam alignment to Y arm cavity. Using access in ETMY chamber, we aligned the input beam parallel to cavity axis. Slight changes were required in ETMY alignment offsets to get first roundtrip in same spot on ITMY. remaining alignment is finer and needs to be done with a help of a reflection photodiode and cameras in the control room. Immediate next step is to setup POY path for locking the Yarm with IR.

Side note: Because of the large PIT correction required in PR3, we found that our upper OSEMs were hitting totally bright limit and lower OSEMs were hitting totally dark limit on PR3. This also destablized our damping loops. We pushed the upper OSEMs slighlty and pulled back the lower OSEMs slightly to get the PD signal in half shadow region again. This worked and our damping loops are stable again. However, we think we should repeat free swing test in future to diagonalize the input matrix for new OSEM positions.

  16762   Thu Apr 7 17:59:51 2022 AnchalSummaryBHDPart IIa of BHR upgrade - IR laser alignment on Yarm

[Anchal, Paco, JC, Tega]

Today we have aligned the Yarm cavity for IR, with verified 1.5 roundtrips. We also placed following optics in the BS table.

  • POXM1 (installed earlier, not eloged)
  • SRMOL2
  • POYM1
  • SRMOL1
  • POYM2

We also cleared the in-air BS table of all previous optics. JC and Tega setup HeNe laser for Oplevs roughly for now. Tega also transported the POY RFPD from ITMY in-air table to the BS in-air table. We aligned the POY path to the table, but we had to move ITMY after that to get 2nd roundtrip in the arm cavity, which misaligned our POY path again. POY path would need to be modified tomorrow.


  16768   Fri Apr 8 17:21:31 2022 Ian MacMillanSummaryBHDPart IIa of BHR upgrade - IR laser alignment on Yarm

[Ian, Paco, Tega]

Paco and I opened the ETMY and ITMY chamber to work on yesterdays efforts to lock the y arm. We temporarily in stalled a camera behind the ETMY to look at the transmission as we adjusted the ETMY and ITMY. We then moved on to setting up the POY. the beam was too large for the apature of the PD so we installed a lens in the beam path to decrease it.

Once that was installed we saw some flashing on the C1:LSC-POYCD_OUT channel. We also could see the flashing on the monitors in the control room. The flashing beam seemed to be in the middle of ITMY but was slightly to the right on the ETMY. From here we tried to walk the beam using PR3 and ETMY to move the beam to the center of the ETMY.

  16770   Mon Apr 11 21:13:21 2022 PacoSummaryBHDPart IIa of BHR upgrade - POY11 debugging

[Paco, Koji]

I asked Koji for some advice regarding closing the loop on YARM using POY11. A few things seemed off including

  • The YARM transmission; which was peaking at ~ 20 (typically, TRY is normalized so that under nominal input power conditions we see TRY in the range [0, 1])
  • The POY11 DCPD level was quite low; we expect a few tens of uW in this low power configuration where no more than 100 mW are going through IMC.

We looked at the POY11 RFPD first. We tried flashing an incandescent lamp in-situ and saw some weak response using an oscilloscope and the DC Out readout. We then used the OPHIR power meter and recorded ~ 1.2 uW of light incident on the POY11 RFPD... Initially, we suspected our beam was not filling the PD sensitive area (~ 2 mm diameter), but a quick estimate using the 200 mm focusing lens currently installed in the ITMY table gave us quite a generous margin of error... so we questioned the OPHIR measurement. We swapped the power meter and this time got ~ 18.4 uW, which is more in line with what we expected (phew).

Moving on, from the POY11 RFPD responsivity, and our ~ 20 uW of incident power, we expected on the order of a 20 mV of DC Output, but weren't really seeing this on the scope, so we decided to test the pins on the power of the RFPD. The DB15 cable not only supplies bipolar 15 VDC but also monitors several other test points such as Tsens, or DCout in the RFPD. We quickly noticed a weird signal on the ENAB testpoint, so we removed POY11 RFPD from the ITMY table and took it to the PD testbench. After redoing the soldering on the breakout board and RF amplifier (ZXX-500LN+), which we tested separately, we saw the expected behavior using a +- 15 VDC power supply... thus verifying that the RFPD and breakout board seemed to work ok. We turned our attention to the upstream DB15 connection, and after quickly checking the newly run cables, we ended up debugging the eurocrate PD interface. After attempting a simple power cycle and failing, we removed this card and looked at the schematic. It would seem that the logic enabling ICs (one or both) failed, thus preventing the card from enabling its outputs correctly.... We bypassed the logic by soldering pins 4,8,14 on U1, U20 and then checked the circuit in-situ, and we saw it worked fine again.

Now none of the status LEDs (which are driven by the logic IC portion) work on this card, but the card itself works fine at least for POY11.

We moved on, and installed the DB15 cables, checking the functionality at every step... Then we looked at the POY11_I_ERR signal and were happy to see nice pdh wavelets. We pushed forward a little bit more to try and lock YARM. First, we went to the Y end and centered the ETMY Oplev so as to register the position where the YARM is flashing... The ITMY Oplev is still not online. Then, we optimized the ETMY damping gains somewhat to try and make it less noisy, and finally, played with the LSC YARM loop gain to attempt locking. This last push was not as successful, but we have an idea of what next steps are needed to reduce the SUS noise, including

  • Install ITMY Oplevs, and close loop
  • Optimize ITMY damping gains

To be continued....

ELOG V3.1.3-