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ID Date Author Type Category Subjectdown
  9231   Thu Oct 10 11:46:43 2013 JenneUpdateSUSITMY OpLev Noise

For my work designing a cost function, so that I can try out new feedback servo designs on the oplevs, I wanted to know what the dark noise of an oplev is.  Since the pitch and yaw channels are divided by the sum channel, when the laser is off, the noise in the pitch and yaw channels looks much higher than it really is.  So, I collected some data from the 4 individual quadrants of the ITMY oplev, when the laser was on (but damping was off), and when the laser was off.  I used the values of the oplev input matrix to re-create the non-normalized pitch and yaw signals.  What I see is that we have some kind of real signal below 1 kHz, but we're hitting the noise at around 1 kHz.  So, we definitely don't want to use oplev error signal information above 1 kHz when designing new servos.

The last word in the title is "off".  OSEM damping was on, but the oplev damping was off.  These are uncalibrated, because the calibrations that we have to go from counts to microradians are for the normalized signals. 

ITMY_OpLev_Noise.png

  5198   Thu Aug 11 18:30:40 2011 KojiUpdateSUSITMY OSEM adjustment

[Jamie, Koji]

ITMX OSEMs were adjusted so as to have the right DC numbers and the more uniform response to POS excitation.

It is waiting for the free-swinging test.

- ITMX was moved from its position to the north side of the table.

- The table was rebalanced.

- We found that the output of the LR OSEM has an excess noise compared with the other OSEMs.
We tried to swap the LR and SD OSEMs, but the SD OSEM (placed at the LR magnet) showed
the same excess noise at around 10-50Hz.

- We found that one of the EQ stops was touching the mirror. By removing this friction, all of the OSEMs
come to show similar power spectra. Good!

 - Then we started to use LOCKIN technique to measure the sensitivity of the OSEMs to the POS excitation.

Originally the response of the OSEMs was as follows
UL 3.4 UR 4.3 
LL 0    LR 2.5   

After the adjustment of the DC values, final values became as follows
UL 3.9 UR 4.4
LL 3.9  LR 3.2

- We decided to close the light door.

  14484   Mon Mar 18 17:06:12 2019 gautamUpdateOptical LeversITMY HeNe replaced

Oplev HeNe was replaced this afternoon. We did some HeNe shuffling:

  1. A new HeNe was being used for the fiber illumination demo at EX. We took that out and decided to use it as the new ITMX HeNe. It had 2.6mW output at 632nm (measured with the Ophir power meter)
  2. Old ETMY HeNe was used for fiber illumination demo.
  3. Old ITMX HeNe was putting out no light - it will be disposed.

Attachment #1 shows the RIN and Attachment #2 and #3 show the PIT and YAW TFs with the new HeNe.

The ITMX Oplev path is still not great - the ingoing beam is within 2mm of clipping on a 2" lens used in the POX path, and there is a bunch of scattered red light everywhere. We should take the opportunity when the chamber is open to try and have a better layout (it may be tricky to optize without touching the two in-vacuum steering optics).

Quote:

I'll ask Chub to replace it this afternoon.

Attachment 1: OLRIN.pdf
OLRIN.pdf
Attachment 2: OL_PIT.pdf
OL_PIT.pdf
Attachment 3: OL_YAW.pdf
OL_YAW.pdf
  17298   Tue Nov 22 10:29:31 2022 AnchalSummarySUSITMY Coil Strengths Balanced

I followed this procedure to balance the coil strengths on ITMY. The position sensor was created by closing PSL shutter so that IR laser is free running, and locking the green laser to YARM, this makes C1:ALS-BEATY_FINE_PHASE_OUT a position sensor for ITMY. The oplev channels C1:SUS-ITMY_OL_PIT_IN1 and C1:SUS-ITMY_OL_YAW_IN1 were used for PIT and YAW sensors. Everything else followed the procedure. The coil gains were changed as follow:

C1:SUS-ITMY_ULCOIL_GAIN :   1.036 -> 1.061
C1:SUS-ITMY_URCOIL_GAIN : -1.028 -> -0.989
C1:SUS-ITMY_LRCOIL_GAIN :   0.930 -> 0.943
C1:SUS-ITMY_LLCOIL_GAIN : -1.005  -> -1.007

I used this notebook and this diaggui to do this balancing.

  4066   Fri Dec 17 00:30:05 2010 KojiUpdateIOOITMY / SRM / BS / PRM OPLEVs aligned

[Steve and Koji]

The invac OPLEV mirrros were aligned before we get to the PMA party.

The OPLEV mirrors were adjusted in accordance with the optical layout.
Surprisingly the optical layout was enough precise such that we have the healthy red beams on the optical tables.
Steve placed the apertures at the position of the returning spots while I shook the stack to check if the range of the spot motion is sufficient.

The sole thing that has been deviated from the optical layout was that the SRM returning beam had to be reroute
as the SRM has better reflectivity on the AR surface in stead of the HR one.

  4069   Fri Dec 17 03:37:47 2010 ranaUpdateSUSITMY / SRM / BS / PRM OPLEVs aligned

Quote:

The sole thing that has been deviated from the optical layout was that the SRM returning beam had to be reroute
as the SRM has better reflectivity on the AR surface in stead of the HR one.

 I suppose that if we were really clever we would intentionally choose either the AR or HR surface so as to minimize the effect of the thermal lensing and/or thermal expansion from the locked interferometer absorption.

