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ID Date Author Type Category Subject
7774   Sat Dec 1 16:58:14 2012 ManasaUpdateWIKI-40M UpdateOptical tables

I have updated the wiki with the layout of the out-of-vac optical tables: Updated optical tables

I used the new camera to take pictures.

Lesson learnt after the update:

To use the new canon to take better pictures of optics tables; set the camera to manual mode; no flash and iso at around 800 or higher if you can hold the camera still for that long. The autofocus works beautifully...so you will not need any minor tweaking of lens to take pictures.

3287   Sun Jul 25 18:47:23 2010 AlbertoUpdateSVNOptickle 40mUpgrade model updated to include short cavity length corrections

I uploaded an updated optickle model of the upgrade to the SVN directory with the optickle models (here).

643   Mon Jul 7 19:15:38 2008 AlbertoUpdateGeneralOptics alignement on the ABS length experiment
Today I started setting up the PLL instruments to lock the frequency of the NPRO beam to the IFO beam. with no need of a new alignment after the weekend I was able to see the beat again, although this time I found at a different temperature of the NPRO laser of about 54 degrees (vs 51 of the last time).
I've got the Marconi as local oscillator (LO), the mixer Koji suggetsed, the SR560 and a 5 MHz low pass filter to cut the 33, 66 and 99 MHz present in the output signal from the PD. The filter worked well and I was able to single out only the beat resonance from the power spectrum.
In the attempt to enhance the amplitude of the beat, as Koji suggested, I tried to work on the alignment of the steering mirrors. While I was doing that, for some reason the pre-modecleaner lost the alignment and I had to ask John to help me lock it again. during the process I lost the old alignment but at the end I got a new one, apparently (from the camera) even better than the other. Although after that the beats were gone. Actually after the lock-in of the PMC the IFO beam didn't look as good as before, so it might be also for that reason.

I'll try again tomorrow, after that probably tonight Rob is going to reset the alignments of the interferometers.
7313   Wed Aug 29 21:02:45 2012 JenneUpdateIOOOptics between Faraday and PRM are centered, realigned

[Jenne, Suresh, with support from Jamie and Koji]

MC spots measured, MC1, MC3 no change.

Beam hitting to the right of center of PZT1.  It was translated sideways so we are now hitting it on the center.  Knobs adjusted so we hit center of MMT1.

Beam totally obscured by Faraday on the way to MMT2.  MMT2 moved north, so that we clear the Faraday by more than a beam diameter.  MMT1 knobs adjusted to hit center of MMT2.

MMT2 knobs adjusted to hit center of PZT2.

PZT2 didn't have enough range with knobs, so we loosened it, pointed then adjusted with knobs so we're hitting center of PRM.

We need to check spot centering on PRM with camera tomorrow.

Suresh checked that we're not clipped by IP ANG/POS pickoff mirrors, but we haven't done any alignment of IP ANG/POS.

Tomorrow:  Open ITMX door.  Check with Watek that we're hitting center of PRM.  Then look to see if we're hitting center of PR2.  Then, continue through the chain of optics.

5729   Mon Oct 24 17:23:14 2011 SUS_DiagonalizerUpdateSUSOptics kicked
This is a cron-elog test. No optics have been kicked.
5823   Sun Nov 6 09:39:25 2011 Dr. SUSUpdateSUSOptics kicked
All suspended optics have been kicked at Sun Nov 6 09:39:25 PST 2011. Watchdogs will be reengaged in 5 hours. Please refrain from disturbing the optics in the meantime.

EDIT ZK: After all that, I left the 'doirun' bit off in runDrSUS. I ran it manually at the above time.
7523   Wed Oct 10 21:50:39 2012 SUS_DiagonalizerUpdateSUSOptics kicked
All suspended optics have been kicked at Wed Oct 10 21:50:39 PDT 2012. Watchdogs will be reengaged in 90 minutes.
7524   Thu Oct 11 00:22:58 2012 SUS_DiagonalizerUpdateSUSOptics kicked

 Quote: All suspended optics have been kicked at Wed Oct 10 21:50:39 PDT 2012. Watchdogs will be reengaged in 90 minutes.

New SUS input matrix diagonalization complete.
7979   Thu Jan 31 22:14:11 2013 ranaSummaryASCOptics lit

Gouy not Guoy:

http://www.rp-photonics.com/gouy_phase_shift.html

pronounced Goo-eee, with the emphasis on the second syllable.

7982   Fri Feb 1 12:22:27 2013 ZachSummaryASCOptics lit

It's OK; even Siegman got it wrong---48 times.

RA: NO, stil not OK.

 Quote: Gouy not Guoy: http://www.rp-photonics.com/gouy_phase_shift.html pronounced Goo-eee, with the emphasis on the second syllable.

13981   Mon Jun 18 14:32:42 2018 gautamUpdatePSLOptics on AS table

Yesterday, I moved the following optics:

1. Lens in front of AS110 PD.
2. BS splitting light between AS110 and AS55.

After moving these components around a bit, I locked them down once I was happy that the beam was pretty well centered on both of them, and also on AS110 and AS55 (measured using O'scope with single bounce from one ITM, other optics misaligned).

