The typical sign of a dying gas laser is that it glows for a few minutes only. The power supplies are fine.
Two new JDS - Uniphase 1103P lasers ( NT64-104 ) arriving on Monday, May 21
Yesterday I swapped in new He/Ne laser with output power 3.5 mW The return spot on qpd is large ~6mm in diameter and 20,500 counts
The spot size reduction require similar layout as ETMX oplev.
The oplev path is relayed and the spot size on the qpd is reduced. I still have to clean up and replace "Miki Mouse" lens holder.
Late entry for Monday morning June 4, 2012
Cables were stress relieved. Cable entry - exit ports enlarged. Air gaps were minimized.
The whitening filters for the ETMY oplevs are back.
The whitening board had been in the rack but the ADC was connected directly to the oplev interface board without going through the whitening board.
In fact the interface board and the whitening board had been already connected. So the ADC was making a shortcut.
I disconnected the ADC from the interface board and plugged it to the output of the whitening board.
Here is an example of the new open-loop transfer function with the whitening filters.
before the measurement I increased the control gain by an arbitrary number to obtain gain of more than 1 around 1 Hz.
I will check the whitening filters.
There was no IP-ANG coming out of the chamber at this time!
Flipped the sign on the ETMY oplev servo gain, since it was wrong. (It was "-" for both, now it is "+" for both)
The ETMY Oplev servo didn't work properly, when it was activated the ETMY moved too much.
We measured the oplev TF for Pitch and Yaw and it turned out that the gain was too low by a factor 3, so we increased the gain from -.250 to -.750 on both.
We also locked the Y arm and we could see that the mirror's oscillations are actually suppressed.
I did relayed the oplev path with new f 500 mm lens
The ETMY oplev quad sum was ~0, so we went to investigate. The power supply was dead. Keying it on and off didn't fix things, and it was certainly getting power since the front indicator light was flickering. We replaced it with a different power supply, and the oplev is back.
Also, the Y-green AUX laser was off, presumably from the power outage a while back. I turned it back on.
EDIT JD: The first power supply we used didn't work....the oplev was on for a few minutes, then went off again. We switched to one of the new (still JDSU) power supplies from Edmund Optics, and it's been happily working for at least an hour now.
And has the temp controller of the green been recovered too? (Push enable button)
Just now, yes.
We then adjusted the position of the second lens to get a ~1 mm spot on the QPD. There is a lot of stray red light from extra reflections, but so be it.
Its possible that we are now clipping the IPANG path, but we will need to lock the Y arm and verify the input pointing to be sure. At this point we are ready to measure the ETMY OL loop gain and tune, etc.
As another proof that sometime is ill with ETMX Optical Lever:
We scanned the ETMX bias in PIT using ezcastep and saw that the OL response is very screwy. In the attached, you can see that the ETMX SUSPIT signal shows that the actual motion is good and linear. In fact, our sus diagonalization is extermely good and there's almost no signal in SUSYAW.
ETMY oplev laser clearly showing a tail when it was projected up the sealing.
PS (10-4-2013): I checked the beam quality again as it was removed from the table: it had a good image at 3 meters
ETMY oplev is still out of order. Hopefully I'll get it under control by tomorrow.
ETMY oplev is currently a work in progress. The HeNe beam is hitting the photodiode, but the spot size there is pretty much the size of the entire QPD. Thus, the ETMY oplev isn't really useful right now. I'm re-figuring things out (note to self: close to the laser, you have to use Gaussian optics...regular ray tracing doesn't really work), and hopefully will have the oplev back under control by the time Alberto is finished realigning the IFO, so this doesn't keep anyone from doing any exciting locking work.
According to c1scy.mdl, OL signals should be connected to adc_0_24 to adc_0_27 but they were connected to adc_0_16 to adc_0_19 which are assigned to QPD signals.
Actually cable connections were messed up. One ribbon cable was connected from QPD driver and ADC ports assigned for OL, and another ribbon cable was connected from the board combining the signals of oplev and QPD to ADC port assigned for QPD.
Now ETMY oplev is working well and aligned to center.
RA: I'm not sure how to interperet this; I think that the SUM channel is divided by the SUM so that this is supposed to be RIN, but not sure. Can someone please take a look into the SUS model and then explain in the elog what the SUM normalization algorithm is?
All ETMY optical table electronics- lasers-pds turned off, disconnected in order to remove enclosure.
ETMY is now in its new nominal position, according to the rails that Kiwamu put in the other day. OSEM voltages are all centered, and the magnets looked pretty well centered in the OSEM bores. We're taking data for some free swinging spectra, to check the decoupling.
Next up: Align Y-green to the arm, then move on to fixing the other optics that Jamie pointed out.
