Filiberto and Kiwamu

Filiberto swapped the delay line phase shifter that has been used for the IMC length PDH demodulation at the R1 field rack because the right half of the unit had malfunctioned (see 6282 from May.2013). Since we were not locking the IMC most of the time today, we took this opportunity to swap it. The delay logic is set the same as that of the old one. In principle, this should not impact on the PDH demodulation, but we just have to keep this in mind. The attached picture is the setting of the delay logic of the old unit. Note that the logic was optimized for the RF phase as of December 3rd (see alog 8792 from yesterday).

Here are some updates on the current PSL status:

• The main beam is blocked by a shutter at the output of the high power oscillator which can be digitally switched through Beckoff.
• In addition, the main beam is blocked by a black-hole-style beam dump right after the EOM for a safety purpose. This stays there until the light pipe business is done.
• The PSL enclosure is in the commissioning mode because there is no point to keep it in the science mode as IMC/PMC/FSS/ISS are not running.
• The entrance of the light tubing on the PSL side is sealed up by a plastic sheet with tape to prevent unnecessary air flow going toward the outside.

J. Kissel, D. Barker

Minimal progress on screens today given back-to-back meetings from 9a to 3p PT. I managed to get most of the way through the HAUX screen before I realized the ISIINF filtering (which imports the GS13s from the ISI below, and calibrateds the signals to [nm] down to 10 [mHz]) didn't need to be in every HSSS library part. I've since pulled it out and stuck it in the generic HAUX / HTTS subsystem that's in each h1susim and h1sushtts model. However, upon attempting to recompile I encountered more bogus, "missing connection," errors from the RCG. I have a feeling that this is more of me "abusing" busses and tags, but Dave and I couldn't rectify the problem in a half-hour's worth of work. Then I got distracted by H1 SUS ETMX TFs. Anyways; tomorrow's another day (with no meetings either!)

Thanks for your patience, I promise you'll be handsomely rewarded!

Stefan, Sheila and Kiwamu with remote assistance from Rich A. and Volker

The mysterious jump in the RF phase (see alog 7941) is now understood and fixed. It was due to a loose connection at DB15 connectors in the EOM box and not due to the SMA connector (see alog 8811 and 8813 for our early detective story). We applied two small in-situ modifications on the EOM box. As a result, now it doesn't show the mysterious RF jump any more.

The box:

I briefly explain the EOM box for those who are not familiar with our custom-made EOM box. The EOM box consists of two boxes -- one contains LC resonant circuits and the other contains the EOM crystal. This two-boxes-design allows one to tune the resonant frequencies by tweaking the LC circuits without messing up the alignment of the EOM crystal because one can simply take out the electronics box and leave the crystal box for solder or tuning some parts in the circuits. To apply voltage across the EOM crystal for normal operation, the LC circuits need to be connected to the EOM crystal. This is done by a DB15 connector attached on each box -- female DB15 on the crystal box and a male DB15 on the electronics box (see pictures shown below). In this way, the two boxes are electrically connected.

A picture of the actual EOM box. The gloved hand is me pressing the SMA downward in order to reproduce the RF jump.

When I pressed the SMA connectors downward in this morning, the RF characteristic of the EOM box changed as if something jumped. This was repeatable, although it seemed that the condition to make it jump was random -- occasionally, pressing the SMA didn't make it jump and sometime pushing the SMA toward the box made it jump. Anyways, at this point, it was clear that the EOM box was the culprit and not the RF cables.

The causes:

• The mechanical connection between the two boxes was not solid.
• The DB15 connectors were not completely all the way in.
• The above two facts resulted in different amount of stray capacitance in the DB15 connectors depending on the relative orientation of the two boxes.
• Though, this doesn't explain the bi-stable impedance modes we have observed. Maybe there was some sort of bi-stable condition in the physical orientations.

