MitchR, JimW, w/ Apollo Chris and Zach

The BSC2 ISI was locked and covered this morning in preparation for the Wed-Thurs power outage. The cover consists of one new BSC Dome Tall cover, a layer of ameristat taped down to the walking plates and a final BSC Dome Cover. Travis is in putting a cover on the locked SUS now. We might be going in again later, to lock HEPI, but otherwise the chamber is ready to be closed up.

In preparation for the power outage Wednesday, the PSL and its relevant components have been turned off. Here is a full list.

For the LVEA racks:

1. DBB HV supply turned off
2. Kepco HV supply turned off (read: 375V, 44 mA)
3. NPRO driver keyed off (UPS on, Richard may turn it off)
4. Control box keyed off and powered off via switch on back (key removed and stored in anteroom to make LAE and LDR laser SAFE)
5. Kepco HV supply turned off
   1. 200V supply was on but drew no current or voltage
   2. 150V supply was reading 160V, 24 mA
   3. -150V supply was reading 160V, 24 mA
6. VCO turned off

For the diode room:

1. Interlock box keyed off and powered off via switch in back
2. PS1-4 switched off
3. TEC1&2 switched off
4. FE DB1 keyed off
5. epics OPC terminal closed
6. Beckhoff computer powered off and switched off

The HEPAs and AC units are still running in the laser and ante room, but will probably have to be turned off before the outage. The reason for this is that the AC units often need a manual restart, and if the software comes up after the power outage with the fans on, the room may overheat.

I transitioned the LVEA to laser hazard and looked at the beam in the IMC, working to understand the yaw needed on MC1 and MC3.

I reinstalled an iris (a 4th one I had made that was "extra") in front of MC1.  The iris I moved to MC1 is the one that IO had used in front of IM2, and then on REFL, and was not installed on any beam when I started.

The 4 irises we now have in HAM2 are:
- in front of MC1 - the extra one that has been floating around the table, that I moved to MC1 today
- in front of MC3 - installed after the last vent per the dog clamps I left on the table marking it's position
- behind MC3 (on MC trans) and before IM1 - installed after the last vent per the dog clamp I left on the table marking it's position
- downstream of PRM - installed last week by IO on the PRM trans beam

The only iris we have in HAM3 is at the edge of the table in front of PR2.  This was installed last week by IO on the PRM trans beam.

 I transitioned the LVEA back to laser safe.

This is a slightly outdated report, but I am writing this for completeness.

The broken infrared QPD (Q3000 SN3), which had been determined to be broken and was then removed from TMSY on 7th of March 2013 [1], was inspected at the lab. As originally suspected [2], indeed the 1st segment is not 'diode-ing' any more and it shows a small resistance of 2.8 Ohm regardless of the polarity. There is no obvious sign in the appearance of the diode. The rest of the segments looks quite healthy and exhibits a usual voltage drop of 0.44 V. Though interestingly the broken segment is still able to produce photo current when it is illuminated by a flashlight.

BTW, don't be confused by this report --- this is different from the newly broken QPDs which reside in HAM3 [3].

[1] LHO alog 5716 "A new PZT mirror installed at ISCTEY and red in-vac QPD swapped on TMSY"
[2] LHO alog 2865 "TMSY red QPD damage report"
[3] LHO alog 5937 " HAM3 ISC IR QPDs are likely broken, in-vac cabling error, IO QPD should be OK"

Attached are plots of dust counts > .3 microns and > .5 microns in particles per cubic foot requested from 5 PM March 28 to 5 PM March 29. Also attached are plots of the modes to show when they were running/acquiring data.

Data was taken from h1nds1.
T0=13-03-29-00-00-00; Length=86400 (s)
1440.0 minutes of trend displayed

Summary:

When we tested the in-vac picomotors on HAM3 again though these picomotors and also in-vac QPDs were tested OK before (here's the alog of these tests done by me, Cheryl and Daniel), nothing moved. Without these things, HIFO test never works.

The problem was traced back to an error in in-vac cabling. ISC IR QPDs were connected to the picomotor feedthrough and vice versa though I have no idea why this happened (see the comments attached to this entry for details). 

The cabling was fixed and the picomotors now work again, but ISC QPDs are likely broken because of multiple attempts to drive picomotors back and forth, which put more than 100V on diodes. We used laser pointer to test the QPDs with the handheld QPD interface but were never able to convince ourselves that they're working. We forgot to test if any of the quadrants are short-circuited.

IO QPD for MC transmission should be OK as it is on a separate cable.

Anyway, we have spare QPDs and we'll replace them on Monday, entering HAM3 from the north opening. It's probably less than 2 hours for replacing, plus an hour for testing. We've done the same thing in EY and we know how to do this.

Spare S/N 20 and 24 from our stock of IR QPDs were bagged and left in a clean room by HAM2 so we can continue on Monday morning.

Richard cleaned the fiber this morning at the Y end patch panel, and after that we had 18-19uW at the table feed-through and I measured 14uW with the power meter in air on the table.  After realigning for the swapped beamsplitter, (and re-aligning the power monitor PD) the beatnote was -38dBm, around -20 dBm after the amplifier.  

A plot of the OLG will follow,  but the main message is that the ALS PLL is working.  It has been locked for almost hours now, based on looking at the striptool of the beat frequency and the control signals.  