  2777   Tue Apr 6 22:54:34 2010 KojiUpdateSUSITMY (south) aligned

Kiwamu and Koji

ITMY (south) was aligned with regard to the 40m-long oplev with the green laser pointer. Now the cavity is waiting for the green light injected from the end table

The OSEMs were adjusted with the aligned optics, but still a bit off from the center. They need to be adjusted again.
One round-shaped counter-weight removed from the table. Some counter weights are moved.

Some tools and the level gauge were removed from the table.

BAD news: I could clearly see scatter of the green beam path because of the dusts in the arm tube. Also many dusts are seen on the ITM surface.

 

Picture of the ETM - reflection from the ITM is hitting the mirror and the suspension structures.

IMG_2362.jpg

 


1. Shoot the ITM center with the green beam.

- Two persons with walkie-talkies required for this work.

- Turn on the end green pointer. We could see the long trace of the beam sliced by the beam tube wall.

- Look at the tube peeping mirror for the CCD.

- Adjust yaw such that the beam trace on the tube wall is parallel to the arm.

- Adjust pitch such that the beam trace on the tube gets longer. This means that spot gets closer to the ITM.

- Continue pitch adjustment until some scatter appears on the ITM tower.

- Once the spot appears on the tower, you can easily adjust it on the mirror

2. Adjust pitch/yaw bias such that the reflection hits the ETM.

- Initially the ITM alignment is totally bad. ==> You clealy see the spot on the wall somewhere close to the ITM.

- Adjust pitch/yaw bias such that the spot goes farther as far as possible.

- Once you hit the suspension tower, the scatter is obviously seen from the peeping mirror.

- You can match the incident beam and the scattering of the reflection. You also can see the reflection from the ETM towards the ITM as the spot size gets huge (1/2 tube diameter).

- We found that the bias is ~-2 for pitch and ~-6 for yaw.

3. Go into the chamber. Check the table leveling.

- Open the light door.

- I found that the table is not leveled. Probably it drifted after the move of the weight (i.e. MOS removal).

- Removed one of the round-shaped weight. Moved the other weights such that the table was leveled.

4. Remove the bias for yaw and rotate suspension tower such that the reflection hit the center of the ETM.

- Removed the yaw bias. This makes the reflected spot totally off from the ETM.

- Rotate suspension tower so that the beam can approximately hit the ETM.

- Look at the peeping mirror, the beam is aligned to the ETM.

5. Adjust OSEMs

- Push/pull the OSEMs such that we have the OSEM outputs at the half of the full scale.

6. Adjust alignment by the bias again.

- Moving OSEMs changes the alignment. The pitch/yaw biases were adjusted to have the beam hitting on the ETM.

- Bias values at  the end of the work: Pitch -0.8159 / Yaw -1.2600

7. Close up the chamber

- Remove the tools and the level gauge.

- Close the light door.

  16370   Fri Oct 1 12:12:54 2021 StephenUpdateBHDITMY (3002) CAD layout pushed to Box

Koji requested current state of BHD 3D model. I pushed this to Box after adding the additional SOSs and creating an EASM representation (also posted, Attachment 1). I also post the PDF used to dimension this model (Attachment 2). This process raised some points that I'll jot down here:

1) Because the 40m CAD files are not 100% confirmed to be clean of any student license efforts, we cannot post these files to the PDM Vault or transmit them this way. When working on BHD layout efforts, these assemblies which integrate new design work therefore must be checked for most current revisions of vault-managed files - this Frankenstein approach is not ideal but can be managed for this effort. 

2) Because the current files reflect the 40m as built state (as far as I can tell), I shared the files in a zip directory without increasing the revisions. It is unclear whether revision control is adequate to separate [current 40m state as reflected in CAD] from [planned 40m state after BHD upgrade]. Typically a CAD user would trust that we could find the version N assembly referenced in the drawing from year Y, so we wouldn't hesitate to create future design work in a version N+1 assembly file pending a current drawing. However, this form of revision control is not implemented. Perhaps we want to use configurations to separate design states (in other words, create a parallel model of every changed component, without creating paralle files - these configurations can be selected internal to the assembly without a need to replace files)? Or more simply (and perhaps more tenuously), we could snapshot the Box revisions and create a DCC page which notes the point of departure for BHD efforts?

Anyway, the cold hard facts:

 - Box location: 40m/40m_cad_models/Solidworks_40m (LINK)

 - Filenames: 3002.zip and 3002 20211001 ITMY BHD for Koji presentation images.easm (healthy disregard for concerns about spaces in filenames)

Attachment 1: 3002_20211001_ITMY_BHD_for_Koji_presentation_images.easm
Attachment 2: 40m_upgrade_layout_20200611-ITMY_Beam_Dim.pdf
40m_upgrade_layout_20200611-ITMY_Beam_Dim.pdf
  2469   Wed Dec 30 20:33:36 2009 rana, albertoConfigurationCamerasITMY & MC2 Camera work

We restored the good state of the ITMY camera and neatened both the MC2 and ITMY camera.

The MC2 camera was driving a triple T jungle into some random cables and spoiling the image. We removed all T's and the MC2 camera now drives only The Matrix.

The ITMY camera was completely unmounted and T'd. So it was misaligned just by the force of gravity acting on its BNC cable. We swapped the lens for a reasonable sized one and remounted it in its can. We then used orange cable ties to secure the power and BNC cable for the MC2 and ITMY cameras so that tugging on the cables doesn't misalign the cameras. This is part of the camera's SOP.

