Koji's design of the SS 2" mirror holder with flexure spring optic retainer like Polaris-K1 has been ordered. We are getting just one to see it's effect on the hysteresis.
Final Summary of changes to mirror holder in Tip-Tilt holder.
Determining minimum range for Side Clamp:
1. The initial distance b/w wire-release point and mirror assembly COM = 0.265 mm
2. But this distance is assuming that wire-release point is at mid-point of clamp. So I'm settling on a range of +/- 1mm. The screenshots below confirm range of ~1mm between (1) side screw & protrusion and (2) clamp screw and clamp.
Determining length of tilt-weight assembly rod at the bottom to get 20mRad range
The tilt-weight assembly is made from following Mcmaster parts:
Rod - 95412A864 18-8 SS #2-56 Threaded Rod
Nuts - 91855A103 18-8 SS #2-56 Acorn Cap Nut
Since the weights are fixed, only rod length can be changed to get the angle range.
So a range of 1 mm between nut's inner face and mirror-holder face should be enough. Since holder is 12 mm thick, rod length = 12mm + 2 x 1mm + 2 x (nut length) = 12 + 2 + 9.6 = 23.6 mm = 0.93 inch. So a 1" rod from Mcmaster will be fine.
5 PR3/SR3 optics from FiveNine Optics were delivered. The data sheets were scanned and uploaded to the following wiki page. https://wiki-40m.ligo.caltech.edu/Aux_Optics
They have been stored on the 3rd shelf from top in the clean optics cabinet at the south end. EX
[Attachment #1]: Computed spectral power transmissivity (according to my model) for the coating design at a few angles of incidence. Behavior lines up well with what FNO measured, although I get a transmission that is slightly lower than measured at 45 degrees. I suspect this is because of slight changes in the dispersion relation assumed and what was used for the coating in reality.
[Attachment #2]: Similar information as Attachment #1, but with the angle of incidence as the independent parameter in a continuous sweep.
Conclusion: The coating behaves in a way that is in reasonable agreement with our model. At 41.1 degrees, which is what the PR3 angle of incidence will be, T<50 ppm, which was what we specified. The larger range of angles was included because originally, we thought of using this optic as a substitute for SR3 as well. But I claim that for the shorter SRC (signal recycling as opposed to RSE), we will not end up using the new optic, but rather go for the G&H mirror. In any case, as Koji pointed out, ~50 ppm extra loss in the RC will not severely limit the recycling gain. Such large variation was not seen in the MC analysis because we only varied the angle of incidence by +/- 0.5 degrees about the nominal design value of 41.1 degrees.
Chub, Koji and I have been talking about Udit's re-design. Here are a few points that were raised. Chub/Koji can add to/correct where necessary. Summary is that this needs considerable work before we can order the parts for a prototype and characterize it. I think the requirements may be stated as:
Some problems with Udit's design as it stands:
A new tool box has been placed at the Y-end! Each drawer has its label so PLEASE put the tools back in their correct location. In addition to this, Each tool has its assigned tool box, so PLEASE RETURN all tools to their designated tool box. The tools can be distinguished by a writing or heat shrink which corresponds to the color of the tool chest or location. Photo #2 is an example of how the tools have been marked.
Each toolbox from now on will contain a drawer for the folllowing: Measurements, Allen Keys, Pliers and Cutters, Screwdrivers, Zipties and Tapes, Allen Ball Drivers, Crescent Wrenches, Clamps, and Torque Wrenches/ Ratchets.
Yoichi's final words on what do next with the interferometer (as of 5 PM on May 21, 2009):
My personal sub-comments to these bullets:
I used Kakeru's instructions in elog 1221 to add the C1OAF screen (still called C1ASS_TOP) to the medm screenshots webpage. The tricky part of this is figuring out that the file that needs editing is in fact in /cvs/cds/projects/statScreen, not /cvs/cds/caltech/statScreen, as claimed in the entry.
