Laser Status: SysStat is good Output power is 33.1 W (should be around 30 W) FRONTEND WATCHdog is Active HPO WATCH is RED PMC: It has been locked 7 day, 21 hr 39 minutes (should be days/weeks) Reflected power is 2.4 Watts, and PowerSum = 25.8 Watts. (Reflected Power should be <= 10% of PowerSum) FSS: It has been locked for 0 days, 0 h and 17 min (should be days/weeks) Threshold on transmitted photo-detector PD = 1.555V (should be 0.9V) ISS: The diffracted power is around 5.700% (should be 5-15%) Last saturation event was 0 days, 0 h and 15 minutes ago (should be days/weeks)
The HEPI Pumps stopped due to a level trip in the reservoir fluid height. I did a 100% scan of the system in the LVEA and found no evidence of a leak. I should have done similar in the MR but went back to my previous assumption that the fluid level declines were from the known motor drips on PS8 (1.) I had lowered the trip position to its lowest level last Tuesday so I proceeded to add fluid (Best to do while pumps are off.) Added ~2.4 gallons and then got the pump stations back running.
It seems someone else had seen a leak on the mezzinine previously--Just before leaving I noticed something (can't remember exactly what) behind the blue drum behind the reservoir, on the floor was an absorbent pad and other puddles. I first thought TCS but no it was HEPI fluid. I found a 5 second drip coming from the pipe/hose joint at the electrical break. I tightened this clamp a bit and will regularly monitor for a few days. I suspect the leak rate may have increased over time but if it had started at full rate, it would take 105 hours to leak a gallon. Since last Tuesday, I'd say the level had to drop about 3/8" or 0.3 gallons. Given the mess I cleaned up this morning, that seems about right.
So, I don't know when this leak started, it may have been much slower for a long time. Was the absorbent pad just luckily in the right spot or had someone put it there? Did someone tell me about it (a long time ago,) possibly?
model restarts logged for Sun 07/Dec/2014
2014_12_07 15:28 h1fw1
2014_12_07 22:42 h1fw0
Both restarts unexpected. Conlog frequently changing channel report attached. FYI: H1:ALS-Y_REFL_SERVO_IN1EN is being toggled every 2 seconds by a non-guardian script.
no restarts reported. Conlog frequently changing channels list attached.
Over the past few days I optimized the damping filters for the HTTS suspensions (RMs, OMs) and the OMC SUS. For the most part this was an exercise of copying the filters from L1 and making sure the gains were sensible. (For the HTTS, I used the filters that Rana had set up at L1.) I've changed the damping gains and filter settings for the DAMP loops on the following suspensions: RM1, RM2, OM1, OM2, OM3, and OMCS. We should update the safe.snap files on Monday.
For each optic and each damping loop I set the gains using the impulse response to judge the Q of the fundamental modes. The first image attached shows the OM1 response in L, P, and Y to impulses. The Q in each case is about 5. (I applied the impulses using the LOCK filter banks, and thanks to Koji's diagonlization of the LOCK inputs to the OMs there is very little DC coupling between the DOFs.)
The second plot is damped spectra for the OMs, compared to the damped spectra before I changed the filters. The OMs were somewhat overdamped before the changes.
For some reason the RM1 damping loops are different by a sign from the other HTTS, I'm not sure where this sign flip is coming from. For RM1 the damping gain is 1.0, for all the other HTTS it's -1.0. The gains that are hard-coded into the 'gain' filter in each L,P,Y filter bank are the same for each optic.
Once I finished with the HTTS suspensions I worked on the OMC. H1's OMCS hadn't been damped before; I tried to do some clever filter work but in the end I found the imported filters from L1 worked well (a zero at 0Hz, two poles at 30Hz, and a 4th-order elliptic rolloff at 50Hz.) The one difference is the YAW loop, I added a boost filter at 0.54Hz. The third plot attached shows the damped and undamped spectra of the OMCS in the six degrees of freedom. The gains for each DAMP filter bank were set using the impulse response. They are:
L |
-400 |
T |
-500 |
V |
-500 |
R |
-5 |
P |
-0.1 |
Y |
-4 |
I also went through the OSEMINF filter banks for each optic and made sure each had a comb(60,30,-50,4).
Evan, Dan
We tested the OMC's fast PZT shutter function today. It works!
We followed the procedure that Zach described for the OMC at L1. On ISCT6, we installed a PDA255 (50MHz) on the OMC TRANS beam path. Then we tee'd off the input to the 'trigger' port on the OMC PZT driver chassis. (The trigger input to the driver chassis comes from the shutter logic controller box on top of ISCT6; the trigger PD is ASC-AS_C.) With the OMC locked on a single-bounce, we closed the shutter by hand using the Beckhoff controls, and triggered a fast oscilloscope on the falling shutter logic signal. Since we triggered on the output of the shutter logic box, we essentially measured how long it takes the OMC TRANS to drop to zero after the shutter logic is flipped. (There will be additional delays due to the logic electronics inside the shutter controller; also the response of the AS_C sum output to a spike in power is finite. We assume that these delays are less than ~1 millisecond, which is the prescribed shutter performance from T1000294.)
