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ID Date Author Type Category Subjectup
  11646   Fri Sep 25 19:06:13 2015 ranaUpdateSUSETMX IS drifting

I don't see any evidence of it getting more stable. It seems there was a big step in January, but the problem we were talking about - the suspension shifting when it gets a big kick - can't be proven to be gone or not by just looking at the trends. The real issue is whether or not it slips when we put in a large step in the LSC.

Quote:

We have talked about the drift of ETMX sus on the Wednesday meeting.

It has stopped moving on Jan 8, 2015 and it has been reasanable stable since than.

 

  7309   Wed Aug 29 17:09:57 2012 jamieUpdateSUSETMX OK, free swinging

ETMX appears to be fine.  It was stuck to its OSEMs in the usual way.  I touched it and it dislodged and is now swinging freely.  Damping loops have been re-engaged.

Screenshot.png

  14902   Fri Sep 20 11:39:04 2019 gautamUpdateOptical LeversETMX Oplev HeNe Dead

While working on recovering interferometer alignment, I noticed that the ETMX Oplev SUM channel reported 0 counts. Attachment #1 shows the 200 day trend - despite the missing data, the accelerating downward decay is evident. I confirmed that there is no light coming out of the HeNe by walking down to EX. The label on the HeNe says it was installed in March 2017, so the lifetime was ~30 months. Seems a little short? I may replace this later today.

  14911   Sun Sep 29 16:08:25 2019 gautamUpdateOptical LeversETMX Oplev HeNe replaced

To facilitate POX locking investigations, I replaced this HeNe today with one of the spares Chub/Steve had acquired some time ago. Details:

  • Part number: Lumentum 22037130 (1103P)
  • Serial number: PA00836
  • Manufacture date: 01/2019
  • Power output: ~2.64 mW (Measured with Ophir power meter in the 632nm setting)
  • Power received on QPD: ~0.37 mW = ~18700 cts (Measured with Ophir power meter in the 632nm setting)

The RIN of the sum channel with the Oplev servo engaged, along with that for the other core FPMI optics, in shown in Attachment #1. The ETMX HeNe RIN is compatible with the other HeNes in the lab (the high-frequency behaviour of the BS Oplev is different from the other four because the QPD whitening electronics are different).

Not sure what to make of the ETMY RIN profile being so different from the others, seems like some kind of glitchy behaviour, I could see the mean level of the ASD moving up and down as I was taking the averages in DTT. Needs further investigation.

The old / broken HeNe is placed i(nside the packaging of the abovementioned replacement HeNe) on Steve's old desk for disposal in the proper way.

*It looked like Steve had hooked up a thermocouple to be able to monitor the temperature of the HeNe head. I removed this feature as I figured if we don't have this hooked up to the DAQ, it isn't a really useful diagnostic. If we want, we can restore this in a more useful way.

Quote:

While working on recovering interferometer alignment, I noticed that the ETMX Oplev SUM channel reported 0 counts. Attachment #1 shows the 200 day trend - despite the missing data, the accelerating downward decay is evident. I confirmed that there is no light coming out of the HeNe by walking down to EX. The label on the HeNe says it was installed in March 2017, so the lifetime was ~30 months. Seems a little short? I may replace this later today.

  14736   Tue Jul 9 08:33:31 2019 gautamSummarySUSETMX PIT bias voltage changed by ~1V

After this activity, the DC bias voltage required on ETMX to restore good X arm cavity alignment has changed by ~1.3 V. Assuming a full actuation range of 30 mrad for +/- 10 V, this implies that the pitch alignment of the stack has changed by ~2 mrad? Or maybe the suspension wires shifted in the standoff grooves by a small amount? This is ~x10 larger than the typical change imparted while working on the table, e.g. during a vent.

Main point is that this kind of range requirement should probably be factored in when thinking about the high-voltage coil driver actuation.

Quote:

We unstuck ETMX by shaking the stack. Most effective was to apply large periodic human sized force to the north STACIS mounts.

