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ID Date Author Type Category Subjectup
  8438   Thu Apr 11 02:00:21 2013 JenneUpdateLockingTRY gone???

TRY signals are all gone!  Both the PD and the camera show no signal.  I went down there to turn off the lights, and look to see what was up, and I don't see any obvious things blocking the beam path on the table.  However, Steve has experimentally bungeed the lids down, so I didn't open the box to really look to see what the story is.

Absent TRY, I redid the IFO alignment.  Yarm locked, so I assumed it was close enough.  I redid Xarm alignment pretty significantly.  Transmission was ~0.5, which I got up to ~0.85 (which isn't too bad, since the PMC transmission is 0.74 instead of the usual 0.83).  I then aligned MICH, and PRM.  After fixing up the BS alignment, the POP beam wasn't hitting the POP PD in the center any more.  I centered the beam on the PD, although as Gabriele pointed out to me a week or two ago, we really need to put a lens in front of POP, since the beam is so big.  We're never getting the full beam when the cavity flashes, which is not so good.

Den is still working on locking, so I'll let him write the main locking report for the night.

We see that the PRC carrier lock seems to be more stable when we lock MICH with +1 for ITMY and -1 for ITMX, and PRCL with -1 for both ITMs.  This indicates that we need to revisit the systematic problem with using the PRM oplev to balance the coils, since that oplev has a relatively wide opening angle.  I am working on how to do this.

  10401   Fri Aug 15 14:09:21 2014 JenneUpdateLSCTRY mystery offset gone

Again unknown, but about 6 hours ago (so ~8am) the offset disappeared. 

Here's a 1-day trend:

TRY_0pt3_offset_gone.pdf

  10402   Fri Aug 15 14:35:57 2014 ericqUpdateLSCTRY mystery offset gone

One question answered, but another raised. The offset came from LSC-TRY switching to the ETMY-QPD signal from ETMY-TRY (Hi gain pd). 

BUT WHY

TRYmystery.png

  5654   Wed Oct 12 00:35:42 2011 kiwamuUpdateLSCTRY path realigned

The TRY (TRansmitted light from Y arm ) path was a bit realigned because there had been a small clipping.

This clipping was introducing offsets on the error signals of the C1ASS servo.

(Story)

During I was running the C1ASS servo on the Y arm I found every time after the auto-alignment is done there still remained a slight offset in the beam pointing,

I looked at the CCD camera which looks at the transmitted light and then introduced an intentional misalignment in ETMY in order to find an obvious clipping.

Indeed there was a clipping in horizontal direction. I checked through the optics on the Y end optical bench.

On the second mirror (beam splitter) the beam was on a very edge. So I steered the first steering mirror to fix it,

In addition to that an iris which is placed between the first and second mirror was also clipping the beam,

So I fully opened the aperture of the iris.

  4656   Sat May 7 02:52:53 2011 kiwamuUpdateLSCTRY photo diode installed

[Suresh / Kiwamu]

 We installed the TRY photo diode (Thorlabs one) and the ETMYT CCD camera in place on the ETMY table.

Now we can see a signal on the TRY digital channel.

It will be quite useful for the Y arm locking, for instance we can do a triggered locking and the maximization of the intracavity power.

Someone has to install the EMTY trans QPD at some point.

  8568   Tue May 14 01:13:35 2013 JenneUpdate40m UpgradingTRY realigned

Koji noticed that earlier this afternoon the Yarm ASS was working, but then after dinner it was no longer working.  I saw that the ETMY trans camera beam was clipped.  These things precipitated a visit to the Yend station. 

I saw that the beam on the optic that steers the camera beam to the camera was very, very low, almost falling off the optic.  The only mirror which steers to this optic is the harmonic separator which reflects the IR, and transmits the green.  I turned the pitch knobs on the harmonic separator until the beam was roughly centered on all 3 optics between the separator and the camera (BS to QPD, BS to TRYDC and Y1 for camera).  The yaw was fine, so I didn't touch it.

