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ID Date Author Type Category Subject
  5272   Fri Aug 19 23:41:20 2011 JennyUpdatePSLRelocking NPRO to reference cavity.

Quote:

I am trying again to measure a temperature step response on the reference cavity on the PSL table.

I have been working to relock the NPRO to the cavity. I unblocked the laser beam, reassembled the setup described in my previous elog entry: 5202. I then did the following:

1) Monitored error signal (from LB1005 PDH servo), transmitted signal, and control signal sent to drive PZT on oscilloscope.

2) With loop open, swept through 0,0-mode resonance, saw a peak in the transmission, saw an accompanying error signal similar to the signal shown in 5202.

3) Tried to lock. Swept the gain on the LB1005 and could not find a gain that would make it lock. Tried changing the PI-corner freq. from 10 kHz to 30 kHz and back and still could not lock.

4) Noticed that the open loop error signal displayed on the scope was DC-offset from zero. Changed the offset to zero the error signal.

5) Tried to lock again and succeeded.

6) Noticed that upon closing the loop, the error signal became offset from zero again. Turning on the integrator on the LB1005 increased DC-offset.

7) Reduced the gain on the SR560 being used as a low pass filter from 5 to 1. Readjusted the open loop error signal offset on the LB1005.

8) Closed the loop and locked. Closing the loop then caused a much smaller DC change in the signal than I had seen with the larger gain (now around 3mV). RMS fluctuations in error signal are now 1 mV (well within the linear region of the error signal).

9) Noticed transmission has a strange distorted harmonic oscillation in it a 1MHz. (Modulation freq is 230kHz, so it's not that). Checked reflected signal and also saw a strange oscillation--in a sawtooth-like pattern.

 

I intend to

1) Post oscilloscope traces here showing transmitted and reflected signal when locked.

2) Look upstream to see if the sawtooth-like oscillation is in the laser beam before it enters the cavity:

  • Sweep the temperature of the laser so that the beam is no longer resonating in the cavity.
  • Compare the reflected signal off the cavity to the signal detected before being directed into the cavity (using the PDA255 that I used for measuring the AM response of the PZT) both with and and without the frequency modulation.

3) At some point, try to close the slow digital loop, perhaps readjusting the gain.

4) Try to measure a temperature step response.

I decided to go forward and try to close the digital loop in spite of the unexplained oscillations in the transmission.

1) Plugged the 20dB attenuator into the slow port on the laser drive. This pushed the laser out of lock and, for some reason, made the laser temperature stop responding to sweeping the set point manually with the knob.

2) Plugged the output from the digital system into the slow port (with the attenuator still in place).

3) Displayed the beam seen by the camera on a monitor in the control room

4) Stepped the laser temperature using MEDM until finding the 0,1 mode. Locked to that mode.

5) Closed the digital loop (input to slow laser drive attenuated 20dB attenuator). Gain 0.010

6) Loop appeared stable for 30 minutes, then temperature began shooting off. I opened the loop, cleared history, reduced the gain to 0.008, and started it again. Loop appears stable after 15 minutes of watching. I'm going to leave it for a few hours, then come back to check on it and, if it's stable, step the can temperature.

  5271   Fri Aug 19 19:08:40 2011 JennyUpdatePSLRelocking NPRO to reference cavity.

I am trying again to measure a temperature step response on the reference cavity on the PSL table.

I have been working to relock the NPRO to the cavity. I unblocked the laser beam, reassembled the setup described in my previous elog entry: 5202. I then did the following:

1) Monitored error signal (from LB1005 PDH servo), transmitted signal, and control signal sent to drive PZT on oscilloscope.

2) With loop open, swept through 0,0-mode resonance, saw a peak in the transmission, saw an accompanying error signal similar to the signal shown in 5202.

3) Tried to lock. Swept the gain on the LB1005 and could not find a gain that would make it lock. Tried changing the PI-corner freq. from 10 kHz to 30 kHz and back and still could not lock.

4) Noticed that the open loop error signal displayed on the scope was DC-offset from zero. Changed the offset to zero the error signal.

5) Tried to lock again and succeeded.

6) Noticed that upon closing the loop, the error signal became offset from zero again. Turning on the integrator on the LB1005 increased DC-offset.

7) Reduced the gain on the SR560 being used as a low pass filter from 5 to 1. Readjusted the open loop error signal offset on the LB1005.

8) Closed the loop and locked. Closing the loop then caused a much smaller DC change in the signal than I had seen with the larger gain (now around 3mV). RMS fluctuations in error signal are now 1 mV (well within the linear region of the error signal).

9) Noticed transmission has a strange distorted harmonic oscillation in it a 1MHz. (Modulation freq is 230kHz, so it's not that). Checked reflected signal and also saw a strange oscillation--in a sawtooth-like pattern.

 

I intend to

1) Post oscilloscope traces here showing transmitted and reflected signal when locked.

2) Look upstream to see if the sawtooth-like oscillation is in the laser beam before it enters the cavity:

  • Sweep the temperature of the laser so that the beam is no longer resonating in the cavity.
  • Compare the reflected signal off the cavity to the signal detected before being directed into the cavity (using the PDA255 that I used for measuring the AM response of the PZT) both with and and without the frequency modulation.

3) At some point, try to close the slow digital loop, perhaps readjusting the gain.

4) Try to measure a temperature step response.

  5270   Fri Aug 19 15:31:53 2011 steveUpdateGeneralpower interruption rescheduled to 10-1-2011

                UTILITY & SERVICE INTERRUPTION

**PLEASE POST**

 

Building:               Central Engineering Services (C.E.S.)

          LIGO Gravitational Physics building adjacent to C.E.S. 40M- Lab

          Safety Storage adjacent to CES

          Steele House 

          Keck Lab

 

Date:                   Saturday, October 1, 2011

Time:                   8:00 a.m. To 9:00 a.m.            

Interruption:   Electricity

Contact:                Mike Anchondo ext. 4999  Tom Brennan 4984

*This interruption is required for maintenance of high voltage switchgear in Campus Sub Station.

(If there is a problem with this Interruption, please notify

 the Service Center X-4717 or the above Contact as soon as possible.

 If no response is received we will proceed with the interruption.)

