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New entries since:Wed Dec 31 16:00:00 1969
ID Date Author Type Category Subjectdown
  2926   Thu May 13 05:06:43 2010 ranaUpdate40m Upgrading216 MHz resonance in the POY11 PD killed


 This idea was tried before by Dale in the ~1998 generation of PDs. Its OK for damping a resonance, but it has the unfortunate consequence of hurting the dynamic range of the opamp. The 100 Ohm resistor reduces the signal that can be put out to the output without saturating the 4107.

I still recommend that you move the notch away from the input of the 4107. Look at how the double notch solution has been implemented in the WFS heads.

  13544   Fri Jan 12 20:35:34 2018 Udit KhandelwalSummaryGeneral2018/01/12 Summary
  1. 40m Lab CAD
    1. Worked further on positioning vacuum tubes and chambers in the building.
    2. Next step would be to find some drawings for optical table positions and vibration isolation stack. Need help with this! 
  2. Tip Tilt Suspension (D070172)
    1. Increased the length of side arms. The overall height of D070172 assembly matches that of D960001.
    2. The files are present in dropbox in [40mShare] > [40m_cad_models] > [TT - Tip Tilt Suspension]
  12055   Wed Mar 30 16:40:24 2016 ericqUpdateLSC2016 vs 2010

I haven't found any data files for the DARM spectrum of the previous generation of 40m, but with some GIMP-fu, I have plotted Monday's spectrum (green) on top of one of the figures from Rob's thesis.

  9730   Mon Mar 17 10:50:58 2014 steveUpdatesafety2014 annual crane certification




 We had our annual safety inspection today.  Our SOPs are outdated. The full list of needed correction will be posted tomorrow.


The most useful found was that the ITMX-ISCT ac power is coming  from 1Y1 rack. This should actually go to 1Y2 LSC rack ?

 Please test this so we do not create more ground loops.

 Annual crane inspection is scheduled for 8-11am Monday, March 17, 2014


The control room Smart UPS has two red extension cords that has to be removed: Nodus and Linux1

 KroneCrane Fred inspected and certified the 3 40m cranes for 2014. The vertex crane crane was load tested at fully extended position.

  4651   Fri May 6 10:20:00 2011 steveSummarySAFETY2011 safety audit

The emphasis of this annual safety audit  was on  safe  electrical housekeeping on March 3, 2011

Safety audit correction list for the electric shop:

1, install breaker panel door in room 101
2, install conduit- AC out let in the east arm for USB camera table and
    south arm for maglev- external fan
3, replace AC cord to south end work bench and door alarm
4, trace breaker of 1Y4

Requested completion date: 3-28-2011 at estimated cost $1,500.
All recommendations  for improvement were done by April 1, 2011
We thank the participants for making the 40m a safer  place to work.
  1620   Fri May 22 01:27:14 2009 peteUpdateSUS200 days of MC3 side

Looks like something went nuts in late April.  We have yet to try a hard reboot.

  547   Fri Jun 20 01:38:55 2008 ranaUpdatePEM20 day Weather
Yoichi showed me that its possible to make PNG images from PS using GS:
gs -sDEVICE=png16m -sOutputFile=foo.png bar.ps
  10899   Wed Jan 14 02:11:07 2015 ranaSummaryTreasure2-loop Algebra Loopology

I show here the matrix formalism to calculate analytically the loop TF relationships for the IMC w/ both FSS actuators so that it would be easier to interperet the results.

The attached PDF shows the Mathematica notebook and the associated block diagram.

In the notebook, I have written the single hop connection gains into the K matrix. P is the optical plant, C is the Common electronic gain, F is the 'fast' NPRO PZT path, and M is the phase Modulator.

G is the closed loop gain matrix. The notation is similar to matlab SS systems; the first index is the row and the second index is the column. If you want to find the TF from node 2 to node 3, you would ask for G[[3,2]].

As examples, I've shown how to get the FAST gain TF that I recently made with the Koji filter box as well as the usual OLG measurement that we make from the MC servo board front panel.

  16464   Thu Nov 11 00:11:39 2021 KojiSummarySUS2" to 3" sleeve issue

Yehonathan and Tega found that the new PR3 and SR3 delivered in 2020 is in fact 3/4" in thickness (!). Digging the past email threads, it seems that the spec was 10mm but the thickness was increased for better relieving the residual stress by the coatings.

There are a few issues.

1. Simply the mirror is too thick for the ring. It sticks out from the hole. And the mirror retainers (four plastic plates) are too far from the designed surface, which will make the plates tilted.

2. The front side of the mirror assembly is too heavy and the pitch adjustment is not possible with the balance mass.

Some possible solutions:

- How about making the recess deeper?
In principle this is possible, but the machining is tricky because the recess is not a simple round hole but has "pads" where the mirror sits. And the distance of the retainer to the thread is still far.
And the lead time might become long.

- How about making new holes on the ring to shift the clamp?
Yes it is possible. This will shift the mirror assembly by a few mm. Let's consider this.

- How about modifying the wire blocks?
Yes it is equivalent to shift the holes on the ring. Let's consider this too.