Uniblitz mechanical shutter installed in the green beam path at ETMY-ISCT The remote control cable has not been connected.
The ETMY shutter can be remotely switched from medm screen POY of mechanical shutters.
The new cable from ETMY controller goes to east vertex EV-ISCT where it is connected to POY shutter hook up BNC cable.
The mechanical shutter on the Y end is now fully functional.
The mechanical shutter on the Y end is now fully functional.
It is newly named to 'C1AUX_GREEN_Y_Shutter' in the EPICS world.
It uses the same binary output channel which had been served for the POY shutter.
To change the EPICS name I edited a db file called ShutterInterLock.db, which resides in /cvs/cds/caltech/target/c1aux.
After editing the file I rebooted the c1aux machine, by telnet and the reboot command in order to make the change effective.
Also I added this new shutter on the ALS overview screen (see the attachment below)
A pair of tweezer is OK as long as there is no magnets around. You need to (somewhat) constrain the mirror with the EQ stops so that you can pull the fiber without dragging the mirror.
I setup the usual mini-cleanroom setup around the ETMY chamber. Then I carried out the investigative plan outlined here.
Main finding: I saw a fiber of what looks like first contact on the bottom left (as viewed from HR side) of ETMY, connecting the optic to the cage. See Attachment #1. I don't know that this can explain the problem with the missing eigenmode, it's not a hard constraint. Seems like something that should be addressed in any case. How do we want to remove this? Just use a tweezer and pull it off, or apply a larger FC patch and then pull it off? I'm pretty sure it's first contact and not a piece of PEEK mesh because I can see it is adhered to the HR side of the optic, but couldn't capture that detail in a photo.
There weren't any obvious problem with the magnet positioning inside the OSEM, or the suspension wire. All the EQ stop tips were >3mm away from the optic.
I also backed out the bottom EQ stops on the far (south side) of the optic by ~2 full turns of the screw. Taking another free-swinging dataset now to see if anything has changed. I will upload all the photos I took, with annotations, to the gPhotos later today eve. Light doors back on at ~1730.
Update 10pm: the photos have been uploaded. I've added a "description" to each photo which should convey the message of that particualr shot, it shows up in my browser on the bottom left of the photo but can also be accessed by clicking the "info" icon. Please have a look and comment if something sticks out as odd / requires correction.
Update 1045pm: I looked at the freeswinging data from earlier today. Still only 3 peaks around 1 Hz.
We went in to have a look-see at ETMY since it looked stuck-ish. Jamie noticed that the side magnet was pretty close to the teflon plates of the OSEM. We rotated it a bit, and now its all better. We also adjusted the OSEMs until their mid-ranges were happy. The U's were a little low, and the L's were a little high, as if the optic were a bit pitched backward. Anyhow, we checked that the table is level, and tweaked the OSEMs. We're starting the free-swinging test now...
Excited all optics
Fri Aug 12 17:38:53 PDT 2011
Excited all optics
Fri Aug 12 17:38:53 PDT 2011
Hmmm. I'm no longer convinced that ETMY is healthy. I think that when I gave it a kick, it's bouncing against something. I can't fit the peaks to get the input matrix. I guess step 1 is to try giving it a smaller kick for the free swinging spectra. But if the owl shift folk feel like it, they might have a look-see.
The SOS ETMY tower had and Aluminum bridge. How is it possible that this was true? Is SS better than Al for some quantitative scientifc reason ???
Their weight ratio as measured = 922 / 307 g = 3
Destinies: SS 304 / Al 6061 > 0.289 / 0.098 [ lb /in3 ] = 2.94
We installed a HV kepco power supply for the green PZT steering the YAUX beam. We did this in anticipation of the YARM alignment to take place this afternoon. We borrowed an unused DC power supply labeled "OMC Power spply" and made an appropriate SMA connection (Attachment #1), Then we set the Vset to 100.0 Volts and the current limit to 10 mA. Once we enabled the output we saw the 5.6 mA of current drawn by the eurocard in accordance with the wiki log (Attachment #2).
It may not be possible to use the PZT as per this so this work may not have a direct impact on our upcoming alignment task.
We probably bumped the ethernet cable (martian network) on c1iscey, so the FE models stopped showing up on the medm screens. When we connected it back, it seemed like the FE kept running the model and only IPC showed error. We restarted the rtcds models on c1iscey and burtrestored to today morning 5:19 am.
ETMY is properly damping now and the oplev is roughly centered as well but the OPLEV Servos are off. We did not turn them on.
We should be able to carry out our cavity arm alignment today afternoon on both arms now.
[Rana Koji Jenne Jamie]
- The situation of the ETMY suspension is improved.
- The damping servos except for Pitch are now functional.
- We intentionally turned off the damping servos for the matrix measurements.