No more driving 50 Ohm cables and T's with video cables, Steve! If you need a portable video, just use a spigot of the Matrix and then you can control it with a web browser.

DSC_1064.JPGDSC_1065.JPGDSC_1066.JPG

I also wiped out the D40's memory card after uploading all of the semi-useful files to the Picasa page.

  6600   Thu May 3 21:13:48 2012 KojiSummarySUSITMX/PRM/BS OPLEV aligned

[Jenne/Den/Koji]

We locked Xarm/Yarm and manually alignmed ITMX/ITMY/BS/ETMX/ETMY/PZT1/PZT2.

ITMY OPLEV was largely misaligned ==> The beam was centered on the QPD.

----

Then we aligned PRM using SB locking PRMI.

We noticed that OPLEV servo does not work. It made the PRM just noiser.

We went into the PRM table and found that the OPLEV beam was clipped in the vacuum chamber.
We tried to maximize the reflected beam from the window by touching the steering mirrors at the injection side.

Then the reflected beam was introduced to the center of the QPD.

After the alignment, the OPLEV QPD SUM increased to 4000ish from 200ish.
According to the OPLEV trend data, this is a nominal value of the QPD SUM.

Now the OPLEV servo does not go crazy.

 --

BS OPLEV beam was centered on the QPD.

  14584   Mon Apr 29 16:34:27 2019 gautamUpdateElectronicsITMX/IMTY mis-labelling fixed at 1X4 and 1X5

After the X and Y arm naming conventions were changed, the labelling of the electronics in the eurocrates was not changed 😞 😔 😢 . This meant that when we hooked up the new Acromag crate, all the slow ITMX channels were in fact connected to the physical ITMY optic. I ♦️fixed♦️ the labelling now - Attachments #1 and #2 show the coil driver boards and SUS PD whitening boards correctly labelled. Our electronics racks are in desperate need of new photographs.

The "Y" arm runs in the EW direction, while the "X" arm runs in the NW direction as of April 29 2018.

ITMX was freed. ITMY is being worked on is also free..

Attachment 1: IMG_7400.JPG
IMG_7400.JPG
Attachment 2: IMG_7401.JPG
IMG_7401.JPG
  799   Tue Aug 5 12:52:28 2008 YoichiUpdateSUSITMX, SRM OSEM spectra
Free swinging spectra of ITMX and SRM.
ITMX seems to be ok after yesterday's work, though the OSEM DC values are still a bit off from the normal value of 0.9.
(ITMX OSEM values: UL=1.12, UR=1.38, LR=0.66, LL=0.41, SIDE=0.66)
SRM is still clearly wrong.
Attachment 1: ITMX-2008_08_05-morning.pdf
ITMX-2008_08_05-morning.pdf
Attachment 2: SRM-2008_08_05-morning.pdf
SRM-2008_08_05-morning.pdf
  16906   Fri Jun 10 13:52:22 2022 JCUpdateOPLEV TablesITMX, ITMY, and Vertex Table Beam Paths

I have at taken photos and added arrows which signify the beam paths for ITMX, ITMY, and Vertex Oplev tables.

Attachment 1: DCE4F1D7-5AE0-491C-8AF6-F8B659C0787E_1_105_c.jpeg
DCE4F1D7-5AE0-491C-8AF6-F8B659C0787E_1_105_c.jpeg
Attachment 2: 4B24C891-654D-4C51-A8D9-D316364FCF68_1_105_c.jpeg
4B24C891-654D-4C51-A8D9-D316364FCF68_1_105_c.jpeg
Attachment 3: F5B115E5-885F-463C-9645-BB2EB73B6144_1_201_a.jpeg
F5B115E5-885F-463C-9645-BB2EB73B6144_1_201_a.jpeg
  5291   Tue Aug 23 17:45:22 2011 jamieUpdateSUSITMX, ITMY, ETMX clamped and moved to edge of tables

In preparation for tomorrow's drag wiping and door closing, I have clamped ITMX, ITMY, and ETMX with their earthquake stops and moved the suspension cages to the door-edge of their respective tables.  They will remain clamped through drag wiping.

ETMY was left free-swinging, so we will clamp and move it directly prior to drag wiping tomorrow morning.

  5055   Thu Jul 28 16:26:42 2011 steveUpdateSUSITMX, ITMY & ETMY OSEM gains adjusted

 

OSEM damping gains were adjusted by observing  real time dataviewer to get Q of 5

OSEMs were kicked up one by one with 200 counts  ~1sec. The error signal was optimized to get 1/2 of exitation amplitude at the 5th sinusoid wave.

C1: SUS-ITMX_SUSPOS_N1 gain   111      ->        65,             PIT        7.2      ->    8,           YAW        12      ->     6,          SIDE     280

                  ITMY                                      277       ->     120,                        19.2     ->     7,                             24     ->     19,                        420    ->      470

                  ETMY                                       10        ->       32,                          20      ->     3,                             20     ->     10,                          50

                  ETMX                                       22        ->      25,                             3,                                                3,                                              -170  

ETMX having problems:  1, YAW can not be excited

                                             2, SIDE has no error signal in dataviewer. Sensing voltage on MEDM screen 0.142V

 

                      

 

  5297   Wed Aug 24 12:08:56 2011 jamieUpdateSUSITMX, ETMX, ETMY free swinging

ITMX: 998245556

ETMX, ETMY: 998248032

  2367   Tue Dec 8 16:27:13 2009 JenneUpdateCOCITMX wiped

Jenne, Kiwamu, Koji, Alberto, Steve, Bob

ITMX was wiped without having to move it. 
After 'practice' this morning on ETMY, Kiwamu and I successfully wiped ITMX by leaning into the chamber to get at the front face. 