         

                                Reza Ohadi,

                                Director, Campus Operations & Maintenance

  5269   Fri Aug 19 10:26:53 2011 steveUpdateSUSOSEM sensor spectra

Free swingging OSEM sensors LL at atm

Attachment 1: 8freeSUSosemSensors.jpg
8freeSUSosemSensors.jpg
  5268   Fri Aug 19 09:14:56 2011 steveUpdateIOOdegrading laser power at atm

Light into the MC is 20 mW at atm, MC_Transmitted ~10 MW = 400 count

The PMC_T is OK but something else is drifting.

Attachment 1: power@atm.jpg
power@atm.jpg
  5267   Fri Aug 19 01:46:06 2011 SureshUpdateGeneralIFO alignment

[Keiko, Jamie, Kiwamu, Anamaria,

We followed the procedure that we laid-out in our elog of yesterday.  We completed the first six steps and we now have the y-arm well aligned to the green beam which passes through the center of of both ETMY and ITMY. 

The IR beam was steered with the PZTs to coincide with the green beam.  The BS was adjusted to see IR beam scatter on a target placed near the center of the ETMX.  And then the AS IR beam was steered to the AS camera by adjusting several components along OM path ( we touched OM1, OM2, OM3, OM4, OM5, OMPO and OM6).  We then looked for IR fringes in the AS port from the Y-arm. But no luck there.  We need to realign the IR beam into the Y-arm cavity axis using the pzts.

We aligned ITMX and PRM to get power recycled Michelson fringes at the AS.

 

  5266   Fri Aug 19 01:15:22 2011 SureshUpdateSUSFreeSwing all optics

I ran "freeswing all" at Fri Aug 19 01:09:28 PDT 2011 (997776583)  and "opticshutdown"  as well.

 

  5265   Thu Aug 18 22:24:08 2011 jamieOmnistructureVIDEOUpdated 'videoswitch' script

I have updated the 'videoswitch' program that controls the video MUX.  It now includes the ability to query the video mux for the channel mapping:

controls@pianosa:~ 0$ /opt/rtcds/caltech/c1/scripts/general/videoswitch -h
Usage:
videoswitch [options] [OUT]      List current output/input mapping [for OUT]
videoswitch [options] OUT IN     Set output OUT to be input IN

Options:
  -h, --help            show this help message and exit
  -i, --inputs          List input channels and exit
  -o, --outputs         List output channels and exit
  -l, --list            List all input and output channels and exit
  -H HOST, --host=HOST  IP address/Host name
controls@pianosa:~ 0$

  5264   Thu Aug 18 15:54:35 2011 steveUpdateSUSdamped and undamped OSEMs

damped sus at atm1 and freeswingging sus at atm2

 

Attachment 1: 5susLL.jpg
5susLL.jpg
Attachment 2: 8freeSUSLL.jpg
8freeSUSLL.jpg
  5263   Thu Aug 18 12:22:37 2011 jamieUpdateSUSsuspension update

Most of the suspension look ok, with "badness" levels between 4 and 5.  I'm just posting the ones that look slightly less ideal below.

  • PRM, SRM, and BS in particular show a lot of little peaks that look like some sort of intermodulations.
  • ITMY has a lot of elements with imaginary components
  • The ETMY POS and SIDE modes are *very* close together, which is severely adversely affecting the diagonalization
 PRM  PRM.png        pit     yaw     pos     side    butt
UL    0.466   1.420   1.795  -0.322   0.866  
UR    1.383  -0.580   0.516  -0.046  -0.861  
LR   -0.617  -0.978   0.205   0.011   0.867  
LL   -1.534   1.022   1.484  -0.265  -1.407  
SD    0.846  -0.632  -0.651   1.000   0.555

5.62863

SRM SRM.png       pit     yaw     pos     side    butt
UL    0.783   1.046   1.115  -0.149   1.029 
UR    1.042  -0.954   1.109  -0.060  -1.051 
LR   -0.958  -0.926   0.885  -0.035   0.856 
LL   -1.217   1.074   0.891  -0.125  -1.063 
SD    0.242   0.052   1.544   1.000   0.029 
4.0198
 BS BS.png        pit     yaw     pos     side    butt
UL    1.536   0.714   0.371   0.283   1.042  
UR    0.225  -1.286   1.715  -0.084  -0.927  
LR   -1.775  -0.286   1.629  -0.117   0.960  
LL   -0.464   1.714   0.285   0.250  -1.070  
SD    0.705   0.299  -3.239   1.000   0.023 
 5.5501
 ITMY  ITMY.png        pit     yaw     pos     side    butt
UL    1.335   0.209   1.232  -0.071   0.976  
UR   -0.537   1.732   0.940  -0.025  -1.068  
LR   -2.000  -0.268   0.768   0.004   1.046  
LL   -0.129  -1.791   1.060  -0.043  -0.911  
SD   -0.069  -0.885   1.196   1.000   0.239 
 4.28384
ETMY ETMY.png       pit     yaw     pos     side    butt
UL    1.103   0.286   1.194  -0.039   0.994 
UR   -0.196  -1.643  -0.806  -0.466  -1.113 
LR   -2.000   0.071  -0.373  -0.209   0.744 
LL   -0.701   2.000   1.627   0.217  -1.149 
SD    0.105  -1.007   3.893   1.000   0.290 
9.25346

 

Attachment 2: SRM.png
SRM.png
  5262   Thu Aug 18 10:59:04 2011 steveUpdateTreasurePrepared for drag wiping

Quote:

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.

  5261   Thu Aug 18 10:17:04 2011 kiwamu, steveUpdateSUSoplevs reestablished at Vertex

Kiwamu and Steve, from yesterday

PRM and BS oplev paths were relaid after setting 1/2 OSEM voltages. The incident beam on suspended optics are centered  within  ~ +- 2 mm

I noticed many unvected ss screws are used on the big Al table tops. The SS 1/4-20 screws

 used on the optical tables in vacuum MUST be VENTED!

Also, please use  SS clamps. Replace aluminum ones when you can. We have plenty baked ones.

 

 

  5260   Thu Aug 18 00:58:40 2011 jamieUpdateSUSoptics kicked and left free swinging

ALL optics (including MC) were kicked and left free swinging at:

997689421

The "opticshutdown" script was also run, which should turn the watchdogs back on in 5 hours (at 6am).

