Betsy, Travis, Rick

After Jim finished locking the ISI this afternoon, Travis hopped in the chamber.  Using the Green LED flashlight (part of the "green lantern" kit) he immediately identified the 3 spots on the HR surface of the ETMy that last week's pcal images highlighted - 2 fairly large chunks of FirstContact (FC) remnants and one quite small one.  I also went into the chamber and with green and white flashlights we then identified the ring observed at 3" diameter around the center of the optic also due to previous FC sheets.  The 3 macroscopic remnants near the center of the optics look very similar to remnants we have observed on other failed FC sheet pulls, and were likely left on there from the March cleaning FC sheet, and not from the original sheet.  Why Margot and I missed them in March is beyond me.

We then:

Installed the ACB locking brackets and dropped the ACB down such that it was partially swung back.  (We did not use the wedge, but instead just let it hang in it's free and open state.  This allowed pcal to still see the optic but also gave enough clearance to attach the green lantern and also to paint FC.)

Installed the Green Lantern on the ETMy structure and reinspected the optic.  Again the large FC remnants lit up well.  However, the ring feature did not show up under this lighting condition.  (The flashlights were better for this.  The ring feature looked more like a staining or clouding that started at the 3" ring boundary and spread ~uniformly outward towards the edge of the optic.  There did not appear to be large macroscopic contaminants or FC remnants at this 3" ring boundary.

Rick took a few pcal photos (see attached) of the remnants and the ring using the green lantern and the green flashlight.

We secured the ETM TM with TFE rails on the EQ stops around the barrel of the optic.

We proceeded to paint FC onto the HR surface, making a nice thick coating after a few layers were applied - this took ~45 mins.  Note, we only observed "spider webs" on the FC sheet/brush toward the end of the 45 min and they were more noticeable around the TFE rail that was nearest the HR face which was likely charged and attracting or even causing(?) the webs.

Set the PETG cap on the face of the optic.

Tomorrow we plan to come in mid morning and then catch up with Richard/Fil to make the ESD connector swap midday.  After that, we can pull the FC and hopefully see that we have removed the remnants and improved the ring feature. 

F. Matichard, K. Venkateswara

This is related to Sheila's alog (15607), where they had trouble locking MICH_DARK. This was being caused by excessive RZ motion as described in the comment to that post.

1. Fabrice and I then tried to understand what was producing this motion, because the ground is very quiet in RZ under normal circumstances. To do so , all the isolation loops were turned OFF (red) and then ON (blue) at ITMX. The result is shown in the first pdf. This led us to conclude that all the RZ/Yaw being produced is self-inflicted. RZ is increased by a factor of ~50 from normal.
2. To see where this comes from, we looked at the coherence between RZ and X, Y  and Z channels. As seen in the second plot, it looks like Z dominates (through the known Z-RZ coupling) near 0.1 Hz, and Y and X cause the rest at lower frequencies.
3. This excess RZ contributes to the problems locking MICH as seen in the third attachment. Note the high coherence between BS_CPS_RZ and the MICH_OUT at very low frequencies.
4.  One possible solution is to close the RZ loop, as seen in the fourth pdf. First page shows the CPS_RZ, second shows the T240_RZ and the third shows the OpLev_Yaw. Green curve is with no sensor correction, blue is with Z sensor correction to HEPI and the red is with Z sensor correction to HEPI and RZ loop closed with a high blend (T750)  (along with Z to Rz subtraction at Stage 1).

Ideally, we should not even need Z to RZ subtraction and a simple position sensor loop ought to be sufficient to hold RZ constant. We will test this configuration soon and look at other chambers as well.

Currently, the RZ loop is engaged on the Beamsplitter.

I have made new snap files for h1iscey, h1iscex, h1asc, h1susetmx. Betsy had recently done h1susetmy, so I did not repeat it.

Kyle, Gerardo-

Venting activities 


Kyle, Gerardo, Bubba, Betsy- 

BSC10 door removal activities

[Peter K., Alexa, Paul, Mackenzie]

(Written by Mackenzie, on Paul's login)

This morning we went into the PSL to set up the RFAM measurement and try to finalize the IO table layout.

We found that IO_AB_W1, which sends the beam to IO_AB_PD1 and IO_AB_PD3, was substituted previously with a temporary 1" HR mirror, so we located and installed the correct AR 2" window. We placed IO_AB_PD3 in transmission of IO_AB_W1 and placed IO_AB_PD1 (the RF 1811 PD) in reflection of the window. IO_AB_PD3 is saturating right now even at the lowest gain setting, so we'll have to attenuate that beam more somehow. 