At the beginning, we thought the culprit was the SMA connectors (see alog 8811 and 8813). However, this turned out to be wrong as we investigated it further. With a remote assistance from Volker, Stefan and I took the electronics box apart from the crystal box while keeping the crystal alignment. In the process of removal, we found that the electronics box was attached to the crystal box merely by friction of the DB15 connectors and three pieces of adhesive tape. So the orientation of the electronics box was not so solid with respect the EOM box. We then checked the return loss of the LC circuits without connecting the EOM and confirmed that wiggling the SMA connector didn't change its impedance. Instead, we discovered that the DB15 connector can easily change the amount of its stray capacitance -- the frequency of the resonant notch could shift by approximately 1 MHz by very gently touching the DB15 connector with our latex-gloved-hand. We put the electronics box back on the EOM crystal box and wiggled the orientation of them. Indeed, it changed the resonant frequency by about 1 MHz in a discontinuous way. So we determined that the loose connection in the DB15 connectors was the culprit and the mysterious RF jump was induced by some change in the orientation of the two boxes.

It seemed that the DB15 connectors were not all the way in because the two aluminum boxes contacted first.

The repair/modification fixed the issue:

We did the following two repair/modification:

• We put washers in the DB15 connector of the electronics box to make the connector stick out a bit more.
• We introduced four screws to mechanically tighten the connection between two boxes.

The DB15 connector have two screws to support it and we put a washer for each screw. They raise the height of the DB15 connector like shims. Also, we newly installed four screws to make the connection of the two boxes more solid. There were already four screw holes on each box to accommodate them. So we just installed them. After these modifications, we checked the return loss of all three RF ports. We didn't observe the mysterious jump at all, even when the electronics box was wiggled hard. Of course, strongly pressing the electronics box downward shifts the notch position by an order of 10 kHz due to the change in the stray capacitance at the DB15 connectors, but the shift is smooth and not in a discontinuous way any more. So the RF jump issue is now solved.

A picture of the electronics box when apart from the EOM crystal box. This DB15 connector was shimmed by washers.

A picture of the EOM crystal box when the electronics box is taken away. There is a threaded screw hole on each corner and these are the ones we used for installing the new screws.

A top view of the EOM box with the lid off. The green circles indicate the screws that we newly installed.

A top view of the EOM box with the lid off. The green circles indicate the screws that we newly installed.

J. Kissel

After chamber closeout, and subsequent close up, I've gathered a set of TFs for H1 SUS ETMX. I attach the results, all looks quite well, and ready for pump-down! I've left the ISI ETMX undamped with the MASTERSWITCH ON, and H1 SUS ETMX and H1 SUS TMSX are damped.

Of interesting note -- checkout the P to P transfer function comparison between the main chains for H1 ETMX, H1/H2 ETMY, and L1 ETMX, on pg 5 of allquads_2013-12-04_Phase3a_H1SUSETMX_ChamberCloseout_ALL_ZOOMED_TFs.pdf. It appears the 2nd Pitch mode (modeled to be at 1.31 [Hz]), whose motion is the top-three masses pitching in concert, differentially with the test mass, is different from the model, and different between these three examples. The one just measured here, H1 ETMX, seems to have the lowest frequency mode of the three, but all are within 6% of the model (-5.34%, 1.37%, 2.90%, respectively). Definitely not a show stopper, but something to consider when designing high-performance damping filters for this DOF -- the gain bump for this mode will have to be reasonably wide if we wanna use the same filter for every ETM.

------------------------
Details:

Data was taken with DTT, using the following templates,
${SusSVN}/sus/trunk/QUAD/H1/ETMX/SAGM0/Data/
2013-12-04_0146_H1SUSETMX_M0_Mono_WhiteNoise_L_0p01to50Hz.xml
2013-12-04_0146_H1SUSETMX_M0_Mono_WhiteNoise_P_0p01to50Hz.xml
2013-12-04_0146_H1SUSETMX_M0_Mono_WhiteNoise_R_0p01to50Hz.xml
2013-12-04_0146_H1SUSETMX_M0_Mono_WhiteNoise_T_0p01to50Hz.xml
2013-12-04_0146_H1SUSETMX_M0_Mono_WhiteNoise_V_0p01to50Hz.xml
2013-12-04_0146_H1SUSETMX_M0_Mono_WhiteNoise_Y_0p01to50Hz.xml

${SusSVN}/sus/trunk/QUAD/H1/ETMX/SAGR0/Data/
2013-12-05_0152_H1SUSETMX_R0_WhiteNoise_L_0p01to50Hz.xml
2013-12-05_0152_H1SUSETMX_R0_WhiteNoise_P_0p01to50Hz.xml
2013-12-05_0152_H1SUSETMX_R0_WhiteNoise_R_0p01to50Hz.xml
2013-12-05_0152_H1SUSETMX_R0_WhiteNoise_T_0p01to50Hz.xml
2013-12-05_0152_H1SUSETMX_R0_WhiteNoise_V_0p01to50Hz.xml
2013-12-05_0152_H1SUSETMX_R0_WhiteNoise_Y_0p01to50Hz.xml

Data was exported, processed, saved, using the usual tools,
${SusSVN}/sus/trunk/QUAD/Common/MatlabTools/
plotquad_dtttfs.m
plotallquad_tfs.m
the latter of which has had its measurement list updated, and is now committed to the repo as with all the above mentioned data and plots.