The beam was close to clipping on the lens mentioned in #1, probably because this wasn't checked when the 90-10 BS was installed for the AUX laser. Furthermore, I believe we are losing more than 10% of the light due to this BS. The ASDC (which is derived from AS55 PD) level is down at ~110cts as the Michelson is fringing, while it used to be ~200 cts. I will update with a power measurement shortly. But I think we should move ahead with the plan to combine the beam into the IFO's AS mode as discussed at the meeting last week.

Unrelated to this work, but c1psl and c1iscaux were keyed.

ASDC has something weird going on with it - my main goal yesterday was to calibrate the actuators of ITMX, ITMY and BS using the Michelson. But with the Michelson locked on a dark fringe, the ASDC level changed by up to 50 counts seemingly randomly (bright fringe was ~1000 cts, I had upped the whitening gain to +21dB), even though the CCD remained clearly dark throughout. Not sure if the problem is in the readout electronics or in the PD itself.

13982   Mon Jun 18 15:59:17 2018 johannesUpdatePSLOptics on AS table
 Quote: Furthermore, I believe we are losing more than 10% of the light due to this BS. The ASDC (which is derived from AS55 PD) level is down at ~110cts as the Michelson is fringing, while it used to be ~200 cts. I will update with a power measurement shortly. But I think we should move ahead with the plan to combine the beam into the IFO's AS mode as discussed at the meeting last week.

Is the 10% specified for P-Pol or for UNP? I contacted CVI about beamsplitters, since their website doesn't list a BS1-1064-90-... option on the website. They say a R=90% beamsplitter would be a custom job. The closest stock item they got is BS1-1064-95-2025-45UNP specified at R=95% for UNPolarized beams. They were kind enough to sent me the measured transmission curves for a recent lot of these, which is attached was uploaded to the wiki [Elog Police K: NO PROPRIETARY DOCUMENTS ON THE ELOG, which is public. Put it on our wiki and put the link here]. The figure is not labeled, but according to the contact Red is S-Pol and Blue is P-Pol, which means that this one actually has R=~90% for P, pretty much what we want. We'll need to buy two of these to make the swap in the setup.

Back to your original point: There's only a BS1-1064-10-2025-45UNP on the website, so unless we got these as custom items, the R for P-Pol is probably NOT actually 10%, just somewhere between 0% and 20%

13983   Mon Jun 18 16:57:54 2018 KojiUpdatePSLOptics on AS table

Of course, many (but no all) of the optics were custom-ordered back in ~2000.

14006   Fri Jun 22 14:18:04 2018 SteveUpdatePSLOptics on AS table

Quote:
 Quote: Furthermore, I believe we are losing more than 10% of the light due to this BS. The ASDC (which is derived from AS55 PD) level is down at ~110cts as the Michelson is fringing, while it used to be ~200 cts. I will update with a power measurement shortly. But I think we should move ahead with the plan to combine the beam into the IFO's AS mode as discussed at the meeting last week.

Is the 10% specified for P-Pol or for UNP? I contacted CVI about beamsplitters, since their website doesn't list a BS1-1064-90-... option on the website. They say a R=90% beamsplitter would be a custom job. The closest stock item they got is BS1-1064-95-2025-45UNP specified at R=95% for UNPolarized beams. They were kind enough to sent me the measured transmission curves for a recent lot of these, which is attached was uploaded to the wiki [Elog Police K: NO PROPRIETARY DOCUMENTS ON THE ELOG, which is public. Put it on our wiki and put the link here]. The figure is not labeled, but according to the contact Red is S-Pol and Blue is P-Pol, which means that this one actually has R=~90% for P, pretty much what we want. We'll need to buy two of these to make the swap in the setup.

Back to your original point: There's only a BS1-1064-10-2025-45UNP on the website, so unless we got these as custom items, the R for P-Pol is probably NOT actually 10%, just somewhere between 0% and 20%

4  std cataloge item fused silica  BS1-1064-95-2025-45UNP

ordered today. They will arrive no later than July 13, 2018

10454   Thu Sep 4 18:30:13 2014 GabrieleSummaryASCOptimal Gouy phase for POP QPD

Jenne asked me to simulate the signals on POP QPD when moving different mirrors, as a function of the Gouy phase where the QPD is placed.

I used the opportunity to create a MIST simulation file of the entire 40m interferometer, essentially based on my aLIGO configuration file. I used the recycling cavity lengths obtained from our survey, and other parameters from the wiki page. The configuration file is attached (fortymeters.mist).

Coming back to the main simulation, here is the result, both for the "regular" POP QPD and for a 22MHz demodulated one. The Gouy phase is measured starting from PR2. Cavity mirrors are easily decoupled from PRM in the "regular" QPD. As already demonstrated in a previous simulation, ETMs signals are very small in the 22 MHz QPD. Moreover, it is possible to zero the contribution from ITMs by choosing the right Gouy phase, at the price of a reduction of the PRM signal by a factor of 3-4. Simulation files are attached.