1. How to hold the mirror with the retainer plates

[Attachment 1] The expected distance between the retainer plate and the threaded hole is 13.4mm. We can insert a #4-40 x L0.5" stand off (McMaster-Carr 91197A150, SUS316) there. This will make the gap down to 0.7mm. With a washer, we can handle this gap with the plate. Note that we need to use vented & silver plated #4-40 screws to hold the plates.

[Attachment 2] How does this look like when the CoM is aligned with the wire plane? Oh, no... the lower two plates will interfere with the EQ stops and the EQ stop holders. We have to remove them. [Attachment 3]
We need to check with the suspension if the EQ stop screws may hit the protruded optics and can cause chipping/cracking.

2. Modifying the wire block

[Attachment 4] The 4x thru holes of the wire block were extended to be +/-0.1" slots. The slots are too long to form ovals and produce thin areas. With the nominal position of the balance mass, the clamp coordinates are y=1.016 (vertical) and z=-2.54mm (longitudinal).
==> The CoM is 0.19mm backside (magnet side) and 0.9134 mm lower from the wire clamping points. This looks mathematically doable, but the feasibility of the manufacturing is questionable.

[Attachment 5] Because the 0.1" shift of the CoM is large, we are able to make new #2-56 thread holes right next to the original ones. The clamp coordinates are y=1.016 (vertical) and z=-2.54mm (longitudinal).
==> The CoM is 0.188mm backside (magnet side) and 0.9136 mm lower from the wire clamping points. With the given parameters, the expected pitch resonant frequency is 0.756Hz

My Recommendation

- Modify the metal ring to shift the #2-56 threads by 0.1"

- The upper two retainer plates will have #4-40 x 0.5" stand off. Use vented Ag-coated #4-40 screws.

- The lower two are to be removed.

- Take care of the EQ stops.

- Of course, the best solution is to redesign the holder for 3/4" optics. Can we ask Protolab for rapid manufacturing???

Why did we need to place the mass forward to align the 1/4" thick optic?

We were supposed to adjust the CoM not to have too much adjustment. But we had to move the balance mass way too front for the proper alignment with a 1/4" thick optic. Why...?
This is because the ring was designed for a 3/8" thick optic... It does not make sense because the depth of the thread holes for the retainer plate was designed for 1/4" optics...

When the balance mass is located at the neutral position, the CoM coordinate is

x 0.0351mm (x+: left side at the front view)
y 0.0254mm (y+: vertical up)
z 0.4493mm (z+: towards back)

So, the CoM is way too behind. When the balance mass was stacked and the moved forward (center of the axis was moved forward by 0.27"), the CoM coordinate is (Attachment 6)

x 0.0351mm
y 0.0254mm
z 0.0011mm

This makes sens why we had to move the balance mass a lot for the adjustment.

  16296   Wed Aug 25 08:53:33 2021 JordanUpdateSUS2" Adapter Ring for SOS Arrived 8/24/21

8 of the 2"->3" adapter rings (D2100377) arrived from RDL yesterday. I have not tested the threads but dimensional inspection on SN008 cleared. Parts look very good. The rest of the parts should be shipping out in the next week.

  16364   Wed Sep 29 09:36:26 2021 JordanUpdateSUS2" Adapter Ring Parts for SOS Arrived 9/28/21

The remaining machined parts for the SOS adapter ring have arrived. I will inspect these today and get them ready for C&B.

  820   Mon Aug 11 00:58:31 2008 ranaUpdatePEM2 years of temperature trend
The PSL RMTEMP alarmed again because it says the room temperature is 19.5 C. Steve said in
an earlier log entry that this is a false alarm but he didn't say why he thought so...

I say that either the calibration of the RMTEMP channel has drifted, the setpoint of the HVAC
has shifted, or there's a drift in the RMTEMP channel. I don't know what electronics exactly
are used for this channel so not sure if its susceptible to so much drift.

However, since the Dust Monitor (count_temp) shows a similar temperature decline in the
last two years I am inclined to blame the HVAC system.

The attached plot shows 2 years of hour-mean trend.
  821   Mon Aug 11 09:39:29 2008 ranaUpdatePEM2 years of temperature trend
Steve and I went around and inspected and then adjusted the thermostats and humidostats.

All the thermostats were set at 70F in 2005 by Steve. We adjusted the ones on the arms up to 72F
and set the one on the wall west of the framebuilder up to 74F (this area was consistently colder
than all the others and so we're over-correcting intentionally).
  5783   Wed Nov 2 10:41:47 2011 steveUpdateGeneral2 spare heliax at the LSC rack

They were traced and labeled. One goes to 1X2 and the other to AS-ISCT. They are Andrew Heliax 1/4" od. made by CommScone,  model number FSJ1-50A

  16778   Thu Apr 14 10:18:35 2022 PacoSummaryBHD2 in oplev mirrors incompatible with LMR2V

[Paco, JC]

We realized the 2 in oplev mirrors (Thorlabs BB2-E02) for ITMYOL, SRMOL, and BSOL, are 0.47 in thick, while the LMR2V fixed mount is 0.46 in deep, even without taking the retaining ring into account. After a brief exchange with Koji, and Ian, we decided to glue the mirrors onto the mounts using Torr Seal (a vac compatible epoxy). They are curating in the clean room and should be ready to install in about 2 hours.