Regarding the RFAM measurement, we were able to see the carrier with 45 MHz and 9 MHz sidebands on the OSA. The resolution was not great, and some of the sidebands were lost in the noise floor. Volker had previously performed this measurement, but needed an amplifier to boost the signal onto the EOM to see the sidebands well. We intend to go back in later today or tomorrow with an amplifier and try again. When we slowed the OSA scan down to try to resolve the peaks better, we found that the carrier peak was quite distorted (see attached pic). Maybe something to do with PZT non-linearity, we're not sure yet. Another attached pic shows the visible 45MHz sidebands along with two carrier FSRs. 

We looked at the RFPD spectrum, and were only able to see 9MHz sidebands. For some reason neither the 24MHz or 45MHz sidebands were visible. We had assumed RFAM/PM would be consistent between different sideband frequencies, but this doesn't seem to be the case. Again, we will know better once we get the amplifier in place. 

Alexa, Peter K., Paul, Mackenize

We have begun the set up for the RFAM measurement in the PSL enclosure.

First we aligned the OSA and attached it to an oscilliscope. We could see the carrier and 45MHz sidebands, but only sort of see one of the 9 MHz sidebands. After we set this up we remembered an email from Volker indicating we must add an amplifier to the EOM in order to better see the sidebands from the OSA. We will do this when we return to the PSL enclosure. At the moment we have a beam dumb in front of the OSA until we continue.

Second we placed an 1811 PD on the table. The PSL layout indiciates that IO-AB_PD1 should be a 1811; however this was not installed on the table. Instead we had found IO-AB_PD3 in the postion of PD1 and the wedge IO_AB_W1 was actually a HR mirror. We moved PD3 to its specified location and put the proper wedge (2025-45P) on the table. We placed the 1811 as specified and connected it to a spectrum analyzer. We could only see the 9 MHz and not the 45 MHz sideband ?? Also PD3 is conntected to H1:PSL-EOM_A_DC_POWER, which reads 2.22 (not sure what this is calibrated in); we noticed we are actually saturating this PD even though we are at this lowest gain setting of the PD.

07:50 Karen in LVEA

08:00 EY VENT TODAY

08:50 I'm covering for Travis today, apparently :)

08:51 Kyle requested picomotor drives be disabled at EY

08:59 Bubba into LVEA

09:04 Switched ESD bias to ETMY L3 off

09:19 Ellie out to LVEA

09:23 Aaron out to LVEA

09:49 Fil out to LVEA

10:25 Compressed air alarm at Mid-X. John and Kyle notified

10:49 Corey out to LVEA - squeezer bay

12:24 Hugh to EY to lock HEPI

12:57 Betsy and Travis will be goin into the LVEA and then to EY - EY control will be turned over to Betsy after the vent for optic cleaning.

13:20 Fil and Essence out in the LVEA

13:22 Jeff at EX to check out contamination stuff13:25 Kyle getting ready to start Kobelco for at HAM1

13:40 Corey back out to squeezer bay

13:43 Cris to EX to stock garb

14:00 Jeff back from EX

14:29 posted PSL report

15:24 Suresh and Doug out of LVEA - replacing BSC3 op Lev LASER

15:35 Cyrus out to LVEA to check on a couple of vacuum computer

15:49 Cyrus out of LVEA

15:51 Dick out to ISC R1

16:00 Jeff maybe out to EY

I did this back 7 February, the numbers still look like they work well.

See the attached where I measure the tilt with the previous values and bracketed values around the good number.  The blue traces are the original values and the green and red traces are with the vlues offset a bit.  Still looks like the old values are the best.  The first attachment is the inline measurements (drive Y) with the second attachment showing the croosline measurement (drive X.)

Laser Status: 
SysStat is good
Output power is 29.3 W (should be around 30 W)
FRONTEND WATCH is GREEN
HPO WATCH is RED

PMC:
It has been locked 4day, 22hr 0minutes (should be days/weeks)
Reflected power is 2.9 Watts  and PowerSum = 25.8 Watts.
(Reflected Power should be <= 10% of PowerSum)

FSS:
It has been locked for 0h and 35 min (should be days/weeks)
Threshold on transmitted photo-detector PD = 1.74V (should be 0.9V)
ISS:
The diffracted power is around 7% (should be 5-15%)
Last saturation event was  h and 16minutes ago (should be days/weeks)

There was a group of four working in the enclosure today taking RFAM measurements causing some grief to the normal stability of things.