Post closeout transfer functions will be running on BSC-ETMX, once SUS is done, starting from 9.30 PCT tonight.

Clean room was moved from BSC 6 to BSC 10, work platform disassembled at BSC 6 and reassembled around BSC 10.
Clean room then moved back over BSC 10.
E module relocated to east side of test stand clean room (only 3 bolts per leg) and in position. TIGHT FIT
West door installed on BSC 9 and bolts torqued. Only 4 bolts in dome and east door, remainder to be installed and torqued tomorrow.

After the ACB crew finished this morning, Travis, Jim and I finished the rest of the closeout work:

- Reapplied FC to ETMx-HR thin alignment windows

- Set and secured all 72 ETMx SUS EQ stops

- Set 4 top stage BOSEMs to counter upcoming buoyancy shift under vac (Left, Right BOSEMs on M0 and R0)

- Removed the ACB locking bracket and 4 screws

- Performed chamber inspection for tools, FC on viewports, tokk a few pix, etc.

- Wiped and wiped and wiped some SUS, ACB, TMS surfaces and the floor many times ("good" IPA + alpha 10 wipes)

- Added a witness plate to the vertical holder mounted off the bottom of the front of the QUAD lower structure (LS)

- Added a 1" witness optic + PEEK holder to side of the QUAD LS

- Pulled the FC from the ETMx-HR and blew with ~10psi Top Gun N2 and inspected

- Blew the TMS telescope mirrors - didn't look great, but lots of stuff lifted with the blowing

- Unlocked the ISI

- Damped ETMx to make sure it seemed healthy

- Placed 2 witness plates (not in holders since I didn't have any with me), one directly under the QUAD, one under the front of ACB towards the tube (these should be pulled asap at next vent!)

- Left Apollo to toss the door on

Steps taken to commission the ITMY ring heater pair:
- Updated to the recently committed Beckhoff code that Joe B and Adam M worked on yesterday.
- Added the calibration values that Aidan B had recommended for running the ring heaters.
- Opened up a strip tool to monitor the vacuum pressure with the closest gauge (HVE-LY:Y1_120BTORR)
- Turned the ring heaters on to low power (~.01 Watts) to make sure that the channels were working properly
- Increased the power to 1 Watt for a 4 hour period starting at 12:00PM Pacific Time, keeping an eye on the pressure gauge previously mentioned.


Upper:
Requested Power = 1.00 Watts
Measured Voltage = 5.94 Volts
Measured Current = 0.17 Amps 
Calculated Power = .99 Watts
Calculated Resistance = 34.94 Ohms

Lower:
Requested Power = 1.00 Watts
Measured Voltage = 5.92 Volts
Measured Current = 0.16 Amps 
Calculated Power = .98 Watts
Calculated Resistance = 37.0 Ohms

A four hour trend of the pressure gauge and ring heater settings is attached.

A quick, back-of-the-envelope calculations shows that the ring heaters are working properly. The next step for measuring the thermal lensing would be to measure the beam diameter of a single reflection off of the back of ITMX independently and then changing the radius of curvature of ITMY using the ring heater to match. This requires looking at the REFL beam either in the HAM1 chamber or on the ISCT1 table, depending on how much power we are able to get out of REFL.  The Thorlabs beam profile we have on site requires a minimum of ~1e-5 Watts of incident beam power to function.

Day's Activities:

Swapping out PSL Chasis (Filiberto)

Greg craning dewar over Beam Tube in LVEA

Move ITMy Lower Structure to LVEA (Jeff/Andres)

Tumbleweed baling on X-arm

Lots of Apollo activity at EY (moving cleanrooms, platforms, E-module; installing BSC6 door, installing hard covers on Spool)

PSL work by Kiwamu (investigating mysterious RF jump by unplugging EOM cable); external shutter was also closed.  EOM was fixed in situ

PSL Shutter was replaced (Gerardo, Joe D.)

