HEPI-HAM3 position loops were designed/tested earlier this week. First performance spectra were posted in LHO aLog #7871.

A new set of controllers was designed today. The goal was to minimize gain peaking, while improving UUG.

HEPI is over constrained. Hence, we do not want to push at DC on all of the 8 DOF. Controllers for HP (Horizontal Pringle mode) and VP (Vertical Pringle mode) were limited to simple notches with no gain at DC.

New performance spectra were taken (purple) and compared to previous performance (blue) and no control (red).

Moving  SUS/SEI field cabling from teststand to BSC9 at End X - Filiberto
Baffle work at the LVEA – Thomas Vo
PSL work – Cheryl
Taking a quick check to the suspensions  at End X – Jeff B.
Work on h1lsc and h1iscex front end models n – Chris W.

   I pulled up the covers on ETM-X and TMS-X to examine the suspensions after the cartridge installation in BSC9. Both suspensions appear to have made the trip in fine shape. All the fibers are intact, the masses have not shifted on the EQ stops, and all suspension wires are intact. 

   Both suspensions are still on their stops and covered in the C3 socks. 

   Note: The lower left flag on the Penultimate mass is very close to the AOSEM on the Pen-Re mass. They are not touching. Extra care will be needed when releasing these masses from the EQ stops to ensure they do not touch.        

Turned on the controls (level 2 filter banks) on HEPI-ITMY so BSC-ITMY could be turned on. Arnaud need it to see if Fil's OSEM satellte amp replaement fixed the 6.18Hz sharp peak feature that has shown in recent BSC-ITMY performance spectra.

Note: Offsets were used to remove the DC content of the IPSs, before feeding the ISO loops.

[Keita, JoeG, Alexa and Kiwamu]

 We continued working on the installation of HAM1 optics today. We did two major missions:

• Insertion of another BS in the REFL path
• Coarse placement of the tip-tilts

Insertion of a 50 % BS in the REFL path

We've been worried that the 90% S-pol BS, which we installed on this Monday (see alog 7851), may not give us a big enough safety margin to prevent the REFL beam from damaging the PDs. Today we decided to put another 50% BS to attenuate the power a bit more. We unpacked the one we removed on this Monday (see alog 7851) and put it back on the table. It was installed between M1 and HW1 (see the layout D1000313-v10) because it is designed for P-pol. To accommodate it we shifted the position of M14 and HW1 by 2 inches toward HAM2. The reflected light from this new BS was directed such that it is dumped by the pre-installed high power beam dump (HBD). Also HBD was shifted toward the East by 12 inches so that the incident angle of M14 and the new BS doesn't have to be far from 45 degrees.

Of course insertion of this new BS shifted the alignment of the downstream and therefore we realigned them. Finally M7 was steered such that the beam hits the center of the upper periscope on ISCT1 through the viewport and light pipe. Once we re-aligned them Paul confirmed that the beam on ISCT1 was reasonably back to where it was. So we are good.

Also during the alignment we noticed that the beam was too high at HW1 by ~ a few mm and M2 by 1 inch. We asked Paul to check the alignment biases on MC1-3, IM1-4 and PRM and he confirmed that they stayed the same these days. So we guess it has been like this and we had not been careful enough to notice this misalignment.

Adjustment of Tip-tilts:

 Keita managed to tune the height of the mirror on the tip-tilts (see the previous alog #7870 about tip-tilts) by replacing the screws by shorter ones and tightening them down. Then after a long time of balancing the mirror holder and centering OSEM, we put them in place coarsely.

Before placing them we adjusted the pitch of the mirror by using a laser pointer as a a optical lever for measuring the horizontality of the reflected light. Then Joe started adjusting the centering of the OSEM and their flags. Both of two tip-tilts showed a similar symptom at the beginning --- the mirror holder was off as if it was shifted along its plane horizontally. RM2 had a bigger horizontal displacement in the mirror holder by about 5 mm or so. RM1 was somewhat smaller. Somehow Joe empirically figured out a way to adjust this horizontal shift. He loosened the four screws which support the entire blade structure on top of the suspension cage and slided to obtain a good horizontal position. Later on Keita came over and told us a way to adjust it, which Bram told him. Interestingly it coincided what Joe did. By looking at the flags, we could tell that the they are well-centered with a precision of roughly 1 mm or perhaps less. Note that all the adjustment described here was done on the HAM1 in-vac table in order to have a flat and leveled surface.