  3622   Wed Sep 29 16:56:36 2010 yutaUpdateVAC2 doors opened

(Steve, Koji, Joe, Kiwamu, Yuta)

 The vent was started on Monday, and finished on Tuesday.
 We were to open the doors on Tuesday, but we couldn't because the vertex crane got out of order.
 Now the crane was fixed, and so we opened the doors today.

What we did:

 We opened the north side of the BS chamber and the west side of the ITMX chamber.
 Now, the light doors are put instead.

  2744   Wed Mar 31 16:55:05 2010 josephbUpdateComputers2 computers from Alex and Rolf brought to 40m

I went over to Downs today and was able to secure two 8 core machines, along with mounting rails.  These are very thin looking 1U chassis computers. I was told by Rolf the big black box computers might be done tomorrow afternoon.  Alex also kept one of the 8 core machines since he needed to replace a hard drive on it, and also wanted to keep for some further testing, although he didn't specify how long.

I also put in a request with Alex and Rolf for the RCG system to produce code which includes memory location hooks for plant models automatically, along with a switch to flip from the real to simulated inputs/outputs.


  9691   Wed Mar 5 11:33:10 2014 KojiSummaryLSC2 arm ALS->LSC transition - road map

Step by step description of transition from 2arm ALS to Common/Differential LSC for FPMI

- Step 0: Place the frequencies of the arm green beams at the opposite side of the carrier green.

- Step 1: Activate stablization loops for ALSX and ALSY simultaneously.
  (Use LSC filter modules for the control. This still requires correct handling of the servo and filter module triggers)

- Step 2: Activate stablization loops for ALS Common and Differential by actuating ETMX and ETMY

- Step 2 (advanced): Activate stabilization loops for ALS Common by actuating MC2 and ALS Differential by ETMX and ETMY

- Step 3: Transition from ALS Common to 1/SQRT(TRX)+1/SQRT(TRY). Make sure that the calibration of TRX and TRY are matched.
  The current understanding is that the offset for 1/SQRT(TRX)+1/SQRT(TRY) can't be provided at the servo filter. Figure out
  what is the correct way to give the offsets to the TR signals.

- Step 4: Lock Michelson with AS55Q and then POP55Q (PD not available yet) or any other PD, while the arms are kept off-resonant using ALS.

- Step 5: Reduce the TR offsets. Transition to RF CARM signals obtained from POP55I or REFL11I in the digital land.

- Step 5 (advanced): Same as test6 but involve the analog common mode servo too.

- Step 6: Transition from ALS Differential to AS55Q

Independent test: One arm ALS (To be done everyday)

- ALS resonance scan

- Measurement of out-of-loop displacement (or frequency) stability 

- Check openloop transer function

Independent test: Common Mode servo for one arm

- Reproduce Decmber CM servo result of transition from one arm ALS to CM servo
  Insert 1/sqrt(TRY) servo in between?

- How can we realize smooth transition from ALS to POY11?

  6851   Fri Jun 22 02:21:57 2012 JenneUpdateGreen Locking2 arm ALS - Success!!!!

[Yuta, Jenne]

We locked both arms using the ALS system simultaneously!  Hooray!

Video of spectrum analyzer during lock acquisition of both beats is attached.

Jamie is super awesome, since he fixed us up a beatbox speedy-quick.  Thanks Jamie!!  speedy_gonzales-5257.jpg


1:  Aligned PSL green optics

     1.1:  We added an amplifier of ~20dB after the X beat PD (more Xgreen power on the PSL table so the signal was ~3dB higher than Y, so required less amplification).  The ~24dB amplifier is still in place after the Y beat PD.  Both beat signals go to a splitter after their amplifiers.  One side of each splitter goes to one of the channels on the beatbox.  The other side of each splitter goes to a 3rd splitter, which we're using backwards to combine the 2 signals so we can see both peaks on the spectrum analyzer at the same time.

2:  Found both beat notes

     2.1:  Y beat was easy since we knew the temps that have been working for the past several days

     2.2:  X beat was more tricky - the last time it was locked was the end of February (elog 6342)

         2.2.1:  We found it by adjusting the PSL laser temp nearly the full range - DC Adjust slider was at 8.8V or so (Y beat was found with the slider at ~1.1V tonight)

          2.2.2:  We then walked the beat around to get the PSL temp back to "normal" by moving the PSL temp, then compensating with the Xend laser temp, keeping the beatnote within the range of the spectrum analyzer.

          2.2.3:  Fine tuned the temps of all 3 lasers until we had 2 peaks on the analyzer at the same time!!

       Yend - measured Temp=34.14 C, thermal Out of Slow servo=29820

       Xend - displayed temp=39.33 C, thermal Out of Slow servo=5070

      PSL - displayed temp=31.49 C, Slow actuator Adjust=1.100V

3:  Locked both arms using ALS!!

     3.1:  We were a little concerned that the Xarm wasn't locking.  We tried switching the cables on the beatbox so that we used the old channels for the Xarm, since the old channels had been working for Y.  Eventually we discovered that the input of the filter module for ETMX's POS-ALS input was OFF, so we weren't really sending any signals to ETMX.  We reverted the cabling to how it was this evening when Jamie reinstalled the beatbox.