Attachment 2: fortymeters.mist
###########################################################################
# Configuration file for full dual recycled 40m interferometer
classname FortyMeters
################################################################ Parameters

# General parameters
const Pin 1             # input power

# Mirror parameters
const T_ITM 0.01384     # ITM transmission [from https://wiki-40m.ligo.caltech.edu/Core_Optics]

... 143 more lines ...
Attachment 3: fortymeters_pop_qpd.mist
###########################################################################
# Configuration file for full dual recycled 40m interferometer
classname FortyMetersPOP_QPD
################################################################ Parameters

# General parameters
const Pin 1             # input power

# Mirror parameters
const T_ITM 0.01384     # ITM transmission [from https://wiki-40m.ligo.caltech.edu/Core_Optics]

... 148 more lines ...
Attachment 4: pop_qpd.m
% compile and create simulation class
clear classes
MIST('fortymeters_pop_qpd.mist');
s = FortyMetersPOP_QPD(4);

% set angular motion of ITMs, ETMs and PRM
s.ETMX.setMotionShape('pitch');
s.ETMY.setMotionShape('pitch');
s.ITMX.setMotionShape('pitch');
s.ITMY.setMotionShape('pitch');

... 47 more lines ...
11407   Tue Jul 14 10:23:27 2015 IgnacioUpdateGeneralOptimal detector array placement thoughts

Over the past few days, I've been thinking about how to workout the details conerning Rana's request about a 'map' of the vicinity of the 40m interferometer. This map will take the positions of N randomly placed seismic sensors as well as the signals measured by each one of them and the calculated cross correlations between the sensors and between the sensors and the test mass of interest to give out a displacement vector with new sensor positions that are close to optimum for better seismic (and Newtonian) noise cancellation.

Now, I believe that much of the mathematical details have been already work out by Jenne in her thesis. She explains that the quantity of interest that we wish to minimize in order to find an optimal array is the following,

$R = \sqrt{1-\frac{\vec{C}_{SN}^T C_{SS}^{-1}\vec{C}_{SN} }{C_{NN}}}$

where  $\vec{C}_{SN}$ is the cross-correlation vector between the seismic detectors and the seismic (or Newtonian) noise, $C_{SS}$ is the cross-correlation matrix between the sensors and $C_{NN}$ is the seismic (or Newtonian) noise variance.

I looked at the paper that Jenne cited from which she obtained the above quantity and noted that it is a bit different as it contains an extra term inside the square root, it is given by

$R' = \sqrt{1-\frac{\vec{C}_{SN}^T (C_{SS}^{-1}+C_{\Sigma\Sigma})\vec{C}_{SN} }{C_{NN}}}$

where the new term, $C_{\Sigma\Sigma}$ is the matrix describing the self noise of the sensors. I think Jenne set this term to zero since we can always perform a huddle test on our detectors and know the self noise, thus effectively subtracting it from the signals of interest that we use to calculate the other cross correlation quantities.

Anyways, the quantity $R$ above is a function of the positions of the sensors. In order to apply it to our situation, I'm planning on:

1) Performing the huddle tests on our sensors, redoing it for the accelerometers and then the seismometers (once the data aquisition system is working... )

2) Randomly (well not randomly, there are some assumptions we can make as to what might work best in terms of sensor placement) place the sensors around the interferometer. I'm planning on using all six Wilcoxon 731A accelerometers, the two Guralps and the STS seismometer (any more?).

3) Measure the ground signals and use wiener filtering in order to cancel out their self noises.

4) From the measured signals and their present positions we should be able to figure out where to move the sensors in order to optimize subtraction.

i have also been messing around with Jenne's code on seismic field simulations with the hopes of simulating a version of the seismic field around the 40m in order to understand the NN of the site a little better... maybe. While the data aquisition gets back to a working state, I'm planning on using my simulated NN curve as a way to play around with sensor optimization before its done experimentally.

i have as well been thinking and learning a little bit about source characterization through machine learning methods, specially using neural networks as Masha did back in her SURF project on 2012. I have also been looking at Support vector machines. The reasons why I have been looking at machine learning algorithms is because of the nature of the everchanging seismic field around the interferometer. Suppose we find a pretty good sensor array that we like. How do we make sure that this array is any good at some time t after it has been found? If the array mostly deals with the usual seismic background (quiet) of the site of interest, we could incorporate machine learning techniques in order to mitigate any of the more random disturbances that happen around the sites, like delivery trucks, earthquakes, etc.

8987   Thu Aug 8 18:43:12 2013 SujanSummaryPEMOptimally subtracting signals from two seismometers.

An exercise of optimally subtracting one seismometer signal by another using weiner filters was done. Results have been summarized document attached.

Attachment 1: Results.pdf
16965   Thu Jun 30 18:06:22 2022 PacoUpdateALSOptimum ALS recovery - part I

[Paco]

In the morning I took some time to align the AUX beams in the XEND table. Later in the afternoon, I did the same on the YEND table. I then locked the AUX beams to the arm cavities while they were stabilized using POX/POY and turned off the PSL hepa off temporarily (this should be turned on after today's work).

After checking the the temperature slider sign on the spectrum analyzer of the control room I took some out-of-loop measurements of both ALS beatnotes (Attachment #1) by running diaggui /users/Templates/ALS/ALS_outOfLoop_Ref_DQ.xml and by comparing them against their old references (red vs magenta and blue vs cyan); it seems that YAUX is not doing too bad, but XAUX has increased residual noise around and above 100 Hz; perhaps as a result of the ongoing ALS SURF loop investigations? It does look like the OLTF UGF has dropped by half from ~ 11 kHz to ~ 5.5 kHz.