  12381   Fri Aug 5 18:21:28 2016 gautamUpdateSUSETMX Ruby Wire Standoff GLUED
  • The latest twist in this apparently never-ending saga was that even though fine pitch balancing was achieved, the wire was out of the groove on both sides!
  • I rectified this situation in the morning, did the fine pitch balancing in the afternoon
  • Koji's suggestion of adjusting the OSEM holding plate totally did the trick, all four magnets are reasonably well centered relative to the vertical now...
  • After the latest round of fine pitch balancing, we are now tilted in pitch backwards (i.e. towards the AR face) by <0.7mrad. 
  • Prior to gluing, I visually inspected the optic to check that (see attachments):
    • Wires are in grooves on both sides
    • Unglued ruby standoff has the correct "rotation", i.e. that the wire contacts the standoff after the groove has started, and leaves it before the groove ends, since the groove doesn't go all the way around the standoff
    • Section of wire around the bottom half of the optic has no obvious kinks/other funny features
    • Unglued standoff is in contact with the barrel
    • All magnets are well clear of teflon in OSEM coils on both sides
  • Eric also checked the frequencies of the various modes (PIT, YAW, POS and SIDE) by looking at the power spectrum of the free-swinging error signals on the coils. The pitch mode is now softer than before, at ~710mHz
  • We then proceeded to glue the optic, using a needle to apply the glue (optic was clamped using face EQ stops, bottom EQ stops were not engaged as we felt this would affect the fine pitch balancing
  • During the process, it looks like we may have inadvertently gotten some glue onto the wire (see attachments) - it doesn't look like any has seeped into the groove itself, but there is definitely some on the wire. We can possibly try cleaning this once the optic is out. In the worst case scenario, we will have to loop another section of wire, but the fine pitch balancing should be unaffected provided we did not perturb the optic too much
  • Bob has said the large oven will be available to bake the cages on Tuesday, August 9th. By this time, we should have ETMY suspended as well (we were unable to glue the knocked off magnet on ETMY as the glass bowl we had for soaking the edge of the optic in acetone to remove the epoxy residue broke while I was assembling the various pieces of Teflon inside it. Steve is procuring a new one on Monday). It is still unclear when we can vacuum bake the two ETMs...

Attachments:

Attachment #1: Wire is in the groove in the unglued wire-standoff, groove rotation looks pretty good.

Attachment #2: Ruby standoff is sitting on the barrel of the optic (if you zoom in)

Attachment #3: Side magnet is well centered w.r.t OSEM coil

Attachment #4: UR magnet is well centered w.r.t OSEM coil

Attachment #5: UL magnet is well centered w.r.t OSEM coil

Attachment #6: LL magnet is well centered w.r.t OSEM coil

Attachment #7: LR magnet is well centered w.r.t OSEM coil

Attachment #8: Wire is in the groove in the glued Ruby standoff

Attachment #9: Standoff after gluing. 3-4 drops of epoxy are visible on the wire, but none looks to have seeped into the groove itself

Attachment #10: Side view of newly glued Ruby standoff

Attachment #11: Before and After gluing shots.

 

 
 
 

 

  12377   Fri Aug 5 02:17:10 2016 gautamUpdateSUSETMX Ruby Wire Standoff Ready for Gluing

Part 1: Rotation of optic

  • As reported in my elog yesterday, both the left magnets (UL and LL) seemed too low relative to the OSEM coils
  • Eric and I checked the height of the scribe lines using the microscope and found that the scribe lines were low on the left side and high on the right side (as viewed from the AR side) by approximately the same amount, confirming our suspicion that the optic was rotated. The position of the scribe line on the bottom of the optic relative to the bottom-rear face EQ stop also suggested the same
  • Eric brought in the bottom EQ stops, and once the wire was slightly unloaded, rotated the optic by the required amount by hand 
  • This process took two tries, but we were successful
  • Re-checked heights of scribe lines using microscope, and once we were satisfied, re-did the coarse pitch balancing

Part 2: Replacement of holder for top pair of OSEMs

  • Eric and I had difficulty removing the UR OSEM-holding screw
  • This is the non-silver-coated new variety of screw
  • It got to a point where I could neither move the screw in or out, even with the help of a pair of pliers
  • I decided to swap out the piece of the suspension tower holding the top two OSEMs (UR and UL) with the same piece from the old ETMX tower that is currently residing on the flow bench at the south end (along with the accompanying piece that overhangs the optic and holds the front-face and top earthquake stops
  • I cleaned the piece 3-4 times with acetone, and then a couple of times with isopropanol. I adjudged this to be sufficient as we are going to air bake the tower anyways prior to installation in the vacuum chamber
  • I then swapped the pieces:
    • First I brought in the bottom pairs of EQ stops
    • Next, I secured the optic using the three lower face EQ stops
    • Then, I removed the EQ stop screws from the overhanging piece, after which I removed the overhanging piece itself
    • After removing the top-back EQ stop, I removed the OSEM-holding piece from the suspension tower
    • Did the above steps in reverse, installing the new piece
  • All went smoothly. This piece does not have a serial number unfortunately
  • After this, I re-inserted the OSEMs, and judged the magnet-coil alignment to be satisfactory to proceed further
  • We decided to use the old variety of silver plated OSEM holding screws for the top two OSEMs (by choice) and the side OSEM (the new variety is too short anyways). During the course of my work tonight, I found this worked way better. The bottom pair of OSEMs remain held by the new variety of unplated screws. We may want to review whether we really want to use this new type of screws (I believe the idea is to make it easier to tighten and loosen the screws)

Part 3: Fine pitch balancing

  • As per the SOS assembly procedure, I turned off the HEPA filters at the clean bench for this part of the work
  • Checked that the HeNe beam incident on the optic was level with the tabletop, beam height set to 5.5"
  • Proceeded to do the fine pitch balancing the same way as described in yesterday's elog (i.e. no PZT buzzer, just fine touches by hand)
  • I was able to converge fairly quickly to a good point in configuration space
  • After re-centering the OSEM coils such that the PD output was ~50% of its maximum value (see Attachment #1), I found over a lever arm length of 56" (=1.42m) a beam height deviation from 5.5" by <2mm. This corresponds to 0.7mrad pitching forwards towards the HR side
  • The suspension assembly procedure tells us to aim for 0.5mrad, but I think this is close enough for standoff gluing, as this misalignment is extremely sensitive to the OSEM coil positions (although I would say, from Attachment #1, that they are actually pretty well centered)
  • The only thing that concerns me is that the LL magnet is still a little low relative to the coil. This can be fixed by shimming if necessary...