          3.1.1:  We need to sort out our SUS screens - Not all buttons in medm-land link to the same versions of the SUS screens!  It looks like the ALS screen was modified to point the ETMY button to a custom ETMY SUS screen which has the ALS path in the POS screen, along with LSC and SUSPOS.  There is no such screen (that I have found) for ETMX.  The regular IFO_ALIGN screen points to the generic SUS screens for both ETMY and ETMX, so we didn't know until Yuta searched around for the filter bank that the ALS input for ETMX was off.  We just need to make sure that all of the screens reflect what's going on in the models.

     3.2:  See the video attached - it shows the beat peaks during locking!!! (how do I embed it? right now you have to download it)

          3.2.1:  First you will see both peaks moving around freely

          3.2.2:  Then X arm is locked briefly, then unlocked

          3.2.3: Y arm is locked, steadily increasing gain

          3.2.4:  X arm is locked, so both arms locked simultaneously

          3.2.5:  Yuta clicked a button, accidentally unlocking the Xarm

4:  The transmission of the X arm was not so great, and both of our green beams (although X green especially) were no longer nicely aligned with the cavities.  Yuta tried to align the X arm to the X green, but it's bad enough that we really need to start over with the whole IFO alignment - we leave this until tomorrow.  Since we didn't have any good IR transmission, we didn't bother to try to find and hold the Xarm on IR resonance using ALS, so we didn't measure a POX out of loop residual cavity motion spectrum.  Again, tomorrow. 

  6852   Fri Jun 22 03:37:42 2012 KojiUpdateGreen Locking2 arm ALS - Success!!!!

Are these correct?

1. It is a nice work.

2. This is not locking, but stabilization of the both arms by ALS.

3. We now have the phase trackers for both arms.

4. There is no coarse (i.e. short) delay line any more.

5. The splitters after the PDs are reducing the RF power to Beat-box.
Actually there are RF monitors on Beat-box for this purpose, but you did not notice them.

6. c1ioo channel list
has to be updated.

7. Video can be uploaded to Youtube as Mike did at http://nodus.ligo.caltech.edu:8080/40m/6513

  6853   Fri Jun 22 10:52:18 2012 yutaUpdateGreen Locking2 arm ALS - Success!!!!

Answers to questions from Koji.

Are these correct?

1. It is a nice work.

Correct, of course!

2. This is not locking, but stabilization of the both arms by ALS.


3. We now have the phase trackers for both arms.


4. There is no coarse (i.e. short) delay line any more.

Correct. No coarse, only fine delay line (30m) with the phase tracker.

5. The splitters after the PDs are reducing the RF power to Beat-box.
Actually there are RF monitors on Beat-box for this purpose, but you did not notice them.

Oh, yes. But distance between beatbox and spectrum analyzer in the control room is longer than distance between BBPD on PSL table and the spectrum analyzer. We were too lazy to do cabling, but maybe we should.

6. c1ioo channel list 
has to be updated.

Yes, we will.

7. Video can be uploaded to Youtube as Mike did at http://nodus.ligo.caltech.edu:8080/40m/6513

We didn't, but we can.

  3295   Mon Jul 26 20:30:35 2010 JenneUpdateSUS2 Tip Tilts suspended and balanced

[Koji, Jenne]

We were on Team Cleanroom, while Kiwamu and Alberto were on Team Chamber.  Team Cleanroom suspended and balanced 2 Tip Tilts this afternoon.

One of the TTs that was suspended today is the one which was broken on Friday (see elog 3278).  We resuspended it using the regular 0.0036" diameter wire (91um).  We balanced it using the HeNe oplev, and then set it aside.  This TT has serial number 2.

We noticed that, like the previous 2 TT suspensions (this one before it was broken, and the one actually installed in the BS chamber on Friday, which is #3), there seems to be a little bit of hysteresis in the pointing.  The difference comes if we poke the top of the mirror holder and observe the place the reflected beam spot comes to rest at, and if we poke the bottom of the mirror holder.  The beam spot stays a little higher when we poke the top vs. when we poke the bottom. 

To combat this, we tried suspending our second TT of the day (the one that Kyung Ha and I had half finished) using thinner wire for the mirror holder.  We used the 0.0017" diameter wire (43um) that is used for the SOSes.  Unfortunately, it still seems like there is a similar hysteresis.  The thin-wire TT has serial number 4.

While working on TT4, we recalled that we have to include rubber dampers for the vertical blade springs.  Oooops!  We used some of the leftover #4-40 screws with viton tips that Zach and Mott had made for Earthquake stops to damp the vertical resonance of the blades.  We measured the Q factor by flicking the blades up or down.  We changed the oplev setup to be a shadow sensor setup, and watched the ringdown of the vertical mode on the 'scope.  We counted #cycles/time = frequency, and the t(1/2) time for the exponential ringdown to calculate the Q.  For the shadow sensor, we positioned the QPD in line with the initial HeNe beam, and placed the edge of the mirror holder clamp partially in the beam, so the beam was partly occluded.  When the mirror shook up and down, more or less of the beam was blocked, and we could see this power fluctuation on the 'scope.

