Looked at ITMX. Johannes and I both saw a fairly large speck of dust near the center of the HR side. We tried to take some photos but couldn't get any with good focus.
We ran out of illuminator juice, and short-term charging couldn't restore enough battery life to continue the work. We should be able to get some better pictures tomorrow.
Looked at ITMX. Johannes and I both saw a fairly large speck of dust near the center of the HR side. We tried to take some photos but couldn't get any with good focus
Multicolor flash light:
- It seems that the usb port charging doesn't work.
- There is a battery charger on Steve's desk. I set the batteries on it.
White LED flash light:
- I temporarily brought a compatible charger from WB. It's charging two batteries behind the LCD display on my desk.
The ITMX 10" flange with four DSUB-25 feedthroughs has been install with the cables connected at the in-vac side. See photo; as requested, LO1-1 and LO1-2 are connected to the top row of feedthroughs from left to right respectively and the opposite ends of the cables placed left to right on the laser table. PR2-1 and PR2-2 are connected to the lower row of feedthroughs from left to right respectively, with the opposite ends placed on the surface below the laser from left to right. This seemed the easiest way to keep the cable orientation clear.
Thanks for the installation.
With regard to the connector convention, let's use the attached arrangement so that it will be consistent with the existing flange DSUB configuration. Not a big deal.
Good job Q! Give us more details please or play Rachmaninoff Piano Concernto #2
Atm2, EQ 3.5 and 4.1
confirming ITMX is really free
Taking inspiration from J. Lewis et. al, ITMX has been freed.
Rana came by and freed ITMX again. I think it shouldn't be a problem for me to free it if it happens again.
In hopes of getting better SNR on the free swing spectra, we kicked all optics at around 7pm. The damping should come back on a little after midnight. ITMX did not get stuck after this kick.
We started an ITMX freeswing run at this time
Thu Aug 11 18:58:59 PDT 2011
But the optic did not repond to the kick. It is possible that the earthquake stops are close to the face and/or rear of the optic and prevent it from oscillating. We will check again and see what is up in a few hours.
Jenne and Koji
We successfully hung ITMX on the SOS. Side magnet is ~2mm off from the center of the OSEM. ITMX aligned using the QPD. The OSEMs changes the alignment. It looks that something magnetic is inside the OSEM PD or LED.
Reguled ITMY side magnet.
Cleaned up the lab for the safety inspection.
We successfully hung ITMX on the SOS. Side magnet is ~2mm off from the center of the OSEM.
Some details on the side magnet situation from today:
To glue the magnets+dumbbells to the optics, we use the magnet-dumbbell gluing fixture. This fixture is supposed to have teflon 'pads' for the optic to sit on while you align it in the fixture, however the fixture which we received from MIT (it's Betsy's....but it came via MIT) only had one of the 4 teflon pads.
Kiwamu and I decided (last week, when we first glued ITMX's magnets) that it would be bad news to let the AR face of the optic sit on bare metal, so we fashioned up some teflon pads using stock in a cabinet down the Yarm. We were focused on thinking about the face magnets, and didn't think about how the thickness of the teflon affected the placement of the side magnet. We chose some teflon that was too thin by ~1mm, so the optic sat too low in the fixture, resulting in the side magnet being glued too close to the HR side of the optic (this is all along the Z - axis, where Z is the direction of beam propagation).
Why it ended up being 2mm off instead of only 1mm I don't really have an explanation for, other than perhaps tightening the set screws to hold the optic (by the barrel) in the fixture pushes the optic up. I observed this happening when I didn't put any effort into keeping the optic flat on the teflon pads, but I thought that I made sure the optic was seated nicely in the fixture before starting to glue. When I glued the new ITMY side magnet tonight I tried to make sure that the optic was seated nicely in the fixture. We'll see what happens.
Before gluing the new ITMY side magnet (and now it's set for all future magnet gluings....), I found 4 teflon pads of all the correct thickness. It turns out that we have a magnet gluing fixture of our own, which I found in the cabinets in the clean room. This fixture had all 4 teflon pads, so I stole them and put them into the one that we're using for this round of upgrade / suspension hangings. The height of all future side magnets should be correct. The thickness of the pads in the 'spare' fixture matched the one which came with the fixture from MIT as closely as I could feel by putting them on the same flat surface next to each other and feeling if there was a step.