I then adjusted the steering mirror to the camera, and the BS pointing to the DC PD.  I have not touched the BS pointing to the QPD.  Once the beam was on the TRY PD, Koji ran the ASS script, and I recentered the beam on the DC PD.  During this time, Koji had the Yarm triggering using -1 in the POYDC element of the matrix.

The harmonic separator is not mounted in a nice way (I'm assuming that Annalisa is in the middle of things, and she'll get back to it after the green work), so the TRY PD and camera will need to be aligned again, so I didn't do any ASS-recentering-ASS iteration tonight.

The Yarm ASS works nicely again, getting TRY to ~0.89 . 

  7443   Wed Sep 26 17:09:15 2012 DenUpdateSUSTT

  [Koji, Steve, Den]

TT alignment is fine, yaw damping is satisfactory, pitch damping is slow. We might want to add magnets to the mirror and attach blades to the frame for pitch edge current damping.

We are moving towards electronics testing.

  7876   Fri Jan 4 15:11:28 2013 JenneUpdate TT

[Jenne, Koji]

D - UL

B - UR

A - LR

C - LL

The sensor card on the bottom of the chamber was not salvaged yet.

  7898   Mon Jan 14 15:15:04 2013 JenneUpdate TT

 

[Manasa, Jenne]

First plug in only one of the quadrupus cables, find out what coil it corresponds to according to screen, then plug in 2nd cable, don't test already-determined cable, but all other 3, find what cable it corresponds to according to the screen.  Repeat for other 2 cables.

TT2, confirmation:

C = LL, not UR, not UL, not LR

D = UL, not UR, not LR

A = LR, not UR

B = UR

 

---------------------------------------------------------------------------------------

After confirming that the correct quadrupus cables were plugged in to the correct coils, I suspected that our problems could be coming from a (or some) magnet(s) touching the inside of the OSEM.  We tested this a little bit, with the goal of finding the range of values where no magnets are touching.

All matrix values are either +1000 or -1000, so, with an example pitch slider value :

                       PIT    YAW

Pit slider           |  1000   1000  | --->  -22000 UL

     -22.2           | -1000   1000  | --->  +22000 LL

Yaw slider           |  1000  -1000  | --->  -22000 UR

    0                | -1000  -1000  | --->  +22000 LR

 

 

Trying some values for pitch, keeping yaw constant:

0 yaw, Pitch bias = 5 -> UR is touching on left side of its osem.

0 yaw, Pitch 0, UR is touching left side.

0 yaw, -1.2 pitch, UR just came off from touching left side.  More neg from here should be non-touching.  all others are fine.

0 yaw, -32.2 pitch, LR not quite touching right side of osem, but is close (much less than 1mm clearance).  UR fine. all others fine.

0 yaw, -22.2 pitch, all 4 are fine.

 

Trying some yaw values, keeping pitch constant:

1.  -22.2 pitch, -32 yaw, LR touching. UR touching.

2.  -22.2 pitch, -12 yaw, LR barely not touching, UR still touching.

3.  -22.2 pitch, 0 yaw, UR still touching.

4.  -22.2 pitch, 16 UR barely not touching.

5.  -22.2 pitch, 32, none touching.

6.  -22.2 pitch, 12, UR close, not touching.

7.  -22.2 pitch, 0, UR touching.

8.  -22.2 pitch, 32 (or 30?) UR came off.

9.  -22.2 pitch, -25, UR close

10.  -22.2 pitch, -32 UR touching.

11.  -22.2 pitch, -4 UR not touching.

12.  -22.2 pitch, 0 yaw, UR not touching.

 

Here is a graphical semi-representation for the yaw data:

 TT2_stuck_unstuck_14Jan2013.png

 

  7899   Mon Jan 14 19:56:48 2013 ManasaUpdate TT

 

 [Manasa, Jenne]

The motion of the magnets (~1.5mm estimated by looking at the magnets moving) correspond to ~2deg. tilt of the mirror. This would mean almost 1.5m shift at the ETM end (~45m from the TT).

  7900   Tue Jan 15 01:41:40 2013 ranaUpdateSUSTT

 That seems like easily enough range; as long as we can put the TT into the middle of their range to start with we should be OK.