Attachment #1: Striptool trace showing OSEMs are pretty well centered (towards the end, I turned on the HEPA filters again, which explains the shift of the traces). The y-axis is normalized such that the maximum displayed corresponds to the fully open PD output of the coils

Attachment #2: Fine pitch balancing optical lever setup

Attachment #3: Tower assembly

Attachment #4: SIDE OSEM close-up

Attachment #5: UR OSEM close-up

Attachment #6: UL OSEM close-up

Attachment #7: LL OSEM close-up (this is the concerning one)

Attachment #8: LR OSEM close-up


We should also check the following (I forgot and don't want to wear my clean jumpsuit again now to take more photos):

  1. Wire is still in groove
  2. Standoff is sitting on the optic barrel and not on epoxy residue of the guiderod
  12378   Fri Aug 5 04:43:09 2016 KojiUpdateSUSETMX Ruby Wire Standoff Ready for Gluing

If only the LL magnet looks too low, doesn't this mean that the OSEMs are not arranged in a square shape?
If so, you can fix this misalignment by moving the OSEM holding plate rather than OSEM shimming, can't you?

  4889   Mon Jun 27 00:23:11 2011 ranaUpdateCDSETMX SIDE problem

The slow readback of the ETMX side seems to also have something flaky and bi-stable. This is not an issue for damping, but it disables the SIDE watchdog for ETMX and makes it unsafe if we accidentally use the wrong damping sign.

  5146   Tue Aug 9 01:35:45 2011 SureshUpdateSUSETMX Side Sensor slow channel down for a long time

The slow signal from the side sensor on ETMX was last seen in action sometime in May 2010!  And then the frame builder has no data for a while on this channel.  After that the channel shows some bistability starting Sept 2010 but has not been working.  The fast channel of this sensor  (C1:SUS-ETMX_SDSEN_OUTPUT) does work so the sensor is working.  Probably is a loose contact... needs to be fixed.

ETMX-SDSEN_trend1.png         ETMX_SDSEN_trend2.png

 

  5255   Wed Aug 17 15:47:18 2011 AnamariaUpdateSUSETMX Side Sensor slow channel down for a long time

Jenne, Anamaria

We aligned the ETMX OSEMs and ran into this issue. Looking at the SENSOR_SIDE channel, we pulled out the OSEM and determined that the open light voltage is 874 counts, so we centered it around 440 as well as we could. This is same channel as its slow counterpart SDSEN_OUTPUT (grey number immediately to the right on SUS medms).

 

 

Quote:

The slow signal from the side sensor on ETMX was last seen in action sometime in May 2010!  And then the frame builder has no data for a while on this channel.  After that the channel shows some bistability starting Sept 2010 but has not been working.  The fast channel of this sensor  (C1:SUS-ETMX_SDSEN_OUTPUT) does work so the sensor is working.  Probably is a loose contact... needs to be fixed.

 

 

  12382   Sun Aug 7 14:53:39 2016 ericq UpdateSUSETMX Standoff gluing was successful

I came in to check on ETMX. I freed the earthquake stops, and found that the OSEMS were reasonably, but not perfectly, centered. Turning on the damping, I found that the pitch balance is biased slightly downwards at about ~0.5mrad, which is acceptable. 

As another check for how much we moved the standoff while gluing, we can look at the spectra of the OSEMS while the mirror is free swinging, and see if/how the resonance frequencies have moved around. As Gautam previously mentioned, the pitch frequency is even softer than we expected from the thicker ruby standoff alone. This is due to the excess glue around the guide rod forcing us to position the standoff even lower to have good contact with the optic's barrel. In the plot below, the design yaw/pit/pos frequencies are the dashed lines, and the measured frequencies are the solid lines. 

[The plot is not in spectral density units, so that the peak heights reflect real units of motion at each resonance frequency. Data and code used to generate the plot is attached] 

  Yaw Pitch Pos Side
Design frequencies from T000134: 0.773 Hz 0.856 Hz 1.001 Hz  
ETMX Measurement in-air 2010 0.828 Hz 1.04 Hz 0.908 Hz 0.949 Hz
Pre-gluing 0.785 Hz 0.709 Hz 0.949 Hz 0.975 Hz
Post-gluing 0.789 Hz 0.705 Hz 0.953 Hz 0.984 Hz

According to the calculations from ELOG 12316, this pitch frequency implies the support point is 0.317mm lower than the design value of 0.985mm. (However, this is just an approximation and does not include the fact that each standoff is at a different height.)