Using the formula Q = pi  f0 T1/2 / ln(2) = 4.53 f0 T1/2, where T1/2 is the the time it takes for the amplitude to decay by half, we measured a Q of 31 for the vertical mode with no damping, and a Q of 14 with damping.  Koji confirmed the calculation and put it into wiki.

We need to go through the other TTs that have been assembled and give them their rubber dampers.


  2574   Fri Feb 5 14:31:46 2010 JenneUpdateSUS2 SOS towers assembled

[Jenne, Kiwamu]

The 2 SOS towers for the ITMs have been assembled, and are on the flow bench in the cleanroom.  Next up is to glue magnets, dumbells, guiderods and wire standoffs to the optics, then actually hang the mirrors.


  4830   Fri Jun 17 00:17:26 2011 ranaConfigurationElectronics2 RFPDs sent to LLO

Koji and I found 2 RFPD boxes to send to LLO. We've put them onto Steve's desk to be overnighted to Valera.

One of them is our old 21.5 MHz gold box RFPD from the FSS (which we don't use). The other one is a 2mm gold box one which was previously tuned for 66 MHz.


They shipped out on Friday

  1349   Tue Mar 3 11:39:50 2009 OsamuDAQComputers2 PCs in Martian

 Kiwamu and I brought 2 SUPER MICRO PCs from Willson house into 40m.

Both PCs are hooked up into Martian network. One is named as bscteststand for BSC which has been set up by Cds people and another one is named kami1 for temporary use for CLIO which is a bland new, no operating installed PC. This bland new PC will be returned Cds or 40m once another new PC which we will order within several days arrives.

IP address for each machine is and respectively.

We have installed CentOS5.2 into the new PC.

  7385   Fri Sep 14 01:18:51 2012 ranaUpdateCOC2 Layout Changes

After looking at the in-vacuum layout I think we should make two changes during the next vent:

1) Reduce the number of mirrors between the FI and its camera. We install a large silvered mirror in the vacuum flange which holds the Faraday cam (in the inside of the viewport). That points directly at the input to the Faraday. We get to remove all of the steering mirror junk on the IO stack.

2) Take the Faraday output (IFO REFL) out onto the little table holding the BS and PRM Oplevs. We then relocate all 4 of the REFL RFPDs as well as the REFL OSA and the REFL camera onto this table. This will reduce the path length from the FI REFL port to the diodes and reduce the beam clutter on the AS table.

  7398   Mon Sep 17 18:04:01 2012 SteveUpdateCOC2 Layout Changes


After looking at the in-vacuum layout I think we should make two changes during the next vent:

1) Reduce the number of mirrors between the FI and its camera. We install a large silvered mirror in the vacuum flange which holds the Faraday cam (in the inside of the viewport). That points directly at the input to the Faraday. We get to remove all of the steering mirror junk on the IO stack.

2) Take the Faraday output (IFO REFL) out onto the little table holding the BS and PRM Oplevs. We then relocate all 4 of the REFL RFPDs as well as the REFL OSA and the REFL camera onto this table. This will reduce the path length from the FI REFL port to the diodes and reduce the beam clutter on the AS table.

 There is just so much room on this table.

  3960   Sat Nov 20 02:25:30 2010 yutaUpdateCDS2 LOCKINs for suspension models

(Suresh, Koji, Yuta)

  No AWG. No tdssine.
  ...... LOCKIN!

What we did:
  1. Added 2 LOCKINs for c1sus model.
   Currently, we cannot put cdsOsc in a subsystem.
   So, we put LOCKINs just for BS for a test.
   The signal going into LOCKIN can be anything. For now, we just put a matrix for selecting the signal and connected the input signals to the ground.

   See the following page for the current simlink diagram of c1sus model.

  2. Edited MEDM screens. (see Attachment #1)

  We succeeded in putting 2 LOCKINs and exciting BS.
  During the update, we might destroyed things. For example, fb status is red in GDS screens.
  We will wait for Joe to fix them.

 - Fix cdsOsc and put LOCKINs for all the other optics
 - Come up with a good idea what to do with this LOCKIN. Remember, LOCKIN is not just a replacement for excitation points.
 - Enhance an oscillator so that we can put a random noise

  3314   Wed Jul 28 18:24:57 2010 JenneUpdateGreen Locking2 Green Periscopes have mirrors, aligned

[Koji, Jenne, Kiwamu]

This is to describe the work that went on in the Cleanroom today.  Kiwamu's entry will detail the tidbits that happened in the chamber.

We engraved the periscope mounts with the mirror info for the mirrors which were placed in the periscope.  We also engraved the barrels of the optics with their info, for posterity.  Koji carefully put the mirrors into the periscopes.  Since we have wedged optics, the goal was to have the front HR surface of the mirror parallel to the plane of the mount, and leave a bit of space behind one side of the optic (if we just pushed the optic fully in, the HR surface wouldn't be flat, and would send the beam off to the left or right somewhere).  Once the mirrors were mounted in the periscopes, we checked the vertical levelness of the outcoming beam.  For the first periscope (the one which has been installed on the BS table), the beam was deflected upward (2.5)/32 inches over 55inches.  This corresponds to a 1.4mRad vertical deflection.  The second periscope (which will eventually be installed on the OMC table) had a deflection of 1/32 over 55inches, or 0.6mRad.  We did not check the side-to-side deflection for either of the periscopes.