We should consider instrumenting the leakage transmission through all TT with a bare QPD on a stick. We can then use those sensors to monitor the spot positions within the input mirrors as well as the PRC / SRC.

  7535   Fri Oct 12 10:39:45 2012 SteveUpdateSUSTT PITCH damping

Quote:

Quote:

  [Koji, Steve, Den]

TT alignment is fine, yaw damping is satisfactory, pitch damping is slow. We might want to add magnets to the mirror and attach blades to the frame for pitch edge current damping.

We are moving towards electronics testing.

Atm1,  TT 1.5" high adaptor base will be back from the shop in 10 days.

Atm2,  There is no PITCH damping, YAW edie current damping works well at 0.5 mm gap

Atm3,  Adjustable Al -disc that contains a small magnet is purely designed.

We have to come up with a solution to have damping in PITCH

 We can only decide the need of pitch damping when the coils are activated.

Attachment 1: IMG_1709.JPG
IMG_1709.JPG
  7536   Fri Oct 12 14:01:33 2012 KojiUpdateSUSTT PITCH damping

Quote:

 We can only decide the need of pitch damping when the coils are activated.

Could you tell us why? Are you thinking about induced current damping?

  7538   Fri Oct 12 16:59:26 2012 steveUpdateSUSTT PITCH damping

Quote:

Quote:

 We can only decide the need of pitch damping when the coils are activated.

Could you tell us why? Are you thinking about induced current damping?

      I  was wrong The instability will be the same when the coils are actuated.

  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)

 

  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?

  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)] ?

 

  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

 

  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

  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

  5222   Sat Aug 13 15:40:38 2011 NicoleSummarySUSTT Shaking Today and Hopefully More?

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

  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

  7831   Fri Dec 14 09:05:04 2012 steveUpdatePEMTT after eq 6.1

 

 SRM, ITMY and MC3 moved some what, but how are the TT? It may worth looking at them before we vent.

Attachment 1: eq6.1.png
eq6.1.png
  7428   Fri Sep 21 22:43:51 2012 DenUpdateSUSTT alignment

I did TT alignment using red laser and QPD.

P9210079.JPG       P9210092.JPG

 I had a problem aligning TT with frame number SN-035 as some screws are damaged so all what I could move were 2 blades on the sides of the mirrors. But this was not enough to align pitch and yaw simultaneously.  It is possible to align pitch only, but then I got a huge yaw angle (~0.05-0.1 rad). The only option I had was to make a reasonable alignment in yaw and then suspend several washes on the screw on the bottom of the mirror to align pitch.

Attached are flag positions inside coils. 1 - SN034, 2 - SN012, 3 - SN006, 4 - SN035. For each TT there are 4 pictures with flag 1-4: UL, LL, UR, LR

Attachment 3: 1.pdf
1.pdf 1.pdf 1.pdf 1.pdf
Attachment 4: 2.pdf
2.pdf 2.pdf 2.pdf 2.pdf
Attachment 5: 3.pdf
3.pdf 3.pdf 3.pdf 3.pdf
Attachment 6: 4.pdf
4.pdf 4.pdf 4.pdf 4.pdf
  7821   Thu Dec 13 04:29:34 2012 DenUpdateSUSTT angle of incidence

I think the angle of incidence on TT inside BSC will be too large because of eddy current damping brackets. I've measured max possible angle of incidence

  Max angle of incidence, degrees
No bracket 72
Original bracket 45
New bracket (with no screws for tiny yaw magnets) 52

This means that we do not have too much range and there is a probability that 45 degree incident beam will start clipping. I think we should just cut off the central part of the bracket. We do not need it anyway, our eddy current damping due to corner magnets is good enough.

I've left the brackets near the laptop in the clean room.

