I think I have finally found a Mode Matching solution for our new Input Mode Matching Telescope! And after looking at the layout diagram with Koji and Raffaele, it seems like all of the optics will fit into the chambers / onto the tables (not true as of last week).
3. RoCMMT1 is -5m
RoCMMT2 is 8m,
with the MMTs 1.89m apart.
This is a 1.6x telescope.
MMT2 is 2.2641m from the PRM
MMT1 is 2m from MC3.
The Condition Number for this optical chain is 89219047.5781.
This layout is very similar to the one that Koji posted on the wiki yesterday: Upgrade09/Optical Layout. The difference is that I want to move MMT1 ~20cm closer to the MC13 table, so just on the other side of the main red beam that goes directly to PRM. There is plenty of space there, so it should be all good. The tricky bit is that the flat steering mirrors fit into things now while they are piezos, but they will be trickier to fit if we make them into Tip Tilts. But I have full faith in Koji's amazing optical table layout skills, that he can make it happen.
Unless there are major objections, I think this is the MMT that we're going to go with. (So speak now or forever hold your peace.) The angle between tilt and translation isn't quite what we'd like it to be (at ~18deg), but it's not too terrible. And we still have 99.5% overlap which is very important.
Using the techniques employed at LLO, and then by Rana here at the 40m a few weeks ago, Wiener filters have been installed on the inputs of all of the PEM IIR channels which are hooked up to the 110B PEM ADCU. Some slight modifications have taken place to the code, and it's all been checked in to the 40m svn.
I have installed the filters into: All 6 Wilcoxon accelerometers, the Ranger seismometer, and one of the Guralps (GUR1). The other Guralp is currently connected through the ASS/OAF machine's ADC, so it's not used in this test. The filters are all labeled "Wiener", and are FM1 in the C1:ASS-TOP_PEMIIR_## filter banks.
The first figure below is the output of the Wiener Filter calculation program. It shows the uncorrected MC_L (black) and the corrected MC_L (red), using the optimal wiener filter. This is as good as we should be able to do with these sensors in these positions.
The second figure is a DTT shot of me trying out the nifty new filters. They seem to maybe do a teensy bit on the microseism, but otherwise it's a bit unremarkable. Hopefully I'll get better subtraction during the day, when the base level for MC_L is higher. Here, Black is uncorrected MC_L, Red is the corrected MC_L, Blue is the actuation channel, and green is an example seismometer channel to illustrate the ground motion at the time.
For posterity, since it's not all in one elog that I can find, the order of operations to install a Wiener Feed Forward filter is as follows:
1. (When you can borrow the IFO) Take a very careful TF of the plant, between your actuation point and your error signal readout. At the 40m, this means between C1:ASS-TOP_SUS_MC1_EXC and C1:IOO-MC_L, since we actuate by pushing on the MC1 coils. At the sites / future 40m, this would be between the HEPI (or STACIS) and the error signal. The limit of how good your Feed Forward can do will depend heavily on how good this TF is. Coherence should be above ~0.95 for all points. Export this data from DTT as a .txt file, using units "Complex (abs/rad)".
2. Run fitMC12MCL.m (or equivalent wrapper file) to fit the transfer function you just took with some Poles and Zeros. Make sure to edit the wrapper file with your new .txt file's name so you're getting a fresh TF (if you've just taken one).
3. (Again, when you can borrow the IFO) Run getMCdata.m (or equivalent) to fetch witness channel data and error signal data. At the 40m, this usually means C1:IOO-MC_L, and witness sensors which are around the MC chambers. This data should be taken at a time when the cavity is locked, but pretty much on it's own. (i.e. probably shouldn't have Common Mode feedback on the MC - so the MC should be locked, but not the full IFO, for example.)
4. Run c1winoiir.m (the main program here, which contains some of these notes). This will take in the TF data you've fit, and the witness channel data you have, and calculate the optimal combination of Wiener filters for your witness channels. It pre-filters your witness data by your TF, then calculates the Wiener filter. The resulting FIR filters are saved in a file.
5. Run firfit.m This will take the FIR Wiener filters you've just created, and convert them conveniently to IIR filters, in a format to be copied directly into Foton. For each witness channel, you'll get the IIR filter in 2 formats: the first is for copying into the Foton .txt file (ex ASS.txt), and the second is for copying into the Foton gui, in the "Command" box on the filter design screen. The "o" at the end of the copy-able filter indicates to Foton that it is a Z-Plane Online filter. Copy filters appropriately (there should be a line preceding each set of SOS filter formats to indicate which channel this Wiener filter is for...these channel names are extracted from your getMCdata.m)
6. Save your Foton file, and update your Coefficients in MEDM. Enable your outputs to actuators, and watch magic happen!
On the To-Do list:
Check the transfer of signal btwn PEMIIR matrix and the 9x1 'matrix' that sends the signals to the SUS inputs. In the SimuLink, the input to the 9x1 matrix is a bundle of 8 numbers (the 8 outputs of the PEMIIR matrix), but it looks like it only pays attention to the first one. Need to figure out how to make it realize that it's a bundle, not a single number.
Also, the OAF up / down scripts don't seem to be working on any of the control room computers. This needs to be checked in to / fixed (but not tonight....)
EDIT 6 Jan 2010: Shouldn't have done this. My bad. The AA32 is on the other PEM matrix because the Adaptive code runs at 64Hz, so there's downsampling, calculating, and upsampling which goes on. The Feed Forward path all runs at 2kHz, the regular rate of the ASS/OAF machine. All of these filters are turned off (although I haven't deleted them from Foton). Since we're focusing on low frequency stuff and trying to get that to do some subtraction, we're not worrying about the junk at higher frequencies just yet.
I have put AA32 filters into the PEMIIR matrix's input filter banks (ie, C1:ASS-TOP_PEMIIR_##), to match the ones that are in the same places in the regular PEM matrix on the OAF screen.
I redid the uncorrected vs. corrected MC_L DTT printout, shown below. You can see that there's less junk at higher frequencies in the Blue (actuation channel) trace, which is good.
All the DAQ screens are bright red. Thumbs down to that.
All better now.
On Friday, Rana and I measured the scatter coming from the 35W beam dumps.
(These are the ones with big aluminum heat sinks on the back that kind of look like little robots with 2 legs...inside the horn is a piece of polished silicon at Brewster's Angle.)
For the measurement, we used the Scatterometer setup at the 40m on the small optical table near MC2.
We used a frequency of 1743 Hz for the Chopper, and this was also used as the reference frequency for the SR830 Lock-In Amplifier.
The settings on the Lock-In were as follows:
Time Constant = 1sec
'Scope reading Output A, Output A set to 'Display', and A's display set to "R" (as in magnitude).
Sensitivity changed throughout the experiment, so that's quoted for each measurement.
