After two rounds of transfer functions two nights ago and yesterday night (aLog 5907 and 5920) the beamsplitter look(ed) fully supsended (it had to be locked again this morning)

The attached pdfs show

1. Transfer functions comparing :
   
   • BSFM model
   • Measurement on March 27th with one of the top EQ stop touching
   • Measurement on March 28th after Travis found the source of rubbing and fixed it
      
2. Power spectra comparing :
   
   • LLO measurement on October 2012 Phase 3a
   • LHO measurement on March 27th with one of the top EQ stop touching
   • LHO measurement on March 28th after Travis fixed it

Yesterday we continued to struggle to get light from the fiber to the end station. Richard is helping us trace down the problem.  Even with the fiber working well, we only get 10uW onto the ALS table, then there are two 50/50 beam splitters, so there were only about 2.5 uW on the PD, giving us a signal level around -40dBm, which is marginal and might be why I thought the ohase frequency discriminator was not working (it works as expected with larger signal levels).  I changed out the 50/50 beam splitter that sends a pick off to the PDs that monitor the power out of the fiber and the polarization to a 10% beamsplitter.

Chris and Max also rerouted the fiber from the patch panel to the table feedthrough. This fiber was on the floor, and probably stepped on, but it seems to work fine, the probelms we are having are upstream of that.  

Also, I spent some time yesterday afternoon labeling cables inside the ALS table, were there is a suprising number of cables with no labels at all.  Most of these cables are also not included in the cable plan, for the cables that go to feedthroughs I've been naming the cable after the cable on the other side of the feedthrough and adding an A to the end of the name. Otherwise I just make a name up.    

[Keita, Corey, Kiwamu]

The alignment of the POP paths in HAM3 are done. We removed the green fiber laser.
The next step is a picomotor test at HAM3 with the Beckoff system.

Forward propagating POP
 The POP path behind PR2 for the forward propagating beam (going from PRM to PR2) were successfully adjusted within a precision of ~ 1 mm or less at the QPDs. Comparing the alignment precision with the QPD diameter of 3 mm, we conclude that our alignment is good enough. This time the issue of the transparent BS [1] was mitigated by fully opening the aperture of the irises to make the HR beam as bright as possible. Luckily the HR beam became visible enough to work with. We tweaked the two steering mirrors to get the beam aligned on the QPD sled.   
 Actually we repeated this alignment twice. After the first round it turned out that the first steering mirror (a 3" mirror) which we established its alignment yesterday [2] gave a beam too low for the other POP path (i.e. backward POP path). The first steering mirror is relatively tall by design because it needs to be at the same height as the PRs and therefore the beam reflected by this mirror has to be angled downward such that the beam height gets lowered to the standard height of 4". Yesterday we adjusted the angle such that only the forward beam hits the center of its second mirror but apparently this wasn't a great idea. It resulted in such a low beam in the backward path due to the fact the backward beam propagates a longer distance than that of the forward beam by 6-ish inches. This too-low-beam was found after we removed the green laser setup at HAM2. Therefore we had to setup the green laser again and repeated the same alignment process. We adjusted the first mirror such that the beam is a bit too high for the forward path by 5-ish mm and a bit too low for the backward path by the same amount.


Backward propagating POP
 The backward propagating POP beam behind PR2 was aligned using the green fiber laser and we confirmed that the beam got through to HAM1. The same fiber laser was used to simulate the backward path. The laser was set up at HAM3 and injected at the front of PR2. We let the reflection go through the two irises. The position of the second steering mirror (2" reflector) was intentionally displaced toward east by ~ 7 mm in order to keep a large clearance for the downstream beam which passes by the west side of the mirror. Hence the beam spot on this mirror is also off by the same amount which shouldn't be a problem because the mirror is large enough and also the incident angle is small (about 10 deg ?). Although the green beam diverges a lot when it arrives at HAM2 we aligned the beam such that it passes by any of the towers in HAM2 with the same amount of the clearance. This resulted in a beam off-centered at the viewport in between HAM2 and HAM1 but this is OK. Some alignment of the optics at HAM1 will be performed later.


BS wedge on POP QPD sled
 This is a minor issue and we write this simply as a record here. We found that the BS on the POP QPD sled had its wedge at a wrong side. Ideally we want the fat side to be at the QPD side to let the ghost beam diverge away, but it seems we placed the BS in the opposite way --- skinny side at the QPD side. We checked the engrave mark on the barrel of the BS and found a "W" mark at the far side from the QPD, indicating that the fat side is at the far side and this is wrong. We are not going to fix this as the ghost beam will not hit the QPD anyway since the QPD is close to the BS.