  7826   Fri Dec 14 01:42:53 2012 DenUpdateSUSTT angle of incidence

I've estimated max possible angle of incidence on TT if we allow 20mm tolerance for the beam size and 5 mm tolerance for spot location on the mirror. It turns out to be

alpha = 43 degrees

So we need to cut the central part of the bracket. Then the max possible angle of incidence will be

alpha = 63 degrees

 

DSC_4791.jpeg

We can start the vent on Monday and use TT with an old bracket for yaw damping and later during the week we can install the brackets after they will be baked.

  7827   Fri Dec 14 02:52:32 2012 KojiUpdateSUSTT angle of incidence

At least, we don't want to use Al-coated mirrors. We should use multilayer dielectric mirrors.

  7828   Fri Dec 14 03:15:49 2012 JenneUpdateSUSTT angle of incidence

But have you looked yet at what angle we need? The first input string mirror has a quite small incidence angle. The other input steering mirror maybe borderline, based on your estimates. Also, have we considered just having new brackets made and cleaned? Is there a reason we would prefer to modify the ones we have?

  7850   Tue Dec 18 15:32:29 2012 JenneUpdateSUSTT angle of incidence

Quote:

At least, we don't want to use Al-coated mirrors. We should use multilayer dielectric mirrors.

 I popped into the cleanroom earlier today, and all 4 active TTs have dielectric coatings.  I'm not sure why the mirror in this photo looks funny, but the actual mirrors installed are correct, at least in type of coating. 

I'm not sure if Den wrote down what mirrors are actually in there, and I didn't look carefully - I don't know if they are G&H, CVI, other mystery company?

  7775   Sun Dec 2 00:37:49 2012 DenUpdateSUSTT cable problem

 This week I've got all TT stuff baked and today was testing eddy current damping and electronics.

In the beginning everything was good: ring magnets fit mirror holder holes and their interaction with actuation magnets is strong enough to keep damping magnets in the wholes. I've put the frame horizontally and kicked it, magnets were still in the whole. Brackets also fit to the TT frame.  

DSC_4945.JPG     DSC_4946.JPG

I've tested eddy current dumping during ring down measurements, it was strong enough.

DSC_4947.JPG    DSC_4948.JPG

Then I started to test electronics. I've provided signal to TT1 channels and could see it in the clean room. But then things went terrible. I just could not connect TT cables to OSEMS, there is not enough space in the OSEM for the connector to plug in.

DSC_4949.JPG     DSC_4952.JPG

Connector should be machines to be more narrow. There is actually no reason for a connector to have this shape. I think it was designed to fit perfectly the OSEM frame but turned out to be ~0.5 mm wider then it should be.

  14899   Thu Sep 19 11:26:18 2019 gautamUpdateIOOTT cables DON'T need to be remade

False alarm - the mistake was mine. Looking at the schematic diagram, the AI/Dewhite board, D000316, accepts the inputs from the DAC on the P2 connector. While restoring the connections at 1Y2, I had plugged the outputs of the DAC interface board into the P1 connectors of the AI boards. Having rectified this problem, I am now able to move the beam on the AS camera in both PIT and YAW using TT1 or TT2. So to zero-th order, this subsystem appears to work. A more in-depth analysis of the angular stability of the TTs can only be done once we re-align the arms and lock some cavities.

  14897   Wed Sep 18 15:27:45 2019 gautamUpdateIOOTT cables need to be remade

Summary:

The custom ribbon cables piping the coil driver board outputs to the eLIGO (?) TTs (a.k.a. TT1 and TT2) are damaged. They need to be re-made. I can't find any pin-mapping for them.

Details:

While waiting for the LSC photodiode whitening switching cross-connect work to be done, I thought I'd re-align the IFO a bit. However, I was unable to find any beam making it to the REFL/AS ports despite some TT steering. I remembered that Chub had undone the TT connections at 1Y2 as well, and thought I'd check the cabling to make sure all was in order. On going to the rack, however, I found that these connections were damaged at the coil-driver end (see Attachment #1), presumably during the cable extraction. These need to be re-made...😔 

Attachment 1: IMG_7945.JPG
IMG_7945.JPG
  14898   Thu Sep 19 09:39:30 2019 gautamUpdateIOOTT cables need to be remade

While debugging this problem, c1lsc models crashed. I ran the reboot script this morning to bring the models back. There was a 0x4000 error on the DC indicators for the c1lsc models (mx_stream error which couldn't be fixed by restarting the mx service) the first time I ran the script so I did it again, now the indicator lights are in their nominal state.