Anyways let this be a reference measurement for current locking tasks, as well as for ongoing SURF projects.

Attachment 1: als_ool_06_2022.png
16154   Sun May 23 18:28:54 2021 JonUpdateCDSOpto-isolator for c1auxey

The new HAM-A coil drivers have a single DB9 connector for all the binary inputs. This requires that the dewhitening switching signals from the fast system be spliced with the coil enable signals from c1auxey. There is a common return for all the binary inputs. To avoid directly connecting the grounds of the two systems, I have looked for a suitable opto-isolator for the c1auxey signals.

I best option I found is the Ocean Controls KTD-258, a 4-channel, DIN-rail-mounted opto-isolator supporting input/output voltages of up to 30 V DC. It is an active device and can be powered using the same 15 V supply as is currently powering both the Acromags and excitation. I ordered one unit to be trialed in c1auxey. If this is found to be good solution, we will order more for the upgrades of c1auxex and c1susaux, as required for compatibility with the new suspension electronics.

16166   Fri May 28 10:54:59 2021 JonUpdateCDSOpto-isolator for c1auxey

I have received the opto-isolator needed to complete the new c1auxey system. I left it sitting on the electronics bench next to the Acromag chassis.

Here is the manufacturer's wiring manual. It should be wired to the +15V chassis power and to the common return from the coil driver, following the instructions herein for NPN-style signals. Note that there are two sets of DIP switches (one on the input side and one on the output side) for selecting the mode of operation. These should all be set to "NPN" mode.

Attachment 1: optoisolator.jpeg
16178   Thu Jun 3 17:15:17 2021 YehonathanUpdateCDSOpto-isolator for c1auxey

As Jon wrote we need to use the NPN configuration (see attachments). I tested the isolator channels in the following way:

1. I connected +15V from the power supply to the input(+) contact.

2. Signal wire from one of the digital outputs was connected to I1-4

3. When I set the digital output to HIGH, the LED on the isolator turns on.

4. I measure the resistance between O1-4 to output(-) and find it to be ~ 100ohm in the HIGH state and an open circuit in the LOW state, as expected from an open collector output.

Unlike the Acromag output, the isolator output is not pulled up in the LOW state. To do so we need to connect +15V to the output channel through a pull-up resistor. For now, I leave it with no pull-up. According to the schematics of the HAM-A Coil Driver, the digital output channels drive an electromagnetic relay (I think) so it might not need to be pulled up to switch back. I'm not sure. We will need to check the operation of these outputs at the installation.

During the testing of the isolator outputs pull-up, I accidentally ran a high current through O2, frying it dead. It is now permanently shorted to the + and - outputs rendering it unusable. In any case, we need another isolator since we have 5 channels we need to isolate.

I mounted the isolator on the DIN rail and started wiring the digital outputs into it. I connected the GND from the RTS to output(-) such that when the digital outputs are HIGH the channels in the coil driver will be sunk into the RTS GND and not the slow one avoiding GND contamination.

Attachment 1: Optical_Isolator_NPN_Input.png
Attachment 2: Optical_Isolator_NPN_Output.png
16181   Thu Jun 3 22:08:00 2021 KojiUpdateCDSOpto-isolator for c1auxey

- Could you explain what is the blue thing in Attachment 1?

- To check the validity of the signal chain, can you make a diagram summarizing the path from the fast BO - BO I/F - Acromag - This opto-isolator - the coil driver relay? (Cut-and-paste of the existing schematics is fine)

16182   Fri Jun 4 14:49:23 2021 YehonathanUpdateCDSOpto-isolator for c1auxey

I made a diagram (Attached). I think it explains the blue thing in the previous post.

I don't know what is the grounding situation in the RTS so I put a ground in both the coil driver and the RTS. Hopefully, only one of them is connected in reality.

 Quote: - Could you explain what is the blue thing in Attachment 1? - To check the validity of the signal chain, can you make a diagram summarizing the path from the fast BO - BO I/F - Acromag - This opto-isolator - the coil driver relay? (Cut-and-paste of the existing schematics is fine)

Attachment 1: Optical_isolator_Wiring.pdf
16183   Fri Jun 4 17:46:25 2021 unYehonathanUpdateCDSOpto-isolator for c1auxey

I mounted the optoisolator on the DIN rail and connected the 3 first channels

 C1:SUS-ETMY_UL_ENABLE C1:SUS-ETMY_UR_ENABLE C1:SUS-ETMY_LL_ENABLE

to the optoisolator inputs 1,3,4 respectively. I connected the +15V input voltage into the input(+) of the optoisolator.

The outputs were connected to DB9F-2 where those channels were connected before.

I added DB9F-1 to the front panel to accept channels from the RTS. I connected the fast channels to connectors 1,2,3 from DB9F-1 to DB9F-2 according to the wiring diagram. The GND from DB9F-1 was connected to both connector 5 of DB9F-2 and the output (-).

I tested the channels: I connected a DB9 breakout board to DB9F-2. I measured the resistance between the RTS GND and the isolated channels while switching them on and off. In the beginning, when I turned on the binary channels the resistance was behaving weird - oscillating between low resistance and open circuit. I pulled up the channels through a 100Kohm resistor to observe whether the voltage behavior is reasonable or not. Indeed I observed that in the LOW state the voltage between the isolated channel and slow GND is 15V and 0.03V in the HIGH state. Then I disconnected the pull up from the channels and measured the resistance again. It showed ~ stable 170ohm in the HIGH state and an open circuit in the LOW state. I was not able to reproduce the weird initial behavior. Maybe the optoisolator needs some warmup of some sort.