Nevertheless, this difference is frequency is not so large that the dynamics of the suspension will be qualitatively changed in some important way; really, the pitch frequency is just ~1.5dB lower. So, I deemed our standoff gluing a success, removed the optic from the suspension, and placed it in an optic holding ring after giving the top of the barrel a gentle drap wipe with some iso. At this point, I used the microscope to look at the ruby standoff groove. As far as I can tell, no glue has invaded the groove - it looks sharp as ever. (whew)

I also wiped the wire with acetone and easily removed the glue droplets. However, I noted that (as is the case for ETMY) the wire is deformed at the points where it was in contact with the standoffs. I wonder if we should re-suspend with new wire, or accept the current deformed wires.

In any case, we can now move on to air baking the ETMX tower and gluing the stray magnet back onto ETMY.

  5517   Thu Sep 22 13:45:17 2011 PaulUpdateSUSETMX actuator response fits

Fitting results: 

 Pitch

-- Fit completed after 305 iterations--
 Started with: Gain = 3e-05,
 Q factor = 5,
 Pole frequency = 0.6776,
 Fit results:  Gain = 1.85497e-06,
 Q factor = 23.7233,
 Pole frequency = 0.956686
 Residual (normalised against the sum of input datapoints) = 0.0202483
 
Yaw
-- Fit completed after 334 iterations--
 Started with: Gain = 3e-05,
 Q factor = 5,
 Pole frequency = 0.6776,
 Fit results:  Gain = 2.518e-06,
 Q factor = 7.21618,
 Pole frequency = 0.853559
 Residual (normalised against the sum of input datapoints) = 0.0570132
  12348   Thu Jul 28 16:43:01 2016 LydiaUpdateGeneralETMX aluminium standoff groove condition

 

I took some pictures with the digital microscope of the aluminum standoffs removed from ETMX. The first one had some leftover epoxy still attached, so I was able to distinguish which part of the groove was occupied by the wire. A better microscope would help (this one has a maximum magification of 80, 200 or so would be much better) but I was still able to see what looks like a second minimum inside the groove at the wire location (see Attachments 1 and 2). The bottom edge of the standoff shows the profile of the groove on the opposite side from the glue. I took several photos with different lighting angles and at different locations on the microscope stage and convinced myself that this was not just an artificial effect. I also took photos of the groove in a different place and did not see this feature (Attachment 3).

The other standoff in the same container had no visible damage to the groove or to the body of the rod. I rotated it under the mocroscope and could celarly see the 'V' shape all the way around. The smooth undanaged groove caught the light more easily and was obvious. The damaged one is scratched around much of the surface, but the undamaged standoff is very smooth. Eric, were both aluminum standoffs in the container with the extra ruby one taken off ETMX, or was one of them new? in any case, see Attachement 4 for a comparison. The believed damage is somewhat visible on the top edge of the lower standoff in the photo. 

[Edit:] Also, in the drawings it looks like the specified radius for the bottom of the groove (0.001 in) is smaller than the radius of the wire (0.00085 in). This would prevent having two clean points of contact like Steve and Gautam were describing as the goal. This is also true of drawings for the new Sapphire guiderods, though the dimensions are in metric units the specified radius of the groove bottom is smaller than the wire's diameter, but larger than its radius. Maybe this providied the initial ability for the wire to move around and carve two distinct grooves. 

  7316   Thu Aug 30 08:37:11 2012 SteveUpdateSUSETMX and ITMX needs more attention

Quote:

ETMX appears to be fine.  It was stuck to its OSEMs in the usual way.  I touched it and it dislodged and is now swinging freely.  Damping loops have been re-engaged.

Screenshot.png

Earthquake m4.1 test for ETMX and moves ITMX.  ITMX-LR sensor 0.3V

  4236   Tue Feb 1 17:34:21 2011 JenneUpdateSUSETMX and PRM watchdogs tripped

I sat down in the control room to find that ETMX and PRM's watchdogs had been tripped.  I don't know how long they've been crazy, but there was a big something that showed up in the seismometers around 16:30UTC, or ~11:30 this morning.  I don't find any significant earthquakes on the USGS site for that time though, so it might be more local, i.e. work next door or trucks or whatever.

I take back the suggestion that it was that seismic event.  Clearly the PRM and the ETMX were kicked at different times, neither of which is the same as the seismic action. Mystery.  You can see they have been ringing down for a while though, which is neat. 

  13576   Wed Jan 24 18:12:31 2018 johannesUpdateDAQETMX auxiliary DAQ work

I replaced the two remaining D-Sub M/M cables that still had gender-changers with M/F cables today, completing the mechanical and wiring work on the ETMX rack. All backplane adapter boards were secured to a cross-strut of the crate using zip ties. This was necessary because the adapter boards don't fit the crate with their panels attached ( the ETMX eurocrate is the only one with slightly different dimensions from all the others), and the we can't mount them to the strut using the panels. This won't be an issue on any of the other crates.