 

  5259   Thu Aug 18 00:53:48 2011 jamie, kiwamu, suresh, jenneUpdateGeneralPUMP PLAN ABORTED; need to work more on IFO alignment

We have decided that the IFO alignment is bad enough that we're not ready to pump down.  PUMP ABORTED.

The IFO alignment is somewhat OK, in that the green and IR beams are flashing in the arms, and the return beams are overlapping at the BS.  However the beams appear to be not centered on any of the optics at the moment.  They are all displaced in yaw by ~0.5 to 1 cm or so in various directions.

From this we have decided that we need to step back and reattack the IFO alignment from square one.  Here is our current suggested procedure:

  1. check ETM positions relative to what we think they should be on the drawings.  This is to verify that the ETMs were not placed in the wrong places laterally.
  2. translate Y green axis north, centering green on ETMY and ITMY (by looking at cards).  North is the opposite direction from how the beams are displaced from the TM centers.
  3. steer input pointing to overlap IR on green beam at BS, ITMY, and ETMY.  IR should visibly overlap green at both BS and ITMY, and we should be able to see IR on target in front of ETMY with ETMY face camera, and in ETMY trans camera.
  4. center IR on ETMX by steering BS with DC bias.
  5. align Y arm cavity for green resonance by adjusting ITMY.
  6. adjust ITMX to achieve michelson fringes at AS
  7. adjust PRM lateral translation to center beam on PRM, if needed
  8. adjust SRM lateral translation to center beam on SRM, if needed
  9. align PRC to see fringes
  10. align SRC to see fringes
  11. extract AS (no clipping)

 Once this is done, we will need to check the following:

  • IPANG/IPPOS extraction
  • pick-off extraction
  • OPLEVs
  • OSEMs
  • green periscopes and green beam extraction at PSL

We've decided to stop for the night, get a good nights rest, and attack all of this tomorrow morning.

Beam_spot_shifts.png

  5258   Wed Aug 17 20:14:49 2011 jamie, kiwamu, suresh, jenne, keiko, anamariaUpdateGeneralin-vacuum work status, prep for pump

This afternoon's work:

  • OSEMs were adjusted on all suspended optics.
  • X and Y-arms were aligned to green.
  • Once that was done, the input pointing was adjusted with the PZTs to get the IR beam centered on ITMY and ETMY.
  • Once the input pointing was ok we extracted IPANG and IPPOS.
  • BS, ITMY, PRM, SRM optical levers (oplevs) were extracted.
  • Prepared rails and stops for TMs for morning drag wiping.

TODO before drag wiping:

  • Check full IFO alignment.
  • Readjust OSEMs if needed.
  • Extract ITMX oplev.
  5257   Wed Aug 17 17:51:54 2011 JenneUpdateTreasurePrepared for drag wiping

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.

  5256   Wed Aug 17 15:55:01 2011 JenneUpdateGeneralin-vac work : the end is near

Quote:

We will pump down the chambers on Thursday Friday morning.

 All hands on deck at 9am Thursday for drag wiping and doors.  We'll do the 5 doors first (including drag wiping), then put on the access connector last.  Steve will then begin pumping early Friday morning.

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

Jenne, Anamaria

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

 

 

Quote:

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

 

 

  5254   Wed Aug 17 12:14:27 2011 Josh SmithOmnistructureComputer Scripts / Programs40m summary page plans

Josh Smith, Fabian Magana-Sandoval, Jackie Lee (Fullerton)

Thanks to Jamie and Jenne for the tour and the input on the pages.

We had a look at the GEO summary pages and thought about how best to make a 40m summary page that would eventually become and aligo summary page. Here's a rough plan:

- First we'll check that we can access the 40m NDS2 server to get data from the 40m lab in Fullerton.

- We'll make a first draft of a 40m summary page in python, using pynds, and base the layout on the current geo summary pages.

- When this takes shape we'll iterate with Jamie, Jenne, Rana to get more ideas for measurements, layout.

Other suggestions: Jenne is working on an automated noisebudget and suggests having a placeholder for it on the page. We can also incorporate some of the features of Aidan's 40m overview medm screen that's in progress, possibly with different plots corresponding to different parts of the drawing, etc. Jenne also will email us the link of once per hour medm screenshots.

 

  5253   Wed Aug 17 06:42:38 2011 kiwamuUpdateGeneralin-vac work : the end is near

We will pump down the chambers on Thursday morning.

Today will be a day of the OSEM and oplev party.

 

 -- to do list for today --

 + OSEM mid-range adjustment

 + oplev realignment

 + placement of beam traps

 + extraction of IPPOS

 + table leveling

 + interferometer alignment

 + AM-PM mystery

 + preparation for drag and wipe

  5252   Wed Aug 17 03:10:06 2011 kiwamuUpdateGeneralcurrent status of in-vac work

[Jamie / Suresh / Kiwamu] 

The in-vac work is ongoing.

Before we run out our energy we are posting this entry to briefly report the current status.

- (done) BS earthquake stop adjustment.

- (done) PRM earthquake stop adjustment

- (done) MC spot position check => They are almost the same within 10 %.

- (done) Injection and alignment of the ABSL laser to make the beam brighter in the vertex region.

- (done) POY => We repositioned an in-vac steering mirror to get the POY beam hitting the center of the steering mirror.

                           It's now coming out from the chamber.

(done)  IPANG => realigned two mirrors on the ETMY table to get the IPANG out from the chamber. Now it's reaching the ETMY optical table.

                             It needs a final touch before we pump down.  We revisited it later in the night after realigning the IFO and it is well aligned now.

- (done)  POP => We have aligned the ABSL laser injected from the AS port to reach the REFL camera.  We turned it up to max power of 300mW and used it as a substitute for the PRC beam.

                         Even this was not enough to see anything in the POP beam path after the PR2 (tip-tilt).  So we used a green beam from the Y-arm as a guide of the POP beam path because the ABSL (POP) beam was too dim to work with.

                         We placed a lens and a CCD camera to detect the green and then blocked the Y-green.  It was then possible to see the ABSL-POP beam in the CCD camera.  The lens and the CCD are markers for this beam. 

                         Do not remove these markers unless absolutely necessary.

-(done) POX => We located the ABSL (mimicking POX) beam on the POXM1 mirror and adjusted the mirror to ensure that the beam exits at the right height and a convenient location on the POX table. 