We still need to wire the rest of the fast channels to DBF9-3 and isolate the channels in DBF9-4. For that, we need another optoisolator.

There is still an open issue with the BI channels not read by EPICS. They can still be read by the Windows machine though.

Attachment 1: 20210604_173420.jpg
16184   Sun Jun 6 03:02:14 2021 KojiUpdateCDSOpto-isolator for c1auxey

This RTS also use the BO interface with an opto isolator. https://dcc.ligo.org/LIGO-D1002593

Could you also include the pull up/pull down situations?

16186   Sun Jun 6 12:15:16 2021 JonUpdateCDSOpto-isolator for c1auxey

Since this Ocean Controls optoisolator has been shown to be compatible, I've gone ahead and ordered 10 more:

• (1) to complete c1auxey
• (2) for the upgrade of c1auxex
• (7) for the upgrade of c1susaux

They are expected to arrive by Wednesday.

16187   Sun Jun 6 15:59:51 2021 YehonathanUpdateCDSOpto-isolator for c1auxey

According to the BO interface circuit board https://dcc.ligo.org/D1001266, PCIN wires are connected to the coil driver and they are not pulled either way.

That means that they're either grounded or floating. I updated the drawing.

 Quote: This RTS also use the BO interface with an opto isolator. https://dcc.ligo.org/LIGO-D1002593 Could you also include the pull up/pull down situations?

Attachment 1: Optical_isolator_Wiring.pdf
16199   Mon Jun 14 15:31:30 2021 YehonathanUpdateCDSOpto-isolator for c1auxey

I checked the BI situation on the HAM-A coil driver. It seems like these are sinking BIs and indeed need to be isolated from the Acromag unit GND to avoid contamination.

The BIs will have to be isolated on a different isolator. Now, the wires coming from the field (red) are connected to the second isolator's input and the outputs are connected to the Acromag BI module and the Acromag's RTN.

I updated the wiring diagram (attached) and the wiring spreadsheet.

In the diagram, you can notice that the BI isolator (the right one) is powered by the Acromag's +15V and switched when the coil driver's GND is supplied. I am not sure if it makes sense or not. In this configuration, there is a path between the coil driver's GND and the Acromag's GND but its resistance is at least 10KOhm. The extra careful option is to power the isolator by the coil driver's +V but there is no +V on any of the connectors going out of the coil driver.

I installed an additional isolator on the DIN rail and wired the remaining BOs (C1:SUS-ETMY_SD_ENABLE, C1:SUS-ETMY_LR_ENABLE) through it to the DB9F-4 feedthrough. I also added DB9F-3 for incoming wires from the RTS and made the required connection from it to DB9F-4.

I tested the new isolated BOs using the Windows machine (after stopping Modbus). As before, I measure the resistance between pin 5 (coil driver GND) and the channel under test. When I turn on the BO I see the resistance drops from inf to 166ohm and back to inf when I turn it off. Both channels passed the test.

Attachment 1: Optical_isolator_Wiring.pdf
16203   Tue Jun 15 21:48:55 2021 KojiUpdateCDSOpto-isolator for c1auxey

If my understanding is correct, the (photo receiving) NPN transistor of the optocoupler is energized through the acromag. The LED side should be driven by the coil driver circuit. It is properly done for the "enable mon" through 750Ohm and +V. However, "Run/Acquire" is a relay switch and there is no one to drive the line. I propose to add the pull-up network to the run/acquire outputs. This way all 8 outputs become identical and symmetric.

We should test the configuration if this works properly. This can be done with just a manual switch, R=750Ohm, and a +V supply  (+18V I guess).

Attachment 1: Acromag_RTS_BI_config.jpg
16205   Wed Jun 16 17:24:29 2021 YehonathanUpdateCDSOpto-isolator for c1auxey

I updated the wiring diagram according to Koji's suggestion. According to the isolator manual, this configuration requires that the isolator input be configured as PNP.

Additionally, when the switch in the coil driver is open the LED in the isolator is signaling an on-state. Therefore, we might need to configure the Acromag to invert the input.

There are the Run/Aquire channels that we might need to add to the wiring diagram. If we do need to read them using slow channels, we will have to pull them up like the EnableMon channels to use them like in the wiring diagram.

Attachment 1: Optical_isolator_Wiring.pdf
16207   Wed Jun 16 20:32:39 2021 YehonathanUpdateCDSOpto-isolator for c1auxey

I installed 2 additional isolators in the Acromag chassis. I set all the input channels to PNP. I ran the digital inputs (EnableMon channels) through these isolators according to the previous post.

I tested the digital inputs in the following way:

I connected an 18V voltage source to the signal wire under test through a 1Kohm resistor. I connected the GND of the voltage source to the RTN wire of the feedthrough. When the voltage source was connected, the LED on the isolator turned on and the EPICs channel under test was Enabled. When I disconnected the voltage source or shorted the signal wire to GND the LED on the isolator turned off and the EPICs channel showed a Disabled state.