   

   

In other news:

I disabled the legacy support in the three Acromag ADC units and set the input averaging to 10 samples via the USB configuration utility. The documentation is unfortunately a little sparse about what this actually means. The manual states that "fresh input data is available to the network every 10ms", so the sampling rate is for sure faster than 100Hz. Since the IOC updates its channels every .1 seconds I assume that an averaging value of 10 to reduce the input noise is safe. The maximum value the configuration tool permits is 200. I tried this using the CryoLab DAQ and set all input channels to 200 and used StripTool to look at the time series of a slow oscillation (.1Hz) with a large amplitude (16Vpp) and looked for missed data points, indicating too long wait times for channels updates. There was no such qualitative difference between 1 sample, 10 samples, and 200 samples, so even pushing the averaging value to max seemed okay. I went with the conservative value of 10 for the ETMX DAQ, but we can likely increase this if noise on the slow inputs becomes an issue.

The input scaling of the ADC channels has been corrected. I changed the conversion method in the EPICS records from manual using the ASLO and AOFF fields to using engineering units via EGUF and EGUL. This required a little attention. The Acromags scale the dynamic input range of +/- 10V to +/- 30,000 raw value, but the EPICS IOC interprets the data type as ranging from -32767 to +32768, so the EGUF and EGUL fields must be set to -10.923 and +10.923 to achieve proper scaling. I also changed the SCAN field on all ADC channels to 0.1 seconds. This has been done for all ADC and DAC channel records.

  10643   Tue Oct 28 01:12:57 2014 JenneUpdateSUSETMX bad :(

ETMX is misbehaving again.  I went to go squish his cable at the rack and at the satellite box, but it still happened at least once.

Anecdotally and without science, it seems to happen when ETMX is being asked to move a "big" amount.  If I move the sliders too quickly (steps of 1e-3, but holding down the arrow key for about 1 second) or if I offload the ASS outputs when they're too large (above 10ish?), ETMX jumps so that it's about 50 urad off in yaw according to the oplev (sometimes right, more often left), and either 0 or 50urad off in pitch (up if right in yaw, down if left in yaw). 

So far, by-hand slowly offloading the ASS outputs using the sliders seems to keep it happy.

I would ask if this is some DAC bit flipping or something, but it's happening for outputs through both the fast front ends (ASS offloading) and the slow computers (sliders moved too fast).  So.  I don't know what it could be, except the usual cable jiggling out issue.

Anyhow, annoying, but not a show stopper.

  10644   Tue Oct 28 02:44:08 2014 JenneUpdateSUSETMX bad :(

Okay, now ETMX's badness is a show-stopper.  I'm not sure why, but after this last lockloss, ETMX won't stay put.  Right now (as opposed to earlier tonight) it seems to only be happening when I enable LSC pushing on the SUS.  ETMX is happy to sit and stay locked on TEM00 green while I write this entry, but if I go and try to turn on the LSC it'll be wacky again.  Daytime work.

Anyhow, this is too bad, since I was feelin' pretty good about transitioning DARM over to AS55. 

I had a line on (50 counts at 503.1 Hz pushing differentially on the ETMs), and could clearly see the sign flip happen in normalized AS55Q between arm powers of 4 and 6.  The line also told me that I needed a matrix element of negative a few x10^-4 in the AS55Q -> DARM spot.  Unfortunately, I was missing a zero (so I was making my matrix element too big by a factor of 10) in my ezcastep line, so both times I tried to transition I lost lock. 

So.  I think that we should put values of 0.5 into the power normalization for our test case (I was using SRCL_IN1 as my tester) since that's the approximate value that the DCtrans uses, and see what size AS55Q matrix element DARM wants tomorrow (tonight was 1.6-3 x 10^-4, but with 1's in the normalization matrix).  I feel positive about us getting over to AS55. 

Also, Q is (I assume) going to work some more tomorrow on PRMI->REFL165, and Diego is going to re-test his new IR resonance finding script.  Manasa, if you're not swamped with other stuff, can you please see if you can have a look at ETMX?  Maybe don't change any settings, but see what things being turned on makes ETMX crazy (if it's still happening in the morning). 

  1340   Thu Feb 26 19:20:08 2009 YoichiConfigurationGeneralETMX camera centered. POX, POY PDs centered
Alberto, Yoichi

We centered the ETMX camera.
Alberto centered the POX and POY PDs.
We also updated the offset values of PD3 and PD4.
  13993   Thu Jun 21 03:13:37 2018 gautamUpdateSUSETMX coil driver noise

I decided to take a quick look at the data. Changes made to the ETMX coil driver board:

  1. Fast path series resistances: 400 ohm ---> 2.25 kOhm (= 2x 4.5 kohm in parallel). Measured (with DMM) resistance in all 5 paths varied by less than 3 ohms (~0.2%).
  2. All thick film resistors in signal (fast and bias) paths changed to thin film.
  3. AD797 ---> Op27 for monitor output.
  4. Above-mentioned mon output (30Hz HPF-ed) routed to FP LEMO mon via 100ohm for diagnostic purposes.
  5. 4x Trim-pots in analog path removed. 

I also took the chance to check the integrity of the LM6321 ICs. In the past, a large DC offset on the output pin of these has been indicative of a faulty IC. But I checked all the ICs with a DMM, and saw no anomalies.