Since the platform was tripped (at the end of my locking up the HEPI) I turned the pump down to get zero pressure readings.  I use these to define the AOFF so the sensors don't have that zero bias offset.  Pump back on within a few minutes and servoing on 70psi differential pressure.

In preparation for HAM1 door removal

Secure for pushing & pulling.

ITmy and ITMx HWS have both been aligned so that the green beam from the X-arm returns through the two irises and onto the respective HWS's.  To do this I had to move both of the upper and both of the lower periscope mirrors about an inch to the right. No other optics were touched.  I took some pictures of the original beam path.  The beam going to the ITMy HWS looked clean as came onto the table (image 1), but clipped the periscope (images 2 & 3).  There were a few beams coming from ITMx, but the brightest one missed the periscope entirely.  I aligned the brightest beam to the HWS.

Once the green beams were returning to both HWS cameras, I tried looking at the HWS camera images to fine tune the alignement.  I could open a camera image using the command

 /opt/Hartmann_Sensor_SVN/release/bin/stream_image_X/distrib/stream_image_X/opt/Hartmann_Sensor_SVN/release/bin/stream_image_X/distrib/stream_image_X

but I couldn't see a beam in this image.  I tried shining a flashlight on the cameras, including without the Hartmann plate for ITMy camera, but the image didn't change.  Either the camera exposure needs to be increased (seems doubtful), or the camera image isn't updating properly.   Once I've figured out how to get the camera image I'll go back and fine tune the alignment.
 

In summary, the health of the laser is okay.



The first plot is of the output power of the frontend laser pump diodes, D1, D2, D3, and D4.  The output power decline for D1 and D2
is fairly small, declining about 2.5% over the last 6 months.  For diodes D3 and D4 the picture is less clear as the signal is a little
noisier, but it looks like about 5% over the last 6 months.

The second plot is of the diode currents.  DCUR1 corresponds to the currents for D1 and D2.  DCUR2 for D3 and D4.  Considering that
none of us have explicitly changed the diode current this should appear constant (and it does).

The third plot is of the output power of the various stages in the power amplifier.  The fluctuations in the power monitors for stages
1 through 3 might be due to relative humidity fluctuations in the LAE.  The output of the frontend laser decreased by ~2 W about 120
days ago.  This might be a real power decrease or the alignment of the beam onto the monitoring photodiode.

The NPRO output power has steadily declined.  Attached are 3 plots of the NPRO output power.  6 months, 2 years and going back to
May 2012.  To recover some out the output power, we should consider increasing the diode current.


/* Note the frontend diode box was switched out on June 6th, 2014. */

Stefan, Sheila

Today we had difficulty locking DRMI, we tried PRMI and found we had difficulty locking that as well.  Then I found that I couldn't even keep MICH DARK locked.  Stefan was able to keep it locked by turning the gain up to -1000, removing the limiter from the BS M3 ISCINF once it locks, and adding a boost (FM4 in LSC_MICH).  I compared the control signal to what we saw on decmber 3rd at a time when DRMI was locked, and see that we have about a facotr of ten higher RMS, all due to motion below 0.2 Hz.  I then tried turning off different parts of sensor correction, first just the ISI XY, then also the HEPI Z. turning off HEPI Z brought the RMS back down to the old value.  For now I'm leaving it all off.  

Evan, Stefan

Did some more WFS/camera loop work on both arms:
 - Added a 0.3Hz LP with a notch at the main pendulum modes into the WFS output filter modules. This allows for a ~3-5 times higher gain.
 - Carefully measured the output matrix for the camera loops (X and Y arm, yaw and pitch) by dragging the ETM around and letting the WFS follow.
   The new output matrix values are in the snaphots #3 below. With them the camera loop no longer relies on gain hierarchy - it's gain was increased ~x10.
 - Some gains were redistributed - see the attached snaps.
 - Cleaned up the arm Guardian. Removed all old slow feed-back stages, and instead added a state commanding Daniel's new setup.
 - Added a WFS relief step to the Guardian.

SudarshanK, TravisS, EvanH, AlexaS, RickS

Using the Pcal beam localization cameras at both end stations, we took images of the ETM surfaces under three conditions: IR and Green resonating; IR only resonating, and Green only resonating.

Attached below are two composite images composed of four separate images taken with the same camera settings:
Upper Left: Xarm Green
Lower Left: Xarm IR
Upper Right: Yarm Green
Lower Right: Yarm IR

The images in the first composite were taken with the following camera settings: F8, ISO 200, 30 second exposure, WB-cloudy.

For the second composite image the aperture was F29 (~13 times less light)

The Yend camera was re-focused for the IR-only images, but the Xend camera was not re-focused.