Most notable (other than the not moving it) was that inspection with the fiber light before touching showed many very small particles on the coated part of the optic (this is versus ETMY, where we saw very few, but larger particles).  The after-wiping fiber light inspection showed many, many fewer particles on the optical surface.  I have high hopes for lower optical loss here!

  4916   Thu Jun 30 01:50:02 2011 JenneUpdateSUSITMX whitening, ETMX left free swinging

While closing up the whitening shop for the night, I noticed that the ITMX whitening state (Whitening "On") is opposite that of all other suspensions (they all have Whitening "Off").  I don't know which way is correct, but I assume they should all be the same.  Once all the whitening and BO testing is done, we should make sure that they're all the way we want them to be.

Also, Koji and I are leaving ETMX free swinging.  That's the way we found it, presumably from Jamie's BO testing at the end station today.  We don't know what the optic's story is, so we're leaving it the way we found it.  Jamie (or whomever left it free swinging), can you please restore it when it is okay to do so?  Thanks!

  4125   Fri Jan 7 15:17:37 2011 steveUpdateCamerasITMX video monitor has tower wide view

The Watec 902, 1/2" CCD camera got new Tamron lens: 1/2" 10-40mm F/1.4  manual iris. IR corrective lens. It is designed to have the same focal point in the IR as

in the visible light range. However, as the depth of field in the IR range is very narrow, focus adjustment should be done carefully in the IR.

Now you can see the sus tower that will make alignment easier.

 

  5752   Fri Oct 28 03:42:50 2011 kiwamuUpdateLSCITMX table needs to be refined

(POX)

The POX beam had been 80% clipped at a black glass beam dump of the POX11 RFPD.

I steered the first mirror in the POX path to fix the clipping. Then the beam was realigned onto the RFPD.

However the beam is still very close to the black glass, because the incident angle to the second mirror is not 45 deg .

We need to refine the arrangement of the POX11 optics a bit more so that the beam will never be clipped at the black glass.

 

(POP)

 The POP optics also need to be rearranged to accommodate one more RFPD.

Additionally Rana, Suresh and I discussed the possible solutions of POP22/110 and decided to install a usual PD (PDA10A or similar) instead of a custom-made.

So a plan for the POP detectors will be something like this:

        + design an optical layout.

        + buy a 2 inch lens whose focul length is long enough (#5743)

        + rearrange the optics and install POP22/110

        + lay down a long SMA cable which sends the RF signal from POP22/110 to the LSC rack.

        + install a power splitter just before the demod board so that the signal is split into the 22MHz demoad board and 110MHz demod board.

           => make sure we have a right splitter for it.

        + install a band pass filter after the power splitter in each path.

           => A 22MHz band pass filter is already in hand. Do we have 110MHz band pass filter somewhere in the lab ?

The picture here shows the latest configuration on the ITMX table.

ITMXtable.png

Quote from #5743

RF photo diodes POP55 and POX11 are installed. The beams are aligned to the photo diodes. 

  16837   Mon May 9 18:43:03 2022 AnchalUpdateBHDITMX table layout corrected

As I went to correct the ITMX Oplev mirrors, I found that both mirrors were placed in very different positions than the design position. Part of the reason I think was to preserve outside oplev path, and party because a counterweight was in ITMXOL1 position. I had to do following steps to correct this:

  • I noted down level meter readings of the table before making any changes.
  • I removed the counter weight from near the center of the table.
  • I placed the Oplev mirrors in the nominal positions.
  • I placed the counter weight near previous position.
  • I moved a edge hanging counter weight to get back the level meter to its previous state coarsely.
  • Then I used dataviewer to find the previous OSEM PD monitor values and changed ITMX PIT and YAW to come closer to those PD values. And voila, I regained the flashing on Xarm. I nudged the ITMX pit and yaw bit more to maximize it.
  • I then went back to aligning the Oplevs properly.
  • Then I adjusted the POP mirrors to get the beam back through center of window. This was very tricky and took a lot of time.
  • Now the beam is going through near center and the oplev beams are far away enough from POP_SM5.
  • On the outside table, I noted the POP beam and the oplev beam. I corrected the pit of the returning beam to get the oplev beam at nominal height on outside table.

ITMX Sat Amp is flaky

[Anchal, Paco]

During the above work, i must have kicked the cable between the vacuum flange and the satellite amplifier box for ITMX. This disconnected all the OSEMs and Coils. We tried several things to debug this and finally found that nudging the connections on Sat Amp box brought the OSEMs and coils back online. Note that the connector was not partially out or in a state that obviously showed disconnection of the pins. I'm glad we are putting in new electronics soon for the vertex optics as well.