Measurement condition was that (i) the Fast input was terminated to ground via 50ohm, (ii) the Bias input was shorted to ground. SR785 was used with G=100 Busby preamp (in which Steve installed new batteries today, for someone had left it on for who knows how long) for making the measurement. The voltage measurement was made at the D-Sub connector on the front panel which would be connected to the Sat. Box, with the coil driver not connected to anything downstream.

Summary of results:

[Attachment #1] - Noise measurement out to 800 Hz. The noise only seems to agree with the LISO model above 300 Hz. Not sure if the low-frequency excess is real or a measurement artefact. Tomorrow, I plan to make an LPF pomona box to filter out the HF pickup and see if the low-frequency characteristics change at all. Need to think about what this corner freq. needs to be. In any case, such a device is probably required to do measurements inside the VEA.

[Attachment #2] - Noise measurement for full SR785 span. The 19.5 kHz harmonics are visible. I have a theory about the origin of these, need to do a couple of more tests to confirm and will make a separate log.

[Attachment #3] - zip of LISO file used for modeling coil driver. I don't have the ASCII art in this, so need to double check to make sure I haven't connected some wrong nodes, but I think it's correct.

Measurements seem to be consistent with LISO model predictions.

*Note: Curves labelled "LISO model ..." are really quad sum of liso pred + busby box noise.

My main finding tonight is: With the increased series resistance (400 ohm ---> 2.25 kohm), LISO modeling tells me that even though the series resistance (Johnson noise) used to dominate the voltage noise at the output to the OSEM, the voltage noise of the LT1125 in the bias path now dominates. Since we are planning to re-design the entire bias path anyways, I am not too worried about this for the moment.

I will upload more details + photos + data + schematic + LISO model breakdown tomorrow to a DCC page


gautam noon 21 June 2018: I was looking at the wrong LISO breakdown curves. So the input stage Op27 voltage noise used to dominate. Now the Bias path LT1125 voltage noise dominates. None of the conclusions are affected... I've uploaded the corrected plots and LISO file here now. 

  13992   Thu Jun 21 00:14:01 2018 gautamUpdateSUSETMX coil driver out

I finished the re-soldering work today, and have measured the coil driver noise pre-Mods and post-Mods. Analysis tomorrow. I am holding off on re-installing the board tonight as it is likely we will have to tune all the loops to make them work with the reduced range. So ETMX will remain de-commissioned until tomorrow.

  13999   Thu Jun 21 18:25:57 2018 gautamUpdateSUSETMX coil driver re-installed

Initial tests look promising. Local damping works and I even locked the X arm using POX, although I did it in a fake way by simply inserting a x5.625 (=2.25 kohm / 400 ohm) gain in the coil driver filter banks. I will now tune the individual loop gains to account for the reduced actuation range.


Now I have changed the loop gains for local damping loops, Oplev loops, and POX locking loop to account for the reduced actuation range. The dither alignment servo (X arm ASS) has not been re-commissioned yet...

  13988   Tue Jun 19 23:27:27 2018 gautamUpdateSUSETMX coil driver work in AM tomorrow

Per discussion today eve, barring objections, I will do the following tomorrow morning:

  1. Remove ETMX coil driver board from 1X9
    • Change series resistances on the fast path to 2x4k in parallel. One will be snipped off once we are happy we can still lock.
    • Remove AD797s, potentiometers.
    • Thick film-->thin film for important components.
  2. Remove ETMX de-whitening board from 1X9
    • Remove x3 analog gain.
    • Thick film-->thin film for important components.
  1588   Fri May 15 00:02:34 2009 peteUpdateSUSETMX coils look OK

I checked the four rear coils on ETMX by exciting XXCOIL_EXC channel in DTT with amplitude 1000@ 500 Hz and observing the oplev PERROR and YERROR channels.  Each coil showed a clear signal in PERROR, about 2e-6 cts.  Anyway, the coils passed this test.

 

  1616   Thu May 21 18:05:03 2009 peteUpdateSUSETMX coils look OK

Quote:

I checked the four rear coils on ETMX by exciting XXCOIL_EXC channel in DTT with amplitude 1000@ 500 Hz and observing the oplev PERROR and YERROR channels.  Each coil showed a clear signal in PERROR, about 2e-6 cts.  Anyway, the coils passed this test.

 

 I also made xfer fctns of the 4 piston coils on ETMY and ETMX with OL_PIT.  (I looked at all 4 even though the attached plot only shows three.)  So it looks ike the coils are OK.

  3957   Fri Nov 19 17:12:22 2010 yutaUpdateCDSETMX damped, but with weird TO_COIL matrix

Background:
  c1iscex machine is currently being setup and RT model c1scx is running.
  But ETMX(south) didn't seem to be damped, so I checked it.

What I did:
  1. Checked the wiring. It seemed to be OK.
    Looked LEMO monitor output of SUS PD Whitening Board(D000210) with oscilloscope and they seemed to be getting some sensor signal except SDSEN.
      SDSEN is funny. C1:SUS-ETMX_SPDMon decreases slowly when PD input cable is disconnected, and increases slowly when connected.
      There might be some problem in the circuits.
    Looked LEMO monitor output of SOS Coil Driver Module(D010001) with oscilloscope and they seemed to be receiving correct signal from DAC.
      When ULCOIL offset is added, ch1 increased and so on.