16243   Fri Jul 9 18:35:32 2021 YehonathanUpdateCDSOpto-isolator for c1auxey

Following Koji's channel list review, we made changes to the wiring spreadsheet.

Today, I made the changes real in the Acromag chassis. I went through the channel list one by one and made sure it is wired correctly. Additionally, since we now need all the channels the existing isolators have, I replaced the isolator with the defective channel with a new one.

The things to do next:

1. Create entries for the spare coil driver and satellite box channels in the EPICs DB.

2. Test the spare channels.

16244   Mon Jul 12 18:06:25 2021 YehonathanUpdateCDSOpto-isolator for c1auxey

I edited /cvs/cds/caltech/target/c1auxey1/ETMYaux.db (after creating a backup) and added the spare coil driver channels.

I tested those channels using caget while fixing wiring issues. The tests were all succesful. The digital output channel were tested using the Windows machine since they are locked by some EPICs mechanism I don't yet understand.

One worrying point is I found that the differential analog inputs to be unstable unless I connected a reference to some stable voltage source unlike previous tests showed. It was unstable (but less) even when I connected the ref to the ground connectors on the power supplies on the workbench. This is really puzzling.

When I say unstable I mean that most of the time the voltage reading shows the right value, but occasionly there is a transient sharp volage drop of the order of 0.5V. I will do a more quantitative analysis tomorrow.

16263   Wed Jul 28 12:47:52 2021 YehonathanUpdateCDSOpto-isolator for c1auxey

To simulate a differential output I used two power supplies connected in series. The outer connectors were used as the outputs and the common connector was connected to the ground and used as a reference. I hooked these outputs to one of the differential analog channels and measured it over time using Striptool. The setup is shown in attachment 3.

I tested two cases: With reference disconnected (attachment 1), and connected (attachment 2). Clearly, the non-referred case is way too noisy.

Attachment 1: SUS-ETMY_SparePDMon0_NoRef.png
Attachment 2: SUS-ETMY_SparePDMon0_Ref_WithGND.png
Attachment 3: DifferentialOutputTest.png
16276   Wed Aug 11 12:06:40 2021 YehonathanUpdateCDSOpto-isolator for c1auxey

I redid the differential input experiment using the DS360 function generator we recently got. I generated a low frequency (0.1Hz) sine wave signal with an amplitude 0.5V and connected the + and - output to a differential input on the new c1auxcey Acromag chassis. I recorded a time series of the corresponding EPICS channel with and without the common on the DS360 connected to the Ref connector on the Acromag unit. The common connector on the DS360 is not normally grounded (there is a few tens of kohms between the ground and common connectors). The attachment shows that, indeed, the analog input readout is extremely noisy with the Ref being disconnected. The point where the Ref was connected to common is marked in the picture.

Conclusion: Ref connector on the analog input Acromag units must be connected to some stable voltage source for normal operation.

Attachment 1: SUS-ETMY_SparePDMon0_2.png
16635   Tue Feb 1 15:33:28 2022 KojiSummaryBHDOptomechanics configuration for the in-vacuum aux small optics

I've summarized the optomechanics configuration for the in-vacuum aux small optics

It's not obvious here but the post for POP_SM4 is the stack of BA2V, Newport 9953, PLS-T238, LMR1V. The mirror is a CM254-750-E03 curved mirror. This should go on the suspension base. I hope I did not make a mistake there...

Attachment 1: Invac_opto_mechanics_v2.pdf
16640   Wed Feb 2 18:55:58 2022 KojiSummaryBHDOptomechanics configuration for the in-vacuum aux small optics

Here is more detail of the POP_SM4 mount assembly.

It's a combination of BA2V + PLS-T238 + BA1V + TR-1.5 + LMR1V + Mirror: CM254-750-E03
Between BA1V and PLS-T238, we have to do a washer action to fix the post (8-32) with a 1/4-20 slot. Maybe we can use a 1" post shim from thorlabs/newport.
Otherwise, we should be able to fasten the other joints with silver-plated screws we already have/ordered.

I think TR-1.5 (and a shim) has not been given to Jordan for C&B. I'll take a look at these.

Attachment 1: Screen_Shot_2022-02-02_at_6.46.46_PM.png
16641   Wed Feb 2 21:16:23 2022 KojiSummaryBHDOptomechanics configuration for the in-vacuum aux small optics

Asked Jordan to clean 2x 1.5" posts (0.5 dia) and a washer with 1" dia.

Attachment 1: PXL_20220203_050156031.jpg
15319   Wed May 6 00:31:09 2020 gautamUpdateALSOptomechanics during CARM offset reduction

Summary:

The apparent increase in the ALS noise (witnessed in-loop, e.g. Attachment #2 here) during the CARM offset reduction may have an optomechanical origin.

Details:

• A simplified CARM plant was setup in Finesse - 3 mirror coupled cavity with PRM, ITM and ETM, 40m params for R/T/L used.
• For a sanity check, DC power buildup and coincident resonance of the PRC and arm cavity were checked. PRG and CARM linewidth also checks out, and scales as expected with arm losses.
• To investigate possible optomechanical issues - I cut the input power to 300 mW (I estimate 600 mW incident on the PRM), set a PRG of ~20, to mimic what we have right now.
• I drive the ITM at various CARM offsets, and measure the m/m transfer function to itself and the ETM.
• Attachement #1 shows the results.

