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ID Date Author Type Category Subject
  8943   Tue Jul 30 19:44:05 2013 gautamConfigurationendtable upgradeSecond mirror glued to PZT and mounted

 

 I have glued a fourth mirror to a PZT (using superglue) and inserted it into a modified mount. This is to be used together with the 1-inch Laseroptik mirror I had glued a couple of weeks back at the Y-endtable. I will be calibrating both these mirrors tonight such that these are ready to put in as soon as we are pumped down.

The mirror was one of those removed from the X-endtable during the switch of the steering mirrors. It is a CVI 2-inch mirror, with HR and AR coatings for 532 nm. 

  8942   Tue Jul 30 19:40:47 2013 gautamConfigurationendtable upgradeDAC-PZT Driver Board Output Signal Chain Tested

 

 [Alex, Gautam]

The signal chain from the DAC output to the output of the PZT driver board (including the HV supply) has been verified. 

I had installed the two boards in the eurocrate yesterday and laid out the cables from 1X9 to the endtable. The output of the AI board had been verified using the monitor port on the front panel, but the output from the PZT driver board was yet to be checked because I had not connected the HV supply yesterday.

When I tried this initially today, I was not getting the expected output from the monitor channels on the front panel of the PZT driver board, even though the board was verified to be working. Alex helped debug the problem, which was identified as the -15V supply voltage not making it onto the board.

I changed the slot the board was sitting in, and used a long screw to bolt the board to the crate. Both the AI board and the PZT driver board seem to be slightly odd-sized, and hence, will not work unless firmly pushed into the eurocrate and bolted down. This would be the first thing to check if a problem is detected with this system. 

In any case, I have bolted both boards to the eurocrate, and the output from the PZT driver board is as expected when I sent a 10Vp sine wave out from the DAC. I think the cables can now be hooked up to the PZTs once we are pumped down.

  8941   Tue Jul 30 18:56:31 2013 manasaUpdateGeneralITMX chamber vented/Closing plan

[Koji,Manasa]

We removed the ITMX heavy door to fix the oplev situation. 

My Plan for closing:

Today: I will work on the ITMX oplev situation today and go through the vent close-up checklist as far as I can get.
Tomorrow: We will do the final alignment check tomorrow with the light doors. The access connector and heavy doors should go in place late afternoon.
Thursday: We will start pumping down early in the morning on Thursday.

  8940   Tue Jul 30 16:21:46 2013 Alex ColeUpdateElectronicsPhotodetector Input Modulation

 [Eric, Alex]

We successfully used our system to modulate the input to a single photodetector. The RF Out of the network analyzer went to the Mod In of our laser, which was operating at 98 mA. The laser's output was sent to our 1x16 optical splitter. This provided input signals for both our reference detector and AS55. Our reference detector's output was sent to the network analyzer's R input, while the AS55's output was sent to the network analyzer's A input. 

We still need to work out the specifics of how the modulation works. Specifically, we want to look at the amplitude of the network analyzer's output. Additionally, we may have been saturating our reference detector, causing noise problems.

  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.

  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.

  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.

  8936   Tue Jul 30 00:21:15 2013 KojiUpdateGeneralVent progress

[Koji, Manasa, Sujan] 

Tomorrow we'll make final checks of the optics inside the chamber.
Then we will pump down the chamber.

- AS beam steering
The AS beam was aligned on the steering mirror (Piezo Jenna i.e. PZT4).
At this point we already found the beam on the AS CCD.
After checking the spots in the OMC chamber, we determined the beam is not clipped inside.
 
On the AS table, there is a weird thick lens with short focal length (like f=37.5mm), this actually clipped the beam significantly
[I take the blame for it from the last vent. The lens was installed thinking it would be temporary which it was not. -Manasa].
We removed this lens and put the CCD camera back so that the spot on the camera became smaller.
 
- SRM debiasing
 
First of all, the bias of the SRM was moved to zero.
Then the tower was rotated so that the beam is aligned in yaw.
After fine alignment of the SRM, the yaw slider was changed from -5.8 to 1.2.
The OSEMs on the SRM suspension was also checked. The OSEM insertions were
adjusted so that they show the half values of the open calibration
(the values can be found on the 40m wiki)
 
- Oplev check
 
SRM / ITMY / BS / PRM oplev paths in the chamber were checked.
The beams were aligned on the steering mirrors and the QPDs on the optical table.
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(!?).

- Checking the alignment
After we closed the light doors, we aligned the MC, the arms and the recycling mirrors.
Now the everything is aligned.
  8935   Mon Jul 29 21:57:45 2013 gautamConfigurationendtable upgradeHardware installed at 1X9

 The following hardware has been installed on rack 1X9;

  • KEPCO high voltage power supply (kept in a plastic box at the bottom of the rack, with the 3m SMA cable carrying 100V running along the inside side wall of the rack). The HV supply has not been connected to the driver board yet.
  • AI board D000186 installed in top eurocrate. The board does not seem to fit snugly into the slot, so I used a longish screw to bolt the front panel to the eurocrate.
  • PZT driver board D980323 installed in top eurocrate adjacent to the AI board.
  • Six 11m SMB-LEMO cables have been laid out from 1X9 to the endtable. I have connected these to the PZT driver board, but the other end (to the PZTs) is left unconnected for now. They have been routed through the top of the rack, and along the cable tray to the endtable. All the cables have been labelled at both ends. 


I have also verified that the AI board is functional in the eurocrate by using the LEMO monitoring points on the front panel.


The driver boards remain to be verified, but this cannot be done until we connect the HV supply to the board. 

 

 

  8934   Mon Jul 29 16:15:13 2013 KojiUpdateVACAC removed

Prior to the access connector removal, Manasa and I aligned the IFO mirrors.
The arms were locked and aligned by ASS.