- (0%) OSEM mid-range adjustment

- (0%) IPPOS

- (0%) oplev re-alignment

  5251   Wed Aug 17 02:48:56 2011 kiwamuUpdateRF SystemRe: AM in the PM

[Keiko / Suresh / Anamaria / Kiwamu]

 The AM components do exist also on the beam after the EOM.

The peaks were found at 11, 29 and 55 MHz, where the PM are supposed to be imposed.

Suresh and Keiko minimized them by rotating the HWP, which is in front of the EOM.

Also Anamaria and I tried minimizing them by adjusting the EOM crystal alignment.

However everytime after we minimized the AM peaks, they grew back in a time scale of ~ 1 min.

Potentially it could be a problem of the HWP and/or EOM alignment.

Since we wanted to proceed the in-vac work anyways, we stopped investigating it and decided to postpone it for tomorrow.

We again adjusted the incident power to 20 mW.

 

-- P.S.

 The incident power going to MC went down to 7 mW for some reasons. This was found after ~ 6 hours from our works on the PSL table.

We haven't touched anything on the PSL table since the daytime work.

Possibly the angle of the HWP is drifting (why?) and changed the amount of the P-polarizing beam power.

Suresh locked the angles of two HWPs, which are the one just after the EOM and the one after the attenuation PBS.

Quote from #5249

So first check is beam out of PSL EOM, to make sure the input beam is aligned to the crystal axis and is not giving AM modulation in adition to PM.

 

  5250   Tue Aug 16 17:09:55 2011 JenneUpdateGeneraltoday's work to do

Quote:

  + Rotate the SRM tower to get the SRMI fringes on the AS CCD camera.

        => This is because the required amount of the YAW correction on SRM is currently beyond the range of the DC bias.

 Kiwamu aligned things for me, and I rotated the SRM tower so that the reflected beam was pretty much totally overlapping the incident beam.  The SRC was aligned to make sure things were good.  Now the DC bias for SRM Yaw is ~1.4, so we're totally good. 

To rotate SRM, Jamie had the idea of using 2 screws so I could push the tower on one side, and back off the screw an equal amount on the other side and push the tower to be touching both screws again, to ensure that I was rotating about the center of the tower and wasn't introducing any Pos action. 

While I was at it, I also moved the OSEM connector tower back to its normal place on the table, so it's not in the way of oplev beams.  It had been moved previously to accommodate ITMY near the door.

  5249   Tue Aug 16 16:59:20 2011 AnamariaUpdateRF SystemAM in the PM

Kiwamu, Keiko, Anamaria

Looking at the I and Q signals coming from REFL11 and REFL55 we saw large offsets, which would mean we have amplitude modulation, especially at 11MHz. We checked the PD themselves with RF spectrum analyzer, and at their frequencies we see stationary peaks (even if we look only at direct reflection from PRM). We changed the attenuation of the PSL EOM, and saw the peak go down. So first check is beam out of PSL EOM, to make sure the input beam is aligned to the crystal axis and is not giving AM modulation in adition to PM.

  5248   Tue Aug 16 11:49:17 2011 jamie, jenneUpdateGeneraltoday's work to do

>If necessary steer ETMs and ITMs to make the X and Y green beam flashing.

Green is now flashing in both X and Y arms

>Open the IOO and OMC chamber and lock MC.

Open, and cover in place. MC is flashing and locking.

 

  5247   Tue Aug 16 10:59:06 2011 jamieUpdateSUSSUS update

Data taken from: 997530498+120

Things are actually looking ok at the moment.  "Badness" (cond(B)) is below 6 for all optics.

  • We don't have results from PRM since its spectra looked bad, as if it's being clamped by the earthquake stops.
  • The SRM matrix definitely looks the nicest, followed by ITMX.  All the other matrices have some abnormally high or low elements.
  • cond(B) for ETMY is better than that for SRM, even though the ETMY matrix doesn't look as nice.  Does this mean that cond(B) is not necessarily the best figure of merit, or is there something else that our naive expectation for the matrix doesn't catch?

We still need to go through and adjust all the OSEM ranges once the IFO is aligned and we know what our DC biases are.  We'll repeat this one last time after that.

TM   M cond(B)
BS  BS.png       pit     yaw     pos     side    butt
UL    1.456   0.770   0.296   0.303   1.035 
UR    0.285  -1.230   1.773  -0.077  -0.945 
LR   -1.715  -0.340   1.704  -0.115   0.951 
LL   -0.544   1.660   0.227   0.265  -1.070 
SD    0.612   0.275  -3.459   1.000   0.046
5.61948
SRM  SRM.png       pit     yaw     pos     side    butt
UL    0.891   1.125   0.950  -0.077   0.984 
UR    0.934  -0.875   0.987  -0.011  -0.933 
LR   -1.066  -1.020   1.050   0.010   1.084 
LL   -1.109   0.980   1.013  -0.056  -0.999 
SD    0.257  -0.021   0.304   1.000   0.006 
4.0291
ITMX  ITMX.png       pit     yaw     pos     side    butt
UL    0.436   1.035   1.042  -0.068   0.728 
UR    0.855  -0.965   1.137  -0.211  -0.969 
LR   -1.145  -1.228   0.958  -0.263   1.224 
LL   -1.564   0.772   0.863  -0.120  -1.079 
SD   -0.522  -0.763   2.495   1.000  -0.156
4.55925
ITMY  ITMY.png       pit     yaw     pos     side    butt
UL    1.375   0.095   1.245  -0.058   0.989 
UR   -0.411   1.778   0.975  -0.022  -1.065 
LR   -2.000  -0.222   0.755   0.006   1.001 
LL   -0.214  -1.905   1.025  -0.030  -0.945 
SD    0.011  -0.686   0.804   1.000   0.240 
4.14139
ETMX  ETMX.png       pit     yaw     pos     side    butt
UL    0.714   0.191   1.640   0.404   1.052 
UR    0.197  -1.809   1.758  -0.120  -1.133 
LR   -1.803  -1.889   0.360  -0.109   0.913 
LL   -1.286   0.111   0.242   0.415  -0.902 
SD    1.823  -3.738  -0.714   1.000  -0.130 
5.19482
ETMY  ETMY.png       pit     yaw     pos     side    butt
UL    1.104   0.384   1.417   0.351   1.013 
UR   -0.287  -1.501   1.310  -0.074  -1.032 
LR   -2.000   0.115   0.583  -0.045   0.777 
LL   -0.609   2.000   0.690   0.380  -1.179 
SD    0.043  -0.742  -0.941   1.000   0.338 
3.57032

 

  5246   Tue Aug 16 04:50:17 2011 kiwamuUpdateSUSfree swinging again

 Since Suresh and I changed the DC biases on most of the suspension, the free swingning spectra will be different from the past.