Next steps:

  • I showed Tega the returning oplev beam and the POP beam coming out of the ITMX chamber.
  • The Oplev beam paths need to be adjusted.
    • The ongoing beam steering mirror is blocking the returning beam, so the ongoing path needs to be changed.
    • First setup two irises to save ingoing path.
    • Then make space for the returning beam by changing the steering mirror positions.
    • Then recover the ingoing path to the center of irises.
    • Steer the returning beam to the QPD.
    • Then maximize the flashing on XARM and center the oplev to save this position.
  • POP beam needs to be directed to previous setup on far side of table.
    • The POP beam is coming out at the rising angle.
    • This is good for us if we do bit unconventional stuff and transfer the beam to other side of table at an elevated height. Given how close all the beams are coming out of the viewport, I think this is the best solution in terms of saving time.
    • Get the beam down to the old setup which was camera and photodiodes all aligned.

 

 

  12518   Mon Sep 26 19:48:09 2016 LydiaUpdateSUSITMX stuck again, ITMY whitening issue

This afternoon around 2:45, ITMX started ringing up at ~.9Hz for about a minute and then got stuck again. When I noticed this evening, I tried to free it with the alignment sliders but was unable to see any signal on UL or UR. It also looks like the damping for ITMY was turned off at the same time ITMX got stuck (not at the start of its ring up). SRM also has a spike in its motion at this time, and another one minute later that ended up with the LR OSEM at a much higher level, though the mirror does not appear to be stuck. We didn't see any strange behavior from any of the other optics.

Teng and I were working on diagnosing a problem with the ITMY UL whitening, but by the time we disconnected any applicable cables, the damping for ITMY was already off. Later we unplugged the ITMX PD whitening cables after verifying that the ITMX damping was also already off. This problem may have occured earlier, while Teng, Eric, and I were examining and pushing in the cables at 1X5 without unplugging anything.

We found that the reason for the bad phase on the ITMY free swing data is because the whitening filter for UL is not being properly turned on. We are in the process of investigating the source of this problem. Right now all the cables to the PD whitening boxes in 1X5 are switched between ITMY and ITMX.
 

Attachment 1: 44.png
44.png
Attachment 2: 26.png
26.png
  13173   Tue Aug 8 20:48:06 2017 gautamUpdateSUSITMX stuck

Somewhere between CDS model restarts and the IFO venting, ITMX got stuck.

I shook it loose using the usual bias slider technique. It appears to be free now, I was able to lock the green beam on a TEM00 mode without touching the green input pointing. The ITMX Oplev spot has also returned to within its MEDM display bounds.

  12520   Tue Sep 27 18:04:50 2016 LydiaUpdateSUSITMX slow channels down, ITMY diagonalization update

[Teng, Lydia]

When we plugged in the back cables yesterday on the whitening boxes after switching them, two of the ITMX PDMon channels (UR and LR) got stuck at 0. This caused me to believe ITMX was still stuck even when it was freed. However, it was left in a stuck state overnight and freed again today after this issue was discovered. The alignment sliders have been set to 0 as a safety net to keep ITMX from getting stuck again if c1susaux is restarted again. We switched the cables back and the problem was still there.

The ITMY UL whitening filter problem, which the cables were originally switched to diagnose, was also still there. Ericq suggested we turn off all the whitening filters in order to get diagonalization data that would not show a phase difference between coils. We ran the diagonalization again with all the dewhitening filters off and got much cleaner results, with no visible cross-coupling peaks remaining between the degrees of freedom (see attachemnt 1). We did not apply this matrix to the damping, however, because there are elements which have the wrong sign compared to the ideal matrix. Significant adjustments to the output matrix will probably need to be made if this result is to be used. We also verified that the phase problem had been solved in DTT, where we saw the same sign discrepancies as in the matrix below. 

Damping can be turned back on, using the old, non-diagonalized matrix currently in effect. There is enough free swing data to diagonalize ITMY now, so feel free to mess with it. 

Matrix (wrong signs red, suspiciously small elements orange):

           pit     yaw     pos         side    butt
UL    1.633   0.138   1.224   0.136   0.984  
UR   -0.202  -1.768   1.179   0.132  -1.028  
LR   -2.000   0.094   0.776   0.107   1.001  
LL   -0.165   2.000   0.821   0.111  -0.987  
SD    0.900   1.131  -1.708   1.000  -0.107  

 

Attachment 1: ITMY_diagsuccess.pdf
ITMY_diagsuccess.pdf
  13182   Thu Aug 10 09:31:57 2017 SteveUpdateSUSITMX sensor voltage

There must be some bad connection

Quote:

Somewhere between CDS model restarts and the IFO venting, ITMX got stuck.

I shook it loose using the usual bias slider technique. It appears to be free now, I was able to lock the green beam on a TEM00 mode without touching the green input pointing. The ITMX Oplev spot has also returned to within its MEDM display bounds.

 

Attachment 1: 9daysITMX.png
9daysITMX.png
Attachment 2: vacGlitchITMX.png
vacGlitchITMX.png
  12489   Tue Sep 13 19:02:56 2016 TengUpdateGeneralITMX sensor

[Lydia,Teng]

Something strange happened to the ITMX osem reading around 4.pm. PDT as shown below.

Also the there was no response of the reading as we adjusted the PITCH and YAW. :(

Note that we restarted the slow machine: c1susaux,c1ausex this afternoon because of the unresponced interface.

 

 

Attachment 1: 47.png
47.png
Attachment 2: 34.png
34.png
  15585   Sat Sep 19 19:14:59 2020 KojiUpdateGeneralITMX released / ETMY UR magnet knocked off

There were two SUSs which didn't look normal.