White Paper Calibration - white paper placed just in front of Beam Dump. Sensitivity = 500microVolts. Reading on 'scope = 7V
Laser Shuttered. Sensitivity = 500microVolts. 'scope reading = 9mV.
Black Glass at Beam Dump location. Sensitivity = 500microVolts. Reading on 'scope = 142mV. (DON'T touch the glass....measure the same setup with different sensitivity)
Black Glass at Beam Dump location (Not Touched since prev. measurement). Sensitivity = 10microVolts. Reading on 'scope = 6.8V
Laser Shuttered. Sensitivity = 10microVolts. 'scope Reading = 14mV +/- 10mV (lots of fluctuation).
Black Glass Wedge Dump at Beam Dump location. Sensitivity = 10microVolts. 'scope = 100mV.
Beam Dump with original shiny front plate. Sensitivity = 10microVolts. 'scope railing at 11V
Beam Dump with front plate removed. Sensitivity = 10microVolts. 'scope reading = 770mV
Beam Dump, no front plate, but horn's opening surrounded by 2 pieces of Black Glass (one per side ~1cm opening), BG is NOT flush with the opening...it's at an angle relative to where the front plate was. Sensitivity = 10microV. 'scope = 160mV +/- 20mV.
Beam Dump, no front plate, only 1 piece of Black Glass. Sensitivity = 10microV. 'scope reading = 260mV.
Beam Dump, no front plate, 2 pieces of Black Glass, normal incidence (the BG is flush with where the front plate would have been). Sensitivity = 10microV. 'Scope reading = ~600mV
Using our calibration numbers (Black Glass measured at 2 different sensitivities, not touching the setup between the measurements), we can find the calibration between our 2 different sets of measurements (at 500microV and 10microV), to compare our Beam Dump with regular white paper.
BG at 500uV was 142mV. BG at 10uV was 6.8V. 6.8V/0.142V = 47.9
So the white paper, which was measured at 500uV sensitivity, would have been (7V * 47.9) = 335 V in 10uV sensitivity units.
This is compared to the BG wedge dump at 10uV sensitivity of 100mV, and the Beam Dump reading of 770mV, and the Beam Dump with-black-glass-at-the-opening reading of 160mV.
So our Silicon/Steel horn dump is ~8x worse than a Black Glass wedge and (335 / 0.77) = 435x better than white paper.
We used regular white paper as a calibration because it has a Lambertian reflectance. For some general idea of how to do these kinds of scatter measurements, you can look at this MZ doc.
Assuming that our white paper had a BRDF of (1/pi)/steradian, we can estimate some numbers for our setup:
Sensitivity (signal with the laser shuttered) = (0.02 / 335 / pi) = 2 x 10^-5 / sr. This is ~3x worse than the best black glass surfaces.
Our wedge = (0.1 / 335 / pi) = 1 x 10^-4 / sr. Needs a wipe.
Our Silicon-Steel Horn = (0.75 / 335 / pi) = 7 x 10^-4 / steradian.
Our measurements were all made at a small angle since we are interested in scatter back along the incoming beam. We were using a 1" lens to collect the scatter onto a PDA55. The distance from the beam to the center of the lens was ~2" and the detector's lens was ~20" from the front of the horn. So that's an incident angle of ~3 deg.
* It seems that any front plate other than Black Glass is probably worse than just having no front plate at all.
* If we put in a front plate, it shouldn't be normal to the incident beam. Black Glass at normal incidence was almost at the same level as having no front plate. So if we're going to bother with a front plate, it should be about 30deg or 40deg from where the original front plate was.
* No front plate on the Dump is about 7x a Black Glass wedge dump.
* The silicon looks like it might have some dust on it (as well as the rest of the inside of the horn). We should clean everything. (Maybe with deionized nitrogen?)
* We should remeasure the Beam Dump using polished steel at a small (30-40deg) angle as the front plate.
* Photos taken with the Olympus camera, which has its IR blocker removed.
* In the photo you can see that we have a lot of reflection off of the horn on the side opposite from the silicon.
* The 2nd picture is of the scatterometer setup.
So that we can use both Guralps for Adaptive stuff, and so that I can look at the differential ground motion spectra, I've reconnected the Guralp Seismometers to the PEM ADCU, instead of where they've been sitting for a while connected to the ASS ADC. I redid the ASS.mdl file, so that the PEM and PEMIIR matricies know where to look for the Gur2 data. I followed the 'make ass' procedure in the wiki. The spectra of the Gur1 and Gur2 seismometers look pretty much the same, so everything should be all good.
When I open dataviewer in terminal, I get the following output:
Warning: communication protocol revision mismatch: expected 11.3, received 11.4
Warning: Not all children have same parent in XtManageChildren
Warning: Not all children have same parent in XtManageChildren
Warning: Not all children have same parent in XtManageChildren
Warning: Not all children have same parent in XtManageChildren
Warning: Not all children have same parent in XtManageChildren
Warning: communication protocol revision mismatch: expected 11.3, received 11.4
msgget: No space left on device
allegra:~>framer4 msgget:msqid: No space left on device
Does anyone have any inspiration for why this is, or what the story is? I have GR class, but I'll try to follow up later this afternoon.
Leaving for dinner. Back in ~1hr.
I left a measurement running. Please don't interfere with it till I'm back. Thanks.
Per Alberto's instructions, I have closed the shutter on his laser so that the Adaptive Team can play with the Mode Cleaner.
It's been an iffy last few hours here at the 40m. Kiwamu, Koji and I were all sitting at our desks, and the computers / RFM network decided to crash. We brought all of the computers back, but now the RefCav and PMC don't want to lock. I'm a wee bit confused by this. Both Kiwamu and I have given it a shot, and we can each get the ref cav to sit and flash, but we can't catch it. Also, when I bring the PMC slider rail to rail, we see no change in the PMC refl camera. Since c1psl had been finicky coming back the first time, I tried soft rebooting, and then keying the crate again, but the symptoms remained the same. Also, I tried burt restoring to several different times in the last few days, to see if that helped. It didn't. I did notice that MC2 was unhappy, which was a result of the burtrestores setting the MCL filters as if the cavity were locked, so I manually ran mcdown. Also, the MC autolocker script had died, so Kiwamu brought it back to life.
Since we've spent an hour on trying to relock the PSL cavities (the descriptive word I'm going to suggest for us is persistent, not losers), we're giving up in favor of waiting for expert advice in the morning. I suppose there's something obvious that we're missing, but we haven't found it yet......
The 2 SOS towers for the ITMs have been assembled, and are on the flow bench in the cleanroom. Next up is to glue magnets, dumbells, guiderods and wire standoffs to the optics, then actually hang the mirrors.