- -

EXcited ETMX ETMY ITMX ITMY PRM SRM BS

Tue Aug 16 04:48:02 PDT 2011
997530498

  5245   Tue Aug 16 04:28:09 2011 kiwamuUpdateGeneraltoday's work to do

The main goal of today is to extract the pick-off beams

Today's menu :

  + If necessary steer ETMs and ITMs to make the X and Y green beam flashing.

  + Open the IOO and OMC chamber and lock MC.

       => cover the place of the access connector by a large piece of aluminum foil. It will give a robust lock of MC.

  + Check the beam pointing down to Y arm by looking at the ETMY face camera.

        => If it's necessary align PZT1 and PZT2 from EPICS to make the IR beam flashing in the X arm.

  + Align BS and let the beam hit the center of ETMX to make the X arm flashing.

        => These alignment procedure will automatically gives us the MICH fringes on the AS CCD camera.

  + Rotate the SRM tower to get the SRMI fringes on the AS CCD camera.

        => This is because the required amount of the YAW correction on SRM is currently beyond the range of the DC bias.

  + Align PRM to get the PRMI fringes on AS CCD camera. Also make sure the beam comes back to the REFL CCD camera.

  + Lock the PRC to make POP/POX/POY bright enough.

     => Probably the REFL11 RFPD needs more power. To increase the power, just rotate the HWP, which is sitting before the RFPDs on the AS table.

     => If the signal on AS55 is too small, we can use REFL11_Q or REFL55 for the MICH lock.

  + OR inject and align the ABSL laser to make those pick-off beams bright enough.

     => This case we don't have to make the DRMI exactly on the resonance, what we need is just the DRMI flashing.

  + Align necessary optics for those pick-off beams.

     => In our definition (aLIGO definition) POP is the beam propagating from BS to PRM. Don't be confused by another one, which propagates from PRM to BS.

  + Steer two mirrors on the ETMY table for aligning IPANG. Also, steer some mirrors on the BS table for IPPOS.

    => IPANG has already reached the ETMY table, so ideally we don't have to steer a mirror on the BS table.

    => IPPOS/ANG are very visible with a sensor card.

  + Align some oplevs.

     => This work is relatively independent from the other tasks. Steve can take care of it.

  + Adjust the OSEM to their mid-range.

     => This work can be done anytime, but everytime we have to recover the alignment of the interferometer.

  5244   Tue Aug 16 04:25:34 2011 Suresh, KiwamuUpdateSUSalignment of MC output to Y-arm using PZTs

We did several things today+night.  The final goal was to lock the PRC so that we could obtain the POX, POY and POP beams.  However there were large number of steps to get there.

1) We moved the ITMY into its place and balanced the table

2) We then aligned the Y-arm cavity to the green beam which was set up as a reference before we moved the ETMY and ITMY to adjust the OSEMS.  We had the green flashing in Y-arm

3) We checked the beam position on PR2. It was okay. This confirmed that we were ready to send the beam onto the Y arm.

4) We then roughly aligned the IR beam on ETMY where Jamie had placed an Al foil with a hole.  We got the arm flashing in both IR and green. 

5) We used the PZTs to make the green and IR beams co-incident and flashing in the Y arm.  This completed the alignment of the IR beam into the Y-arm.

6) The IPPO (pick-off) window had to be repositioned to avoid clipping.  The IPANG beam was aligned such that it exits the ETMY chamber onto the ETMY table.  It can now be easily sent to the IPANG QPD.

7) Then BS was aligned to direct the IR beam into the X-arm and had the X-arm flashing.  It had already been aligned to its green.

8) It was now the turn of the SRC.  The beam spots on all the SRC related optics were off centered.  We aligned all the optics in the AS path to get the AS beam on to the AP table.

9) The AS beam was very faint so we repositioned the AS camera to the place intended for AS11 PD, since there was a brighter beam available there. 

10) We could then obtain reflections from ITMY, ITMX and PRM at the AS camera. 

11) Problems:

      a) ITMY osems need to be readjusted to make sure that they are in mid-range.  Several are out of range and so the damping is not effective.

      b) When we tried to align SRC the yaw OSEM had to be pushed to its full range.  We therefore have to turn the SRM tower to get it back into range.

 12)  We stopped here since moving the SRM is not something to be attempted at the end of a rather long day. Kiwamu is posting a plan for the rest of the day.

  5243   Mon Aug 15 21:43:29 2011 Anamaria and KeikoSummaryLockingcentral part ifo locking project

 REFL33 and REFL165 cables were connected from the AP table to the rack.  Cables on the rack for REFL33I, 33Q, 165I, 165Q ports were connected, too. Connections were confirmed by the data viewer. Two SMA cables which will be used for the two PDs on the AP tabl were built. We will be able to place the two PDs tomorrow. The beamsplitters to split the laser to REFL33 and REFL165 ports were mounted and ready to be placed.

  5242   Mon Aug 15 17:38:07 2011 jamieUpdateGeneralFoil aperture placed in front of ETMY

We have placed a foil aperture in front of ETMY, to aid in aligning the Y-arm, and then the PRC.  It obviously needs to be removed before we close up.

  5241   Mon Aug 15 17:36:10 2011 jamieUpdateSUSStrangeness with ETMY (was: Monday SUS update)

For some reason ETMY has changed a lot.  Not only does it now have the worst "badness" (B matrix condition number) at ~10, but the frequency of all the modes have shifted, some considerably.  I did accidentally bump the optic when Jenne and I were adjusting the OSEMs last week, but I didn't think it was that much.  The only thing I can think of that would cause the modes to move so much is that the optic has been somehow reseated in it's suspension.  I really don't know how that would have happened, though.