A side note about this magnet gluing fixture that I found: It has the word "TOP" etched into it, to prevent exactly my problem with the ITMY side magnets in the first place. Unfortunately the threads for the set screws which hold the optic are shot (or something is funny with them), so we can't just use this fixture.
Gluing notes regarding the standoffs and guiderods:
There's more glue than I'd like on the guiderods / standoff for ITMX. The glue was starting to get a little tacky when I glued the standoff in place after we balanced the optic, so it was hard to get it in the right place. I'm confident we have a good epoxy contact, and we don't have much glue that I think it'll be a big problem. Certainly I'll be a lot better at manuvering my glue-stick a.k.a skinny piece of wire around the suspension tower to get to the standoff for the rest of the optics that we're hanging, and I won't have glued something like ITMY side magnet immediately beforehand, which took enough time that the glue started to get tacky (not very tacky, just barely noticeably tacky).
I'd say that most gluing activities should be completed within ~10-15min of mixing the glue, after spending ~2min stirring to make sure it's nice and uniform. It doesn't dry fast enough to be a huge rush, but you should get right on the gluing once the epoxy has been mixed.
As well as the oplev construction for ITMs.
We anticipate the drift of the stack. So we need to revisit the alignment again.
Some tools and the level gauge were removed from the table.
Picture of the ETMX - reflection from the ITMX is hitting the mirror and Jamie's windmill.
0. The suspension tower had been placed on the table close to the door.
1. Brought the OSEMs from the clean room. Connected the satellite box to the ITMX suspension.
2. Went into the chamber. Leveled the table.
3. Released the mirror from the clamp. Put and adjust the OSEMs.
- Note that the side OSEM is located to the south side of the tower
so that we can still touch it after the placement of the TT suspension at the north side of the SOS tower.
4. Clamped the mirror. Moved the SOS tower according to the CAD layout.
5. Leveled the table again.
6. Released the mirror again and adjusted the OSEMs.
7. Turned on the end green laser pointer.
- The spot was slightly upside and left of the mirror. Adjusted it so that the spot is at the center.
8. Align ITMX in Pitch
- The spot was hitting the tube. Moved the pitch bias such that the beam get horizontal.
9. Align ITMX in Yaw
- Moved the SOS tower such that the approximate spot is on the ETMX. If I hit the right spot I could see the tube get grown green because of the huge scatter.
10. Adjusted the OSEMs again and check the alignment again. Repeated this process 2~3 times.
- Bias values at the end of the work: Pitch 0.7800 / Yaw 0.270
11. Close up the chamber
- Remove the level gauge. Some of the screws are still in the Al ship in the chamber.
- Close the light door.
In other, semi-unrelated news, the ITMXF camera has been not working for a while. The bottom right quad on the test mass tv has been dark for at least a week or two. Steve, when you have a chance (after the oplevs are all taken care of), can you see if there's something obvious that's wrong?
While helping Charles string the ethernet cable (elog 7698) for the power strip in the vertex (from 1Y1 to 1X1), I looked at the ITMX power cord. It was connected to the same power strip as the illuminator, which, since the illuminator was turned off by turning off the power strip, meant no power was going to the camera. Since Charles is very close to having the new power strips set up, I unplugged the ITMX illuminator and turned the power strip back on. ITMX camera is back to normal.
I was investigating several issues on the IFO. As many of you noticed and not elogged, ITMX had frequent kicking without its oplev servo.
Also I had C1:LSC-TRY_OUT flatted out to zero even though I could see some fringes C1:SUS-ETMY_TRY_OUT.
Restarted all of the realtime models (no machine reboot).
Now I don't find any beam on REFL/AS/POP cameras.
If I look at BS-PRM camera, I can see big scattering, the beam is in the BS chamber.
I jiggled TT1 but cannot find neither a Michelson fringe nor POP beam.
So far I can't figure out what has happened but I'm leaving the lab now.
IMC is locked fine.
I can see some higher order mode of the Yarm green, so the Y arm alignment is no so far from the correct one.