The settings are: cg -15, fg 22, common compensation on, slow ugf set to -0.015Hz and slow pole set to 0.0001 Hz. 

The beatnote frequency has glitches that are not present in the channel for the VCO frequency, where the signal level is much higher.  It might be easier to write an autolocker if we could get rid of those glitches, perhaps by amplifying the signal.  

Today we fine tuned the rotation of the HWP that rotates the polarization of the beam after the IMC. We followed these steps:

- we used an HWP at the bottom of the PSL periscope to set the polarization approximately "wrong", so to have considerable power transmitted through the unlocked IMC

- we used the HWP after IM1 to make sure that a good amount of power would go in the first forward rejected beam

- we rotated IM2 in yaw so that the first forward rejected beam would clear the FI and be transmitted all the way to (almost) IM4

- we position a power meter there

- we removed the HWP on HAM2, and rotated the HWP in the PSL so to minimize the power in the forward rejected beam. Because of the absence of the HWP in HAM2, this beam contained the "good" polarization: this way we made sure that the polarization off the PSL was as bad as possible.

- we steered IM2 back in its original position, and we placed the power meter in the main beam

- we re-inserted the HWP in HAM2 and optimized it to minimize the power in the main beam, thus rotating the polarization coming out from the IMC by 90 deg, that is what we want.

Unfortunately, during this process we had the opportunity to compare the beam out of the IMC with the re-routed IMC_REFL beam that had been setup couple of weeks ago and used since then as a more powerful reference for alignment. What we discovered is that the beams are not well aligned (more than a beam diameter at the FI). Note that:

• the beam from the PSL, reflecting off of MC2 is still well centered in two irises that we have in HAM2, in front and behind MC3. Thus, is seems that the beam out of the IMC has not drifted.
• To center the beam into the FI, IM2 now needs to be steered in yaw by about 10000 cts, while it's aligned position is supposed to be -520 cts (and still work with the rerouted REFL beam). This suggests that the misalignment between the two has not happened this week, but probably much earlier in the process of IO alignment.

The good news is that the situation can probably be easily recovered, without moving other components, using IM1 and IM2 to make sure that the current IMC beam is aligned, at the FI and further downstream, to the reference we have been using up to now. If the offsets turn out to be big, we may need to relieve them.

This morning I started floating the BS ISI, after asking SUSsers to lock their optic up. No real problems, beyond a missing wrench that had to be retrieved from staging and a CDS laptop that had too aggressive power saving settings (it would sleep the monitor after 1 minute, enough time to change out gloves...sigh). The ISI is currently floating within spec, cps were regapped where necessary, lockers were adjusted, the actuators were visually inspected for spacing, and cables were surveyed for rubbing. This should mean BSC2 is in a good position for in-chamber testing, but the BS is still locked.

- Mark L, and group changed pre-filters for AHU 1 and 2, per WP 3783.
- LVEA transition to laser safe at 9:00 am.
- Corey G. work in the squeezer area, East Bay of LVEA.
- Rick S, Michael R, and others to visit MID-Y, inventory of 3rd IFO PSL items.
- Jim W work at BSC2, top area.
- Betsy W and Filiberto C, work at HAM2, mission aborted.
- Betsy W and Travis S, BS is locked now.
- LVEA transition to laser hazard for IO work.
- IO group work, PSL enclosure --> HAM02.
- LVEA transition to laser safe, 3:32 pm.

 

- Joe, Giacomo, Cheryl

- Filiberto started the process to attach pins/connector to FI HWP pico motor.  Lack of information about the connector convinced us to push this out to at least tomorrow.

- the half wave plate was re-installed in the IMC trans beam path after IM1.  The beam through the FI was misaligned with IM2 to give an unclipped Forward Rejected Beam to minimize, which was minimized to around 40 uW of power.

- IOT2R was moved into place today, on the East side of HAM2, beams were aligned onto the single periscope and onto the table.  The table position needs to be marked before moving the table.

- beams transmitted through IM4 were measured - some measurements will be used to compare expected and actual transmittance of 2" fixed optics.  Actual power readings to be attached.

- AOE1 was aligned downstream of HWP per Rodica's instructions to move it along the beam path by 20mm.  With HA1 at 0, the front of the HWP is at 25mm , and the front plate of AOE1 is at 95mm along the beam path.

- PR2 scrapper baffle was installed.  Joe did the install, and centered the baffle w.r.t  the PR2 optic, since the beam at HAM3 iris was about a beam radius off in yaw, and off in pitch.  Earlier work of adding the HWP back into the beam path is the likely source of the change seen at PR2.  Using IM2, we deturmined that the correction was 100 slider counts or less, i.e. small.

Friday:
Plan is to flash the IMC, though there have been rumors of locking it in air...

Starting a round of transfer functions overnight on the beamsplitter.

Starting a round of matlab transfer functions overnight for the beamsplitter.

Before the power outage of next week, new h1sus${mc1/mc2/mc3/prm/pr2/pr3}safe.snap files have been saved in /opt/rtcds/userapps/release/sus/h1/burtfiles.
It includes alignment offsets with the right values from aLog 5851 for PR3/PR2 and 5825 for MC1/MC2/MC3. It also includes the ODC recent update aLog 5809

The safe state has been defined as the following :

**alignment offsets off
**damping filters on
**master switch off

The snap files have been commited in the svn repository.