The upgrade's input mode matching telescope design is complete. A summary document is on the MMT wiki page, as are the final distances between the optics in the chain from the mode cleaner to the ITMs. Unless we all failed kindergarden and can't use rulers, we should be able to get very good mode matching overlap. We seem to be able (in Matlab simulation land) to achieve better than 99.9% overlap even if we are wrong on the optics' placement by ~5mm. Everything is checked in to the svn, and is ready for output mode matching when we get there.
[Jenne, Kiwamu, with moral support from Koji, and loads of advice from Steve and Bob]
New upgrade ITMX (ITMU03) has it's guiderod & standoff glued on, as step 1 toward hanging the ITMs.
1. Make sure you have everything ready. This is long and complicated, but not really worth detail here. Follow instructions in E970037 (SOS Assembly Spec), and get all the stuff in there.
2. Set optic in a 'ring stand', of which Bob has many, of many different sizes. They are cleaned and baked, and in the cleanroom cupboard on the bottom just behind the door. We used the one for 3" optics. This lets you sit the optic down, and it only rests on the bevel on the outside, so no coated surface touches anything.
3. Drag wipe the first surface of the optic, using Isopropyl Alcohol. We used the little syringes that had been cleaned for the Drag Wipe Event which happened in December, and got fresh Iso out of the bottle which was opened in Dec, and put it into a baked glass jar. The drag wipe procedure was the same as for the December event, except the optic was flat on the bench, in the ring holder.
4. Turn the optic over.
5. Drag wipe the other surface.
6. Align the optic in the guiderod gluing fixture (Step 3 in Section 3.2.1: Applying Guide Rod and Wire Standoff of E970037).
7. Set guiderod and standoff (1 guiderod on one side, 1 standoff on the other, per instructions) against the side of the optic.
8.a. Use a microscope mounted on a 3-axis micrometer base to help align the guiderod and standoff to the correct places on the optic (Steps 4-5 of Section 3.2.1). This will be much easier now that we've done it once, but it took a looooooong time.
8.b. We put the optic in 180deg from the way we should, based on the direction of the wedge angle in the upgrade table layout (wedge angle stuff used a "Call a Friend" lifeline. We talked to Koji.) The instructions say to put the guiderod and standoff "above" the scribe lines in the picture on Page 5 of E970037 - the picture has the arms of the fixture crossing over the scribe lines. However, to make the optic hang correctly, we needed to put the guiderod and standoff below the scribe lines. This will be true as long as the arrow scribe line (which marks the skinniest part of the optic, and points to the HR side) is closest to you when the optic is in the fixture, the fixture is laying on the table (not standing up on end) with the micrometer parts to your right. We should put the other ITM into the fixture the other way, so that the arrow is on the far side, and then we'll glue the guiderod and standoff "above" the scribe lines. Mostly this will be helpful so that we can glue in exactly the places the instructions want us to.
8.c. The biggest help was getting a flashlight to help illuminate the scribe lines in the optic while trying to site them in the microscope. If you don't do this, you're pretty much destined to failure, since the lights in the cleanroom aren't all that bright.
8.d. The micrometer mount we were able to find for the microscope has a max travel of 0.5", but the optic is ~1" thick. To find the center of the optic for Step 5 in the guiderod and standoff alignment we had to measure smaller steps, such as bevel-to-end-of-scribe-line, and length-of-scribe-line then end-of-scribe-line-to-other-bevel. Thankfully once we found the total thickness and calculated the center, we were able to measure once bevel-to-center.
9. Apply glue to the guiderod and standoff. We made sure to put this on the "down" side, which once the optic is hung, will be the top of the little rods. This matches the instructions as to which side of the rods to apply the glue on. The instructions do want the glue in the center of the rod though, but since we put the optic in the fixture the wrong way, we couldn't reach the center, so we glued the ends of the rods. We will probably apply another tiny dab of glue on the center of the rod once it's out of the fixture, perhaps while the magnet assemblies are being glued.
10. We didn't know if the airbake oven which Bob showed us to speed up the curing of our practice epoxy last night was clean enough for the ITM (he was gone by the time we got to that part), so for safety, we're leaving the optic on the flow bench with a foil tent (the foil is secured so there's no way it can blow and touch the optic). This means that we'll need the full curing time of the epoxy, not half the time. Maybe tomorrow he'll let us know that the oven is in fact okay, and we can warm it up for the morning.
The Vac pressure measured at P1 is at 2.5mTorr. I expect we'll hit 3mTorr sometime this afternoon, at which point (according to Steve) the interlock will shut the shutter, and we won't have light in the IFO. Anything which needs to happen with light in the IFO before Monday needs to happen fairly soon.
This work happened on Friday, after Nodus and the elog went down....
The guiderod and standoff for ITMY were epoxied, and left drying over the weekend on the flow bench under a foil tent. The flow bench was off for the weekend, so we made tents which hopefully didn't have any place for dust to get in and settle on the mirrors.
There is a small chance that there will be a problem with glue on the arm of the fixture holding the guiderod to the optic. Kiwamu and I examined it, and hopefully it won't stick. We'll check it out this afternoon when we start getting ready for gluing magnets onto optics this afternoon.
The magnets + dumbbell standoffs have been glued to ITMX. We're waiting overnight for them to dry.
Since I broke one of the magnet + dumbbells on the ITMY set, we've glued another dumbbell to the 6th magnet, and it should be ready for us to glue to ITMY tomorrow, once ITMX is dry and out of the fixture. This doesn't put us behind schedule at all, so that's good.
We had been concerned that there might be a problem with the arm of the guiderod fixture being glued to ITMY, but it was fine after all. Everything is going smoothly so far.
Zach and Mott are almost prepared to start cutting the viton for the earthquake stops. We need 2 full sets by Wednesday morning, when we expect to begin hanging the ITMs.
Since we're going to open the MC1 tank tomorrow, I've moved the MC1 accelerometers and the Guralp over to underneath MC2 for the vent. I'll reconnect them later.
This is going to be a laundry list of the mile markers achieved so far:
* Guiderod and wire standoff glued to each ITMX and ITMY
* Magnets glued to dumbbells (4 sets done now). ITMX has 244 +- 3 Gauss, ITMY has 255 +- 3 Gauss. The 2 sets for SRM and PRM are 255 +- 3 G and 264 +- 3 G. I don't know which set will go with which optic yet.
* Magnets glued to ITMX. There were some complications removing the optic from the magnet gluing fixture. The way the optic is left with the glue to dry overnight is with "pickle picker" type grippers holding the magnets to the optic. After the epoxy had cured, Kiwamu and I took the grippers off, in preparation to remove the optic from the fixture. The side magnet (thankfully the side where we won't have an OSEM) and dumbbell assembly snapped off. Also, on the UL magnet, the magnet came off of the dumbbell (the dumbbell was still glued to the glass). We left the optic in the fixture (to maintain the original alignment), and used one of the grippers to glue the magnet back to the UL dumbbell. The gripper in the fixture has very little slop in where it places the magnet/dumbbell, so the magnet was reglued with very good axial alignment. Since after the side magnet+dumbbell came off the glass, the 2 broke apart, we did not glue them back on to the optic. They were reattached, so that we can in the future put the extra side magnet on, but I don't think that will be necessary, since we already know which side the OSEM will be on.