Attachment 1: CDSoverview.png
CDSoverview.png
  14469   Fri Feb 22 12:19:46 2019 gautamUpdateIOOTT coil driver Vmon

To debug the issue of the suspected drifting TTs further, I temporarily hijacked CH0-CH8 of ADC1 in the c1lsc expansion chassis, and connected the "MON" outputs of the coil drivers (D010001) to them via some DB9 breakouts. The idea is to see if the problem is electrical. We should see some  slow drift in the voltage to the TTs correlated with the spot walking off the IPPOS QPD. From the wiring diagram, it doesn't look like there is any monitoring (slow or fast) of the control voltages to the TT coils, this should be factored into the Acromag upgrade of c1iscaux/c1iscaux2. EPICS monitoring should be sufficient for this purpose so I didn't setup any new DQ channels, I'll just look at the EPICS from the IOP model.

Quote:
Already, in the last ~1 hour, there has been considerable drift - see Attachment #2. The spot, which started at the center of the CCD monitor, has now nearly drifted off the top end. The ITMX and BS Oplev spots have been pretty constant over the same timescale, so it has to be the TTs?
  7446   Thu Sep 27 15:21:04 2012 SteveUpdateSUSTT height adaptor & PTICH damping

Quote:

  [Koji, Steve, Den]

TT alignment is fine, yaw damping is satisfactory, pitch damping is slow. We might want to add magnets to the mirror and attach blades to the frame for pitch edge current damping.

We are moving towards electronics testing.

Atm1,  TT 1.5" high adaptor base will be back from the shop in 10 days.

Atm2,  There is no PITCH damping, YAW edie current damping works well at 0.5 mm gap

Atm3,  Adjustable Al -disc that contains a small magnet is purely designed.

We have to come up with a solution to have damping in PITCH

Attachment 1: 09271201.PDF
09271201.PDF
Attachment 2: IMG_1656.JPG
IMG_1656.JPG
Attachment 3: IMG_1654.JPG
IMG_1654.JPG
  7869   Fri Dec 21 16:50:30 2012 RanaUpdateSUSTT in vac DB25 pin swapping

[Koji, Rana, Nic, Steve]

We went to the 25-pin D cable which connects to the TT1 quadropus and succeeded eventually in swapping pins 12/24 into the 13/25 positions.

  1. The D-sub connector is a custom made LIGO part and so it doesn't at all work to use the standard pin extractor tools to move the pins out; we should have investigated this before spending all this time poking at and possibly damaging the existing connector.
  2. To move the pins, we have to partially dis-assemble the connector and fish the pins/wires through the appropriate holes. Unfortunately, the design is such that we nearly lose all of the pins when trying to do this. Pictures describe the story better than words.
  3. After the swap we tried to test the TT, but again wasted some time because the vac feedthrough was incorrectly labeled. The 25-pin feedthrough labeled as "PZT1" does not, in fact, connect to the TT. Instead, its the one slightly above it that is labeled "Pico". I have moved the PZT1 sticker up to match the actual connector. In order to discover this, we beeped through several stages of the coil driver, cable system. WE need to order some in-line D-sub breakouts for 25pin, 37pin, and 9pin which are similar to the ones we have now for 15pin. These are better than the green terminal block breakouts.
  4. After this, we were able to see the TT move, but elected to leave the final piece of the work (determining which microD goes with which coil) to when Jamie gets back.
  5. The TT screen is not good: it needs to be just like the usual sus screen so that we can put in offsets, excitations, etc. Perhaps also the ASC-TT screen can link to the TT:SUS screens. We can just copy the eLIGO TT screens to get going.
  7871   Wed Jan 2 06:52:50 2013 KojiUpdateSUSTT in vac DB25 pin swapping

[Koji, Rana, Nic, Steve]

I recalled that we used an optical lever to check if the TT is moving or not.
We used a laser pointer on a tripod, which was prepared by Steve.