- ITMX was easily released by the bias slider -> Shake the pitch slider and while all the OSEM values are moving, turn on the damping control (with x10 large watchdog threshold)

- ETMY has UR OSEM 0V output. This means that there is no light. And this didn't change at all with the slider move.
- Went to the Y table and tried to look at the coils. It seems that the UR magnet is detached from the optic and stuck in the OSEM.

We need a vent to fix the suspension, but until then what we can do is to redistribute the POS/PIT/YAW actuations to the three coils.

Attachment 1: IMG_6218.jpeg
IMG_6218.jpeg
  5342   Tue Sep 6 11:21:33 2011 JenneUpdateSUSITMX rehung (Friday)

[Jenne, Katrin, Jamie]

I'm a bad kid, and forgot to elog my Friday morning work...

Bob gave me back ITMX after a 48hour bake at 80C + clean RGA scan Friday morning after coffee and doughnuts.  Katrin helped me put it back in the suspension wire. 

While I was leveling the optic (making sure the scribe lines on each side of the optic are at the same height off the table), Katrin cut some new viton for replacement EQ stops.  The optic was missing one lower earthquake stop (the one that Jamie noticed last week), and somehow one other rubber piece came out of the EQ stop on another lower screw while we were re-suspending the optic.  We put the new stops in, and then checked the balance of the test mass.

The oplev is still the HeNe laser that is leveled to the level optical table in the cleanroom.  The lever arm is ~1.5 meters, and over that distance the reflected beam was pointed "up" in pitch by ~1.5mm, which is less than one beam diameter of the HeNe.  This is well within our ability to correct using the OSEMs.

We then locked the test mass, and installed it in the chamber.  I approximately did the half-voltage centering of the OSEMs, leaving the fine-tuning to Kiwamu for after lunch. 

  5337   Fri Sep 2 17:52:16 2011 kiwamuUpdateSUSITMX realigned

The new ITMX was aligned by changing the DC biases.

The resultant DC biases are reasonably small.

C1:SUS-ITMX_PIT_COMM = -0.2909

C1:SUS-ITMX_YAW_COMM = -0.0617

 

The alignment was done by trying to resonate the green light in the X arm cavity.

The spot position of the green light on the ITMX mirror looked good. This was confirmed by inserting a sensor card.

I did the OSEM mid-range adjustment and the rotation adjustment but at the end the OSEM DC voltage has changed due to the DC bias operation.

The OSEM rotation was approximately optimized so that all the face shadow sensors are sensitive to the POS motion but the SIDE shadow sensor is insensitive to the POS motion.

It needs a free swinging diagnosis.

  11755   Thu Nov 12 09:15:56 2015 SteveUpdateSUSITMX osems

The ITMX OSEMS are oscillating.

Attachment 1: ITMX.png
ITMX.png
  16843   Tue May 10 16:31:14 2022 TegaUpdateBHDITMX optlev return beam steered to QPD

Followed the steps below to complete the ITMX optlev installation. The ITMX optlev return beam now reaches its QPD without being blocked by the input steering mirror.

Although, I centered the ITMX optlev readout, this was not done when the XARM flashing is maximized bcos the IMC chamber was being worked on, so this should be done later when the IR beam is back.

Quote:

Next steps:

  • The Oplev beam paths need to be adjusted.
    • The ongoing beam steering mirror is blocking the returning beam, so the ongoing path needs to be changed.
    • First setup two irises to save ingoing path.
    • Then make space for the returning beam by changing the steering mirror positions.
    • Then recover the ingoing path to the center of irises.
    • Steer the returning beam to the QPD.
    • Then maximize the flashing on XARM and center the oplev to save this position.
  5660   Thu Oct 13 14:23:09 2011 steveUpdateSUSITMX oplev with 3 mm beam on qpd

 I replaced the JDSU-Uniphase 1125P by 1103P He/Ne laser. This new laser had 2.8 mW output yesterday. It degraded to 0.5 mW by this morning.

The beam size on the QPD is ~3 mm  This should give us  better sensitivity. These are not the perfect lenses at all, but we have them here.

On the other hand, there are still some coherence below 1 Hz, so the laser intensity noise or clipping dominating  this  part of the spectrum.

 

Attachment 1: ITMXoplev1103p#2.png
ITMXoplev1103p#2.png
Attachment 2: ITMXoplev.png
ITMXoplev.png
  11160   Mon Mar 23 13:27:33 2015 ericqUpdateSUSITMX oplev quadrant gains unbalanced

I've been poking around the oplev situation. One thing I came across regarding ITMX was that the gain on segment 4 seems to be about higher than the other segments. I was led to believe this by steering the optic around, and looking at the counts on each quadrant when the other 3 were dark.

Putting a gain of 0.86 (the ratio of the other segments' max counts over segment 4's max counts) in the segment 4 FM flattens the 1 Hz peak in the ITMX_OL_SUM spectrum, as well as significantly reducing the sub-Hz coherence of the sum with the individual quandrant counts. This is what I would expect from reducing the coupling of angular motion due to quadrant gain mismatch into the sum. 

Here are the ITMX_OL_SUM spectra before and after (oplev servos are off).

The "burps" and control filter saturations are still unexplained. Investigations continue...

Attachment 1: olsum.png
olsum.png
  5437   Fri Sep 16 17:09:07 2011 PaulUpdateSUSITMX oplev plan

 I just drew a basic picture of how the ITMX oplev path could be reworked to minimise the number of optics in the path. Only possible problem with this might be the turning mirror onto the ITMX getting in the way of the collimating lenses. Should be easy to solve though. Does anyone know if there is a ITMX pick off beam I should be careful to avoid?