* Magnets glued to ITMY. This happened today, so it's drying overnight. Hopefully the grippers won't be sticky and jerky like last time when we were removing them from the fixture, so hopefully we won't lose any magnets when I take the optic out of the fixture.
* ITMX has been placed in its suspension cage. The first step, before getting out the wire, is to set the optic on the bottom EQ stops, and get the correct height and get the optic leveled, to make things easier once the wire is in place. Koji and I did this step, and then we clamped all of the EQ stops in place to leave it for the night.
* The HeNe laser has been leveled, to a beam height of 5.5inches, in preparation for the final leveling of the optics, beginning tomorrow. The QPD with the XY decoder is also in place at the 5.5 inch height for the op lev readout. The game plan is to leave this set up for the entire time that we're hanging optics. This is kind of a pain to set up, but now that it's there, it can stay out of the way huddled on the side of the flow bench table, ready for whenever we get the ETMs in, and the recoated PRM.
* Koji and Steve got the ITMX OSEMs from in the vacuum, and they're ready for the hanging and balancing of the optic tomorrow. Also, they got out the satellite box, and ran the crazy-long cable to control the OSEMs while they're on the flow bench in the clean room.
Koji and I discovered a problem with the small EQ stops, which will be used in all of the SOS suspensions for the bottom EQ stops. They're too big. :( The original document (D970312-A-D) describing the size for these screws was drawn in 1997, and it calls for 4-40 screws. The updated drawing, from 2000 (D970312-B-D) calls for 6-32 screws. I naively trusted that updated meant updated, and ordered and prepared 6-32 screws for the bottom EQ stops for all of the SOSes. Unfortunately, the suspension towers that we have are tapped for 4-40. Thumbs down to that. We have a bunch of vented 4-40 screws in the clean room cabinets, which I can drill, and have Bob rebake, so that Zach and Mott can make viton inserts for them, but that will be a future enhancement. For tonight, Koji and I put in bare vented 4-40 screws from the clean room supply of pre-baked screws. This is consistent with the optics in our chambers having bare screws for the bottom EQ stops, although it might be nicer to have cushy viton for emergencies when the wire might snap. The real moral of this story is: don't trust the drawings. They're good for guidelines, but I should have confirmed that everything fit and was the correct size.
Jenne and Koji
We successfully hung ITMX on the SOS. Side magnet is ~2mm off from the center of the OSEM.
Reguled ITMY side magnet.
Cleaned up the lab for the safety inspection.
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.
First, the easy story: SRM got it's guiderod & standoff glued on this evening. It will be ready for magnets (assuming everything is sorted out....see below) as early as tomorrow. We can also begin to glue PRM guiderods as early as tomorrow.
The magnet story is not as short.....
Problem: ITMX and ITMY's side magnets are not glued in the correct places along the z-axis of the optic (z-axis as in beam propagation direction).
ITMX (as reported the other day) has the side magnet placement off by ~2mm. ITMX side was glued using the magnet fixture from MIT and the teflon pads that Kiwamu and I improvised.
It was determined that the improvised teflon pads were too thin (maybe about 1m thick), so I took those out, and replaced them with the teflon pads stolen from the 40m's magnet gluing fixture. (The teflon pad from the MIT fixture and the ones from the MIT fixture are the same within my measuring ability using a flat surface and feeling for a step between them. I haven't yet measured with calipers the MIT pad thickness). The pads from the 40m fixture, which were used in the MIT fixture to glue ITMY side last night were measured to be ~1.7mm thick.
Today when Koji hung ITMY, he discovered that the side magnet is off by ~1mm. This improvement is consistent with the switching of the teflon pads to the ones from the 40m fixture.
We compared the 40m fixture with the one from MIT, and it looks like the distance from the edge of where the optic should sit to the center of the hole for the side magnet is different by ~1.1mm. This explains the remaining ~1mm that ITMY is off by.
We should put the teflon pads back into the 40m fixture, and only use that one from now on, unless we find an easy way to make thicker teflon pads for the fixture we received from MIT. (The pads that are in there are about the maximum thickness that will fit). I'm going to use my thickness measurements of SRM (taken in the process of gluing the guiderods) to see what thickness of pads / what fixture we want to actually use, but I'm sure that the fixture we found in the 40m is correct. We can't use this fixture however, until we get some clean 1/4-28 screws. I've emailed Steve and Bob, so hopefully they'll have something for us by ~lunchtime tomorrow.
The ITMX side magnet is so far off in the Z-direction that we'll have to remove it and reglue it in the correct position in order for the shadow sensor to do anything. For ITMY, we'll check it out tomorrow, whether the magnet is in the LED beam at all or not. If it's not blocking the LED beam enough, we'll have to remove and reglue it too.
Why someone made 2 almost identical fixtures, with a 1mm height difference and different threads for the set screws, I don't know. But I don't think whoever that person was can be my friend this week.
MC1 and MC3 seem to have kept themselves together, but all the other optics' watchdogs tripped.
This morning the pencil soldering iron of our Weller WD2000M Soldering Station suddenly stopped working and got cold after I turned the station on. The unit's display is showing a message that says "TIP". i checked out the manual, but it doesn't say anything about that. I don't know what it means. Perhaps burned tip?
Before asking Steve to buy a new one, I emailed Weller about the problem.
There should be a supply of extra tips in the Blue Spinny Cabiney (I can never remember it's French name....) The drawer is something like the top row of one of the bottom sets of drawers. You can pick the shape of tip you want, and stick it in.
I pulled the Guralp breakout box from the rack, and it's sitting on the EE bench here. The game plan is to check out the Gur2X channel.
Rana and Steve have been investigating, and found that the X channel has been funky (which has been known for ~a month or two) when the seismometer has been plugged in, and also when the seismometers have been unplugged, but the box is left on. The funkyness goes away when the box is turned off. Since it's not there when the box is off, it seems that it's not a problem with the cable from the box to the ADC, or in the ADC channel. Since it is there when the box is on, but the seismometer is unplugged, it's clear that it's probably in the box itself.
Preliminarily, I've connected a set of BNC clipdoodles to the input testpoints, and another set to the output. They're both connected to a 'scope (which is on it's battery so it's not connected to any Ground), and when I tap on the circuit board the input trace is totally unchanged, but the output trace goes kind of crazy, and gets more fuzzy, and picks up a DC offset. Koji is concerned that some of the big capacitors may have an iffy connection to the board.
Investigations will continue Monday morning.