We also engraved one more DLC mount with mirror info, and put a mirror into the mount.  This is one of the optics that was placed onto the BS table today, which Kiwamu will describe.

We removed TT#3 from the BS chamber so that it could have rubber vertical dampers installed, and be characterized.  For future reference, the #'s of the Tip Tilts refers to the serial number of the suspension block piece, which forms the top horizontal bar of the frame. 

  329   Thu Feb 21 19:55:46 2008 ranaUpdateElectronics2 BNC Cables, 1 Tee
I'm not sure where Ward and Miller went to Analyzer school, but it was probably uncredited.
I turned it on and used 2 BNC cables and a T to hook up the source to the 2 inputs and measured the always-exciting TF of cable.

Score:  HP Analyzer  1
        Rob & John   0

I have left the analyzer on in this complicated configuration. RTFM boys.

The HP 4195A network analyser may be broken, measurements below 150MHz are not reliable. Above 150MHz everything looks normal. This may be caused by a problem with its output (the one you'd use as an excitation) which is varying in amplitude in a strange way.

  7626   Thu Oct 25 21:02:34 2012 DenUpdatePEM1x7 dc power

 We now stop using bench DC power supplies for microphone preamp and PEM AA board. DC power is wired from 1x5 rack suppliers. I've installed a beam to mount fuse houses in the 1x7 as we did not have one.


  6076   Tue Dec 6 02:57:44 2011 kiwamuUpdateGreen Locking1st trial of handing off

I succeeded in handing off the servo from that of the ALS to IR-PDH.

However the handing off was done by the coarse sensor instead of the fine sensor because I somehow kept failing to hand off the sensor from the coarse to the fine one.

The resultant rms in the IR-PDH signal was about a few 100 pm, which was fully dominated by the ADC noise of the coarse sensor.


Tomorrow I will try :

  (1) Using the fine sensor.

  (2) Noise budgeting with the fine sensor.


Here is the actual time series of the handing off.


(Upper left ):  intracavity power.
            As the offset was adjusted the power increased to ~ 0.8. Eventually the power becomes close to the nominal value of 1 after the handing off.
(Lower left) : Frequency of the beat-note.
            After the engagement of the ALS servo, I was scanning the arm length and searching for the resonance by changing the error point of this signal.
(Lower right) : IR-PDH signal.
  8507   Mon Apr 29 18:53:03 2013 JenneUpdateElectronics1pps timing fiber to OMC rack may be bent

While helping Riju out this afternoon, I noticed that the timing fiber that goes to the OMC rack (near the AP table) was bent, and is now possibly kinked, after the installation of the fiber splitter box. 

The fiber was hanging from the back of the rack, and had been strain relieved.  However, the path that the fiber was taking is now occupied by the fiber splitter for the RF PD diagnostic stuff.  So, the installation of the fiber splitter box put the old timing fiber under tension, causing the fiber to be bent at a little over 90 degrees, since it was pulled tightly against the corner of the splitter's front panel. 

I adjusted the strain relief so that the fiber is loose again, although there is still a bit of a kink that you can feel.  Things (for now) seem to be working, since the 1pps light on the front of the box at the top of the OMC rack is still blinking happily, indicating that the 1pps is still getting there. 

We are not using most of the stuff in that rack right now, but if we have problems in the future, we should check out the fiber to make sure it is still good.

  593   Sun Jun 29 18:58:43 2008 ranaSummaryComputers1e20 is too big for AWG and/or IOVME
While testing out my matlab/awgstream based McWFS diagnostic script I accidentally put a
huge excitation into
. This went to 1e20 and then caused
some SUS to trip and c1susvme2 to go red. I tried booting it via the normal procedures
but it wouldn't come back, even after 2 crate power cycles. I also tried booting AWG
via the vmeBusReset, but that didn't do it. Then I booted c1iovme from the telnet prompt
and then I could restart c1susvme2 successfully.

The reason the excitation was so large is that the following filter command is unstable:
[b,a] = butter(4,[0.02 30]/1024);

The low pass part is OK, but it looks like making such a low frequency digital filter
is not. Que lastima. On the bright side, the code now has some excitation amplitude
  2173   Tue Nov 3 12:47:01 2009 KojiConfigurationCDS1Y9 Rack configuration update

For the CDS upgrade preparation I put and moved those stuff at the rack 1Y9:

Placed 1Y9-12 ADC to DB44/37 Adapter LIGO D080397

Placed 1Y9-14 DAC to IDC Adapter LIGO D080303

Moved the ethernet switch from 1Y9-16 to 1Y9-24

Wiki has also been updated.

  948   Mon Sep 15 14:00:52 2008 josephbConfigurationComputers1Y9 Hub and C1asc
The 1Y9 switch is now using a labeled Cat6 cable in cable trays to connect to the main switch in the offices. In addition, the c1asc cable which had been coming out the door was fixed last Friday, and is now labeled, going out the top and connects to the hub in 1Y2.