Interpretation:

• ericq had similar plots in his thesis, but I don't think the full implications of this effect were investigated, the context there was different.
• The optomechanical resonance builds up at ~10 Hz and sweeps up to ~100 Hz as the CARM offset approaches zero, with amplification close to x100 at the resonance.
• What this means is that the arm cavity is moving by up to 100x the ambient seismically driven dispalcements.
• The EX/EY uPDH servos have considerable gain at these frequencies, and so the AUX laser frequency can keep up with this increased motion (to be quantified exactly what the increase in residual is).
• However, the ALS loop that maintains the frequency offset b/w the PSL and the AUX lasers is digitial, and only has ~20 dB gain at 30 Hz. - so the error signal for CARM control becomes noisier as we see.
• I speculate that the multiple peaky features in the in-loop error signal are a result of some dynamical effects which Finesse presumably does not simulate.
• The other puzzler is: this simulation would suggest that approaching the zero CARM offset from the other side (anti-spring) wouldn't have such instabilities building up. However, I am reasonably sure I've seen this effect approaching zero from both sides, though I haven't checked in the last month.
• Anyways, if this hypothesis is correct, we can't really take advantage of the ~8pm RMS residual noise performance of the IR ALS system sadly, because of our 250g mirrors and 800mW input power
• Possible workarounds:
• High BW ALS - this would give us more gain at ~30 Hz and this wouldn't be a problem anymore really. But in my trials, I think I found that the IN2 gain on the CM board has to be inverted for this to work (the IN1 path and the IN2 path share a common AO path polarity, and we need the two paths to have the opposite polarity).
• Cut the input power - this would reduce the optomechanical action, but presumably the vertex locking becomes noisier. In any case, this isn't really practical without some kind of motorized/remote-controlled waveplate for power adjustment.

Update 415pm 5/6: Per the discussion at the meeting, I have now uploaded as Attachment #2 the force-->displacement (i.e. m/N) transfer functions. I now think these are appropriate units. For the ALS case, we could convert the m/N to Hz/N of extra frequency noise imprinted on the AUX laser due to the increased cavity motion. Is W/N really better here, since the mechanism is extra frequency noise on a beatnote, and there isn't really a PDH or DC error signal?

Attachment 1: CARMplant.pdf
Attachment 2: CARMplant_force2disp.pdf
16953   Tue Jun 28 09:03:58 2022 JCUpdateGeneralOrganizing and Cleaning

The plan for the tools in 40m

As of right now, there are 4 tool boxes. X-end, Y-end, Vertex, and the main tool box along the X-arm. The plan is the give each toolbox a set of their own tools. The tools of X-end, Y-end, and Vertex toolboxes will be very similar containing the basic tools such as pliers, screwdrivers, allen ball drivers. Along with this, each tool box will have a tape measure, caliper, level, and other measuring tools we find convinient.

As for the new toolbox, I have done research and found a few good selections. The only problem I have ran into with this is the width of the tool box corresponding with the prices. The tool cabinet we have now is 41" wide. The issue I have is not in finding another toolbox of the same width, but for a similar price we can find a 54" wide tool cabinet. Would anyone be objected to making a bit more space for this?

How the tools will stay organized.

I the original idea I had was to use a specified color of electrical tape for each tool box. Then to wrap the corresponding tools tools with the same color tape. But it was brought to my attention that the electrical tape would become sticky over time. So, I think the using the label maker would be the best idea. with the labels being 'X' for X-end, 'Y' for Y-end, 'V' for vertex, and 'M' for main toolboxes.

An idea for the optical tables:

Anchal brought it up to me that it is a hassle to go back and forth searching for the correct sizes of Hex Keys and Allen Wrenches. The idea of a pouch on the outside of each optical table was mentioned so I brought this up to Paco. Paco also gave me the idea of a 3D printed stand we could make for allen ball drives. Does anyone have a preference or an idea of what would be the best choice and why?

A few sidenotes:

Anchal mentioned to me a while back that there are many cables that are laying on the racks that are not being used. Is there a way we could identify which ones are being used?

I noticed that when we were vented that a few of the chamber doors were leaning up against the wall and not on a wooden stand like others. Although, the seats for the chamber doors are pretty spacious and do not give us much clearance. For the future ones, could we make something more sleek and put the wider seats at the end chambers?

The cabinets along the Y-Arm are labelled, but do not correspond with all the materials inside or are too full to take in more items. Could I organize these?

5969   Mon Nov 21 15:47:58 2011 MirkoUpdateIOOOsem loop shape

[Jenne, Mirko]

To reiterate: We changed the OSEM loop shape for MC1-MC3. Below in black is the old loop shape, which simulated pendulum response in there. In red is the new loop shape.

The differences are due to extra filter in C1:SUS-MC?_SUSPOS module 6,7,9

6: Elliptical LP @ 2.5Hz
7: Inverse Chebychev HP @0.3Hz
8: 1st order LP @ 10Hz

### This has the potential to be unstable, but is not. At some point these filters should be tuned further.

13071   Fri Jun 16 23:27:19 2017 Kaustubh, JigyasaUpdateComputersOttavia Connected to the Netgear Box

I just connected the Ottavia to the Netgear box and its working just fine. It'll remain switched on over the weekend.