[Jenne, Kiwamu, Koji]
We got the IFO back up and running! After all of our aligning, we even managed to get both arms locked simultaneously. Basically, we are awesome.
This morning, we did the following:
* Turned on the PZT High voltages for both the steering mirrors and the OMC. (For the steering mirrors, turn on the power, then hit "close loop" on each. For the OMC, hit Output ON/OFF).
* Looked at the PZT strain gauges, to confirm that the PZTs came back to where they had been. (Look at the snapshot of C1ASC_PZT_Al)
* Locked all components of the PSL (This had already been done.)
* Removed beam dump which was blocking the PSL, and opened the PSL mechanical shutter. Light into the IFO!
* Locked the Mode Cleaner. The auto-locker handled this with no problem.
* Confirm that light is going through the Faraday. (Look at the TV sitting on top of MC13 tank...it shows the Faraday, and we're hitting the input of the Faraday pretty much dead-on).
* Look at IP_ANG and IP_POS. Adjust the steering mirrors slightly to zero the X&Y readings on IP_ANG. This did not change the PZTs by very much, so that's good.
* Align all of the Core Optics to their OpLev positions.
* On the IFO_Align screen, save these positions.
* Run the IFO_Configure scripts, in the usual order. (Xarm, Yarm, PRM, DRM). Save the appropriate optics' positions after running the alignment scripts. We ended up running each alignment script twice, because there was some residual misalignment after the first iteration, which we could see in the signal as viewed on DataViewer (Either TRX, TRY, or SPOB, for those respective DoFs).
* Restore Full IFO.
* Watch the beauty of both arms and the central cavity snapping together all by themselves! In the attached screenshot, notice that TRX and TRY are both ~0.5, and SPOB and AS166Q are high. Yay!
* The wiping may have helped. While aligning X and Y separately, TRX got as high as ~1.08, and TRY got as high as 0.98 This seems to be a little bit higher than it was previously.
* Since everything locked up in pretty short order, and the free swinging spectra (as measured by Kiwamu in elog 2405) looks good, we didn't break anything while we were in the chambers last week. Excellent.
* We are now ready for a finesse measurement to tell us more quantitatively how we did with the wiping last week.
We got the IFO back up and running! After all of our aligning, we even managed to get both arms locked simultaneously.
I'm going to do it right now.
We are celebrating Rob's promotion to thesis poetry. These pictures were taken on December 9, 2009
Rob has finished all his measurements in the lab and is officially well prepared to graduate.
"They (shellfish) shall be an abomination to you; you shall not eat their flesh, but you shall regard their carcasses as an abomination." (Leviticus 11:11)
Bad CDS team. Bad.
Woops, I am sorry about that. I've just cleaned them up.
Bad CDS team. Bad.
This totally creeped me out when I found it wandering around on the floor not so far from my desk:
John Miller has arrived from Australia with 3 bags of Wagonga Coffee. Trade bargaining has started on
250 mgs of Sumatran Mandehling, Timur and Papua New Guine.
I'm cleaning out to make room for our new optical cabinet. Are we keeping these? There are ~20 pieces of 10" od 1" wide tapes and large number of cassettes.
AJW, Zucker, Stuart A and Koji were notified in this matter.
Alan suggested to save data of Bruce Allen paper of observation of binary neutron stars in the 40m on 1994 November 14-20 and save back up tapes of his period in the 40m.
Mike: reels are not readable any more, it is time to let go
At Koji's request, we disassembled 2 of the old Green suspension towers that have been sitting along the X-arm forever (read that last word in a 'Sandlot' voice. Then you'll know how long the suspensions have been sitting there).
They are now hanging out in plastic trays, covered with foil. They will now be much easier to store.
We should remember that we have these, particularly because the tables at the top are really nice, and have lots of degrees of freedom of fine adjustment.
Atm1, there is one more of these old suspension towers
We pondered the idea of clamping the PRM optic to measure the OSEM noise. So we opened up the BS tank to give this a try. We rediscovered that Jenne is too short to reach the other side of the PRM tower, so we couldn't fully clamp the optic (when is Jaime coming again? He's kind of tall...) If we only did the back 2 EQ stops, the optic would still be able to rock, and thus defeat the purpose of clamping anyway. So we didn't go for it.