  8933   Mon Jul 29 16:04:40 2013 SteveUpdateVACAC removed

 Manasa, Eric, Evan, Koji and Steve,

Access connector removed in order to complete alignment. Light aluminum with acetate windows AC installed.

 

 

Attachment 1: acout.png
acout.png
Attachment 2: AlAcACa.jpg
AlAcACa.jpg
Attachment 3: AlAcACb.jpg
AlAcACb.jpg
  8932   Mon Jul 29 13:39:25 2013 gautamConfigurationendtable upgradePZT Driver Board-further changes

 

 

I have updated the schematic of the D980323 PZT driver boards to reflect the changes made. The following changes were made (highlighted in red on the schematic):

  • Gain of all four HV amplifier stages changed from ~15 to ~5 by swapping 158k resistors R43, R44, R69 and R70 for 51k resistors.
  • Electrolytic 10 uF capacitors C11, C12, C29 and C31 swapped for 470pF, 500V mica capacitors.
  • Fixed resistor in voltage divider (R35, R40, R59 and R64) replaced with 0 ohm resistors so as to be able to apply a bias of -10V to the HV amplifier
  • The DC-DC Series components, which I think were originally meant to provide the 100V DC voltage, have been removed.
  • The path between the point at which +100V DC is delivered and jumpers J3 and J6 has been shorted (bypassing R71 and R11 for J3, R73 and R12 for J6).
  • Tantalum capacitors C38 and C39 have been replaced with electrolytic capacitors (47 uF, 25V). One of the original tantalum capacitors had burned out when I tried installing the board in the eurocrate, shorting out -15V to ground. At Koji's suggestion, I made this switch. The AD797s do not seem to be oscillating after the switch.


I have also changed the routing of the 100V from the HV power supply onto the board, it is now done using an SMA T-connector and two short lengths of RG58 cable with SMA connectors crimped on.

The boards are functional (output swings between 0 and 100V as verified with a multimeter for input voltages in the range -10V to +10V applied using a function generator.

 



Revised schematics:

D980323-C-modified.pdf

D980323-C-modified-pg2.pdf

 

 

 

  8931   Sun Jul 28 20:13:41 2013 AnnalisaUpdateGreen LockingY Phase tracker calibration

I did a calibration measurement for the Y part of the BeatBox using a Marconi. This is in order to get a more accurate calibration for the arm cavity scan measurement.

The calibration factor I found is:

C1:ALS-BEATX_FINE_PHASE_OUT   50.801 +/- 0.009 deg/MHz

Procedure

During my cavity scan measurement, I had recorded the beat frequency and amplitude from the Spectrum Analyzer at each zero crossing.

I connected the Marconi to the RF in of the Y part of the BeatBox, and I set the Marconi carrier frequency at one of this zero-crossing frequency that I had recorded, while I set the amplitude in way to have on the spectrum analyzer the same beat amplitude that I read during the measurements or, equivalently, in order to have C1:ALS_BEATY_FINE_Q of the order of 1200 (which is the same value I had during my measurements).

I started with

  • Carrier frequency = 80.2 MHz
  • Amplitude = -3dBm

Then I monitored the C1:ALS_BEATY_FINE_I on the oscilloscope and I adjusted the carrier frequency so that I had zero signal on the oscilloscope. Eventually the frequency corresponding to the zero crossing was 79.989 MHz.

I resetted the phase (clear history in the BEATY_FINE_PHASE panel) and I started changing the frequency by steps of 0.2 MHz, and I spanned about 70 MHz (from 32 to 102 MHz).

Resutls

The calibration coefficient I found is not so different from the one that Yuta measured (elog 8199).

Here are the fit parameters:

y = a + bx

a = -4239.7 +/- 0.6 deg

b = 50.801 +/- 0.009 deg/MHz

Attachment 1: YbeatBox_Calibration.pdf
YbeatBox_Calibration.pdf
  8930   Sun Jul 28 19:39:04 2013 AnnalisaUpdateendtable upgradePicture

 Yend table picture updated on the wiki page

  8929   Fri Jul 26 22:45:14 2013 manasaUpdateGeneralVent progress

[Koji, Manasa]

The arms were brought back to resonance after yesterday's vent work.
DCPD gains were changed (TRX gain from -0.002 to -0.04; TRY gain changed from 0.002 to 0.04) to lock the arm with low power. 
 
X arm and Y arm were locked for IR.

We then decided to align IPANG because the input pointing seemed good - the right time to fix IPANG. The IPANG spot at the last in-vac steering mirror was aligned to be an inch low in pitch.
 
We then aligned SRC. SR2 and SR3 were adjusted to center the beam at SRM. SRM was aligned to the retro-reflected beam until we saw flashes. But this position of SRM is not at the good OSEM range. We should correct the SRM suspensions. We postponed this activity for next week and went ahead to look at the status of the AS beam.
 
Looking through the window and using IR viewer were not convincing enough. We will have to get the access connector out on Monday to do the AS alignment.
We then closed the chamber with light doors and locked the arm cavities again. We brought SRC and PRC to resonance and saw strong flashes at the BS_PRM camera. 
 
To do:
SRM need to be moved in order to remove the big bias in yaw
SRM OSEMS need to be adjusted
Access connector should come out
AS needs to be aligned satisfactorily
ITMX oplev steering mirrors in vacuum should be checked.
  8928   Fri Jul 26 22:19:24 2013 CharlesUpdateISSISS - Full Schematic - Updated

Quote:

 I have made significant changes to the ISS schematic, mostly in the form of adding necessary subsystems.