ITMX is kicked up periodically. ITMX_PD_MAX_VAR is lowered to 500 from 1350
It started at Friday morning 8-1
Tonight we've noticed that ITMX local damping was kicking the optics. This happened because LR shadow sensor was not working. In ~30 minutes it started to work again. Evan and I were working on installation, moving and focusing cameras and locking prcl and mich. We've installed a camera on BSC and plugged it in to PSL_SPARE input.
I'm not sure that this can be correlated to ITMX LR shadow sensor behaviour.
As I feared, since I couldn't see the magnet-to-dumbbell joint from all angles, they ended up being off by ~1/3 of a magnet diameter.
Because I don't want to deal with finding another failed glue joint tomorrow, I removed the magnet and dumbbell from the optic, and broke the manget off of the dumbbell. As with yesterday, I kept track of which end of the magnet had been glued to the dumbbell.
I got a new dumbbell, removed all the glue from the magnet, and reglued them together, in the fixture that ensures they are well aligned.
Tomorrow I will come in and glue the magnet dumbbell assembly to the ITM.
Tomorrow afternoon I'll remove the optic from the fixture, and put it in the oven.
I believe that the UR and LR magnets are stuck. There was no earth quake at 16:18 yesterday. Something had to kick it into this position. See 4days plot
Please advise freeing details.
Something strange happened to the ITMX osem reading around 4.pm. PDT as shown below.
Also the there was no response of the reading as we adjusted the PITCH and YAW. :(
Note that we restarted the slow machine: c1susaux,c1ausex this afternoon because of the unresponced interface.
When I restarted c1susaux yesterday, I didn't know that I needed to disable the coil outputs first. So when it came back online, it attempted to damp all the vertex area optics and ITMX got stuck
We should make a note in the Computer Restart Procedures wiki page indicating the importance of disabling the coils before rebooting c1susaux, c1auxex, and c1auxey. Today c1auxey was rebooted properly without incident. If the slider values etc go back to their previous values on their own, is it necessary to do a BURT restore? I tried doing one for c1susaux today and there were some errors for ASC channels, but the alignment sliders went right back to the proper place after reboot yesterday.
Please advise freeing details
I misaligned ITMX. The oplev servo for ITMX is now turned off. You can restore ITMX alignment by running "restore".
The new ITMX was aligned by changing the DC biases.
The resultant DC biases are reasonably small.
C1:SUS-ITMX_PIT_COMM = -0.2909
C1:SUS-ITMX_YAW_COMM = -0.0617
The alignment was done by trying to resonate the green light in the X arm cavity.
The spot position of the green light on the ITMX mirror looked good. This was confirmed by inserting a sensor card.
I did the OSEM mid-range adjustment and the rotation adjustment but at the end the OSEM DC voltage has changed due to the DC bias operation.
The OSEM rotation was approximately optimized so that all the face shadow sensors are sensitive to the POS motion but the SIDE shadow sensor is insensitive to the POS motion.
It needs a free swinging diagnosis.
ITMX OSEMs UL 1.8V, UR 1.7V, LR 0V, LL 0V, SD 1.3V at the same bias setting shown above. May be a lose earth quake tip?or magnet is touching?
[Koji, Manasa, Sujan]
[Steve, Gautam, Manasa]
While we checked the ITMX oplev situation yesterday, we found that the beam hitting the ITM and the in-vacuum steering mirrors had a halo around them. We used the set of irides in the path of the ingoing beam and cut the stray light around the beam. This reduced the intensity of the halo around the mirrors. We noticed that the halo accounted for 2000 counts of 6500 at the oplev QPD. We tried changing the laser and this did not make the situation any better.
Also there are a couple or more strong stray beams from the BS oplev.
I suspect that the BS oplev leakage is messing with the ITMX oplev. Why?? We have been seeing the breathing of transmitted beam from the X arm cavity and the shadow sensor readings have been bigger than usual since the last vent (when we changed the BS oplev path). Also, the ingoing oplev beam is close to clipping at the PR2 stack.
I think it would be best to open the ITMX chamber and modify the in-vac steering mirror layout of the oplev.
I wonder what optics is causing the halo on the oplev beam.
It this comes from any uncoated lens (or similar) it should be identified.
I wonder what optics is causing the halo on the oplev beam.
It this comes from any uncoated lens (or similar) it should be identified.
We identified this to be coming from the uncoated concave lens that we have right after the He-Ne laser which should also be replaced in addition to the other problems with the oplev.