Note: Do not connect new ethernet cable from switch to switch without disconnecting the old cable to the rest of the network - this tends to make the Ethernet network unhappy with white flashing alarms.
  14848   Fri Aug 16 16:40:04 2019 gautamUpdateCDS1Y3 work

[chub, gautam]

Installation: The following equipment were installed in 1Y3, see Attachment #1:

  1. Supermicro server, which is the new c1iscaux machine, with IP Address
  2. 6U Acromag chassis which contains all the ADCs, DACs and BIO units.
  3. 2 Sorensen DC power supplies to provide +24 V DC and +15 V DC to the Acromags.
  4. Fusable DIN rail power blocks were installed on the North side of the 1Y3 rack - I placed 2 banks of 5 connectors each for +15 V DC and +24 V DC.

Removal: The following equipment was removed from 1Y3:

  1. VME crates that were the old c1iscaux and c1iscaux2 machines.
  2. Spare VME crate that used to be c1susaux, which Chub and I brought over to 1Y3 in an attempt to revive the broken c1iscaux2.
  3. Approximately 30 twisted ribbon cables that were going to the cross connects. For now, we have not done a full cleanup and they are just piled along the east arm (see Attachment #2), beware if you are walking there!


  1. I connected the c1iscaux machine to the martian network.
  2. Then I edited the relevant files on chiara to free up the IP addresses previously used by c1iscaux ( and c1iscaux2 (, and re-assigned the IP address used for c1iscaux to be
  3. I also changed the hostname of the c1iscaux machine (it was temporarily called c1iscaux3 to allow bench testing).
  4. I moved the old /cvs/cds/caltech/target/c1iscaux and /cvs/cds/caltech/target/c1iscaux2 directories to /cvs/cds/caltech/target/preAcromag_oldVME/c1iscaux and /cvs/cds/caltech/target/preAcromag_oldVME/c1iscaux2 respectively.
  5. I moved the temporarily named /cvs/cds/caltech/target/c1iscaux3 directory, from which I was running all the tests, to /cvs/cds/caltech/target/c1iscaux.
  6. I edited all references to c1iscaux3 in the systemd files so that we can run the approriate systemd services.

Next steps: 

  1. We did not get around to running the DB37 cables between the Acromag chassis and the 1Y2 Eurocrates today - this operation itself took the whole day as we also needed to lay out some support struts etc on the rack to support the Sorensens and the Acromag chassis.
  2. Once the Acromags are connected to the Eurocrates, we have to run in-situ tests to make sure the appropriate functionality has been restored.
  3. We must have bumped something in the c1lsc expansion chassis - the CDS FE overview screen is reporting some errors (see Attachment #3). I will fix this.
  4. General tidiness, strain-relief etc.

I judge that we are good to go ahead with an install tomorrow.

  4609   Tue May 3 10:59:31 2011 josephbUpdateCDS1Y2 binary output adapter board now powered

I temporarily turned off the power to the 1Y2 rack this morning while wiring in the binary output adapter board power (+/- 15V) into the cross connects.

The board is now powered and we can proceed to testing if can actually control the LSC whitening filters.

  4717   Sat May 14 14:50:21 2011 KojiUpdateLSC1Y2 5V Blown Fuse found -> Fixed

Incidentally, a blown fuse on 5V line at 1Y2 rack was found during the intallation of Sorensens.
The fuse (5A 125V) has been replaced and fixed.

When I plugged the fuse in, I heard some sound like relays were switched. Are there any relays in the LSC rack?

It was a 9th fuse from the top as seen in the picture.

  16453   Mon Nov 8 10:13:52 2021 PacoSummaryBHD1Y1 rack work; Sorensens removed

[Paco, Chub]

Removed all sorensen power supplies from this rack except for 12 VDC one; that one got pushed to the top of the rack and is still powering the cameras.

  16454   Mon Nov 8 13:13:00 2021 KojiSummaryBHD1Y1 rack work; Sorensens removed

Updated the rack layout. Now there is an issue.
We were supposed to have 1U space at the top, but it was occupied by the 12V.
We need to either lower the c1sus2 and IO chassis 1U or move the Sorensen at the bottom.

  16455   Mon Nov 8 15:29:05 2021 PacoSummaryBHD1Y1 rack work; New power for cameras

[Paco, Anchal]

In reference to Koji's concern (see previous elog), we have completely removed sorensen power supplies from 1Y1. We added a 12 Volts / 2 Amps AC-to-DC power supply for the cameras and verified it works. We stripped off all unused hardware from shutters and other power lines in the strips, and saved the relays and fuses.

We then mounted SR2, PR3, PR2 Sat Amps, 1Y1 Sat amp adapter, and C1SUS2 AA (2) and AI (3) boards. We made all connections we could make with the cables from the test stand, as well as power connections to an 18 VDC power strip.

  16540   Mon Jan 3 16:46:41 2022 PacoUpdateBHD1Y1 rack work for SR2, PR2, PR3

[Paco, Anchal]

Continued working on 1Y1 rack. Populated the 6 coil drivers, made all connections between sat amp, AA chassis, DAC, and ADC adapters for SR2, PR2, and PR3 suspensions. Powered all boxes and labeled them and cables where needed. Near the end, we had to increase the current limit on the positive rail sorensen (+18 V) from ~ 7 to > 8.0 Amps to feed all the instruments. We also increased the negative (-18 V) current limit proportionally.