While we were in there we saw that the SRM OSEMs were just hanging out on the table, and decided to go with them. See Valera's elog for details on our measurement. We closed up the tank without making any changes to anything.
In other news, we still need to figure out how to change up the connectors to get those OSEMs over to the ITM table. This needs to happen pretty soonish.
I tidied up some of the stuff that was on the SP table. The ISS box that has been sitting on there for months is now underneath the X-arm on top of the spare Marconi which is stored there.
I put the ETMY trans QPD in.
The ETMY trans beam was already going toward the TRY DC PD, and a CCD camera. I put a beam splitter in that beam (reducing the power to TRY and the CCD by 50%), and sent my picked-off beam to the ETMY QPD. Since there is a lens in this path to focus the beam onto TRY and the camera, I put the QPD ~the same distance from the lens as the camera. Due to space requirements (because of all the green stuff on the table now), I had to put a Y1 turning mirror between the beam splitter and the QPD. The beam is aligned onto the PD, although the signal isn't super strong. When the PD is blocked, the sum is ~(-92 counts). When the beam is on the PD, the sum is ~(-78 counts).
Just a reminder that a film crew will be here Monday morning, filming Christian Ott for some Discovery channel show.
They are slated to be here from 8am to 12:30pm or so. They will take a couple of shots inside the lab, and the rest of the filming should be of Christian in the control room (which they will "clean up" and fit with "sexy lighting"). I will try to be here the whole time to oversee everything.
Also, according to Steve, there will be some crane guys for fixing the Y end crane issue (#5124) Monday morning.
a film crew will be here Monday morning. They are slated to be here from 8am to 12:30pm or so.
Konecrane Fred was early this morning. He diagnosed the ETMY crane horizontal drive gear box dead and left just before the film crew showed up.
New gear box should be here by the end of this week for installation.
The lab air quality is high ~20,000 counts of particles of 0.5 micron. Keep an eye on this before you open the chamber.
While waiting for the IFO team to align things (there were already ~5 people working on a ~1 person job...), I got all of our supplies prepped for drag wiping in the morning.
The syringes are still on the flow bench down the Xarm. I put fresh alcohol from unopened spectrometer-grade bottles into our alcohol drag wiping bottles.
The ITMs already had rails for marking their position in place from the last time we drag wiped. I placed marker-rails for both ETMs.
We should use the deionizer before drag wiping with isopropanol.
We will begin drag wiping and putting on doors at 9am tomorrow (Tuesday).
We need to get started on time so that we can finish at least the 4 test masses before lunch (if possible).
We will have a ~2 hour break for LIGOX + Valera's talk.
I propose the following teams:
(Team 1: 2 people, one clean, one dirty) Open light doors, clamp EQ stops, move optic close to door. ETMX, ITMX, ITMY, ETMY
(Team 2: K&J) Drag wipe optic, and put back against rails. Follow Team 1 around.
(Team 3 = Team 1, redux: 2 people, one clean, one dirty) Put earthquake stops at correct 2mm distance. Follow Team 2 around.
(Team 4: 3 people, Steve + 2) Close doors. Follow Team 3 around.
Later, we'll do BS door and Access Connector. BS, SRM, PRM already have the EQ stops at proper distances.
I made a super sweet new foam box for our EOM. It's awesome, and should be reasonably easy to duplicate. Check out the PHOTOS!
* I didn't think I was going to cover the inside of the box at first, since the foam is non-fuzz-generating, but Koji suggested it would be a good idea anyway. The foam was cut perfectly to the EOM, so adding the tape inside makes it a tight fit. Especially height-wise...leave a little space next time.
* To cover the insides of the optical path holes, do it in 2 parts. One half-cylinder, and then another. Way easier than trying to do the whole thing at once. Also, pre-cut the tabs on both sides of the foil before inserting. Then you just have to grab the tabs with tweezers and flatten them, and they hold the aluminum tape in place.