The OMC TRANS signal drops to 10% of the full light level zero 3.84 microseconds after the shutter logic output switched to the closed condition. This was calculated using a sigmoid fit to the PD data, see figure. We repeated the test three times, and the results in each case were the same to within 10 nanoseconds. Plots and data files are attached; Channel 1 is the output of the shutter logic controller (5V is nominal/open state, 0V is triggered/closed state), Channel 2 is the PDA255 on the OMC TRANS path. The drop from full lock to no transmission is less than a microsecond, the other 2.84 usec of the delay must come from the LV path on the PZT driver board.
One more thing we need to do before the HAM6 shutter electronics are functional for full IFO locks is swap a resistor on the AS_C transimpedance board. We want to set the shutter threshold at 1 W into HAM6, and AS_C gets 2.5% of the light going into the chamber, so the threshold should be 25mW. Currently the AS_C sum output calibration is 200 V/watt of power on the QPD. With this calibration the threshold level should be 5 volts, but due to some factors of five in the Beckhoff settings and the shutter logic box that I don't understand, we only have a range of 0-2 volts for the threshold. So we need to swap R23 on the AS_C transimpedance board again, for a 420 ohm resistor. With this change the threshold for the trigger will be 1.6V.
no restarts reported. Conlog frequently changing channels list attached.
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.
Thomas Abbott at LLO applied the Pcal beam localization analysis the the LHO ETMY image to calculate the position of the center of the optic in the image from last Friday. The image below contains lines that indicate the center of the optic using the Pcal image analysis.
Attached is a picture of the original FirstContact (FC) sheet, circa ~Jan 2014, showing the "IAS window" which is a thinner film of FC in the central 3" of the larger sheet. To me, the shape of the FC window looks similar to the 3" ring showing up in green on the recent optic photo above. SYS is working with us to get our cleaning game plan together in order to remove the ring. As well, they are investigating other possible scenarios of where the ring came from if not the window. Note, there was a full FC sheet re-cleaning in March that apparently did not remove all of the ring that was left behind apon the removal of the first sheet. To be continued...
I've attached an overlay of (a) the SolidWorks CAD view of ETMy along the PCal camera path and (b) the PCal camera image of H1 ETMy (scaled and rotated). Since SolidWorks does not diffract the image viewed through the ETM optic, I indicate the shift in the ETM Telescope Baffle aperture as well. Three of the 4 bright areas are along the ETM Telescope Input aperture/baffle edge (a coincidence?). (The upper one is red.) One of the 4 bright spots does not correspond to any feature in the CAD image and is likely a spot of residual First Contact. As subsequently shown by the zoomed in PCal image using the Green Lantern flashlight (green LED) after venting (see entry #15635), it is simply a coincidence that the two prominent bright areas appeared to be along the ETM Telescope baffle aperture edge.
Dave, Alexa, Evan
We’ve now completed a scan of the equivalent ETMY loss as a function of spot position on the Y optics.
cdsutils.avg
.Loss vs. alignment is given in the attached plot. The attached zip contains the data and the code used to perform the measurement. The measurement uncertainty is about 45 ppm, and comes from the uncertainty in the number of ASAIR counts with the cavity unlocked. Note that this plot is equivalent ETMY loss; i.e., all the observed loss (including power in the rf sidebands and mode-mismatched light) is assigned to the ETM.
We are repeating the measurement for the ITM. Then the script will try to get a bigger spiral on the ETM.
I’ve attached the results of Friday night’s ITM scan data (first attachment). The arm unlocked shortly into the ETM scan, so there is no data there. Note that the axes indicate the ITMY spot position, but the quantity plotted is the equivalent ETMY loss (for the sake of consistency with the previous measurement).
First, the data indicate that the spiral is centered around an especially lossy spot for the arm. Second, it seems that sweeping the spot on the ITM can change the measured arm loss by several hundred ppm. That magnitude seems comparable to the effect of sweeping the spot on the ETM, as we measured on Friday. There are several possible things we might conclude from this:
The ITMY coating also has anisotropic loss.
Moving the spot on ITMY is causing clipping somewhere (e.g., the edge of the optic).
The scan strategy is also moving the spot on ETMY. Since the ROCs of the ETM and ITM are similar (2.2 km and 1.9 km, respectively), we require the alignment sliders to be calibrated to better than 7 % of each other in order for this to work [since (4 km - ROC_I) / ROC_I = 1.07].
The unlocked value of ASAIR is changing with alignment.