I should also note that we stepped back the eddy current dampers from the magnets
in order to enhance the motion of the suspension. They should be restored in the end.

The mini-D connectors on the OSEMs are loosened so that we can plug the cables in.
This requires a specific metric allen key
that is stored in a clean tool box with an aluminum foil.

  7888   Thu Jan 10 12:22:36 2013 JenneUpdateAlignmentTT matrix is funny

Quote:

* TT1 is in place, aligned so beam hits center of TT1, hits center of MMT1 (used pitch biases to finish pitch).

 I had asked Q to write this down on a piece of paper, but then I forgot to transcribe it into the elog....

The TT screen matrix, at least for TT1, is flipped or something.  When Eric moved the pit slider, the optic moved in yaw, and vice versa. 

We need to fix this, but for now, here's the situation when TT1 was pointed correctly at MMT1:

                       PIT    YAW

TT1 Pit slider     |  1000   1000  | --->   700 UL

     0             | -1000   1000  | --->   700 LL

TT1 Yaw slider     |  1000  -1000  | --->  -700 UR

    0.7            | -1000  -1000  | --->  -700 LR

 

The confusing thing is that Koji and I confirmed (by plugging in the correct cable to the correct sensor) that "UL" on the screen goes to the UL coil, and the same for the other 3 coils.  This needs investigation / fixing.

  7528   Thu Oct 11 11:36:52 2012 SteveUpdateSUSTT pitch adjustment

Tip Tilt pitch adjustment on existing-in vacuum suspension. This can be added by a simple installation of a 1.25" long 2-56 threaded rod with nuts.

Attachment 1: IMG_1702.JPG
IMG_1702.JPG
  14753   Thu Jul 11 17:58:38 2019 gautamUpdateEquipment loanTT suspension --> Downs

Arnaud has taken 1 TT suspension from the 40m clean lab to Downs for modal testing. Estimated time of return is tomorrow evening.

  7861   Thu Dec 20 10:11:12 2012 ManasaUpdateIOOTT1 connections

[Jamie,Manasa]

We've been trying to figure out the connector for the TTs. Since, we found the cables were plugged in wrong in TT1; when triggered in pitch, the mirror moves in yaw and viceversa.

Referring to the cabling diagram, D1000234-v10, we infer that connectors go as J2 - LR, J3 - UR, J4 - LL, J5 - UL and the connections are made looking at the mirror from behind.

  7862   Thu Dec 20 10:35:27 2012 SteveUpdateIOOTT1 connections

Quote:

[Jamie,Manasa]

We've been trying to figure out the connector for the TTs. Since, we found the cables were plugged in wrong in TT1; when triggered in pitch, the mirror moves in yaw and viceversa.

Referring to the cabling diagram, D1000234-v10, we infer that connectors go as J2 - LR, J3 - UR, J4 - LL, J5 - UL and the connections are made looking at the mirror from behind.

 The view looking at the optic from the back:  

UL    UR

LL    LR

 

 

  8336   Mon Mar 25 15:01:33 2013 ManasaUpdateLockingTT1 drift

Quote:

2. TT1 drifting in pitch (Bistable)
During the arm alignment routine for spot centering, we observed that TRY dropped (from TRY = 0.9 until the arm lost lock) every 40minutes or so. The arm was relocked by moving TT1 in pitch. The (locking - unlocking due to drift - relocking) cycle was monitored and we observed that it was bistable i.e. if TT1 was moved up in pitch (0.2 on the slider) to relock for the first time ; the next time it lost lock, TT1 had to be moved down by nearly the same distance to relock the arm.
Moving TT2 or the testmasses did not help with relocking the arms; so TT1 seems to be the one causing all th trouble atleast for today.

Update

TT1 was moved in pitch to restore flashing in the arms on Wednesday (Mar 20) so that it doesn't drift too far off making it difficult to lock again. Since then, the arms have been flashing without any drifting and TTs have remained untouched. The hysteresis has disappeared.