  2. Checked the direction of SUSDOF motion when kicked with one coil.
    The result was;

kick (+) POS PIT YAW
ULCOIL + + +
URCOIL + - +
LRCOIL + - -
LLCOIL + + -


    This table tells you, when ULCOIL_OFFSET increases, SUSPOS increases and so on.
    If URCOIL and LLCOIL are swapped, they look correct.
    Also, they have opposite sign to the usual optics(e.g. MCs, BS, PRM).

  3. Changed TO_COIL matrix according to the table above(see Attachment #1). Changed signs of XXCOIL_GAINs.

  4. ETMX damped!

Plan:
  - Check the wiring after SOS Coil Driver Module and circuit around SDSEN
  - Check whitening and dewhitening filters. We connected a binary output cable, but didn't checked them yet.
  - Make a script for step 2
  - Activate new DAQ channels for ETMX (what is the current new fresh up-to-date latest fb restart procedure?)

  12889   Thu Mar 16 08:22:16 2017 SteveUpdateSUSETMX damping

Finally I see what kicks the sus damping off

Quote:

Huh? So should we ask them to put the container back? Or do you have some other theory about ETMX tripping that is not garbage related?

Quote:

ETMX sus damping recovered.

Note: The giant metal garbage container was moved from the south west corner of CES months ago.

 

 

  12855   Tue Feb 28 08:04:48 2017 steveUpdatePEMETMX damping recovered

ETMX sus damping recovered.

Note: The giant metal garbage container was moved from the south west corner of CES months ago.

Quote:

ETMX sus damping recovered.  PSL enclousure is dusty at 20V rotation speed. Rainy days as outside condition.

 

 

  12856   Tue Feb 28 18:25:22 2017 ranaUpdatePEMETMX damping recovered

Huh? So should we ask them to put the container back? Or do you have some other theory about ETMX tripping that is not garbage related?

Quote:

ETMX sus damping recovered.

Note: The giant metal garbage container was moved from the south west corner of CES months ago.

 

  13261   Mon Aug 28 10:51:21 2017 steveUpdateSUSETMX damping recovered
  4836   Mon Jun 20 09:04:13 2011 steveUpdateSUSETMX damping restored

ETMX sus damping restored

  6180   Mon Jan 9 08:47:35 2012 steveUpdateSUSETMX damping restored

ETMX sus damping restored

  6181   Mon Jan 9 13:19:09 2012 kiwamuUpdateSUSETMX damping restored

No we can't do that because the c1scx model is not working properly.

If you look into the real time controller screen you will find what I mean.

Quote from #6180

ETMX sus damping restored

  6644   Tue May 15 08:44:55 2012 steveUpdateSUSETMX damping restored

ETMX sus damping restored

  7937   Thu Jan 24 11:31:45 2013 SteveUpdateSUSETMX damping restored

ETMX sus damping restored.  It is still noisy

  7938   Thu Jan 24 11:40:55 2013 JenneUpdateSUSETMX damping restored

Quote:

ETMX sus damping restored.  It is still noisy

 I should have elogged, but I turned off the watchdog to remind myself that iscex computer is still crashed.  "Turning on" the damping doesn't do anything since there aren't any signals going to the coils from the computer.

  9024   Mon Aug 19 07:53:48 2013 SteveUpdateSUSETMX damping restored

ETMX sus damping restored

  10284   Tue Jul 29 07:54:34 2014 SteveUpdateSUSETMX damping restored

ETMX sus damping restored

  10361   Mon Aug 11 08:04:01 2014 SteveUpdateSUSETMX damping restored
  10495   Thu Sep 11 15:50:49 2014 SteveUpdateSUSETMX damping restored
  10738   Mon Dec 1 07:30:29 2014 SteveUpdateSUSETMX damping restored

ETMX sus damping restored and PMC locked manually.

  11234   Wed Apr 22 11:43:28 2015 SteveUpdateSUSETMX damping restored

ETMX sus damping restored.

  11476   Mon Aug 3 08:16:19 2015 SteveUpdateSUSETMX damping restored
  11927   Tue Jan 12 07:54:23 2016 SteveUpdateSUSETMX damping restored

PMC locked and ETMX suspension damping restored.

  11939   Wed Jan 20 09:36:11 2016 SteveUpdateSUSETMX damping restored

ETMX suspension damping restored.

 

  8106   Tue Feb 19 08:42:31 2013 KojiUpdateVACETMX door open

[Steve, Yuta, Koji]

The ETMX heavy door was removed.

  2361   Mon Dec 7 18:18:55 2009 JenneUpdateCOCETMX drag wiped

[Koji, Jenne, Alberto, Steve, Bob]

ETMX has been drag wiped. 