[1] LHO alog 5774 "50-50 IR beam splitter is a good AR for green"
[2] LHO alog 5911 "Alignment of POP QPD path : ongoing"
 

- 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...

Attached are plots of dust counts > .3 microns and > .5 microns in particles per cubic foot requested from 5 PM March 27 to 5 PM March 28. Also attached are plots of the modes to show when they were running/acquiring data.

Data was taken from h1nds1.
T0=13-03-28-00-00-00; Length=86400 (s)
1440.0 minutes of trend displayed

Occupy Mon AM506 (-2133.6x,-182.8y) at HI -82.9 Lz, BackSite LV-22 (-2133.6x,-22692y)
Nominal Turn: HAR 270-01'45" ZA 90-00'02".  Sited Baffle Target at BS at HAR 270-03'10" ZA 89-59'28" for 85" & 34" error.
Over 1931mm these angles give position errors 0.8mm -Y & 0.3mm +Z from nominal
BS position (-202.7x,-183.8y) yields distance from AM506 1930.9mm nominal.  EDM w/ -30mm prism offset shot 1.8617m to retro-reflector.  Retro-reflector measured to be 2.709"=68.8mm from optic face (FC).  1930.9-1.8617-68.8 = 0.4mm -X of nominal.  I am told this is within spec (percomm DCook.)
Of course to get it here we did a number of HEPI moves monitoring the Dial Indicators on the ends of the Support Tubes.  Based on the DIs and 'adding' to the Optical Table leveling results from 25 March, the 'level' of the Optical Table is still +-0.1mm so should be fine.  Would like to confirm with AutoLevel shots directly on the Optical Table, maybe tomorrow.

Starting a round of transfer functions overnight on the beamsplitter.

The numerous 80K pump alarms today (and tomorrow, this weekend?) are the result of my cracking open the LN2 "bypass" valves on the site dewar plumbing.  The motivation for doing this is to prepare for the upcoming extended power outage.  As such, there are now two flow paths for the LN2 to fill each 80K pump, one is via the nominal CDS PID-controlled valve and a second which "goes around" this valve and which has no external control.  A few days of tweaking should allow us to maintain the pump levels with only a minor contribution from the PID-controlled flow path.  This will guarantee that some LN2 is always flowing through the "transfer" line even when the PID-controlled valve is closed (as will be the case with the loss of instrument air during the outage).  Having a minimum flow will prevent the transfer line from warming up and will greatly facilitate manual adjustments to the pump levels during the outage.  

WP 3785. Modified h1iopsusb123 model to add the BS suspension to the software watchdog system. Restarted h1susb123 at 16:06. The h1iopseib2 model was already setup for this and did not need restarting.

So now if either ITMY or BS or both have tripped top OSEM channels, both SEI BSC1 and SEI BSC2 will be tripped if SUS B123 is not bypassed.

I created a new BSC1 and BSC2 WD MEDM screen and made the appropriate links from the top WD screen.

• Pcal work in H2 PSL room
• Kyle manually adjusting bypass valves on cryo pump tanks, resulting in overflows
• Work on aligning IMC will go on later tonight
• Dave rebooting SUS frontends

After the recent update of the HLTS and HSTS opticalign sliders (see aLog 5866), I modified a few things for the alignment offsets in BS, ETMY and ITMY.

• Modified the sliders' range (in urad), to make it consistent with DAC's maximum output.

• Modified the OPTICALIGN gain for ETMY/ITMY, to make it consistent with the units displayed on the medm screen (urad instead of nrad)
• Entered the values of the OPTICALIGN gain for BSFM

Details :

In order to change the sliders range I modified the OPTICALIGN adl files by opening it with medm in edit mode, and changed the limit of the sliders.

SUS_CUST_BSFM_M1_OPTICALIGN.adl located in /opt/rtcds/userapps/release/sus/common/medm/bsfm for BSFM
SUS_CUST_QUAD_${M0/R0}_OPTICALIGN.adl located in /opt/rtcds/userapps/release/sus/common/medm/quad for ETM/ITM

The files have been commited to the svn as well as the new safe.snap files

We assisted Pablo with P-Cal fixtures today in the H-2 PSL enclosure and craned the dirty parts over the X arm for Michael Rodruck, and into the LEA on pallets. John and I cut the coupons out of the show and tell beam tube out at the weld shop, I will bend them next week at the Apollo shop. Viewports VPA2F1 &VPA2F4 were installed and torqued on HAM 1. Started installation of viewport G2 on BSC 2, will complete tomorrow. We wraped and transported 4 TMS Optical tables from EY to EX. We reajusted the lower limit on the EX crane so the hook and block do not contact the floor. We relocated IOT2 table from the east bay to the south bay near HAM 2 for Joe Gleason and Cheryl Vorvick and installed the viewport simulator for Cheryl.