  8337   Mon Mar 25 15:24:41 2013 ranaUpdateLockingTT1 drift

 

 I doubt that it has truly disappeared. Can you please make a measurement of it and quantify the hysteresis using some angle sensor?

  14362   Sat Dec 15 20:04:03 2018 gautamUpdateIOOTT1/TT2 stepping

I'm running a script that moves TT1 and TT2 randomly in some restricted P/Y space to try and find an alignment that gets some light onto the TRY PD. Test started at gpstime 1228967990, should be done in a few hours. The IMC has to remain locked for the duration of this test. I will close the PSL shutter once the test is done. Not sure if the light level transmitted through the ITM, which I estimate to be ~30uW, will be enough to show up on the TRY PD, but worth a shot I figure.

Test was completed and PSL shutter was closed at 1228977122.

  14368   Wed Dec 19 15:15:56 2018 gautamUpdateIOOTT1/TT2 stepping

I removed the ND filter from the ETMYT camera to facilitate searching for a TRY beam. This should be replaced before we go back to high power.

  7893   Fri Jan 11 17:32:10 2013 ManasaUpdateAlignmentTT2 connections

 

 Manasa, Jenne

We started off to try and get TT2 working. We used the cables Jamie had already prepared while working on TT1 and used them to connect TT to the channels in 1Y3.

There were sma cable connectors already running between the channels 5-8 on the board to the UL,LL,UR and LR. Triggering the UL LL UR LR matrix on epics did not show any analog voltage at the output analog channels on the board. Talking to Jamie over phone, we inferred  that the  SMA cables that were already left connected corresponded to channels assigned for TT4 in epics.  So we set the connections right and could see analog voltage outputs corresponding to epics triggers.

We connected the ribbon cables running from the board to the TT. But changing pitch and yaw did not do anything to the TT2 mirror. We opened the BS door and checked if  the tt cables were connected to the post. We beeped the cable running from the board to TT (we also traced the cable's trail through the cable rack pile from 1Y3 to BSC). Using a function generator at the board end of the cable, we could not observe anything at the TT end of the cable.

We ran out of options on what can be done next and closed the doors. We hope Jamie can fix the problem once he returns next week.

  7894   Fri Jan 11 19:12:20 2013 KojiUpdateAlignmentTT2 connections

Was the connection between the feedthrough (atmosphere side) and the connector on the optical table confirmed to be OK?

We had a similar situation for the TT1. We found that we were using the wrong feedthrough connector (see TT1 elog).

  7896   Mon Jan 14 10:12:09 2013 JenneUpdateAlignmentTT2 connections

Quote:

Was the connection between the feedthrough (atmosphere side) and the connector on the optical table confirmed to be OK?

We had a similar situation for the TT1. We found that we were using the wrong feedthrough connector (see TT1 elog).

 The major problem that Manasa and I found was that we weren't getting voltage along the cable between the rack and the chamber (all out-of-vac stuff).  We used a function generator to put voltage across 2 pins, then a DMM to try to measure that voltage on the other end of the cable.  No go.  Jamie and I will look at it again today.

  7897   Mon Jan 14 12:08:39 2013 jamieUpdateAlignmentTT2 connections

Quote:

Quote:

Was the connection between the feedthrough (atmosphere side) and the connector on the optical table confirmed to be OK?

We had a similar situation for the TT1. We found that we were using the wrong feedthrough connector (see TT1 elog).

 The major problem that Manasa and I found was that we weren't getting voltage along the cable between the rack and the chamber (all out-of-vac stuff).  We used a function generator to put voltage across 2 pins, then a DMM to try to measure that voltage on the other end of the cable.  No go.  Jamie and I will look at it again today.

Everything was fine.  Apparently these guys just forgot that the cable from the rack to the chamber flips it's pins.  There was also a small problem with the patch cable from the coil driver that had flipped pins.  This was fixed.  The coil driver signals are now getting to the TTs.

Investigating why the pitch/yaw seems to be flipped...

ELOG V3.1.3-