Jenne and I went in to investigate ETMY, to see if we could see anything obviously wrong.  Everything looks to be ok.  The magnets are all well centered in the OSEMs, and the PDMon levels look ok.

We rechecked the balance of the table, and tweaked it a bit to make it more level.  We then tweaked the OSEMs again to put them back in the center of their range.  We also checked the response by using the lockin method to check the response to POS and SIDE drive in each of the OSEMs (we want large POS response and minimal SIDE response).  Everything looked ok.

We're going to take another freeswing measurement and see how things look now.  If there are any suggestions what should be done (if anything), about the shifted modes, please let us know.

  5240   Mon Aug 15 17:23:55 2011 jamieUpdateSUSfreeswing script updated

I have updated the freeswing scripts, combining all of them into a single script that takes arguments to specify the optic to kick:

pianosa:SUS 0> ./freeswing
usage: freeswing SET
usage: freeswing OPTIC [OPTIC ...]

Kick and free-swing suspended optics.
Specify optics (i.e. 'MC1', 'ITMY') or a set:
'all' = (MC1 MC2 MC3 ETMX ETMY ITMX ITMY PRM SRM BS)
'ifo' = (ETMX ETMY ITMX ITMY PRM SRM BS)
'mc'  = (MC1 MC2 MC3)
pianosa:SUS 0>

I have removed all of the old scripts, and committed the new one to the SVN.

  5239   Mon Aug 15 14:10:56 2011 JenneUpdateSUSMonday SUS update

The moral of the story here is that none of the suspensions are overwhelmingly awesome, but most of them will be fine if we leave them as-is.

SUS DoF Plot Input Matrix "BADness" (1==good)
ITMX inMatDiag.png       pit     yaw     pos     side    butt
UL    0.438   1.019   1.050  -0.059   0.717 
UR    0.828  -0.981   1.128  -0.215  -0.956 
LR   -1.172  -1.201   0.950  -0.275   1.241 
LL   -1.562   0.799   0.872  -0.120  -1.087 
SD   -0.579  -0.847   2.539   1.000  -0.170 

 
4.68597
 
 ITMY  inMatDiag.png        pit     yaw     pos     side    butt
UL    1.157   0.185   1.188  -0.109   0.922 
UR    0.020  -1.815   0.745  -0.051  -0.970 
LR   -1.980  -0.090   0.812  -0.024   1.158 
LL   -0.843   1.910   1.255  -0.082  -0.949 
SD   -0.958   1.080   1.859   1.000   0.325  
4.82756
ETMX  inMatDiag.png        pit     yaw     pos     side    butt
UL    0.338   0.476   1.609   0.316   1.046  
UR    0.274  -1.524   1.796  -0.069  -1.180  
LR   -1.726  -1.565   0.391  -0.100   0.938  
LL   -1.662   0.435   0.204   0.286  -0.836  
SD    0.996  -2.629  -0.999   1.000  -0.111
 
 
 4.32072
 ETMY  inMatDiag.png        pit     yaw     pos     side    butt
UL    1.123   0.456   1.812   0.231   0.936 
UR   -0.198  -1.489   0.492  -0.096  -1.098 
LR   -2.000   0.055   0.188  -0.052   0.764 
LL   -0.679   2.000   1.508   0.275  -1.201 
SD    0.180  -0.591   3.355   1.000   0.200  
 10.643
 BS  inMatDiag.png        pit     yaw     pos     side    butt
UL    1.575   0.697   0.230   0.294   1.045 
UR    0.163  -1.303   1.829  -0.133  -0.958 
LR   -1.837  -0.308   1.770  -0.171   0.944 
LL   -0.425   1.692   0.171   0.257  -1.053 
SD    0.769   0.345  -3.380   1.000   0.058 
6.111
 
 PRM  inMatDiag.png        pit     yaw     pos     side    butt
UL    0.597   1.553   2.000  -0.469   1.229  
UR    1.304  -0.447   0.383  -0.043  -0.734  
LR   -0.696  -1.048  -0.277   0.109   0.687  
LL   -1.403   0.952   1.340  -0.317  -1.350  
SD    0.518  -1.125  -1.161   1.000   0.394  

 
 8.43363
SRM inMatDiag.png       pit     yaw     pos     side    butt
UL    0.831   1.039   1.153  -0.140   1.065 
UR    1.071  -0.961   1.104  -0.057  -1.061 
LR   -0.929  -0.946   0.847  -0.035   0.837 
LL   -1.169   1.054   0.896  -0.118  -1.037 
SD    0.193  -0.033   1.797   1.000   0.045 
 4.17396

 

  5238   Mon Aug 15 14:07:39 2011 kiwamuUpdateIOORe: MC misaligned a lot

The leveling was still okay. The MC mirrors were realigned and now they all are fine.

We will go ahead for the vertex alignment and extraction of the pick-off beams.

 

Here is a summary of the spot measurement.

    Feb 26 2011      May 08 2011 Aug 2 2011  Aug 10 2011 (in air) [NEW!!] Aug 14 2011 (in air)
MC1 pit [mm]   1.6   1.9  1.93 -0.858 -0.2
MC2 pit [mm]   6.4   9.0 9.03 -0.844 -0.8
MC3 pit [mm]   1.4   2.0 2.01 -1.03 -0.1
MC1 yaw [mm]   -1.5   -1.7 -1.72 -0.847 -1.1
MC2 yaw [mm]   1.0   0.2 0.178 0.582 0.6
MC3 yaw [mm]   -1.3   -1.9 -1.87 -1.06 -1.1

 

Quote from #5236

Anyways we should check the leveling of the IOO table and the spot positions on the MC mirrors again to make sure.

 

  5237   Mon Aug 15 13:16:50 2011 JenneUpdateSUSRe: ETMY hopefully good again

Quote:

I guess the ETMY suspension is still fine. Their OSEM DC voltage and the free swinging spectra look healthy.

It could be a failure in the initial guess for fitting.

Quote from #5216

I'm no longer convinced that ETMY is healthy. I can't fit the peaks to get the input matrix.

 Turns out I was missing a critical step in the process...running makeSUSspectra.m  After I do that, everything is back under control, and ETMY looks fine. 

I'm almost done doing the peak-fitting and matrix inversion for all optics.

  5236   Mon Aug 15 10:58:52 2011 kiwamuUpdateIOOMC misaligned a lot

This morning Steve and I opened the doors on the IOO and OMC chamber to let the IR beam go to MC.