The Guralp Box appears to be back in working order. It's reinstalled with the 2 seismometers plugged in.
* Koji suggested retouching the through-board solder joints on the broken channel (EW2 = Gur2X) with a bit of solder to ensure the connections were good. Check.
* "C7", one of the giant 1uF capacitors on each channel is totally bypassed, and since that was one of the original suspects, Rana removed the (possibly) offending capacitor from EW2.
* Rana and I isolated the craziness to the final differential output stage. We tried each of the testpoints after the individual gain / filter stages, and found that the signals were all fine, until after the output stage.
* I started to remove the resistors in the output stage (with the plan to go through the resistors, capacitors, and even the amplifier chip if neccessary), and noticed that 2 of the 1k resistors came off too easily, as if they were just barely connected in the first place. After replacing only the 4 1k resistors, the craziness seemed to be gone. I poked and gently bent the board, but the output wouldn't go crazy. I declared victory.
* I reinstalled the box in its normal spot, and put Gur2 (which had been out by the bench for use as a test signal) back next to the other seismometers. We are in nominal condition, and should be able to do a huddle test this week.
I looked at the time traces of all the seismometer channels, and they all looked good. I'll put a spectra in in the morning....I'm too impatient to wait around for the low frequency FFTs.
Attached are the before and after pictures of the output stage of EW2 / Gur2X. The "before" is the one with the OUT+ and OUT- words upsidedown. The "after" picture has them right side up.
I have redone the beam fit, this time omitting the M2, which I believe was superfluous. I have made the requested changes to the plot, save for the error analysis, which I am still trying to work out (the function I used for the least squares fit does not work out standard error in fit parameters). I will figure out a way to do this and amend the plot to have error bars.
Are you sure about your x-axis label?
We removed the old SRM and PRM from their cages, and are temporarily storing them in the rings which we use to hold the optics while baking. Steve will work on a way to store them more permanently.
We then hung the new SRM (SRMU03) and new PRM (SRMU04) in the cages. We were careful not to break the wires, so the heights will not have changed from the old heights.
The optics have not been balanced yet. That will hopefully happen later this week.
The 3 seismometers are now on the granite slab. The Ranger is now aligned with the Xarm (perpendicular to the Mode Cleaner) since that's the only way all 3 would fit on the slab.
The attached plot shows the spectra of the 3 Z axes of the 3 seismometers we have (this data is from ~20Aug2009, when the Ranger was in the Z orientation) in Magenta, Cyan and Green, and the noise of each of the sensors in Red, Blue and Black. The noise curves were extracted from the spectra using the Huddle Test / 3 Corner Hat method. The Blue and Black traces which are just a few points are estimates of the noise from other spectra. The Blue points come from the Guralp Spec Sheet, and the Black comes from the noise test that Rana and I did the other day with the Ranger (elog 2223).
I'm not really happy with the black spectra - it looks way too high. I'm still investigating to see if this is a problem with my calibration/method....
So, as it turns out (surprise), I'm a spaz and forgot a 2*pi when calibrating the Guralp noise spectra from the spec sheet. I noticed this when redoing the Huddle Test, and comparing my Spec Sheet Guralp noise with Rana's, which he shows in elog 2689. When going from m/s^2, the units in the spec sheet, I just tilted the line by a factor of frequency. Koji pointed out that I needed a factor of 2*pi*f. That moves the Guralp spec line in the plot in elog 2237 (to which this entry is a reply) down by ~6, so that my measured noise is not, in fact, below the spec. This makes things much more right with the world.
In other news, I redid the Huddle analysis of the 2 Guralp seismometers, ala Rana's elog 2689. The difference is now we are on the granite slab, with soft rubber feet between the floor and the granite. We have not yet cut holes in the linoleum (which we'll do so that we're sitting directly on the 40m's slab).
Rana> this seems horrible. Its like there's a monster in there at 6-7 Hz! Either the seismos are not centered or the rubber balls are bad or Steve is dancing on the granite slab again.
The accelerometer power supply / preamp board has been OFF because of exciting new accelerometer measurements. It's now on, so watch out and make sure to turn it back off before plugging / unplugging accelerometers.
For reasons unknown, the seismic spectra posted above Rosalba has been wrong since ~January when it was first posted. The noise that we were claiming was waaaay lower than is really possible.
Rana and I checked the calibrations, and the numbers in DTT for the Ranger and the Guralp are correct (it's unknown what was being used at the time of the bad plot) - Cal for the Guralp is 3.8e-9 m/s, and for the Ranger is 1.77e-9 m/s.
Something is funny with the accelerometer calibration. Hopefully Kevin's investigation will sort it out. Their calibration used to be 1.2e-7 m/s^2 , but it was changed to be 7e-7 m/s^2 to match the noise level of the accelerometers with the seismometers at ~10Hz. We need to go through the calibration carefully and figure out why this is!
Posted above Rosalba for easy reference, and attached below, is the new seismic spectra. The black trace is when the Ranger's mass is locked down, and the teal circle markers indicate the Guralp Spec-Sheet Noise Floor.
** Rana says> the y-axis in Jenne's plot is (m/s)/sqrt(Hz). The Guralp has a velocity readout bandwidth of 0.03-40 Hz, so we would have to modify the calibration to make it right in those frequencies. I believe the Ranger cal has the correct poles in it. The huge rise at low frequencies is because of the 1/f noise of the SR560.
We took apart and examined one of the Guralp seismometers this afternoon. For the most part we think we understand how it works. The horizontal sensors are a little more confusing, since we didn't end up finding the moving masses. The vertical sensor is a flat rectangle, hinged at one edge. There are capacitive sensors above and below the rectangle. The hinged end is connected to a leaf spring.
The PCBs are packed full of old-school 80's components. We probably need an actual schematic to figure out where the preamp circuit is, which is what we'd want to think about fitzing with, if we were to try to improve the noise of the seismometer. For now, we put it all back together, and back out on the granite slab.
There was a wee bit of confusion when putting the N/S marker-spikes back on as to where they should go. The solution is that the handle of the seismometer is aligned with the North/South axis, so the spikes should be aligned with the handle. The lid of the seismometer is uniquely aligned to the stuff inside by the ribbon cable connector, as well as the holes in the lid for accessing the centering potentiometers. So, align the lid to the pots, and then align the spikes to the handle.
Photos are on Picasa.
[Jenne, Kevin, Steve]
We made some progress toward getting the MC's beam profile measured. In the end, no changes were made to anything today, but we're more prepared to go for tomorrow.
What we did:
* Grabbed the scanning slit beam scan from the PSL lab. It's the same kind as we had here at the 40m, so Kevin was able to hook it up to the computer, and confirmed that it works.
* Opened the IOO and OMC chamber doors, and locked the MC. Unfortunately the MC mode was awful in Yaw. Awful like TEM(0,10+). But it still locked.