- Opened the light door of the ETMY chamber.
- We set up the CDS SUS lockin:
Excite UL/UR/LL/LR equally [by setting the output matrix (1, 1, 1, 1, 0)] at 3.12Hz with 2000 cnts
Put the OSEM PD outputs into lockin one by one. For the image rejection, 0.1Hz 4th order LPF has been used though we like to use a faster settling LPF.
- Found only UL was responding to the excitation. After fitzing with the cables and connectors, it was found that the DAC card was loose from the bus.
By pushing the card the responses have been back. [Note we had the reboot of c1iscey almost at the same time.]
- Checked the response in the I channel of the lockin.
UL -8ish / UR +7ish / LR +5ish / LL +2ish
- Tweaked LL sensor to get better response ==> in vain. Decided to move the lower OSEM plate for the better positioning of the LR/LL.
- Got reasonable (+5ish) response for LL.
- Confirmed that the POS/YAW/SIDE damping works with positive gains. PITCH did not work with the negative gain (but that could be a good sign.)
- Let the suspension freely swinging for a while (~30min). Checked the side/pos separation. They are not perfect but seemed diagonalizable.
- Closed the light door.
- Jenne will make a better kick/free-swing test later.
02:27am, ran the new freeswinging-ifo.csh script. It's just a copy of freeswinging-all.csh, but it doesn't include the MC mirrors, since Suresh and Kiwamu are still working.
Now we have copies of the script for -all, -mc, -ifo to cover the various sections of the suspended interferometer.
I updated the photo of ETMY end table on the wiki.
There were small pieces of glass, remnants of a fluorescent tube, which were lying around on the ETMY end table for a while now. We picked up the larger pieces by hand and used the HEPA filtered vacuum cleaner to pick up the remaining glass and dust on the table.
Enclosure cover #1 transmission measured in 1064 nm, 156 mW, P polarization and beam size ~ 1 mm
As condition: fully assembled, protective layer removed, tinted- adhesive activated on yellow acrylic on top of each other.
T = 1.2 % in 20 minutes exposure test. This agrees with the test measurement of 6-18-2012
There is a reflected 2-3 cm circular glare that is barely visible on sensor card. It is well below 1 mW level
As we are installing the NPRO with ~350 mW of power we have to address what additional shield should be installed.
The June 2012 test with 1W power burned through of the 3 layer IR coated films in 3-4 hours.
We 'll use Aluminum shields in the high power path till we come up with better solution.
It will arrive around 10 am Monday morning.
Jenne, Kiwamu, Alberto, Steve, Bob, Koji
We wiped ETMY after recovery of the computer system. We take the lunch and resume at 14:00 for ITMX.
Detailed reports will follow.
I collected some free-swinging data from earlier today evening. There are still only 3 peaks visible in the ASDs, see Attachment #1.
Plan for tomorrow:
TBH, I don't have any clear ideas as to what we are supposed to do to to fix the problem (or even what the problem is). So here is my plan for now:
I anticipate that these will throw up some more clues
I made some efforts in order to damp ETMY, however it still doesn't happily work.
It looks like something wrong is going on around the whitening filters and the AA filter borad.
I will briefly check those analog parts tomorrow morning.
- - -(symptom)
Signs of the UL and the SD readouts are flipped, which I don't know why.
At the testpoints on the analog PD interface board, all the signs are the same. This is good.
But after the signals go through the whitening filters and AA filters, UL and SD become sign-flipped.
I tried compensating the sign-flips by changing the sign by means of the software, but it didn't help the damping.
In fact the suspension got crazy when I activated the damping. So I have no idea if we are looking at exactly right readouts or some sort of different signals.
- - -(fixing DAC connector)
I fixed a connector of the DAC ribbon cable since the solderless connector was loosely locked to its cable.
Before fixing this connector I couldn't apply voltages on some of the coils but now it is working well.
ETMY damping restored.
Cryo interlock closed VC1 ~2 days ago. P1 is 6.3 mTorr. Cryo temp 12K stable, reset photoswitch and opened VC1
ETMY sus damping was restored
ETMY's watch dogs were found tripped. They were restored.
ETMY sus damping restored.
ETMY sus damping restored
Last Saturday I succeeded in damping the ETMY suspension eventually.
This means now ALL the suspensions are happily damped.
It looked like some combination of gains and control filters had made unstabie conditions.
I actually was playing with the on/off switches of the control filters and the gain values just for fun.
Then finally I found it worked when the chebyshev filters were off. This is the same situation as Yuta told me about two months before.
Other things like the input and the output matrix looked nothing is wrong, except for the sign flips at ULSEN and SDSEN as I mentioned in the last entry (see here).
So we still should take a look at the analog filters in order to make sure why the signs are flipped.