And found the MC flashing is way far from TEM00, there were very higher order modes.

The MC suspensions were realigned based on an assumption that the incident beam didn't change recently.

Anyways we should check the leveling of the IOO table and the spot positions on the MC mirrors again to make sure.

  5235   Mon Aug 15 10:02:27 2011 kiwamuUpdateSUSBS OSEM adjustment done

[Suresh / Kiwamu]

 Adjustment of the OSEMs on BS has been done.

All the bad suspensions (#5176) has been adjusted. They are waiting for the matrix inversion test.

  5234   Sun Aug 14 22:48:37 2011 kiwamuUpdateSUSfree swinging again

Excited all optics
Sun Aug 14 20:22:33 PDT 2011
997413768

  5233   Sun Aug 14 20:04:40 2011 Keiko, Anamaria, Jenne, and KiwamuSummaryLockingcentral part ifo locking plan
GOAL : To lock the central part of ifo

Here is the plan:

Mon - assemble all the cables from PDs and mixers, and check the CDS channels. Prepare the beamsplitters.

Tue - The current paths to REFL11 and REFL55 will be modified to the four paths to REFL11, 33, 55, 165. And the PDs will be placed.
Wed, Thu - during waiting for the ifo available with vacuum, help aligning the POP, POX, POY. In parallel, a simulation to find the PRC length SRC 
length tolerance will be proceeded.

Fri - When the ifo becomes available with vacuum, the sensing signals by 3-f scheme will be obtained with proper demodulation phases.

Sat - Try to lock the central part of the ifo with the new 3-f signals.
  5232   Sun Aug 14 19:06:50 2011 JenneUpdateelogelog dead. Brought back to life

like the subject says...

  5231   Sun Aug 14 17:47:39 2011 NicoleSummarySUSTT Shaking Today and Hopefully More?

Quote:

As reported in my  previous entry of TT supsension bode plots, I found that my experimental data had what appears to be very noise peaks above 20 Hz (as mentioned earlier, the peak at 22 Hz is likely due to vertical coupling, as 22 Hz is the resonant frequency of the cantilever blades). This is very unusual and needs to be explored further. I would like to vertically-shake the TTs to obtain more data on possible coupling. However, I am leaving on Monday and will not return until Thursday (day of SURF talks). I am leaving campus Friday afternoon or so. I would may need some help coming up with an assembly plan/assembling set-up for vertical shaking (if it is possible to do so in such a limited time frame).

 

Today I wanted to see if the "noisy peaks" above 30 Hz were due to EM noise coupling. I tested this hypothesis today, seeing if EM fields generated by the coil at higher frequencies were injecting noise into my transfer function measurements. I found that the "noisy peaks" above 30 Hz are NOT DUE TO EM NOISE COUPLING. I am very curious as to what is causing the high peaks (possibly coupling from other degrees of freedom)?

 

 emnoise_and_flex.jpg

 I have been redoing the noise test multiple times today. Here is the best plot that I got

noisetest.jpg

  5230   Sun Aug 14 15:37:39 2011 JennyUpdatePSLTemperature steps and slow actuator railing

Quote:

Below are some plots from dataviewer of temperature-step data taken over the past 32 hours. (They show minute trends). I am looking at the thermal coupling from the can surrounding the reference cavity on the PSL table to the cavity itself, and trying to measure the cavity temperature response via the control signal sent to heat the NPRO laser, which is locked to the cavity.

Picture_6.png

Picture_7.png

  • Top left: out-of-loop temperature sensor on can surrounding ref cav (RCTEMP)
  • Top right: control signal sent to slow drive of laser (laser heater), which is supposed to follow the cavity temperature (TMP_OUTPUT)
  • Bottom left: in-loop can temperature sensors (MINCOMEAS)
  • Bottom right: room temperature reading (RMTEMP)

 

I stepped the temperature set point from 35 to 36 deg. C for the can at 12:30am last night. Then I waited to see the cavity temperature change and the slow actuator (laser heater: TMP_OUTPUT) follow that change.

I was a bit worried about the oscillations that were occuring in the TMP_OUTPUT signal even long after this temperature step was made, but I figured that they were simply room-temperature changes propagating into the cavity, since they seemed to have a similar pattern to the room-temperature variations, and since it is clear that the out-of-loop temperature sensor on the can (RCTEMP) experiences variations, even when the in-loop sensors are recording no variation.

At 8:46pm tonight I stepped the temperature down 2 degrees to 34 deg. C. The step had a clear effect on TMP_OUTPUT. The voltage to the heater dropped and eventually railed at its lowest output. I'm worried that the loop is unstable, although I haven't ruled out other possibilities, such as that a 2 deg. C temperature step is too large for the loop. I will investigate further in the morning.

 The lock was lost when I came in around noon today to check on it. The slow actuator was still railing.

1) I got lock back for a few minutes, by varying the laser temperature set point manually. TMP_OUTPUT was still reading -30000 cts (minimum allowed) and the transmission was not as high as it had been.

2) I toggled the second filter button off. The TMP_OUTPUT started rising up to ~2000 cts. I then toggled the second filter back on, and TMP_OUTPUT jumped the positive maximum number of counts allowed.

3) I lost the lock again. I turned off the digital output to the slow actuator.

4) I have so far failed at getting the lock back. My main problem is that when the BNC cable to the slow port is plugged in, even when I'm not sending anything to that port, it makes it so that changing the temperature set point manually has almost no effect on the transmission (it looks as though changing the setpoint is not actually changing the temperature, because the monitor shows the same higher order mode even when with +-degree temperature setpoint changes).

  5229   Sun Aug 14 13:57:52 2011 NicoleSummarySUSTT Optimization Curves

Quote:

Quote:

1) Drawing has the dimensions => You can calculate the volume => You can calculate the mass
Complicated structure can be ignored. We need a rough estimation.

2) Your restoring force can have two terms:
- one comes from the spring constant k
- the other from the gravity

 

 Thank you.

 

The wire used to suspend the EDCs is tungsten?

To verify, for my model, the EDC will be the mass of all four dampers or a single damper? The length of the wire used to suspend the EDC will be the combined length of 4 wires or length of  a single wire?