Attachment 1: ITMX_oplev_plan.png
ITMX_oplev_plan.png
  12125   Mon May 23 10:55:49 2016 steveSummarySUSITMX oplev laser replaced

 

      May 23, 2016             ITMX dead He/Ne laser sn P845648 replaced after 1062 days [2.9 yrs] by 1103P, sn P859884, with output  2.6 mW, nicely round beam quality at 15 meters.

                                                                                                                                                    Power just before viewport 1 mW,  returning light on qpd 154 microW =  7,500 counts

 

Attachment 1: ITMXoplev.png
ITMXoplev.png
  5655   Wed Oct 12 08:43:30 2011 steveUpdateSUSITMX oplev improved a bit

 Atm2 is before optical path adjustment. The idea was to remove possible clipping in vacuum.

Coherense significantly reduced below 4 Hz

Today I will replace the He/Ne laser 1125P with 1103P

 

Attachment 1: ITMXoplev.png
ITMXoplev.png
Attachment 2: ITMXoplevservo_ON.png
ITMXoplevservo_ON.png
  1595   Sun May 17 21:45:40 2009 robUpdateASCITMX oplev centered
  4032   Thu Dec 9 00:34:53 2010 OsamuUpdateSUSITMX oplev Pitch OLTF

We measured Open loop TF for oplev pitch on ITMX.

2010128_01_ITMX_oplev_pit_oltf_fine.jpg

2010128_01_ITMX_oplev_pit_oltf_fine.pdf

 All feed back filter of oplev  was on as same as before. Original notch filters which notches above 10Hz resonance should be modified with some measurements of present resonant frequency. Up to 10Hz, a simple f^2 filter is used, so the notch should not affect this measurement.

Measured upper UGF is about 2Hz with gain slider 1, and lower UGF is 1.3Hz. Phase margin is 40 degree, so it is not a good idea to increase the gain drastically.

I have measured the coherence also but I could not find a way to put it on this picture. Anyway coherence below 0.6Hz was not so good like ~0.95. This can be improved if larger excitation is used next time.

During this measurement around 0.2-0.3Hz, small earthquake happened but seemed OK for the control.

We will measure the other TF, yaw, ETMX or somthing, maybe tomorrow, due to free swinging ITMX and ETMX tonight.

 

  5749   Fri Oct 28 01:13:17 2011 kiwamuUpdateSUSITMX oplev : iris fully opened

I found that the sum of the ITMX oplev signals had gone down to zero yesterday.

I checked the ITMX table and found two iris on the He-Ne laser path were blocking the beam on their apertures.

I guess this is because we were working around there for installation of POP/POX and may have touched some of the oplev optics.

Then I fully opened the apertures of those two iris and the sum went back to nominal of 600 counts.

  5395   Tue Sep 13 16:57:44 2011 steveUpdateLSCITMX oplev **

Quote:

I lined up the Y Arm for locking and then centered the oplevs for ETMY and ITMY.

* The ITMY OL has still got the old style laser. Steve, pleaes swap this one for a HeNe. Also the optical layout seems strange: there are two copies of the laser beam going into the chamber (??). Also, the QPD transimpedance needs to be increase by a factor of ~10. We're only getting ~500 counts per quadrant. Its worth it for someone to re-examine the whole ITMY OL beam layout.

* The ETMY OL beam was coming out but clipping on the mount for the ETMY OL HeNe. This indicates a failure on our part to do the ETMY closeout alignment properly. In fact, I get the feeling from looking around that we overlooked aligning the OL and IPPOS/ANG beams this time. If we're unlucky this could cause us to vent again. I undid part of the laser mount and changed the height on the receiving mirror to get the beam back onto the QPD.

I noticed that there is significant green light now getting into some of the IR PDs; beacuse of this there are weird offsets in the TRY QPD and perhaps elsewhere. We had better purchase some filters to tape over the front of the sensitive IR sensors to prevent the couplling from the green laser.

* There is a beam on IPPOS, but its too big for the detector (this has always been the case). We need to put a 2" lens with a weak focusing power on this path so as to halve the beam size on the detector. Right now its clipping and misleading. There is also a 0.9V offset on the SUM signal. I'm not sure if this readout is working at all.

* I couldn't find any beam on IPANG at all. Not sure what's changed since Kiwamu saw it.

 Old Coherent diode laser was replaced by Uniphase HE/NE 1125P at ITMX.

Newport 10B20NC.1 broadband beam sampler set up as beamspitter to dump 90% of the light into beam trap. Beam in to test mass  0.7 mW ,  returning to qpd 0.07 mW  = ~ 3,700 counts

f 1.5 m lens placed into ingoing beam path to reduce the spot size on the qpd.         ITMY oplev will be done in this manner tomorrow.

 

* IP-ANG is lost with the Piezo Jena PS

* IP-POS cable have to be found at the LSC rack

 

  8937   Tue Jul 30 11:30:55 2013 manasaUpdateGeneralITMX oplev

Quote:

[Koji, Manasa, Sujan]

The ITMX oplev was also checked from the windows without removing the door.
The beam is actually hitting the right positions of the steering mirror and the test mass
although there are lots of stray beams because of the BS oplev and some halo assciated with the ITMX He-Ne laser(!?).