* Having 1" wide, 2" wide and 3" wide aluminum tape was handy. 3" to make the top, 2" for the sides, and 1" for the inside of the holes.
Yuta retrieved the IR card that had fallen to the bottom of the IOO chamber, just before we put on the access connector yesterday. The clean "pickle picker" long grabber tool worked wonders.
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C1IOO_MC_ASS.adl C1IOO_MC_TRANS_QPD.adl C1IOO_WFS2_SETTINGS.adl C1IOO_WFS_QPD.adl.old
C1IOO_MC_ASS_LOCKIN1.adl C1IOO_Mech_Shutters.adl C1IOO_WFS2_SETTINGS.adl.old fmX
C1IOO_MC_ASS_LOCKIN2.adl C1IOO_MODECLEANER.adl C1IOO_WFS_HEADS.adl junk
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helppp: command not found
controls@rosalba:/opt/rtcds/userapps/trunk/isc/c1/medm/c1ioo/master/master/master/master 127$ help me
bash: help: no help topics match `me'. Try `help help' or `man -k me' or `info me'.
its an acquired taste, but its a must since we're sending an interferometer to India
I *finally* figured out how to bend Matlab to my will, and close a very simple oplev loop using LQR technology.
This is super, super simple, but it's a step in the right direction. There is no noise, just a simple pendulum with a resonant frequency of 0.75Hz, and a Q of 10. The LQR tries to keep the position of the pendulum at a minimum, and does not care at all about the velocity. You cannot (with Matlab's LQR, at least that I can find) make it care "0" about the control output, so it cares about the control output a factor of 1e-4 as much as the position.
Here are some plots:
The first plot has the open loop system (just the pendulum, no control at all), as well as the closed loop system (the pendulum under control).
Plot 2 is the open loop gain of the controller that the LQR designed.
Plots 3 and 4 are the step and impulse responses of the open loop (pendulum with no control), and closed loop (pendulum with feedback) systems.
The conclusion from the plots (if this were an interesting system) is that it doesn't take much to damp an ideal pendulum. The real conclusion here is that I think I now know how to use the Matlab LQR function, and can make a loop with some noise now.
From Linda and Bram:
I hereby confess to having a secret script. But it is secret no longer!
It's a "goLock" script, and it is now in the path from any terminal. It kills any open medm sessions (to clean up desktops), and then opens a palette of screens that I find useful. It also starts up the CARM and DARM ALS watch scripts, and the toggle shutter scripts. It then leaves the terminal in .../scripts/PRFPMI/ , which is where the carm_cm_up.sh script that we've been using lives.
I also made tonight a "goHome" script, but all that one does so far is set the LSC mode to OFF. The other thing that this could / should do is restore all optics so we don't have hysteresis problems.
Also, also, my "new" misalign / restore scripts had a bug, in that they were always switching oplevs for the PRM, no matter what optic was requested. This sometimes caused the PRM oplev to be engaged while the optic was misaligned, so the PRM would get rung up. This has been fixed.
The attached PDF shows the Mathematica notebook and the associated block diagram.
In the notebook, I have written the single hop connection gains into the K matrix. P is the optical plant, C is the Common electronic gain, F is the 'fast' NPRO PZT path, and M is the phase Modulator.
G is the closed loop gain matrix. The notation is similar to matlab SS systems; the first index is the row and the second index is the column. If you want to find the TF from node 2 to node 3, you would ask for G[[3,2]].
As examples, I've shown how to get the FAST gain TF that I recently made with the Koji filter box as well as the usual OLG measurement that we make from the MC servo board front panel.
Welcome to your new abode, Donatella!
SP table has been a mess because Q and I had let our SURF leave without cleaning up.
I cleaned up the SP table, put things back where they belong and did some sorting. I will put back the optomechanics where they belong sometime later.
For now, check out the SP table next time you are looking for a Y1 or lens or BS.