Some changes I have made:

  • Added a front page with sheet symbols that are representations of the other schematic sheets.
  • Added an 'Excitation' subsystem for use in determining the closed-loop transfer function
  • Added an instrumentation amplifier (with ADA4004s at Rana's recent suggestion) to handle the differential input from the PD
  • Included a switchable inverting amplifier (Gain of 1 or -1) to ensure we have the correct polarity
  • Made it so the first filtering stage is immediately active when the ISS loop is closed
  • Added LP filters with large time constants to buffer/delay trigger signals
  • Added test points all over the board
  • Refined a few buffer amplifiers

On the front page, all inputs and outputs are currently BNC ports, although this is most likely not the final design that will be used. For instance, the ports ENABLE, INPUT GND and INVERT are supposed to be logic inputs for a MAX333a switch. These will most likely be front panel switches that either connect the switch's logic pin to GND (Logic 0) or something like a +5 V supply (Logic 1).

I also have not included power regulation for my board although I have some of the actual D1000217 Chasis Power Regulator boards and I'll incorporate those in my design soon.

 More changes that I've made:

  • Added daughter boards for power regulation. Currently I have ±24V going into two boards, with ±15V coming out of one and ±5V coming out of the other. Again, these are based off of LIGO-D1000217
  • Added an optional Dewhitening filter (with p=1Hz and z=100Hz, although these can easily be changed) to accommodate any PD's that have whitening
  • Added a bypass to allow the boosts (stages 2 and 3 of the filtering servo) to be enabled/disabled by a front panel switch
  • I also put in jumpers that can be used to provide Logic 1 (boost enabled) to both Boost 1 and Boost 2 without depending on the internal RMS detection/triggering
  • Changed the input grounding switch so that it's set up correctly. Before, it was taking the PD signal and sending it to GND, not actually grounding the input to the rest of the ISS 
Attachment 1: 40mServo_v1.pdf
40mServo_v1.pdf 40mServo_v1.pdf 40mServo_v1.pdf 40mServo_v1.pdf 40mServo_v1.pdf
  8927   Fri Jul 26 14:39:08 2013 CharlesUpdateISSPower Regulation for ISS Board

I constructed a regulator board that can take ±24 V and supply a regulated ±15 V or ±5 V. I followed the schematics from LIGO-D1000217-v1.

I was going to make 2 boards, one for ±15 V and one for ±5, but Chub just gave me a second assembled board when I asked him for the parts to construct it 

 

  8926   Fri Jul 26 13:39:30 2013 KojiUpdateASCPOP QPD analysis

It was not actually easy to see from the entry what signal was taken in what condition but from the shape of the spectra
I had the impression that the ASC & OPLEV signals were measured under the presence of the ASC control.
That is (moderately to say) tricky as the ASC control imprints the angular noise
from unkown mirror on the PRM, and then the oplev observes it. The original stability of the oplev is
obscured by the injection from the servo and the fair comparison of the stability is almost impossible.

So the true comparison between the ASC and oplev signals should be done without the control loop.
http://nodus.ligo.caltech.edu:8080/40m/8532

http://nodus.ligo.caltech.edu:8080/40m/8535

We can recover the free running spectrum of the ASC signals by compensating the loop transfer functions
because the ASC signals are the in-loop error signals. The oplev signals should be measured without
the ASC loop engaged.

  8925   Thu Jul 25 14:45:06 2013 ranaUpdatePEMGuralp specgram with ligoDV and NDS2

 Once you install a matlab newer than 2012a, you can install ligoDV as a matlab app and get the NDS2 client software for free. So you can easily get the 40m data from the outside world now and do the analysis on your own computer rather than login through nodus.

Attachment 1: a.pdf
a.pdf
  8924   Thu Jul 25 14:02:53 2013 JenneUpdateSUSSR3, PR3 flipped

Yesterday afternoon, I went back into the BS chamber, and flipped both PR3 and SR3. Now all of the recycling cavity folding mirrors have been flipped.

For PR3, I followed the same procedure as SR2, setting a reference position, removing the optic, flipping it, etc.  When I put it back in, I realized that since this has a 41 degree angle of incidence, the beam going to the BS had translated north by ~1cm.  After some fiddling, Koji pointed out that the 2 degree wedge probably had a more significant effect than just the HR surface having moved back a small amount.  Anyhow, we adjusted PR3 such that we were going through the BS aperture, as well as the ITMY aperture. 

During the flip of PR3, Annalisa and I noticed that the arrow on the barrel of the LaserOptik mirrors also indicates the thickest part of the wedgeThis is opposite of our SOS optics, where the arrow's position on the barrel indicates the thinnest part of the wedge.  For both PR3 and SR3, I kept the arrow on the same side of the optic as it was originally.

I then flipped SR3, following again the same procedure.  PR3 I had done a tiny bit of pitch rebalancing, although I think it was unneccessary, since it is within what we can do with the poking/hysterisis method.  SR3 I did not do any pitch rebalancing.  With PR3 aligned at least to the ITM, Koji and I aligned SR3 and SR2 so that the AS beam was hitting the center of all the SRC optics.  We also adjusted the steering mirrors after the SRM to get the beam centered on PZT3, the last optic on the BS table, which launches the beam over to the OMC chamber.  We scanned around a bit by turning the PZT's knobs, but we were unable to see the AS beam on the camera. 

 

  8923   Thu Jul 25 13:54:35 2013 manasaUpdateGeneralPR3 clamped and Y arm is back flashing

[Jenne, Annalisa, Manasa]

After yesterday's flipping of PR3, we lost our input pointing. Koji spent a few hours last night but couldn't restore the Y arm. I did my set of trials this morning which also didn't help.

So Jenne and I went ahead and requested Steve to get the ETMY door off.