We think we are ready for all the new SOS on this side electronics-wise.

Photos: https://photos.app.goo.gl/GviuqLQviSPo1M3G6

  16444   Tue Nov 2 16:42:00 2021 PacoSummaryBHD1Y1 rack work

[paco, ian]

After the new 1Y0 rack was placed near the 1Y1 rack by Chub and Anchal, today we worked on the 1Y1 rack. We removed some rails from spaces ~ 25 - 30. We then drilled a pair of ~ 10-32 thru-holes on some L-shaped bars to help support the c1sus2 machine weight. The hole spacing was set to 60 cm; this number is not a constant across all racks. Then, we mounted c1sus2. While doing this, Paco's knee clicked some of the video MUX box buttons (29 and 8 at least). We then opened the rack's side door to investigate the DC power strips on it before removing stuff. We did power off the DC33 supplies on there. No connections were made to allow us to keep building this rack.

When coming back to the control room, we noticed 3/4 video feed (analog) for the Test masses had gone down... why?

Next steps:

  • Remove sorensen (x5) power supplies from top of 1Y1 .. what are they actually powering???
  • Make more bars to support heavy IO exp and acromag chassis.
  • Make all connections (neat).

Update Tue Nov 2 18:52:39 2021

  • After turning Sorensens back up, the ETM/ITM video feed was restored. I will need to hunt the power lines carefully before removing these.
  16448   Thu Nov 4 15:03:43 2021 KojiSummaryBHD1Y1 rack work

I have visited the binder file for the 40m wiring file in the control room.
The 12V power supply on 1Y1 is for the CCD cameras. So we still want to keep the 12V 0.8A power and the side connections for these. It is not necessary to be Sorensen. Can we replace it with an AC-DC adapter with +12V/1A for example? BTW, the video matrix and quads are AC-powered.

The mysterious thick cables and cross-connects (green wires) on the side panel (labeled AP1/AP2/SP/IMCREFL) are for "EO shutters". It was meant for the protection of the PDs from bright beams.
I don't think they have been used. And we don't need them.

  16440   Fri Oct 29 14:39:37 2021 AnchalSummaryBHD1Y1 cleared. IY3 ready for C1SUS2 I/O and FE.

[Anchal, Paco]

We cleared 1Y1 rack today removing the following items. This stuff is sitting on the floor about 2 meters east of 1Y3 (see attachment 1):

  • A VME crate: We disconnected it's power cords from the side bus.
  • A NI PXIe-1071 crate with some SMA multiplexer units on it.

We also moved the power relay ethernet strip from the middle of the rack to the bottom of the rack clearing the space marked clear in Koji's schematics. See attachment 2.

There was nothing to clear in 1Y3. It is ready for installing c1sus2 I/O chassis and FE once the testing is complete.

We also removed some orphaned hanging SMA RG-405 cables between 1Y3 and 1Y1.

  16539   Mon Jan 3 12:05:08 2022 PacoUpdateBHD1Y0 rack work for LO2 AS1 AS4

[Paco, Anchal]

Continue working on 1Y0. Added coil drivers for LO2, AS1, AS4. Anchal made additional labels for cables and boxes. We lined up all cables, connected the different units and powered them without major events.

  16506   Tue Dec 14 19:29:42 2021 PacoUpdateBHD1Y0 rack work for LO1


Two coil drivers have been installed on 1Y0 (slots 6, 7, for LO1 SOS). All connections have been made from the DAC, AI board, DAC adapter, Coil driver, Sat Amp box. Then no SOS load installed, all return connections have been made from Sat Amp box, ADC adapter, AA board, and to ADC. We will continue this work tomorrow, and try to test everything before closing the loop for LO1 suspension.

  16463   Tue Nov 9 19:02:47 2021 AnchalSummaryBHD1Y0 Populated and 1Y1,1Y0 powered

[Anchal, Paco]

Today we populated 4 Sat Amp boxes for LO1, Lo2, AS1, and AS4, 2 BO boxes for C1SU2, and 1 Sat Amp Adaptor box, at 1Y0 according the latest rack plan. We also added 2 Sorenson power supplies in 1Y0 at the top slots to power +/- 18V DC strips on both 1Y1 and 1Y0. All wiring has been done for these power connections.

  5993   Thu Nov 24 01:28:09 2011 kiwamuUpdateGeneral1X8 sorensen came back

Quote from #5963

 - One of the Sorensens in 1X8 rack is showing the current limit sign. This is exactly the same situation as we saw before (#5592).

       Currently it's off. It needs an investigation to find who is drawing such a large amount of current.

 The 1X8 Sorensen's issue has been solved somehow.

 To investigate what is going on with the Sorensen in the 1X8 rack, I turned on the Sorensen.
Then this time it didn't show the current limit sign, the voltage went up to 15.0, where it is supposed to be.
Surprisingly this is exactly the same recovery process as we saw before (#5592).
ELOG V3.1.3-