I lined up the Y Arm for locking and then centered the oplevs for ETMY and ITMY.
* The ITMY OL has still got the old style laser. Steve, pleaes swap this one for a HeNe. Also the optical layout seems strange: there are two copies of the laser beam going into the chamber (??). Also, the QPD transimpedance needs to be increase by a factor of ~10. We're only getting ~500 counts per quadrant. Its worth it for someone to re-examine the whole ITMY OL beam layout.
* The ETMY OL beam was coming out but clipping on the mount for the ETMY OL HeNe. This indicates a failure on our part to do the ETMY closeout alignment properly. In fact, I get the feeling from looking around that we overlooked aligning the OL and IPPOS/ANG beams this time. If we're unlucky this could cause us to vent again. I undid part of the laser mount and changed the height on the receiving mirror to get the beam back onto the QPD.
I noticed that there is significant green light now getting into some of the IR PDs; beacuse of this there are weird offsets in the TRY QPD and perhaps elsewhere. We had better purchase some filters to tape over the front of the sensitive IR sensors to prevent the couplling from the green laser.
* There is a beam on IPPOS, but its too big for the detector (this has always been the case). We need to put a 2" lens with a weak focusing power on this path so as to halve the beam size on the detector. Right now its clipping and misleading. There is also a 0.9V offset on the SUM signal. I'm not sure if this readout is working at all.
* I couldn't find any beam on IPANG at all. Not sure what's changed since Kiwamu saw it.
Old Coherent diode laser was replaced by Uniphase HE/NE 1125P at ITMX.
Newport 10B20NC.1 broadband beam sampler set up as beamspitter to dump 90% of the light into beam trap. Beam in to test mass 0.7 mW , returning to qpd 0.07 mW = ~ 3,700 counts
f 1.5 m lens placed into ingoing beam path to reduce the spot size on the qpd. ITMY oplev will be done in this manner tomorrow.
* IP-ANG is lost with the Piezo Jena PS
* IP-POS cable have to be found at the LSC rack
I found that the sum of the ITMX oplev signals had gone down to zero yesterday.
I checked the ITMX table and found two iris on the He-Ne laser path were blocking the beam on their apertures.
I guess this is because we were working around there for installation of POP/POX and may have touched some of the oplev optics.
Then I fully opened the apertures of those two iris and the sum went back to nominal of 600 counts.
We measured Open loop TF for oplev pitch on ITMX.
All feed back filter of oplev was on as same as before. Original notch filters which notches above 10Hz resonance should be modified with some measurements of present resonant frequency. Up to 10Hz, a simple f^2 filter is used, so the notch should not affect this measurement.
Measured upper UGF is about 2Hz with gain slider 1, and lower UGF is 1.3Hz. Phase margin is 40 degree, so it is not a good idea to increase the gain drastically.
I have measured the coherence also but I could not find a way to put it on this picture. Anyway coherence below 0.6Hz was not so good like ~0.95. This can be improved if larger excitation is used next time.
During this measurement around 0.2-0.3Hz, small earthquake happened but seemed OK for the control.
We will measure the other TF, yaw, ETMX or somthing, maybe tomorrow, due to free swinging ITMX and ETMX tonight.
Atm2 is before optical path adjustment. The idea was to remove possible clipping in vacuum.
Coherense significantly reduced below 4 Hz
Today I will replace the He/Ne laser 1125P with 1103P
May 23, 2016 ITMX dead He/Ne laser sn P845648 replaced after 1062 days [2.9 yrs] by 1103P, sn P859884, with output 2.6 mW, nicely round beam quality at 15 meters.
Power just before viewport 1 mW, returning light on qpd 154 microW = 7,500 counts
I just drew a basic picture of how the ITMX oplev path could be reworked to minimise the number of optics in the path. Only possible problem with this might be the turning mirror onto the ITMX getting in the way of the collimating lenses. Should be easy to solve though. Does anyone know if there is a ITMX pick off beam I should be careful to avoid?
I've been poking around the oplev situation. One thing I came across regarding ITMX was that the gain on segment 4 seems to be about higher than the other segments. I was led to believe this by steering the optic around, and looking at the counts on each quadrant when the other 3 were dark.