Around 2:45pm, after the main IFO volume had come up to atmospheric pressure, we removed both doors to the ETMX chamber.  Regular procedures (wiping of O-rings with a dry, lint-free cloth, covering them with the light O-ring covers, etc.) were followed.  Koji took several photos of the optic, and the rest of the ETMX chamber before anything was touched. These will be posted to the 40m Picasa page.  Steve and Koji then deionized the optic.

Koji removed the bottom front earthquake stop, and clamped the optic with the remaining earthquake stops.

The clean syringes were prepared: These are all glass and metal (nothing else) medical syringes.  The size used was 100microliters.  Earlier today, we had prepared our solvents in small little beakers which had been baked over the weekend.  Brand new glass bottles of Acetone and Isopropyl Alcohol were opened, and poured into the small beakers.  To make sure we have enough, we have 3 ~10ml beakers of each Acetone and Isopropyl.

We started with Acetone.  The syringe was filled completely with acetone, then squirted onto a kimwipe.  This was repeated ~twice, to ensure the syringe was well rinsed.  Then the syringe was filled a little past the 100 microliter mark.  Koji held a piece of lens cleaning paper to ETMX and used an allen wrench underneath the optic to help guide the paper, and keep it near the optic (of course, the only thing in actual contact with the optic was the lens paper).  In one smooth shot, the plunger of the syringe was pressed all the way down.   (This is a bit tricky, especially when the syringe is totally full.  You have to squeeze it so the plunger moves fairly quickly down the barrel of the syringe to get a good arc of liquid.  The goal is to shoot all of the solvent to the same place on the lens paper, so that it makes a little circle of wetness on the paper which covers the coated part of the optic.  The amount of solvent used should be balanced between having too little, so that the paper is dry by the time it has been wiped all the way down, and too much such that there is still a residue of liquid on the optic after the paper has been removed.)  The target was to hit the optic just above the center mark (the oplev was on, so I went for just above the red oplev dot).  Immediately after applying the liquid onto the paper, Koji slowly and smoothly pulled down on the lens paper until it came off of the bottom of the optic.  The acetone was repeated, for a total of 2 acetone wipes.  Because acetone evaporates very quickly, more acetone is used than isopropyl.  The optimal amount turned out to be ~115 microliters of acetone.  It is hard to say exactly how much I had on the second wipe, because the syringe is not marked past 100 microliters.  On the first wipe, with about 105 microliters, the lens paper was too dry at the bottom of the optic.

We then switched to Isopropyl.  A new syringe was used, and again we rinsed it by filling it completely with isopropyl, and emptying it onto a kimwipe.  This was repeated at least twice.  We followed the same procedure for applying liquid to the optic and wiping the optic with the lens paper.  On the first try with isopropyl, we used 100 microliters, since that was the preferred amount for acetone.  Since isopropyl evaporates much slower than acetone, this was determined to be too much liquid.  On the second isopropyl wipe, I filled the syringe to 50 microliters, which was just about perfect.  The isopropyl wiping was done a total of 2 times.

After wiping, we replaced the front bottom earthquake stop, and released the optic from the other earthquake stops' clamping.  The OSEM values were checked against the values from the screenshots taken yesterday afternoon, and were found to be consistent.  Koji took more photos, all of which will be placed on the 40m Picasa page.

We visually inspected the optic, and we couldn't see anything on the optical surface of the mirror.  Koji said that he saw a few particulates on some horizontal surfaces in the chamber.  Since the optic seemed (at least to the level of human vision without a strong, focused light) to be free of particulates on the optical surface to start with, the suspense will have to remain until we button down, pump down, and try to lock the IFO to determine our new finesse, to see if the wiping helped any substantial amount. 

We replaced the regular, heavy door on the inner side of the ETMX chamber (the side closer to the CES building), and put only a light door on the outer side of the chamber (the side closer to the regular walkway down the arm).  We will look at the spectra of the OSEMS tomorrow, to confirm that none of the magnets are stuck.

We commence at ~9am tomorrow with ETMY.

LESSONS LEARNED:

The LED lights are awesome.  It's easy to use several lights to get lots of brightness (more than we've had in the past), and the chamber doesn't get hot.

We should get larger syringes for the acetone for the large optics.  It's challenging to smoothly operate the plunger of the syringe while it's so far out.  We should get 200 microliter syringes, so that for the acetone we only fill them about half way.  It was noticeably easier to apply the isopropyl when the syringe only had 50 microliters.

* It may be helpful to have a strong, focused optical light to inspect the surface of the mirror.  Rana says that Garilynn might have such an optical fiber light that we could borrow.

  12931   Fri Apr 7 13:46:23 2017 SteveUpdateSUSETMX enclosure feedthough

ETMX enclosure feedtrouh cabeling corrected.

  12039   Mon Mar 21 10:07:45 2016 SteveUpdateSUSETMX enclosure update

The enclosure top piece in the middle is still in the machine shop.

The carpenter who helps in the built just left for one week vacation.

The unit will be ready  on April 1

I'd prefer doing the installation with the enclosure on the new table.

It's the only way to minimize the resonances of the enclosure with shimming.

ELOG V3.1.3-