[Steve, Gautam, Manasa]

While we checked the ITMX oplev situation yesterday, we found that the beam hitting the ITM and the in-vacuum steering mirrors had  a halo around them. We used the set of irides in the path of the ingoing beam and cut the stray light around the beam. This reduced the intensity of the halo around the mirrors. We noticed that the halo accounted for 2000 counts of 6500 at the oplev QPD. We tried changing the laser and this did not make the situation any better.

Also there are a couple or more strong stray beams from the BS oplev.

Thoughts:
I suspect that the BS oplev leakage is messing with the ITMX oplev. Why?? We have been seeing the breathing of transmitted beam from the X arm cavity and the shadow sensor readings have been bigger than usual since the last vent (when we changed the BS oplev path). Also, the ingoing oplev beam is close to clipping at the PR2 stack.

I think it would be best to open the ITMX chamber and modify the in-vac steering mirror layout of the oplev.

  8938   Tue Jul 30 13:41:35 2013 KojiUpdateGeneralITMX oplev

I wonder what optics is causing the halo on the oplev beam.
It this comes from any uncoated lens (or similar) it should be identified.

  8939   Tue Jul 30 15:38:24 2013 manasaUpdateGeneralITMX oplev

Quote:

I wonder what optics is causing the halo on the oplev beam.
It this comes from any uncoated lens (or similar) it should be identified.

We identified this to be coming from the uncoated concave lens that we have right after the He-Ne laser which should also be replaced in addition to the other problems with the oplev.

  5341   Tue Sep 6 08:05:53 2011 steveUpdateSUSITMX must be touching

Quote:

The new ITMX was aligned by changing the DC biases.

The resultant DC biases are reasonably small.

C1:SUS-ITMX_PIT_COMM = -0.2909

C1:SUS-ITMX_YAW_COMM = -0.0617

 

The alignment was done by trying to resonate the green light in the X arm cavity.

The spot position of the green light on the ITMX mirror looked good. This was confirmed by inserting a sensor card.

I did the OSEM mid-range adjustment and the rotation adjustment but at the end the OSEM DC voltage has changed due to the DC bias operation.

The OSEM rotation was approximately optimized so that all the face shadow sensors are sensitive to the POS motion but the SIDE shadow sensor is insensitive to the POS motion.

It needs a free swinging diagnosis.

 ITMX OSEMs   UL 1.8V,   UR 1.7V,   LR 0V,   LL 0V,   SD 1.3V  at the same bias setting shown above. May be a lose earth quake tip?or magnet is touching?

Attachment 1: osemITMX.jpg
osemITMX.jpg
  11806   Tue Nov 24 14:58:40 2015 yutaroUpdateLSCITMX misaligned

I misaligned ITMX. The oplev servo for ITMX is now turned off. You can restore ITMX alignment by running "restore".

  12512   Thu Sep 22 15:44:21 2016 SteveUpdateGeneralITMX magnets are stucked again

 

 

Attachment 1: StuckAgain.png
StuckAgain.png
  12491   Wed Sep 14 09:33:54 2016 SteveUpdateGeneralITMX magnets are stucked

I believe that the UR and LR magnets are stuck. There was no earth quake at 16:18 yesterday. Something had to kick it into this position. See 4days plot

Please advise  freeing details.

Quote:

[Lydia,Teng]

Something strange happened to the ITMX osem reading around 4.pm. PDT as shown below.

Also the there was no response of the reading as we adjusted the PITCH and YAW. :(

Note that we restarted the slow machine: c1susaux,c1ausex this afternoon because of the unresponced interface.

 

 

 

Attachment 1: ITMXmagStuck.png
ITMXmagStuck.png
  12494   Wed Sep 14 20:05:32 2016 LydiaUpdateGeneralITMX magnets are stucked

When I restarted c1susaux yesterday, I didn't know that I needed to disable the coil outputs first. So when it came back online, it attempted to damp all the vertex area optics and ITMX got stuck frown

We should make a note in the Computer Restart Procedures wiki page indicating the importance of disabling the coils before rebooting c1susaux, c1auxex, and c1auxey. Today c1auxey was rebooted properly without incident. If the slider values etc go back to their previous values on their own, is it necessary to do a BURT restore? I tried doing one for c1susaux today and there were some errors for ASC channels, but the alignment sliders went right back to the proper place after reboot yesterday.

Quote:

I believe that the UR and LR magnets are stuck. There was no earth quake at 16:18 yesterday. Something had to kick it into this position. See 4days plot

Please advise  freeing details

 

  5311   Sat Aug 27 14:33:04 2011 JenneUpdateSUSITMX magnet status

As I feared, since I couldn't see the magnet-to-dumbbell joint from all angles, they ended up being off by ~1/3 of a magnet diameter. 

Because I don't want to deal with finding another failed glue joint tomorrow, I removed the magnet and dumbbell from the optic, and broke the manget off of the dumbbell.  As with yesterday, I kept track of which end of the magnet had been glued to the dumbbell. 

I got a new dumbbell, removed all the glue from the magnet, and reglued them together, in the fixture that ensures they are well aligned. 

Tomorrow I will come in and glue the magnet dumbbell assembly to the ITM.

  5314   Sun Aug 28 20:15:11 2011 JenneUpdateSUSITMX magnet status

Quote:

Tomorrow I will come in and glue the magnet dumbbell assembly to the ITM.

 Glued.

Tomorrow afternoon I'll remove the optic from the fixture, and put it in the oven.

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