ACB work at EX (Gerardo/Mitch)

SUS work at EX (Betsy/Travis)

Had a couple of IOP SUS Watchdog INVALID alarms during shift; not really sure of the cause (also popped up window stating:  "Channel Access Exception...")

PSL Checks:

• Laser:  ON (in lower power mode), Watchdog is active/green, Status GOOD
• PMC:  6+days of lock, and reflected power at ~10%
• FSS:  locked for last 16hrs, Trans PD has been around 1V for many days
• ISS:  Diffracted power good and saturation event rate is good

Gerardo M, Mitchell R

The ETM-x Arm Cavity Baffle has been dog clamped. All class B tools and hardware has been removed from chamber. The ACB is still locked.

Bubba, Randy, Scott, Tyler, Ed, Mark, Corey, Jim

Yesterday, we completed the removal of the BSC6 cartridge. The assembly is now resting comfortably on the test-stand, 180 degrees to it's final in-chamber position (necessary for cleanroom clearances). Both suspensions are covered, and the ISI has 3 separate covers. No unusual difficulties beyond some misplaced hardware, but Apollo took an early lunch so I could scramble and find it.

Kiwamu, Stefan

Attached is a new RF return loss measurement for the EOM cable taken at the PSL rack end. This was taken after the latest RF phase jump.
As before, the marker labeled 24.08MHz is at the actual IMC modulation frequency of 24.078360MHz.

Compare this to alog 7959 (before RF jump).

Sheila and Kiwamu

We improved the clipping of the IM1 trans beam by moving the uncontrolled degree of freedom in the IMC alignment control.

As a result, the amount of the light detected at the trans PD went up from about 240 counts to more than 800 counts. Also the beam shape on the camera became more round-looking.

The clipping was mainly in yaw. The shift we introduced was visible in the IM4 trans QPD. The spot moved in yaw from -0.3 to 0.

The screen shots below are the current alignment settings that gives a less clipping on the IM1 trans beam. Note that we didn't touch IM1-4 suspensions.

Stefan and Kiwamu

We continued working on the alignment of IMC today. We managed to get the alignment back i.e. the beam hits the center of the IM4_TRANS QPD with all WFSs in action. It is now happiy locking.

However, we found that the IM1 trans path, which is used for a camera and trigger PD, seemed clipped. By moving the mirrors on IOT2L, we concluded that the clipping happened in chamber, namely in HAM2. This is not a critical issue as this light is used only for triggering purpose and it still gives a reasonable amount of the light. We will keep studying what is happening in the chamber. Perhaps this could be due to the uncontrolled degrees of freedom in the IMC alignment control.

What we did:

• We tried to bring the alignment back to a good-in-air-alignment which was established 18 th of November (see alog)
  • We tweaked both HEPIs and MC SUSs.
  • This didn't give a signal on MC2_TRANS, indicating that the cavity axis is quite off from the MC2_TRAN didoe.
• We tried to bring the alignment back to a good-in-vac-alignment which exhibited a nice long streach around 15 th of September.
  • This didn't give a signal on MC2_TRANS either, indicating that the cavity axis is quite off from the MC2_TRAN diode.
• We brought the alignment back to that of yesterday by typing in the numbers from the previous alog (see alog)
  • Note that the HEPI offsets were kept the same as that of September 15 th.
  • This gave a power build up of about 2 counts on MC2_TRANS. This is still way too low.
• The setting of the whitening filters for the MC2_TRANS QPD signals were found to be wrong.
  • In particular, the gain was too low. It was found to be 0 dB while it used to be 36 dB.
  • We found the same issue on the IM4 TRANS QPD and set it back to how they were.
  • MC2_TRANS became approximately 200 counts when it was resonance.
• Because the beam hit the MC2_TRANS, we became confident that the alignment was getting better.
• We moved on the WFS loops.
  • We flipped the demodulation phases by 90 deg to compensate the mysterious RF phase rotation.
  • All of them worked OK.
  • The loops recovered the spot position on MC2_TRANS and now it is centered well.
  • We ran mcwfsreleive to offload the control signals to the suspensions sides
• We realigned the optics on the IOT2L table.
• Then we found that the IM1 trans beam was clipped.