We set the tiptilts TT1 and TT2 to the slider values from yesterday and started aligning the PR3 to hit the center of ITMY.
When we were hitting close to the center of ITMY, we decide to use the tip-tilts because the movement of PR3 was coarse at this point.
We used TT1 to get the beam to the center of ITMY and TT2 to get the beam at the center of ETMY. We did this iteratively until we were at the center of both the ITMY and ETMY.
We then went to fix IPANG.
The IPANG steering mirror on the BS table was steered to hit the center of the steering mirrors at the ETMY table. We aligned the beam to the IPANG QPD on the green endtable. The steering mirror on the BS table was then steered to misalign the beam in pitch by an inch at the last IPANG steering mirror. This should fix the IPANG clipping we have everytime we pump down.
We closed the chambers with light doors and saw IR flashing in the arm cavity. Koji is now trying to lock the cavity with IR.

  8922   Thu Jul 25 12:53:45 2013 CharlesUpdateISSComparator + Triggering Prototype

 I realized I totally forgot to post this last week, but I prototyped the comparator and boost triggering portion of the ISS, at least in part. Below is a schematic that shows the prototype circuit I made. Note that it includes ports for the oscilloscope channels that appear in the second image included. Essentially, I was able to verify that the output from the LT1016, as it's currently constructed in the ISS schematic, would be sufficient logic to switch the MAX333a.

Comparator_Prototype.png

Below, we can first see that the comparator is switching its output as desired. When the DC level of the input drops below a certain threshold (~1.6 V) the output of the comparator switches on to ~4 V. When the DC level of the input goes back up above the upper threshold (~3.2 V), the comparator switches off to ~0.3 V. The exact values of the threshold voltages can be determined/tuned at a later date, but this is the basic behavior that the comparator circuit will have.

To detect whether or not the MAX333a was switching properly, I connected the common terminal of one of the switches to a +5 V supply, and looked at the voltage coming off both the 'open' and 'closed' terminals of said SPDT switch. We can see that with Logic 0 (comparator output ~0.3 V) Channel 4 exhibits a ~5 V signal, just as we would expect from the above schematic. With Logic 1 (comparator output ~4 V), Channel 3 exhibits the characteristic 5 V signal.

Comp_Triggering_Behavior.jpg

  8921   Thu Jul 25 02:53:00 2013 KojiUpdateGeneralIFO Alignment after TT flipping - no progress

There was no progress tonight after Jenne left.
I could not find any reasonable fringes of the IFO after 3 hours of optics jiggling.

* I jiggled TT1 and TT2. The slider has not been restored.
We should probably look at the value in the day time and revert them.
(Still this does not ensure the recovery of the previous pointing because of the hysteresis)

* The arms are still aligned for the green.
It's not TEM00 any more because of the vent/drift but the fringe is visible (i.e. eigenaxis is on the mirror)

* As we touched PR3, the input pointing is totally misaligned.

To Do / Plan

* We need to find the resonance of the yarm by the input TTs. Once the resonance is found, we will align the PRM.

* Move the BS to find the xarm resonance.

* Finally align SRM

* It was not possible to find the resonance of the yarm without going into the chamber. Definitely we can find the spot on the ITMY by a card, but we are not sure the beam can hit the ETMY. And the baffles makes the work difficult.

* One possibility is to align the input beam so that the ITMY beam is retroreflected to the PRM. I tried it but the beam was not visible form the camera.

  8920   Wed Jul 24 22:58:03 2013 CharlesUpdateISSISS - Full Schematic - Updated

 I have made significant changes to the ISS schematic, mostly in the form of adding necessary subsystems.

Some changes I have made:

  • Added a front page with sheet symbols that are representations of the other schematic sheets.
  • Added an 'Excitation' subsystem for use in determining the closed-loop transfer function
  • Added an instrumentation amplifier (with ADA4004s at Rana's recent suggestion) to handle the differential input from the PD
  • Included a switchable inverting amplifier (Gain of 1 or -1) to ensure we have the correct polarity
  • Made it so the first filtering stage is immediately active when the ISS loop is closed
  • Added LP filters with large time constants to buffer/delay trigger signals
  • Added test points all over the board
  • Refined a few buffer amplifiers

On the front page, all inputs and outputs are currently BNC ports, although this is most likely not the final design that will be used. For instance, the ports ENABLE, INPUT GND and INVERT are supposed to be logic inputs for a MAX333a switch. These will most likely be front panel switches that either connect the switch's logic pin to GND (Logic 0) or something like a +5 V supply (Logic 1).

I also have not included power regulation for my board although I have some of the actual D1000217 Chasis Power Regulator boards and I'll incorporate those in my design soon.

Attachment 1: 40mServo_v1.pdf
40mServo_v1.pdf 40mServo_v1.pdf 40mServo_v1.pdf 40mServo_v1.pdf 40mServo_v1.pdf
  8919   Wed Jul 24 19:21:56 2013 JamieHowToSUSSUS MEDM screen modernization

I started poking around at what we want for new SUS MEDM screens.  Rana and I decided we'd start with the ASC TIPTILT screens:

newsusmedm.png

It's missing some things (like SIDE OSEMS) but it should provide a good starting point.

I copied the entire <userapps>/asc/common/medm/asctt directory to a new directory in our sus area:

controls@rossa:/opt/rtcds/userapps/release 0$ cp -a asc/common/medm/asctt sus/c1/medm/new

I then removed all the useless file name prefixes.  We still need to go through and sed out all the ASC stuff in the MEDM files themselves.