* Confirmed that the beam went through the Faraday. I looked at the beam before and after the Faraday on a card, and it was the same nasty beam both before and after. So it looks like Zach did a good job aligning the Faraday and everything else. I was going to clamp the Faraday, but I didn't yet, since I wanted to see the nice happy TEM00 mode go through without clipping before risking moving the Faraday during clamping (I don't know how heavy it is, so I'm not sure how much it might potentially move during clamping.)
* Noticed that there is a whole lot of crap on both the OMC and BS tables that's going to have to move. In particular, one of the weights leveling the OMC table is right where I need to put MMT2. Steve suggested putting the optic there, in its approximate place, before doing too much other stuff, since it could potentially affect the leveling of the table, and thus the input pointing to the MC. Unfortunately, to do that I'll need to move the weight, which is definitely going to change things. Sad face. Moving the weight will likely be one of the first things I do tomorrow, so that all 3 profile measurements have the same configuration.
* Before closing up, I tried to align the MC, to get back to TEM00, to no avail. I got as far as achieving TEM11 flashing, along with a bunch of other crappy modes, but didn't get 00. That's also on the to-do list.
What we're going to do:
* Open the chambers, and align the MC to TEM00 (using the sliders on the MC align screen).
* Check with an IR card that the beam goes through the Faraday.
* Clamp the Faraday, reconfirm.
* Remove the weight on the OMC table.
* Place MMT2 on the OMC table in it's approximate final location.
* Realign the MC, and make sure the beam goes through the Faraday. If this doesn't happen smoothly, I may need more instruction since I've never dealt with aligning the Faraday before. What are the appropriate mirrors to adjust?
* Move the PZT flat steering mirror from the BS table to the IOO table. (Thoughts on this? This will change the table leveling, and also includes the trickiness of needing to move the connectors for the PZT.)
* Place a flat mirror on the BS table to route the MC beam out to the BS/PRM/SRM oplev table.
* Measure the mode using the beam scan: on the BS oplev table, on the POX table, and then perhaps by shooting the beam through the beamtube on the ETMY (new convention) table.
* Place MMT1 on the BS table, use flat mirrors to get it out of the chambers, repeat measurements.
* Place MMT2 in the correct position, use flat mirrors to get it out of the chambers, repeat measurements.
All of this may require some serious cleaning-up of the BS table, which is going to be ugly, but it has to happen sometime. Hopefully I can get away with only moving a minimal number of things, in order to get these measurements done.
Another note: Don't trust the PSL shutter and the switch on the MEDM screens! Always use a manual block in addition!!! We discovered upon closeup that hitting the "Closed" button, while it reads back as if the shutter is closed (with the red box around the buttons), does not in fact close the shutter. The shutter is still wide open. This must be fixed.
No real progress today. We opened the chambers and again tried to lock the MC. Gave up after ~2.5 hours (and closed up the chambers with light doors, replaced manual beam block, etc...). With Koji's helpful coaching, hopefully we'll finally get it done tomorrow. Then we can move forward with the actual to-do list.
We opened up the MC chambers again, and successfully got the MC locked today! Hooray! This meant that we could start doing other stuff....
First, we clamped the Faraday. I used the dog clamps that Zach left wrapped in foil on the clean cart. I checked with a card, and we were still getting the 00 mode through, and I couldn't see any clipping. 2 thumbs up to that.
Then we removed the weight that was on the OMC table, in the way of where MMT2 needs to go. We checked the alignment of the MC, and it still locks on TEM00, but the spot looks pretty high on MC2 (looking at the TV view). We're going to have to relevel the table when we've got the MMT2 optic in the correct place.
We were going to start moving the PZT steering mirror from the BS table to the IOO table, place MMT2 on the OMC table, and put in a flat mirror on the BS table to get the beam out to the BS oplev table, but Steve kicked us out of the chambers because the particle count got crazy high. It was ~25,000 which is way too high to be working in the chambers (according to Steve). So we closed up for the day, and we'll carry on tomorrow.
Photos of the weight before we removed it from the OMC table, and a few pictures of the PZT connectors are on Picasa.
Please don't go down the Yarm (Old Xarm) for right now, or if you do, please be very careful. Kiwamu and I are set up to take beam scan measurements down the walkway, and so there are some cables / carts / other stuff down there. We are going to get dinner really quickly before beginning the measurements.
Right now, the PSL shutter is Closed, so there is no beam hazard outside of the chambers, just crowded space hazard.
[Jenne, Kiwamu, and Steve via phone]
Around 9:30pm, Kiwamu and I came back from dinner, and were getting ready to begin the beam scan measurements. I noticed that one of the vacuum pumps was being very loud. Kiwamu noted that it is the fore pump for TP3's turbo, which he and Steve replaced in January (elog 2538). We had not noticed these noises before leaving for dinner, around 8pm.
We called Steve at home, and he could hear the noise through the phone. He said that even though it was really loud, since it was reading 3.3mTorr (on the display of the controller, in the vacuum rack just above head-height) which is close to the nominal value, it should be fine to leave. He will check it out in the morning. If it had been reading at or above ~1Torr, that's indicative of it being really bad, and we would have needed to shut it off.
For future reference, in case we need to turn it off, Steve said to use the following procedure:
1. Close VM3, to isolate the RGA, which is what this pump is currently (while we're at atmosphere) pumping on. I don't know if there are other things which would need to be shut at this stage, if we were at vacuum nominal.
2. Close VM5, which is right in front of TP3, so TP3's pump is just pumping on itself.
3. Push the "Stop" button on the Turbo controller for TP3, in the vacuum rack, about waist level. Turning off the turbo will also turn off the fore pump.
UPDATE, 1am: The controller in the rack is reading 3.1mTorr, so the pump, while still noisy, still seems to be working.
[Jenne, Kiwamu, Steve]
Round 1 of measuring the MC mode is pretty much done. Yay.
Earlier today, Steve and I launched the MC beam off the flat mirror just after the Faraday, and sent it down toward ETMY(new convention). We ended up not being able to see it all the way at the ETM because we were hitting the beam tube, but at the ITM chamber we could see that the beam looked nice and circle-y, so wasn't being clipped in the Faraday or anywhere else. To do this we removed 2 1inch oplev optics. One was removed from the BS table, and wrapped in foil and put in a plastic box. The other was just layed on its' side on the BS table.
I then took the beam out of the BS chamber, in order to begin measuring the mode. I left the flat fixed mirror in the place of what will be PZT SM1, and instead used the PZT mirror to turn the beam and get it out the BS chamber door. (Thoughts of getting the beam to the BS oplev table were abandoned since this was way easier, since Kiwamu and Steve had made the nifty table leg things.) Kiwamu and I borrowed an 2inch 45P Y1 optic from the collection on Koji's desk (since we have ZERO 2inch optics on the random-optic-shelf....no good), to shoot the beam down the hallway of the Yarm (new convention). We used the beam scan on a rolling cart to measure the beam at various distances. I made some sweet impromptu plum bobs to help make our distance measurements a bit more accurate.