I sealed up the two new HXTS that were placed in the meat locker yesterday. I also attached signage/drawings/ICS records to the five HXTS in the meat locker. I inventoried and separated MC Baffle parts this morning: small parts were placed in a tote and large parts were wrapped/attached to their shelf with plastic wrap and a few lengths of blue tamper-evident tape. I worked on AC and Elliptical Baffle parts this afternoon: there are two plastic wrapped and taped pallets on the floor level of Shelving Unit B in the West Bay containing these parts. I also applied signage to a HAM Shipping, HAM Storage, and BSC Storage Container for show-and-tell purposes.

For the 35W beam

Yesterday, as Gerardo noted, the PSL tripped. This was due to the NPRO shutting off, which then tripped the power watchdog and shut off the amplifier. The attached plot shows the power for the 2 NPRO diodes dropping out shortly before the power watchdog trips and shuts off the amplifier. The rack where the NPRO power supply is looked fine, so I don't know what exactly caused this.

[Keita, Corey, Kiwamu]
We worked at HAM2 and HAM3 to get the POP QPD path aligned and this is ongoing.

 We have set up a fiber-coupled green laser with a telescope at the stage by HAM2. This laser mimics the actual forward infrared beam (going toward PR2 from PRM). Since the laser launching setup is on the stage which is not quite stiff we found that the injection angle of the laser can be statically misaligned when a person stands on the same stage (typically a few mm shift of the beam spot at the iris in HAM3).
 After tweaking the green laser and a temporary in-vac steering mirror to get it through two existing irises (one at HAM2 and the other at HAM3), we moved on to alignment of the optics behind PR2. The position of the first steering mirror (3 inch mirror) was corrected such that the green beam hits a point which is 9 mm off from the center of the mirror in yaw. This is because that this mirror is supposed to catch both forward and backward POP beams who are separated by 18 mm from each other in yaw. Then we started tweaking two steering mirrors to let the beam go in to the QPD sled. An issue at the moment is that the green light is too dim on one of the QPDs and this is a known issue : the HR surface of the pick-off-BS is extremely transparent for 532 nm [1]. We tried a half-wave-plate to make the HR beam brighter like we did at EY [2], but this didn't help. We will try aligning them using the AR beam since the AR beam is bright enough to work with (although we have to do a math to predict the beam position of the HR beam from that of AR).

[1] LHO alog 5774 "50-50 IR beam splitter is a good AR for green"

[2] LHO alog 5829 "The alignment works in TMSY completed"

First check is to the wall - PSL input beam reflected off the vacuum input viewports.  Picture attached is annotated with progression of beam positions.  Beam is mapping out a space that is neither here (under vacuum position) nor there (in-air position), and currently at some new in-between position.  Two pictures attached.

Second check is in HAM2 at the periscope - beam is off in yaw by a beam radius, 2-3mm (on card).  One picture attached.

Third check - MC2 - centered there to the 2mm I could see on PRM.

Fourth check - MC3 - less precision but not off by a centimeter.

Beam from MC2 is going through the iris in front of MC3.

I found that the markers for the irises in front of MC1 and MC2 were gone, along with the irises (taken to align PRM).  This can be recovered, if we chose to do that, but unfortunately the original marked position is no longer.

- Cheryl, with help from Giacomo and Joe

The out-of-loop PD for the PSL intensity stabilization (H1:PSL-ISS_PDA_OUT_DQ) was used to produce the fake strain channel during engineering run 3 in February. It was very clean overall, but there were a lot of low-frequency glitches. The glitches are all short and below about 55 Hz, and there seem to be more in the 10-25 Hz range. The glitches are every few seconds, not regular, but the rate was pretty much constant during the day. These glitches are still there in recent data. Robert Schofield told me that this frequency range isn't environmental but is likely to be electronic. The glitches are also seen in QPD_DX and QPD_DY.

If we can help diagnose this, don't hesitate to contact detchar@ligo.org and andrew.lundgren@ligo.org.

The attached plots are:
1. A typical day of ER3 as seen by Omicron (the replacement for the OmegaOnline web reports).
2. A similar plot for 5 minutes of recent (last weekend) data.
3. As above, but QPD_DX.
4. As above, but QPD_DY.
5. A selection of 2-second spectra, showing the instability.