It makes heavy use of macro substitution, which is good (it's what we're using now).  So once we clean up all the channel names, we should just be able to swap out the pointers in our overview screens to the new screens (or rename things).  In the mean time, during development, you can run:

controls@rossa:/opt/rtcds/userapps/release 0$ medm -x -macro "IFO=C1,ifo=c1,OPTIC=ITMX" sus/c1/medm/new/OVERVIEW.adl 

  8918   Wed Jul 24 15:07:54 2013 KojiUpdateSUSSR2 flipped

After the first flipping, X/Y arms were aligned and locked. Then the ASS aligned the arms.

  8917   Wed Jul 24 14:26:24 2013 ranaUpdateIOOFound the cause of mysterious MC motion

Yes, this was not ELOG'd by me, unfortunately. This was the MC tickler which I described to some people in the control room when I turned it on.

As Koji points out, with the MCL path turned off this injects frequency noise and pointing fluctuations into the MC. With the MCL path back on it would have very small effect. After the pumpdown we can turn it back on and have it disabled after lock is acquired. Unfortunately, our LOCKIN modules don't have a ramp available for the excitation and so this will produce some transients (or perhaps we can ezcastep it for now). Eventually, we will modify this CDS part so that we can ramp the sine wave.

  8916   Wed Jul 24 13:41:13 2013 JenneUpdateSUSSR2 flipped

[Jenne, Annalisa]

SR2 is flipped, and reinstalled.  We did that before lunch, and we're about to go in and work on SR3 and PR3.

EDITS / Notes:

I set dog clamps to have a reference position of where the tip tilt was, then I removed SR3 from the chamber.  Once out, I followed the same procedure I used for PR2 during the last vent - I removed the whole suspension (top mount, wires, optic) from the cage, and laid it down flat.  Then I loosened the set screw which pushes on the teflon nudge, removed the mirror, inspected it, and put it back in, with the HR side facing the back side of the ring.  Then I replaced the suspension system in the cage, and put the mirror back into the chamber. 

When I loosened the teflon nudge at the top of the mirror holder ring, the optic seemed to fall down a tiny bit.  I think this implies that the HR surface of the optic did not used to be parallel to the front face of the mirror holder ring.  When I put the suspension back onto the cage, the pitch balancing was very bad.  We checked the level of the table that I had the cage on, and it was miraculously pretty level, so I did the pitch balancing out of the chamber. 

Also, during my quick inspection of the mirror (not thorough, just using room lights), I noticed a small fleck of lint near the edge of the optic on the HR surface.  The HR surface is now on the outside of the SRC, but we should still blow at the optic with the ionized nitrogen to get it off.

I did not think to check the fine-tuning alignment of SR2....Koji did that after lunch (which I will elog about in a separate elog).

 

  8915   Wed Jul 24 10:35:41 2013 SteveUpdateVACBS, ITMY doors are removed

Quote:

We will open the BS and ITMY doors first thing tomorrow morning. I plan to try to be in around 9 am. The first order of business will be to flip the folding mirrors that are not currently flipped (SR2, SR3, PR3).

 Jenne, Annalisa & Steve

Attachment 1: beforeDoorsOff.png
beforeDoorsOff.png
Attachment 2: particlecount10d.png
particlecount10d.png
  8914   Tue Jul 23 22:55:13 2013 JenneUpdateVACBS, ITMY doors to be opened in the morning

We will open the BS and ITMY doors first thing tomorrow morning. I plan to try to be in around 9 am. The first order of business will be to flip the folding mirrors that are not currently flipped (SR2, SR3, PR3).

  8913   Tue Jul 23 21:32:43 2013 KojiUpdateIOOFound the cause of mysterious MC motion

Thesedays we were continuously annoyed by unELOGGED activities of the interferometer.

MC2 LOCKIN was left on and has continuously injected frequency noise and beam pointing modulation
during all of the comissioning / vent preparation.

C1:SUS-MC2_LOCKIN2_OSC_FREQ was 0.075
C1:SUS-MC2_LOCKIN2_OSC_CLKGAIN was 99

For more than a week ago we noticed that the curve of the MC WFS stripchart suddenly got THICKER.
MC WFS, arm transmission, beam pointing... everything was modulated.
It was not WFS instability, and it was not the cavity mirrors.

Today I made the investigation and finally tracked down the cause of this issue to be on MC2 suspension.
Then it was found that this LOCKIN was ON.

There is no direct record of this lockin in the frame files.
From the recorded channel "C1:IOO-WFS2-YAW_OUT16" (which is the trace on the StripTool chart on the wall)
It was turned on at July 10th, 2:00UTC (July 9th, 7PM PDT)

  8912   Tue Jul 23 20:41:40 2013 gautamConfigurationendtable upgradeFull range calibration and installation of PZT-mounted mirrors

 Given that the green beam is to be used as the reference during the vent, it was decided to first test the PZT mounted mirrors at the X-endtable rather than the Y-endtable as originally planned. Yesterday, I prepared a second PZT mounted mirror, completed the full range calibration, and with Manasa, installed the mirrors on the X-endtable as mentioned in this elog. The calibration constants have been determined to be (see attached plots for aproximate range of actuation):

M1-pitch: 0.1106 mrad/V

M1-yaw: 0.143 mrad/V

M2-pitch: 0.197 mrad/V

M2-yaw: 0.27 mrad/V


Second 2-inch mirror glued to tip-tilt and mounted:

  • The spot sizes on the steering mirrors at the X-end are fairly large, and so two 2-inch steering mirrors were required.
  • The mirrors already glued to the PZTs were a CVI 2-inch and a Laseroptik 1-inch mirror.
  • I prepared another Laseroptik 2-inch mirror (45 degree with HR and AR coatings for 532 nm) and glued it to a PZT mounted in a modified mount as before.
  • Another important point regarding mounting the PZTs: there are two perforated rings (see attached picture) that run around the PZT about 1cm below the surface on which the mirror is to be glued. The PZT has to be pushed in through the mount till these are clear of the mount, or the actuation will not be as desired. In the first CVI 2-inch mirror, this was not the the case, which probably explains the unexpectedly large pitch-yaw coupling that was observed during the calibration [Thanks Manasa for pointing this out]. 