To test the last of these, I locked the Y arm, turned on the WFS loops, and looked at the locked vs. unlocked values of ASAIR for several different arm alignments (separated from each other by 2 urad in pitch/yaw). I first measured ASAIR while locked. Then I held the outputs of the WFS loops, unlocked the arm, and measured the ASAIR value again. I found consistently that the unlocked value was 1370(15) ct. So it seems this is not the issue.
To test the idea that the spot location on ITMY is causing clipping, I adjusted the arm alignment to give lower loss. I ran the ITM sweep again (second attachment). Here the overall loss values are much lower (as low as 550 ppm), but again we find a variation of 100 ppm or so.
The limiting aperture for an ITM scan is probably the BS baffle. Not sure we can (yet) conclude that these losses come from the ITMY.
Here are the expected clipping losses as a function of offset from the mirror center. This assumes a 62mm radius beam on a 326mm radius optic coating. The pdf shows the clipping loss as a function of offset, and the other attachment is an animation showing the intensity spilled over the edge as the offset is increased (since gifs are all the rage these days).
Hanford hauling has been running on day shift today (12/5) and they will operate on swing shift tonight also. We've received no indication that they'll do weekend work.
LVEA: Laser Hazard Observation Bit: Commissioning 07:15 Karen & Cris – Cleaning in the LVEA 09:00 Tweaked the ISS Reference Signal voltage to raise Diffracted Power up to 7.5% 09:00 Peter – Working in the Diode Room 09:00 Travis & Sudarshan – Going to End-Y to work on PCal cameras 09:19 Andres – Working in the 3IFO Storage Container cleanroom & looking for TCS parts 09:28 Filiberto & Aaron – Cabling work in the HAM3 area 09:43 Mitch – Going into the LVEA to work on Elliptical baffle 10:11 Rick S. – Going to End-Y 10:20 Dave – Going to End-Y to work on camera 10:35 Mitch – Out of LVEA 10:37 Karen – Going to End-Y for cleaning 10:57 Dave – Back from End-Y 11:00 Kyle – Going to End-Y 11:01 Travis – Going to End-X 11:07 Platt Electric on site to deliver electrical parts. Richard will escort 11:00 Turn off sensor correction while Travis is at End-X 11:14 Sudarshan – Back from End-Y 11:20 Kyle – Back from End-Y 11:45 Andres – Out of LVEA 11:48 Gerardo – Turn on cleanroom fans at HAM1/2 11:51 Rick, Travis, & Sudarshan – At End-Y installing camera 12:12 Filiberto & Aaron – Out of the LVEA 12:30 Filiberto & Manny – Going to End-Y & End-X for PCal camera work 12:59 Aaron – Measuring power output at HAM3 area 13:28 Corey – Out of H2/Squeezer bay 13:40 Andres – Going into the LVEA looking for parts 13:40 Bubba – Going to Mids and Ends to drop off filters 14:16 Andres – Out of LVEA 14:55 Travis & Sudarshan – Going to End-X to work on PCal camera 15:19 Rick – Going to End-Y to work on PCal cameras
(Jeff B, Gerardo M)
Found some goop on the cleanroom curtains, yes the cleanroom over HAM1-HAM2.
The goop appears to be generated from a reaction between the glue of the tape and the vinyl of the curtain, so far the reaction does not appear to take place on "ameristat", we will look further into that.
Note: on photos attached only look at curtain content.
Years ago, the cleaning crew were wiping down these curtains with some sort of solvent (Acetone?) which caused similar issues. Could this be happening again?
Dave O. Elli, Daniel, Kiwamu,
We briefly checked how lossy our arm cavities are by locking the individual arm without recycling.
For the X arm:
ASAIR_A_LF = 1180 cnts when unlocked.
ASAIR_A_LF = 1155 cnts when locked.
For the Y arm:
ASAIR_A_LF = 1180 cnts when unlocked.
ASAIR_A_LF = 970 cnts when locked.
We made a corase estimation of intra cavity loss (or a.k.a round trip loss) for the y arm, which is estimated to be about 750 ppm (!). In the calculation, we did not take a mode-mismatch or RF sidebands into accout. We need a closer look at this arm cavity to see why it is so lossy.
If beam mis-centering on the TMs is the cause of all the extra loss, it will have to be quite a big mis-centering. I did a quick calculation, and to get 750ppm loss at the ETM, the beam has to be offset from the center by about 6cm (roughly one beam size). The attached plots show the intensity spill over for a 62mm radius beam on a 163mm radius coating, with no offset and with a 6cm offset. The proportions of beam power outside the coating, with no offset and 6cm offset, are 0.991ppm and 762ppm respectively.
Just in case someone wants a plot ...
Dave has a calculation which makes some assumptions about mode-mismatch and sideband power for the X arm.
Suppose the power in the sidebands is 6% of the incident beam, and 15% of the incident carrier doesn't enter the cavity because of mode matching issues; i.e., about 20% of the light is nonresonant. Then the equivalent power reflection is (1155 - 236) / (1180 - 236) = 0.974. This gives a loss of 108 ppm in the X arm.