We stopped at ~25 feet from the BS chamber, since the spot was getting too big for the beam scanner. If it turns out that I can't get a good fit with the points I have, I'll keep everything in-chamber the same, and do the farther distances using the good ol' razor blade technique.
I have measurements for the distances between the beam scan head and the opening of the BS chamber. Tomorrow, or very soon after, I need to measure the distances in-chamber between the MC and the BS chamber opening. Plots etc will come after I have those distances.
Next on the to-do list:
1. Measure distances in-chamber for first mode scan.
2. Plot spot size vs. distance, see if we need more points. Take more points if needed.
3. Put in MMT1, repeat measurements.
4. Put in MMT2, rinse and repeat.
5. Move the PZT mirror to its new place as SM1, and figure out how to connect it. Right now the little wires are hooked up on the BS table, but we're going to need to make / find a connector to the outside world from the IOO table. This is potentially a pretty big pain, if we don't by happenstance have open connectors on the IOO table.
[Jenne, Kevin, Kiwamu]
We moved some optics in preparation for measuring the MC mode after the first MMT curved optic, RoC -5m.
Kevin and I found the box of DLC (sp?) mounts with the 2" Y1-45P optics in the clean tupperware boxes. We removed one of the Y1-45P's, and replaced it with the MMT1 -5m optic, which was baked several weeks ago. We left the Y1-45P on the cleanroom table next to where the MMT optics are. We placed this MMT mirror in the place it belongs, according to Koji's table layout of the BS table.
We drag wiped one of the other Y1-45P's that was in the box since it was dirty, and then placed the optic on the IOO table, on the edge closest to the BS table, with the HR side facing the BS table, so that the beam reflected off the curved mirror is reflected back in the direction of the BS table. This was aligned so the beam hits the same PZT mirror we were using last time, to get the beam out of the BS chamber door. We left a razor dump on the edge of the BS table, by the door, which will need to be removed before actual measurements can take place.
Rana pointed out that the anticipated mode calculation should be modified to include the index of refraction of the crystals in the Faraday, and the polarizers in the Faraday. This may affect where we should put MMT1, and so this should be completed before round 2 measurements are taken, so that we can move MMT1.
Also, the optics are in place now, and the beam is going out the BS chamber door, but we have not yet measured distances (design distances quoted on the MMT wiki page), and confirmed that everything is in the right place. So there is a bit more work required before beginning to measure round 2.
Note: While I was poking around on the BS table, I had to move several optics so that we could fit MMT1 in the correct place. When preparing to move these optics, I found 2 or 3 that were totally unclamped. This seems really bad, especially for tall skinny things which can fall over if we have an earthquake. Even if something is in place temporarily, please clamp it down.
That's true. But I thought that you measured the mode after those optics and the effect of them is already included.
Yes, the measured mode takes all of this into account. But in Kevin's plot, where he compares 'measured' to 'expected', the expected doesn't take the Faraday optics into account. So I should recalculate things to check how far off our measurement was from what we should expect, if I take the Faraday into account. But for moving forward with things, I can just use the mode that we measured, to adjust (if necessary) the positions of MMT1 and MMT2. All of the other transmissive optics (that I'm aware of) have already been included, such as the PRM and the BS. This included already the air-glass curved interface on the PRM, etc.
Valera and I put the 2 Guralps and the Ranger onto the big granite slab and then put the new big yellow foam box on top of it.
There is a problem with the setup. I believe that the lead balls under the slab are not sitting right. We need to cut out the tile so the thing sits directly on some steel inserts.
You can see from the dataviewer trend that the horizontal directions got a lot noisier as soon as we put the things on the slab.
You'll have to ask Steve how deep he cut, but the tile is cut around the lead balls, so they are not sitting on the linoleum. They might just be sitting on the concrete slab, or whatever Steve found underneath the tile, instead of fancy steel inserts, but at least they're not on the tile. I don't know why things got noisier though...
We started a vacuum work in this morning. And still it's going on.
Although the last night the green team replaced a steering mirror by an 80% reflector on the PLS table, the beam axis to the MC looks fine.
The MC refl beam successfully goes into the MCrefl PD, and we can see the MC flashing as usual.
We started measuring the distance of the optics inside the vacuum chamber, found the distance from MC3 to MMT1(curved mirror) is ~13cm shorter than the design.
We moved the positions of the flat mirror after the Faraday and the MMT1, but could not track the beam very well because we did not completely lock the MC.
Now we are trying to get the lock of the MC by steering the MC mirrors.
I just finished redoing the calc based on the measurements that happened last week. Using the average of the Vert and Horz measurements in Kevin's elog 2986, I find that we need to make the MMT telescope ~8cm longer. So, can you please place the flat mirror after the Faraday in the same place as the drawing, but move the MMT1 79mm farther away from that flat mirror? Looking at the table layouts that Koji has on the wiki, this should still (barely) fit.
d2a = 884.0mm (no change) ------ MC3 to Flat after Faraday
d2b = 1123.2mm (move MMT1 farther toward center of BS table) -------- Flat after Faraday (SM1) to MMT1
d3 = 1955.0mm (result of moving MMT1) --------- MMT1 to MMT2
d4a = 1007.9mm (no chnage) ----------- MMT2 to SM2
d4b = 495.6mm (no change) ------------ SM2 to PRM
I just got off the phone with Alberto and Kiwamu, and I'm going to try to recalculate things based on their measurements of the distances between MC3 and SM1. It sounds like the CAD drawings we have aren't totally correct. I know that when we opened doors just before Christmas we measured the distances between the BS table and the ITM tables, but I don't think we measured the distance between the IOO table and the BS table. Hopefully we can fit everything in our chambers.....
I checked the measured data of the mode profile which was taken on the last Tuesday.
For the vertical profile,
the plot shows a good agreement between the expected radius which is computed from the past measurement, and that measured on the last Tuesday.
However for the horizontal profile,
it looks like being overestimated. This disagreement may come from the interference imposed on the Gaussian spot as we've been worried.
So we should solve this issue before restarting this mode matching work.
- The next step we should do are;
checking the effect of MMT1 on the shape of the beam spot by using spare MMT1
The expected curve in the attached figure were computed by using the fitted parameter listed on the entry 2984 .
In the calculation the MMT1 is placed at 1911mm away from MC3 as we measured.
And the focal length of MMT1 is set to be f=-2500mm.