Putting a gain of 0.86 (the ratio of the other segments' max counts over segment 4's max counts) in the segment 4 FM flattens the 1 Hz peak in the ITMX_OL_SUM spectrum, as well as significantly reducing the sub-Hz coherence of the sum with the individual quandrant counts. This is what I would expect from reducing the coupling of angular motion due to quadrant gain mismatch into the sum.
Here are the ITMX_OL_SUM spectra before and after (oplev servos are off).
The "burps" and control filter saturations are still unexplained. Investigations continue...
I replaced the JDSU-Uniphase 1125P by 1103P He/Ne laser. This new laser had 2.8 mW output yesterday. It degraded to 0.5 mW by this morning.
The beam size on the QPD is ~3 mm This should give us better sensitivity. These are not the perfect lenses at all, but we have them here.
On the other hand, there are still some coherence below 1 Hz, so the laser intensity noise or clipping dominating this part of the spectrum.
Followed the steps below to complete the ITMX optlev installation. The ITMX optlev return beam now reaches its QPD without being blocked by the input steering mirror.
Although, I centered the ITMX optlev readout, this was not done when the XARM flashing is maximized bcos the IMC chamber was being worked on, so this should be done later when the IR beam is back.
The ITMX OSEMS are oscillating.
The new ITMX was aligned by changing the DC biases.
[Jenne, Katrin, Jamie]
I'm a bad kid, and forgot to elog my Friday morning work...
Bob gave me back ITMX after a 48hour bake at 80C + clean RGA scan Friday morning after coffee and doughnuts. Katrin helped me put it back in the suspension wire.
While I was leveling the optic (making sure the scribe lines on each side of the optic are at the same height off the table), Katrin cut some new viton for replacement EQ stops. The optic was missing one lower earthquake stop (the one that Jamie noticed last week), and somehow one other rubber piece came out of the EQ stop on another lower screw while we were re-suspending the optic. We put the new stops in, and then checked the balance of the test mass.
The oplev is still the HeNe laser that is leveled to the level optical table in the cleanroom. The lever arm is ~1.5 meters, and over that distance the reflected beam was pointed "up" in pitch by ~1.5mm, which is less than one beam diameter of the HeNe. This is well within our ability to correct using the OSEMs.
We then locked the test mass, and installed it in the chamber. I approximately did the half-voltage centering of the OSEMs, leaving the fine-tuning to Kiwamu for after lunch.
There were two SUSs which didn't look normal.
- ITMX was easily released by the bias slider -> Shake the pitch slider and while all the OSEM values are moving, turn on the damping control (with x10 large watchdog threshold)
- ETMY has UR OSEM 0V output. This means that there is no light. And this didn't change at all with the slider move.
- Went to the Y table and tried to look at the coils. It seems that the UR magnet is detached from the optic and stuck in the OSEM.
We need a vent to fix the suspension, but until then what we can do is to redistribute the POS/PIT/YAW actuations to the three coils.
There must be some bad connection
When we plugged in the back cables yesterday on the whitening boxes after switching them, two of the ITMX PDMon channels (UR and LR) got stuck at 0. This caused me to believe ITMX was still stuck even when it was freed. However, it was left in a stuck state overnight and freed again today after this issue was discovered. The alignment sliders have been set to 0 as a safety net to keep ITMX from getting stuck again if c1susaux is restarted again. We switched the cables back and the problem was still there.
The ITMY UL whitening filter problem, which the cables were originally switched to diagnose, was also still there. Ericq suggested we turn off all the whitening filters in order to get diagonalization data that would not show a phase difference between coils. We ran the diagonalization again with all the dewhitening filters off and got much cleaner results, with no visible cross-coupling peaks remaining between the degrees of freedom (see attachemnt 1). We did not apply this matrix to the damping, however, because there are elements which have the wrong sign compared to the ideal matrix. Significant adjustments to the output matrix will probably need to be made if this result is to be used. We also verified that the phase problem had been solved in DTT, where we saw the same sign discrepancies as in the matrix below.
Damping can be turned back on, using the old, non-diagonalized matrix currently in effect. There is enough free swing data to diagonalize ITMY now, so feel free to mess with it.