 Quote: Kaustubh and I are going to enable the ethernet connection to Ottavia and secure the wiring now.

13065   Thu Jun 15 14:24:48 2017 Kaustubh, JigyasaUpdateComputersOttavia Switched On

Today, I and Jigyasa connected the Ottavia to one of the unused monitor screens Donatella. The Ottavia CPU had a label saying 'SMOKED''. One of the past elogs, 11091, dated back in March 2015, by Jenne had an update regarding the Ottavia smelling 'burny'. It seems to be working fine for about 2 hours now. Once it is connected to the Martian Network we can test it further. The Donatella screen we used seems to have a graphic problem, a damage to the display screen. Its a minor issue and does not affect the display that much, but perhaps it'll be better to use another screen if we plan to use the Ottavia in the future. We will power it down if there is an issue with it.

13067   Thu Jun 15 19:49:03 2017 Kaustubh, JigyasaUpdateComputersOttavia Switched On

It has been working fine the whole day(we didn't do much testing on it though). We are leaving it on for the night.

 Quote: Today, I and Jigyasa connected the Ottavia to one of the unused monitor screens Donatella. The Ottavia CPU had a label saying 'SMOKED''. One of the past elogs, 11091, dated back in March 2015, by Jenne had an update regarding the Ottavia smelling 'burny'. It seems to be working fine for about 2 hours now. Once it is connected to the Martian Network we can test it further. The Donatella screen we used seems to have a graphic problem, a damage to the display screen. Its a minor issue and does not affect the display that much, but perhaps it'll be better to use another screen if we plan to use the Ottavia in the future. We will power it down if there is an issue with it.

13068   Fri Jun 16 12:37:47 2017 Kaustubh, JigyasaUpdateComputersOttavia Switched On

Ottavia had been left running overnight and it seems to work fine. There has been no smell or any noticeable problems in the working. This morning Gautam, Kaustubh and I connected Ottavia to the Matrian Network through the Netgear switch in the 40m lab area. We were able to SSH into Ottavia through Pianosa and access directories. On the ottavia itself we were able to run ipython, access the internet. Since it seems to work out fine, Kaustubh and I are going to enable the ethernet connection to Ottavia and secure the wiring now.

Quote:

It has been working fine the whole day(we didn't do much testing on it though). We are leaving it on for the night.

 Quote: Today, I and Jigyasa connected the Ottavia to one of the unused monitor screens Donatella. The Ottavia CPU had a label saying 'SMOKED''. One of the past elogs, 11091, dated back in March 2015, by Jenne had an update regarding the Ottavia smelling 'burny'. It seems to be working fine for about 2 hours now. Once it is connected to the Martian Network we can test it further. The Donatella screen we used seems to have a graphic problem, a damage to the display screen. Its a minor issue and does not affect the display that much, but perhaps it'll be better to use another screen if we plan to use the Ottavia in the future. We will power it down if there is an issue with it.

9925   Wed May 7 23:09:06 2014 rana, jamieSummaryComputer Scripts / ProgramsOttavia back on network

After Jamie fixed the third party repo issue with Ottavia, he was able to upgrade it to Ubuntu 12.04 Precise Pangolin. But its network stopped working.

I tried to fix its issues by ifconfig and GUI, but what it really wanted was for me to put the network cable back into its eth0 slot. The eth1 network card appears not be working anymore.

All seems fine now. Next I will mount the shared user disk from linux1 and put in a .bashrc.

2878   Tue May 4 14:57:53 2010 josephbUpdateComputersOttavia has moved

Ottavia was moved this afternoon from the control room into the lab, adjacent to Mafalda in 1Y3 on the top shelf.  It has been connected to the camera hub, as well as the normal network.  Its cables are clearly labeled.  Note the camera hub cable should be plugged into the lower ethernet port. Brief tests indicate everything is connected and it can talk to the control room machines.

The space where Ottavia used to be is now temporarily available as a good place to setup a laptop, as there is keyboard, mouse, and an extra monitor available.  Hopefully this space may be filled in with a new workstation in the near future.

11091   Tue Mar 3 04:43:12 2015 JenneOmnistructurePEMOttavia is dead?

After some searching, including help from 4 security guys (I think they don't have a lot to do at 4:30am :), we found that Ottavia is super warm, and smelled burn-y.  She has been powered down and unplugged.  Security guys may call Steve's desk to follow up later today.

10535   Wed Sep 24 18:56:45 2014 ericqUpdateGeneralOttavia slowness

Ottavia was having some severe interaction latency today. Xorg was taking up >90% of the CPU, just sitting around. The machine was logged in to a desktop session with lots of graphical effects turned on. I changed the system default session to "gnome-fallback" in /etc/lightdm/lightdm.conf, which was already set as the default for controls, but wouldn't get chosen for the autologin that happens on boot.

Hopefully this helps ottavia stay usable...

9144   Fri Sep 20 08:15:30 2013 SteveUpdateComputer Scripts / ProgramsOttavia, Rossa and Pianosa

Ottavia, Rossa  and Pianosa are running out of storage  space.

Attachment 1: Ottavia.png
Attachment 2: Rossa.png
Attachment 3: Pianosa.png
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