Nothing new below the control room roof:

- Kiwamu and company still working in HAM1

- Jim W. and company installed the cartridge at EX (see Jim W aLOG 7881)

- Hugo waiting for works on HAM1 to start HAM2/3 TF

- Isolation measurement on hold while HAM1 work continues

Have a nice evening!

pablo

Apollo (Bubba, Randy, Scott, Tyler), GregG, MitchR, JeffB, AndresR, JimW

After an earlyish start at 8am and an abbreviated lunch, the cartridge install wrapped up at 2pm. No major hitches beyond a somewhat "poofier" C3 wrap job than previous installs. This necessitated the removal of a cleanroom filter unit to allow the cartridge to clear. (Note: SUS covers need to their  bottoms clipped to the side (for maximum clearance), not bunched at the bottom, as is the usual practice). Otherwise very smooth. SUS and TMS should head in chamber next to inspect their systems.

Corner: --------

- HAM1 work
--- continues today with alignment - needs IMC locked

- IO
--- isolation measurement on hold while HAM1 work continues 

- HAM2/3
--- HEPI transfer functions tonight

- Optics lab to laser hazard, now back to laser safe
--- Kiwamu and Pablo measuring reflectivity

MY: -------------
- Corey going to get a bin

EX: --------------
- flying the cartridge today, as of 1PM cartridge is partly lowered into the clean room

Alarms: -------------
- some spikes at EX, but due to move, and cartridge is wrapped in C3
- CP1 filled, level is coming down, currently at 101.2%

[Pablo and Kiwamu]

 We have measured the reflectivity of another 2" P-polarizing beam splitter (E040512-B3 SN: I0822-07) for S-polarization this morning at the OSB optics lab.
The results are :
    HR reflectivity R = 92.5 % for S-pol @ 1064 nm, 45 deg
    AR reflectivity R =  2.8 % for S-pol @ 1064 nm, 45 deg

Background :

Even though we already installed a 90% S-polarizing beam splitter on HAM1, we still thinks that this 90% might not be big enough to attenuate the reflection beam to avoid damaging the detectors. One way to increase the safety margin is to simple replace this 90% BS by one with a higher reflectivity. Because we have 90% P-pol BS in hand we simply wanted to try measuring the reflectivity with a S-polarizing beam.

Setup:

Same as the previous measurement (see alog #7817).
 

	Alexa and I mounted the PD interface box on the new end Y table this morning.  We used brackets from Mcmaster, and 2 inch long 10-32 bolts from the mechanical room.   The bolts are long enough that the box hangs just below the lights.  This is a little different from what they've done at LLO  LLO alog 8847 , but it works with the brackets we have.  We turned the box around with respect to the way it is on the ISCEX table, so that it will be easier to reach the connectors when the HWS interface box is installed. This is the position we had in mind when we measured the cable lengths. 

The last image attached is the ISCEX table, with the HWS interface box already installed just for reference.  

Pictures of today's HAM1 activity are posted in ResourceSpace:

https://ligoimages.mit.edu/?c=1375

Attached are plots of dust counts requested from 4 PM September 24 to 4 PM September 25.

I designed an initial a set of position loops for HEPI-HAM3. 

Those are not polished at all, and cause un-necessary gain peaking. They however show that our matrices (which I reinstalled today) are good.

Performance spectra are attached.

(Update: The title of this entry turns out to be wrong. See addendum.)

After putting optics in the tip-tilts and very roughly balancing, the BOSEM flags looked very high, probably between 1.5mm and 2mm even though the blades were brought all the way down. See the first and second picture, note that the table is not level in these pictures, but it's obvioius that the mirror is too high. 

Bram pointed out over the phone that the wire clamps should be under the blades, not the other way round. And sure enough, our clamps were sitting on top of the blades on both of two pre-assembled tip-tilts. In the third picture you can see that the clamp is on the wrong side and that the left blade adjustment is already bottoming out (tension screw is too long). 

If the clamps move to the correct side of the blades the mirror height will be OK (though the blades should be set as low as possible).

It seems as if the wire length is about right (Alexa measured the height difference of the blade clamp and the mirror clamp, and it was about 140mm). 

Problem is, there might be no way to move the clamps from one side to the other without compromising the wire direction. I'm asking Bram the best way to proceed.

After a third ADC card was added to the h1lsc0 I/O chassis (alog 7842), I edited the h1lsc model as follows:

• added a DAC part and a third ADC part
• a few ADC/DAC channels were added or rewired according to T1100472-v10
• and a few ALS parts were added or renamed accordingly
• ALS-C_REFL_DC_ERR is now summed into the LSC input matrix
• added Beckhoff communication link (grounded for now)
• added iscex IPCs
• updated IMC and PSL blocks to match LLO (the LSC block is still divergent)

The new model has been compiled, started, and checked into SVN.  Its MEDM overview, safe.snap and filter files will be updated and checked in tomorrow.

Arnaud P. Betsy W. 

Did B&K hammer measurements on Friday feb 8th on the BeamSplitter that will be installed in BSC2. 
Config: BSC-ISI Unlocked, QUAD Unlocked, Baffles ON, Vibration Absorbers ON, Damping ON.

Attached, pictures describing the position of hammer impacts, and accelerometer + corresponding pulse files.