When / if you use the other MMT1 mirror, make sure to take note whether or not it says "SPARE" on it in pencil. I don't remember if it's the other MMT1, or if it's one of the MMT2's that says this. The mirror was baked, so it's okay to use in the vacuum, however it's the one which was dropped on the floor (just prior to baking), so any discrepancies measured using that optic may not be useful. I don't know how strong the CVI coatings are to scratches resulting in being dropped from a ~1m height. Bob and I didn't see any obvious big scratches that day, but that doesn't necessarily give it a clean bill of health.
The optic labeled "SPARE" should NOT be used as the final one in the IFO.
We measured the mode after the Mode Matching Telescope.
---- fitted parameters ----
w0_h = 2.85 +/- 0.0115 mm
w0_v = 2.835 +/- 0.00600 mm
z0_h = 5.4 +/- 0.447 m
z0_v = 6.9 +/- 0.305 m
[Jenne, Kiwamu, Rana, Eric Gustafson]
The SRM and PRM have been re-hung, and are ready for installation into the chambers. Once we put the OSEMs in, we may have to check the rotation about the Z-axis. That was not confirmed today (which we could do with the microscope on micrometer, or by checking the centering of the magnets in the OSEMs).
Also, Eric and Rana inspected the Tip Tilt magnets, and took a few that they did their best to destroy, and they weren't able to chip the magnets. There was concern that several of the magnets showed up with the coatings chipped all over the place. However, since Rana and Eric did their worst, and didn't put any new chips in, we'll just use the ones that don't have chips in them. Rana confiscated all the ones with obvious bad chips, so we'll check the strengths of the other magnets using a gaussmeter, and choose sets of 4 that are well matched.
Eric, photographer extraordinaire, will send along the pictures he took, and we'll post them to Picasa.
Someone has been moving the big blue recycling bin in front of the laser-chiller-chiller (the air conditioner in the control room). This is unacceptable. The chiller temp was up to 20.76C. No good.
You are free to move the recycling bin around so you can access drawers or the bike-exit-door in the control room, but make sure that it does not block air flow between the chiller-chiller and the chiller.
The attached photo shows the BAD configuration.
[Jenne, Steve, Nancy, Gopal]
We made an attempt at hanging some of the Tip Tilt eddy current dampers today.
Photo 1 shows the 2 ECDs suspended.
(1) Loosen the #4-40 screws on the side of the ECDs, so the wire can be threaded through the clamps.
(2) Place the ECDs in the locator jigs (not shown), and the locator jigs in the backplane (removed from main TT structure), all laying flat on the table.
(3) Get a length of Tungsten wire (0.007 inch OD = 180um OD), wipe it with acetone, and cut it into 4 ~8cm long segments (long enough to go from the top of the backplane to the bottom).
(4) Thread a length of wire through the clamps on the ECDs, one length going through both ECDs' clamps.
(5) One person hold the wire taught, and straight, and as horizontal as possible, the other person tightened the clamping screws on the ECDs.
(6) Again holding the wire in place, one person put the clamps onto the backplane (the horizontal 'sticks' with 3 screws in them).
(7) The end. In the future, we'll also clip off extra pieces of wire.
When we held up the backplane to check out our handy work, it was clear that the bottom ECD was a much softer pendulum than the top one, since the top one has the wire held above and below, while the bottom one only has the wire held on the top. I assume we'll trim the wire so that the upper ECD is only held on the top as well?
* This may be a 3 person job, or a 2 people who are good at multitasking job. The wire needs to be held, the ECDs need to be held in place so they don't move during the screwing/clamping process, and the screws need to be tightened.
* Make sure to actually hold the wire taught. This didn't end up happening successfully for the leftmost wire in the photo, and the wire is a bit loose between the 2 ECDs. This will need to be redone.
* We aren't sure that we have the correct screws for the clamps holding the wire to the backplane. We only have 3/16" screws, and we aren't getting very many threads into the aluminum of the backplane. Rana is ordering some 316 Stainless Steel (low magnetism) 1/4" #4-40 screws. We're going for Stainless because Brass (the screws in the photo), while they passed their RGA scan, aren't really good for the vacuum. And titanium is very expensive.
The 2nd photo is of the magnet sticking out of the optic holder. The hole that the magnet is sitting in has an aluminum piece ~2/3 of the way through. A steel disk has been placed on one side, and the magnet on the other. By doing this, we don't need to do any press-fitting (which was a concern whether or not the magnets could withstand that procedure), and we don't need to do any epoxying. We'll have to wait until the ECDs are hung, and the optic holder suspended, to see whether or not the magnet is sticking out far enough to get to the ECDs.
I fitzed with the PRM and SRM briefly, and I now believe that they're both ready to go into the chambers.
For each optic, I used the microscope on a micrometer to check that the scribe lines on each side of the optic were at the same height. Basic procedure was to center the microscope on one scribe line, move the microscope to the other side, to see how far the line was from center, and try to (very gently!!) rotate the optic in the wire about the z-axis about half the distance that the one scribe line needed to be. Rinse and repeat several times until satisfied.
I then checked that our HeNe oplev was still at 5.5" beam height, and that the beam traveled straight across the table. I put the SRM in the oplev, unclamped the EQ stops, and waited for it to settle. The HEPA filters were turned off, to minimize the breeze. While the SRM settled, I worked on the height/rotation for the PRM on the other table.
After checking the SRM balance, I clamped it and moved it, and checked the PRM balance, then turned off the HeNe and rewrapped everything in foil, and turned on the HEPAs.
Both the SRM and the PRM seem a little off in Pitch. The beam returning to the QPD (placed just next to the laser) was always ~1cm above the center of the QPD. The beam travel distance was ~3m (vaguely) from laser to optic to QPD. This effect may be because the optics were originally balanced with OSEMs in place, and I didn't have any OSEMs today. Koji and I found several months ago that the OSEMs have some DC affect on the optics.
Anyhow, since our optics are so small, I think the OSEMs and coils can handle this small DC offset in pitch, so I think we're ready to rock-n-roll with putting them in the chambers.
Still on the to-do list......Tip Tilts!
The photo shows the oplev beam position on (kind of) the QPD, for the SRM. The PRM was basically the same.
[Jenne, Megan, Frank]
We rebooted c1iovme, c1susvme1, and c1susvme2 during lunch. Frank is going to write a thrilling elog about why c1iovme needed some attention.
C1susvme 1&2 have had their overflow numbers on the DAQ_RFMnetwork screen red at 16384 for the past few days. While we were booting computers anyway, we booted the suses. Unfortunately, they're still red. I'm too hungry right now to deal with it....more to follow.
The 40m corner station crane is out of order, and it's stuck in a way that prohibits entry to the 40m LVEA / IFO room for safety. The crane has been locked out / tagged out.
Until further notice, absolutely no one may enter the 40m LVEA. Work is permitted in the desk / control room areas.
Signs have been posted on all doors into the LVEA. Please consider those doors locked out / tagged out.