 

Taking into account the densities for each material (specific material of each component was listed, so I looked up the densities), and trying my best to approximate the volumes of each component, I have determined

the mass of the mirror + mirror holder to be ~100 g and the mass of a single EDC to be ~19 g

 I am thinking that perhaps my mass estimations were off? The model that I have used fits the data better than the model that I have made (changing the masses to fit my estimations of the values)

FLEX_exp_mod_comp.jpg

  5228   Sun Aug 14 04:12:37 2011 JennyUpdatePSLTemperature steps and slow actuator railing

Below are some plots from dataviewer of temperature-step data taken over the past 32 hours. (They show minute trends). I am looking at the thermal coupling from the can surrounding the reference cavity on the PSL table to the cavity itself, and trying to measure the cavity temperature response via the control signal sent to heat the NPRO laser, which is locked to the cavity.

Picture_6.png

Picture_7.png

  • Top left: out-of-loop temperature sensor on can surrounding ref cav (RCTEMP)
  • Top right: control signal sent to slow drive of laser (laser heater), which is supposed to follow the cavity temperature (TMP_OUTPUT)
  • Bottom left: in-loop can temperature sensors (MINCOMEAS)
  • Bottom right: room temperature reading (RMTEMP)

 

I stepped the temperature set point from 35 to 36 deg. C for the can at 12:30am last night. Then I waited to see the cavity temperature change and the slow actuator (laser heater: TMP_OUTPUT) follow that change.

I was a bit worried about the oscillations that were occuring in the TMP_OUTPUT signal even long after this temperature step was made, but I figured that they were simply room-temperature changes propagating into the cavity, since they seemed to have a similar pattern to the room-temperature variations, and since it is clear that the out-of-loop temperature sensor on the can (RCTEMP) experiences variations, even when the in-loop sensors are recording no variation.

At 8:46pm tonight I stepped the temperature down 2 degrees to 34 deg. C. The step had a clear effect on TMP_OUTPUT. The voltage to the heater dropped and eventually railed at its lowest output. I'm worried that the loop is unstable, although I haven't ruled out other possibilities, such as that a 2 deg. C temperature step is too large for the loop. I will investigate further in the morning.

  5227   Sun Aug 14 00:26:51 2011 NicoleSummarySUSTT Optimization Curves

Quote:

1) Drawing has the dimensions => You can calculate the volume => You can calculate the mass
Complicated structure can be ignored. We need a rough estimation.

2) Your restoring force can have two terms:
- one comes from the spring constant k
- the other from the gravity

 

 Thank you.

 

The wire used to suspend the EDCs is tungsten?

To verify, for my model, the EDC will be the mass of all four dampers or a single damper? The length of the wire used to suspend the EDC will be the combined length of 4 wires or length of  a single wire?

 

Taking into account the densities for each material (specific material of each component was listed, so I looked up the densities), and trying my best to approximate the volumes of each component, I have determined

the mass of the mirror + mirror holder to be ~100 g and the mass of a single EDC to be ~19 g

  5226   Sat Aug 13 21:48:17 2011 KojiSummarySUSTT Optimization Curves

1) Drawing has the dimensions => You can calculate the volume => You can calculate the mass
Complicated structure can be ignored. We need a rough estimation.

2) Your restoring force can have two terms:
- one comes from the spring constant k
- the other from the gravity

 

  5225   Sat Aug 13 21:15:47 2011 NicoleSummarySUSTT Optimization Curves

Quote:

What are the parameters you are using? As you have the drawings of the components, you can calculate the masses of the objects.

 

Reducing the ECD resonance from 10Hz->6Hz looks nice.

The resonant freq of the ECDs are not (fully) determined by the gravitational energy but have the contribution of the elastic energy of the wire.

Q1: How much is the res freq of the ECDs if the freq is completely determined by the grav energy? (i.e. the case of using much thinner wires)

Q2: How thin should the wires be?

 The drawings do not have the masses of the objects.

 

For the resonant frequency:

Instead of sqrt (g/l) would the numerator in the square root be[ g + (energy stored in wire)/(mass of damper)] ?

 

  5224   Sat Aug 13 19:08:01 2011 KojiSummarySUSTT Optimization Curves

What are the parameters you are using? As you have the drawings of the components, you can calculate the masses of the objects.

 

Reducing the ECD resonance from 10Hz->6Hz looks nice.

The resonant freq of the ECDs are not (fully) determined by the gravitational energy but have the contribution of the elastic energy of the wire.

Q1: How much is the res freq of the ECDs if the freq is completely determined by the grav energy? (i.e. the case of using much thinner wires)

Q2: How thin should the wires be?

  5223   Sat Aug 13 15:47:47 2011 NicoleSummarySUSTT Optimization Curves

Using my Matlab model of the flexibly-supported eddy current damping system, I have changed parameters to see if/how the TTs can be optimized in isolation. As I found earlier, posted in my bode plot entry, there is only a limited region where the flexibly-supported system provides better isolation than the rigidly-supported system.

 

Here is what I have found, where \gamma is the scale factor of the magnetic strength (proportional to magnetic strength), \beta is the scale factor of the current damper mass (estimated by attempting to fit my model to the experimental data), and \alpha is the scale factor of the current resonant frequency of the dampers.

magstrength1.jpgdampermass.jpg resfreq.jpg

 

Here are my commentaries on these plots. If you have any commentaries, it would be very helpful, as I would like to incorporate this information in my powerpoint presentation.

It seems as if the TT suspensions are already optimized?

It may be difficult to lower the resonant frequency of the dampers because that would mean changing the lengths of the EDC suspensions). Also, it appears that a rather drastic reduction (at most 0.6*current EDC resonant frequency --> reduction from about 10 Hz to 6 Hz or less) is required . Using the calculation that the resonant frequency is sqrt(g/length), for my single-suspended EDC model, this means increasing the wire length to nearly 3 x its current value. I'm not sure how this would translate to four EDCs...

The amplification at resonance caused by increasing the magnet strength almost offsets the isolation benefits of increasing magnet strength. From my modeling, it appears that the magnet strength may be very close (if not already at) isolation optimization.

 

Lowering the mass to 0.2 the current mass may be impractical. It seems as if the benefits of lowering the mass only occur when the mass is reduced by a factor of 0.2 (maybe 0.4)

 

ELOG V3.1.3-