These needed to be restarted after an apparent power glitch from a wind storm.

- Joe, Paul, Cheryl

FI Isolation Measurement:

Two 2" beam splitters were installed in the main IO path, and the IMC was relocked. The beam splitters are at about 45 degrees w.r.t. the beam, and both reduce the power going into the IMC, requiring a change in threshold to lock the IMC.  Locking was briefly delayed after a reboot to the LSC brought it back with outputs turned off, but after reenabling the LSC the IMC relocked right away.  WFS were engaged, and the offsets WFS sent to each IMC optic were within +/-4 (units?) of the offsets during the IMC lock before we installed the two beam splitters, so input pointing was very closely restored.

The purpose of the two beam splitters is to catch the beam that makes it back through the FI and IMC, which gives us a measurement of the isolation ratio of the FI. The return beam should reflect off the back surface of the second beam splitter, but unfortunately, the return beam was either not present or overwhelmed by a direct reflection of the 2" lens downstream. 

The rework of the IO path in March left that 2" lens (dowstream of the second beam splitter) at a very shallow angle to the IO beam, so basically 90 degrees to the beam. This means the reflection from that lens it makes back to the EOM is now actually clipping on the output aperture of the EOM.  Before the rework the reflection was offset from the EOM output aperture by about 10mm. When Volker was at LHO this Summer and I made him aware of the clipping, it was decided to delay the fix (rotating the lens), until we go to high power, since it will efect the input pointing to the IMC.

Rotating the lens to eliminate the clipping on the EOM will be necessary before going to high power.  Rotating the lens now would be beneficial to the isolation measurement, and given the feducials we have, and the reliability of the IMC locking, I believe we should go ahead and rotate the lens.

General PSL comments:

Both temporary beamsplitters have their reflected beams dumped on razor blade dumps. I installed s ome additional dumps on the PSL table. My alignment irises that track the pointing of the IO path on the PSL show that the beam has shifted in YAW since I aligned the irises. My iris that looks at the leakage beam from the steering mirror at the output of the PMC also shows a change in pointing, probably related to the recent PSL work.

Attached are plots of dust counts requested from 4 PM September 26 to 4 PM September 27.

Attached are plots of dust counts requested from 4 PM September 25 to 4 PM September 26.

[JoeG, Keita and Kiwamu]

We continued working on the HAM1 installation this afternoon.  All the optics except for the detectors are now on the table including the newly installed QPD sled. We removed the counter weights although didn't check the table level yet.

Besides, there are two (unhonourable) highlights to mention from today's HAM1 incursion.

1. The mirror of a tip-tilt (RM1) was found to be backward. So we flipped it to the right direction in situ.
2. The other tip-tilt (RM2) started showing a too big pitching

A big pitching in a tip-tilt (RM2):

After the removal of the counter weights we went through the alignment process again in the in-vac detector path. The alignment needed a slight touch mainly in pitch. Then we found that RM2, which is a tip-tilt , showed a large pitching so that the reflected beam went too low. Joe tried to correct it by screwing the bottom 8-32 screw further in. This screw is designed such that as we screw it in, the center of its mass changes the pitching of the whole holder (so as to lower reflected beam). We wanted screw it in further but however the screw was too long and in fact it was already touching the back cage. Keita brought a shorter screw which is 8-32 x 1" and we tried this. However sadly it still hit the back cage because of too large pitching. Joe translated the upper blades to the front to separate the back cage and holder further apart, but this didn't fix the issue. Note the mirror holder was picthing in the same direction even without the screw.

According to our inspection, the clamping point of the wire on the left wire clamp (when looking from the front) on the mirror holder is too close to the back side. Probably about 1 mm off from the center toward the back side. The other side looked also close to the back side but not as big as the left side. At the moment we think this gives such pitching in the mirror holder. Pictures of the clamping point for both left and right sides are attached below. You can see how they are clamped through a rectangular window of the side cage. We have no idea of if it has been like this or when and why this happened. Adjusting the clamping point is certainly beyond what we can do in the chamber because it probably involves with all the alignment and adjustment process. Therefore we removed the tip-tilt our of the chamber. It is now in the clean booth nearby HAM1.

Plan :

 Next week we will bring another tip-tilt which was assembled for HAM6 and swap the bad one with it. Hopefully we can smoothly place the tip-tilt and move on to some measurements for checking the mode matching.

12:00 Thomas V. out of the LVEA, to return later
12:14 I increased the dust alarm levels at end Y location 1 to conditions outside of a clean room
13:01 Dave B. and Jim B. to end Y
13:33 Dave B. power cycling ISCEY to fix an IPC error
13:56 Jim B. trying to start h1susey
14:10 Jim B. trying to start h1susauxey
14:16 Jim B. and Dave B. to end Y to swap the cabling between the sus and susaux frontends and their chassis. (sus was going to susaux, susaux was going to sus)
14:51 fw1 has stopped writing frames, Dave B., Jim B., Cyrus R. and Dan M. investigating
15:52 Cheryl V. and Paul F. done working in H1 PSL laser room on isolation measurements

High dust count spike at .3 microns in H1 PSL diode room, investigated, lights off, nobody responded
Hugo P. waiting for work to complete in HAM1 to start MC measurements
Filiberto C. done with SUS and SEI field cabling at end X

Jim and Dave

The EY IO Chassis for h1susey and h1susauxey are powered and ready for use. We started the EY SUS front end computers this afternoon. I'll hold off until next week adding these to the DAQ. h1seiey will wait until its IO Chassis is ready to be powered up. Work done under WP#4154

While investigating an IPC error between the end station ISC models and the LSC in the corner, we ended up power cycling h1iscey to clear RFM receive errors at the LSC front end.

I scheduled a tilt frequency mesaurement on HAM3-ISI. It wil start tonight at 9pm PCT. It will last most of Saturday.

All field cables have been dressed to BSC9 chamber for SEI and SUS. Associated electronics are currently off ( SUS coild drivers, SEI/ISI GS13 T240 L4C ect.).

Kyle Ryan, R. Weiss
The total hydrocarbon pressure of the selected set is 6.2 e-13 torr. There is a good chance that
after another several hundred days and the additional pumping speed provided by both
cryo traps the total pressure will get close to 1 e -13. The report is on the DCC as T1300840 
as well as appended to this entry. 

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.

[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).
 

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.