Full range calibration of PZT:

Having prepared the two steering mirrors, I calibrated them for the full range of input voltages, to get a rough idea of whether the tilt varied linearly and also the range of actuation. 

Methodology:

  • The QPD setup described in my previous elogs was used for this calibration. 
  • The linear range of the QPD was gauged to be while the output voltage lay between -0.5V and 0.5V. The calibration constants are as determined during the QPD calibration, details of which are here.
  • In order to keep the spot always in the linear range of the QPD, I stared with an input signal of -10V or +10V (ie. one extreme), and moved both the X and Y micrometers on the translational stage till both these coordinates were at one end of the linear range (i.e -0.5V or 0.5V). I then increased the input voltage in steps of ~1V through the full range from -10V to +10V DC. The signal was applied using a SR function generator with the signal amplitude kept to 0, and a DC offset in the range -5V to 5V DC, which gave the desired input voltages to the PZT driver board (between -10V DC and 10V DC).
  • When the output of the QPD amp reached the end of the linear regime (i.e 0.5V or -0.5V), I moved the appropriate micrometer dial on the translational stage to take it to the other end of the linear range, before continuing with the measurements. The distance moved was noted. 
  • Both the X and Y coordinates were noted in order to investigate pitch-yaw coupling.

Analysis and remarks:

  • The results of the calibration are presented in the plots below. 
  • Though the measurement technique was crude (and maybe flawed because of a possible z-displacement while moving the translational stage), the calibration was meant to be rough, and I think the results obtained are satisfactory. 
  • Fitting the data linearly is only an approximation, as there is evidence of hysteresis. Also, PZTs appear to have some drift, though I have not been able to quantify this (I did observe that the output of the QPD amp shifted by an amount equal to ~0.05mm while I left the setup standing for an hour or so).  
  • The range of actuation seems to be different for the two PZTs, and also for each degree of freedom, though the measured data is consistent with the minimum range given in the datasheet (3.5 mrad for input voltages in the range -20V to 120V DC). 

 

PZT Calibration Plots

The circles are datapoints for the degree of freedom to which the input is applied, while the 'x's are for the other degree of freedom. Different colours correspond to data measured with the position of the translational stage at some value.

                                            M1 Pitch                                                                                             M1 Yaw

M1_Pitch_calib.pdf     M1_Yaw_calib.pdf

 

                                              M2 Pitch                                                                                        M2 Yaw 

M2_Pitch_calib.pdf     M2_Yaw_calib.pdf

 



Installation of the mirrors at the X-endtable:

The calibrated mirrors were taken to the X-endtable for installation. The steering mirrors in place were swapped out for the PZT mounted pair. Manasa managed (after considerable tweaking) to mode-match the green beam to the cavity with the new steering mirror configuration. In order to fine tune the alignment, Koji moved ITMx and ETMx in pitch and yaw so as to maximise green TRX. We then got an idea of which way the input pointing had to be moved in order to maximise the green transmission.

 

Attachment 5: PI_S330.20L.pdf
PI_S330.20L.pdf
  8911   Tue Jul 23 19:38:58 2013 gautamUpdateCDSCharacterisation of DAC at 1X9

 

 I just finished carrying out the same checks for the DAC at 1X9 (with channels 9 through 16 that are unused as of now) as those I had done for the DAC at 1Y4, as the hardware prep up till now was done with the characterisation of the DAC at 1Y4. Conclusions:

  • The accessible range of output voltage are -10 V to +10V w.r.t ground --> No change needs to be made to the gain of the HV amplifier stage on the PZT Driver Board
  • The pin-outs of the DAC Adaptor Board at 1X9 is identical to that at 1Y4 --> Custom ribbons do not need to be modified.
  • The PSD of the DAC output has a peak at 64 kHz --> Notches on AI Board do not need to be moved again.

I will now proceed to install various pieces of hardware (AI Board, PZT driver board, HV Power Supply and cabling) at 1X9, while not making the connection to the PZTs till I receive the go ahead. 

  8910   Tue Jul 23 19:37:08 2013 AnnalisaUpdateendtable upgradeEnd table picture

Quote:

The spot on the IPANG QPD was checked. The spot is higher than the center and South side of the lens.
Some photos are found below.

The spot on the IPANG steering mirrors in the ETMY chamber was also checked.
It is clipped at the top of the steering mirror. (See attachment 4)
So basically the spot is about 1" above the center of the mirror.

 After the vent, the IPang spot position on the steering mirrors on the Yend table moved approximately by 1 inch down.

Inside the chamber, the spot position is in the center of the steering mirror. (difficult to take a picture because the PSL beam power has been reduced)

Attachment 1: IMG950073.jpg
IMG950073.jpg
Attachment 2: IMG950072.jpg
IMG950072.jpg
  8909   Tue Jul 23 16:47:01 2013 gautamUpdateCDSExcitation points set up on c1scx

 I just compiled and installed the model with the excitation points on c1scx and then restarted framebuilder. The channels I set up are now showing up in the awggui dropdown menu. I will do the tests on the DAC channels shortly.