Matrix (wrong signs red, suspiciously small elements orange):
pit yaw pos side butt
UL 1.633 0.138 1.224 0.136 0.984
UR -0.202 -1.768 1.179 0.132 -1.028
LR -2.000 0.094 0.776 0.107 1.001
LL -0.165 2.000 0.821 0.111 -0.987
SD 0.900 1.131 -1.708 1.000 -0.107
This afternoon around 2:45, ITMX started ringing up at ~.9Hz for about a minute and then got stuck again. When I noticed this evening, I tried to free it with the alignment sliders but was unable to see any signal on UL or UR. It also looks like the damping for ITMY was turned off at the same time ITMX got stuck (not at the start of its ring up). SRM also has a spike in its motion at this time, and another one minute later that ended up with the LR OSEM at a much higher level, though the mirror does not appear to be stuck. We didn't see any strange behavior from any of the other optics.
Teng and I were working on diagnosing a problem with the ITMY UL whitening, but by the time we disconnected any applicable cables, the damping for ITMY was already off. Later we unplugged the ITMX PD whitening cables after verifying that the ITMX damping was also already off. This problem may have occured earlier, while Teng, Eric, and I were examining and pushing in the cables at 1X5 without unplugging anything.
We found that the reason for the bad phase on the ITMY free swing data is because the whitening filter for UL is not being properly turned on. We are in the process of investigating the source of this problem. Right now all the cables to the PD whitening boxes in 1X5 are switched between ITMY and ITMX.
As I went to correct the ITMX Oplev mirrors, I found that both mirrors were placed in very different positions than the design position. Part of the reason I think was to preserve outside oplev path, and party because a counterweight was in ITMXOL1 position. I had to do following steps to correct this:
During the above work, i must have kicked the cable between the vacuum flange and the satellite amplifier box for ITMX. This disconnected all the OSEMs and Coils. We tried several things to debug this and finally found that nudging the connections on Sat Amp box brought the OSEMs and coils back online. Note that the connector was not partially out or in a state that obviously showed disconnection of the pins. I'm glad we are putting in new electronics soon for the vertex optics as well.
The POX beam had been 80% clipped at a black glass beam dump of the POX11 RFPD.
I steered the first mirror in the POX path to fix the clipping. Then the beam was realigned onto the RFPD.
However the beam is still very close to the black glass, because the incident angle to the second mirror is not 45 deg .
We need to refine the arrangement of the POX11 optics a bit more so that the beam will never be clipped at the black glass.
The POP optics also need to be rearranged to accommodate one more RFPD.
Additionally Rana, Suresh and I discussed the possible solutions of POP22/110 and decided to install a usual PD (PDA10A or similar) instead of a custom-made.
So a plan for the POP detectors will be something like this:
+ design an optical layout.
+ buy a 2 inch lens whose focul length is long enough (#5743)
+ buy a 2 inch lens whose focul length is long enough (
+ rearrange the optics and install POP22/110
+ lay down a long SMA cable which sends the RF signal from POP22/110 to the LSC rack.
+ install a power splitter just before the demod board so that the signal is split into the 22MHz demoad board and 110MHz demod board.
=> make sure we have a right splitter for it.
+ install a band pass filter after the power splitter in each path.
=> A 22MHz band pass filter is already in hand. Do we have 110MHz band pass filter somewhere in the lab ?
The picture here shows the latest configuration on the ITMX table.
RF photo diodes POP55 and POX11 are installed. The beams are aligned to the photo diodes.
The Watec 902, 1/2" CCD camera got new Tamron lens: 1/2" 10-40mm F/1.4 manual iris. IR corrective lens. It is designed to have the same focal point in the IR as
in the visible light range. However, as the depth of field in the IR range is very narrow, focus adjustment should be done carefully in the IR.
Now you can see the sus tower that will make alignment easier.
While closing up the whitening shop for the night, I noticed that the ITMX whitening state (Whitening "On") is opposite that of all other suspensions (they all have Whitening "Off"). I don't know which way is correct, but I assume they should all be the same. Once all the whitening and BO testing is done, we should make sure that they're all the way we want them to be.
Also, Koji and I are leaving ETMX free swinging. That's the way we found it, presumably from Jamie's BO testing at the end station today. We don't know what the optic's story is, so we're leaving it the way we found it. Jamie (or whomever left it free swinging), can you please restore it when it is okay to do so? Thanks!