Just to keep things on record, these are the steps I followed:

  • opened the model c1scx (path: /opt/rtcds/userapps/release/sus/c1/models) with MATLAB
  • Added 8 excitation points and saved the model. A copy has been saved as c1scx.mdl.r2010b because of the recent upgrade to r2013a. 
  • ssh to c1iscex (computer running the model c1scx). 
  • Entered the following sequence of commands in terminal: rtcds make c1scx ,  rtcds install c1scx , rtcds start c1scx 
  • ssh to framebuilder, and restarted the framebuilder by entering telnet fb 8088   and then   shutdown.
  8908   Tue Jul 23 16:39:31 2013 KojiUpdateGeneralFull IFO alignment recovered

[Annnalisa Koji]

Full alignment of the IFO was recovered. The arms were locked with the green beams first, and then locked with the IR.

In order to use the ASS with lower power, C1:LSC-OUTPUT_MTRX_9_6 and C1:LSC-OUTPUT_MTRX_10_7 were reduced to 0.05.
This compensates the gain imbalance between TRX/Y siganls and the A2L component in the arm feedback signals.

Despite the IFO was aligned, we don't touch the OPLEVs and green beams to the vented IFO.

Attachment 1: alignment.png
alignment.png
  8907   Tue Jul 23 14:00:03 2013 SteveUpdateVACthe vent is completed

 The 40m IFO has reached  atmospher in 5 hours. It is ready to open chamber condition. The RGA is pumped with the maglev.

P1 pirani gauge is contact dependent as you see it on the linear plot It will be replaced during this vent.

The venting speed was 2-4 Torr / min

Atm2 shows how the BS is sensing the venting air cylinder changes. 

The 4th cylinder of instrument  grade air  bump is overlapping with our janitor working at the BS chamber.

 

 

Attachment 1: Atm.png
Atm.png
Attachment 2: 5cyl.png
5cyl.png
Attachment 3: ventSum1d.png
ventSum1d.png
  8906   Tue Jul 23 13:55:08 2013 KojiUpdateIOOMC manually aligned

The MC was manually aligned. The spot positions were measured and it is consistent with the measurements done yesterday.

Attachment 1: MCalignment.png
MCalignment.png
Attachment 2: MCspot.png
MCspot.png
  8905   Tue Jul 23 13:29:58 2013 KojiSummaryGeneral 

record of the initial state

Attachment 1: initial_state_130723.png
initial_state_130723.png
  8904   Tue Jul 23 08:21:31 2013 SteveUpdateVACVent has started

 

Thanks for the good preparation.  IFO pressure P1=20 Torr

Attachment 1: beforVent.png
beforVent.png
Attachment 2: startVent.png
startVent.png
  8903   Tue Jul 23 04:31:36 2013 JenneUpdateGeneralVent preparation - Ready for Vent

After everyone's work today (good teamwork everybody!!), we are a GO for the vent.

Steve, please check the jam nuts, and begin the vent when you get in.  Thanks.

  8902   Tue Jul 23 04:26:54 2013 JenneUpdateGeneralMC spot positions

After Koji and I lowered the power into the PMC and saw that the MC locked nicely, I remeasured the spot positions (no alignment on the PSL table, or of the MC mirrors has been done.  Also, WFS are off, since there isn't any power going to them).

spot positions in mm (MC1,2,3 pit MC1,2,3 yaw):
[1.1999406656184595, 0.63492727550953243, 1.0769104750021909, -1.0260011922577466, -1.059439987970527, -1.2717741991488549]

MCdecenter_22July2013_lowpower.png

The spot positions seem to have actually gotten a bit better in pitch (although between 2 consecutive measurements there was ~0.5mm discrepancy), and no real change in yaw.  This means that Rana was right all along (surprise!), and that decreasing the power before the PMC reduces alignment pain significantly.

  8901   Tue Jul 23 04:22:03 2013 KojiUpdateGeneralVent preparation - In progress

[Koji Jenne]

Low power MC locking

- Rotated HWP right after the laser

- Put a knife edge beam dump at the output of the PBS after the HWP.

- Replaced the PO mirror for the MC refl by an HR mirror.

- PMC:
Input offset from 0 to 0.29
Servo Gain from 10 to 30
=> Transmission 0.84 (1.2W at the MC input) to 0.069 (100mW)

- MC:

VCO Gain from 25 to 31
MC REFL: Unlocked 3.6 Locked 0.38-0.40

  8900   Tue Jul 23 04:07:48 2013 gautamUpdateCDSExcitation points set up on c1scx

 

 In light of recent events and the decision to test the piezo tip-tilts for green beam steering on the X-end table, I have set up 8 excitation points to channels 8 through 15 of the DAC on c1scx (as was done earlier for the DAC at 1Y4 with Jenne's help) in order to verify that the pin-outs of the DAC interface board. I have not yet compiled the model or restarted the computer, and will do these tomorrow, after which I will do the test. The channels are named YYY_CHAN9 etc. 

 

 

 

 

  8899   Tue Jul 23 03:43:32 2013 manasaUpdateGeneralVent preparation - In progress

There seems to be an unexplained oscillation in X arm cavity transmission for IR when the cavity is locked using the POX error signal.

Their origin is not related to the oplevs because the oscillation does not exist when LSC is OFF and the arms are controlled only by the oplevs and OSEMs.

  8898   Tue Jul 23 03:10:57 2013 KojiUpdateGeneralVent preparation - In progress

Centering of the oplev beams: done

Recording the OSEM values: done

Attachment 1: OSEM_RECORD.png
OSEM_RECORD.png
Attachment 2: OPLEVS.png
OPLEVS.png
  8897   Tue Jul 23 01:30:27 2013 JenneUpdateASCPOP QPD analysis

I have some data for how much motion of any PRMI-relevant optic affects the beam seen by the POP QPD. 

For this, I am using the QPD calibration from the micrometer (elog 8851) to get me from counts to mm of motion.  Note that the pitch calibration hasn't been redone (I tried locking the PRMI this afternoon, but ITMX kept drifting away from me**, so I didn't get any more data.) The pitch calibration is obviously very rough, since I only have 2 points defining my fit line. 

Anyhow, if we assume that's close enough to get us started, I now have a calibrated QPD spectrum:

QPD_spectra_only.png

As detailed in elog 8854, I took single frequency transfer functions, to determine the effect at the QPD from shaking any single PRMI optic.  These transfer functions gave me a conversion factor between the optics' oplev readings (in microradians) to the counts seen at the QPD.  I used this number, as well as the QPD calibration from the micrometer data, to convert each optics' oplev spectra to motion that one would expect to see at the QPD. 

I have not yet completely figured out how to make an estimate of the PR folding optics' affect on the POP QPD spot position, if I know their motion.  The current plan is to do as Den did in elog 8451, and infer the PR2/3 motion from the ITMX/BS motion measured by the oplevs.  My plan was to take the spectra of the oplev signals while the BS/ITMX are undamped, divide by the SOS pendulum transfer functions, then multiply by the TT transfer functions (which I finally wrote down in elog 8564).  I'm planning on using the undamped data, since the oplev signals are still within the linear range of the oplev QPDs, and I won't have to take the SUS damping into account.  Anyhow, after I do that, I'll have an idea of how much the tip tilts are moving, but not what that does to the cavity axis.

However, after looking at the plots below, it seems like the PRM is the main culprit causing the PRC axis motion, although the BS (and to a smaller extent the ITMs) are not innocent.  Since the plots get very busy very quickly, I have many plots, each plot comparing one of the above QPD spectra (either pitch or yaw) with a single optics' oplev inferred motion.

EDIT:  After talking with Koji, I realize that, since the ASC was engaged during the PRM oplev spectrum measurement, I cannot yet say whether the motion is due to PRM, or if it is from PR2 or PR3, and imprinted on the PRM via the ASC servo.  The lump where the PRM-caused motion is greater than the QPD spectra is entirely in the region where the ASC is active.  So, the QPD motion I expect without the ASC would be something like the green trace in the PRM comparison plots.  The blue trace is then the closed loop measurement.  Since the ITMs and BS are below the closed loop values, they aren't the ones causing the big lump.  I should retake all of these spectra at a time when the PRMI is locked, but the ASC is not engaged.  I'm not sure if I'll have a chance to do that tonight or not.  If I can find some GPS times when the PRMI was locked, before we had ASC, I can get the oplev data.

PRM:

QPD_yaw_motion_from_PRM.pngQPD_pit_motion_from_PRM.png

BS:

QPD_yaw_motion_from_BS.pngQPD_pit_motion_from_BS.png

ITMX:

QPD_yaw_motion_from_ITMX.pngQPD_pit_motion_from_ITMX.png

ITMY:

QPD_yaw_motion_from_ITMY.pngQPD_pit_motion_from_ITMY.png

 I think part of the reason PRM is dominating is that it's damped motion is ~10x greater than any other optics', most noticeably the BS'.  I'll write a quick separate elog about this.  Also, note that the ~3Hz resonant gain had been turned off in the PRM oplev loop, but not in any other loops.  This is why there isn't the sharp dip in the PRM's oplev motion.  Also, since the PRM ASC was engaged for this measurement, and the ASC pushes on the PRM to minimize the QPD motion, it isn't totally crazy that the PRM's motion is greater than what we actually see at the QPD, if it is compensating for the motion of other optics.

 

** Re: PRMI locking this afternoon, it was almost as if ITMX were bi-stable.  I aligned both arms, to set the ITM positions.  Then, I would lock and tweak up the michelson to get the AS port nice and dark (usually touching ITMX today, since it seemed like the drifter....ITMX at this point was usually between -7 and -15 microradians in pitch from the center of the oplev QPD).  When I then brought the PRM back into alignment, ITMX was starting to drift away.  As soon as I hit the LSC Enable switch, and looked back over to the OpLev screen, ITMX was misaligned, usually around -65 urad in pitch.  I did this circus probably 3 or so times before giving up.  Koji said that he had seen this bi-stability before, but he didn't remember what fixed it.  The drifting that Koji mentioned in elog 8801 seems to have been fixed by centering all the PRMI oplevs every day, but I had already done that, and was still seeing ITMX drift.

  8896   Tue Jul 23 00:51:46 2013 KojiUpdateendtable upgradeEnd table picture

The spot on the IPANG QPD was checked. The spot is higher than the center and South side of the lens.
Some photos are found below.

The spot on the IPANG steering mirrors in the ETMY chamber was also checked.
It is clipped at the top of the steering mirror. (See attachment 4)
So basically the spot is about 1" above the center of the mirror.

Attachment 1: P7224222.JPG
P7224222.JPG
Attachment 2: P7224223.JPG
P7224223.JPG
Attachment 3: P7224224.JPG
P7224224.JPG
Attachment 4: P7224238.JPG
P7224238.JPG
  8895   Mon Jul 22 22:06:18 2013 KojiUpdateCDSFE Web view was fixed

FE Web view was broken for a long time. It was fixed now.

The problem was that path names were not fixed when we moved the models from the old local place to the SVN structure.

The auto updating script (/cvs/cds/rtcds/caltech/c1/scripts/AutoUpdate/update_webview.cron) is running on Mafalda.

Link to the web view: https://nodus.ligo.caltech.edu:30889/FE/

  8894   Mon Jul 22 21:23:04 2013 manasaUpdateGeneralVent preparation - In progress

[Gautam, Manasa]

Green steering mirrors have been swapped with PZT mirrors at the X end table. We aligned the green to the X arm.

X arm green transmission +PSL green  ~ 0.95

That's better than before the swap...woohooo

ELOG V3.1.3-