We attempted to center the beam on the HAM2 ISS array PDs using the steering picomotors; we set the IMC at 50W for this. We started with HAM2 picomotor 8, which is upstream of the ISS diode array telescope. The PD 1-4 signals were centered at maxima when the beam on the ISS array QPD was centered (BTW, as Cheryl pointed out, pitch and yaw are reversed on this QPD screen). Two of the diodes had significant improvements.  We then scanned with picomotor 1, which is closest to the array, and again decided to leave the beam centered on the QPD. I have not yet seen evidence of an improvement in jitter coupling from this centering. I suggest sticking with PD4 if we use only one.

Robert, Cheryl

Kiwamu, Stefan

We looked at the optical gain change during the 80min lock at 50W (alog 29556) as measuired by the 331.9Hz cal line, see plot 1. The reduction between the beginning of the lock (8:10 UTC, blue) and the end (9:15 UTC, red) is about 22%.

Plot 2 plots ASAIR_45_Q for the the period from 8:10 UTC to 9:15 UTC, since it should be a measure of effective fringe offset. Its value drops by 41% (from -526 to -373 microcounts). Also it shows a significantly bigger variation in the DARM offset towards the end of the lock.

While qualitatively this would be consistent with a decreased contrast defect feeding carrier light through the OMC, the magnitude of the gain reduction doesn't quite add up  - the percent reduction ought to agree since both optical gain and AS_Q DC value are proportional to the DARM offset. Also, the AS_45_I DC offset remains rougly constant (not plotted).

at 22:15 UTS (15:15PDT) the h1iopoaf0 model detected both an ADC and a DAC error, resulting in zero'ed dac outputs. I restarted all the models within 10 minutes, which restored h1tcscs's control of the chiller setpoint DAC channels. The itmx laser temp had dropped from 23.25C to 21.5C in the 14 minutes which had elapsed, a rate of 0.14C/min

The IOPs STATE_WORD went from 512 (OVF) to 652 (ADC,DAC,DK,OVF)

We should schedule a complete power cycle of h1oaf0's IO Chassis to hard reset the 16bit DAC.

Over-filled CP3 with the exhaust bypass valve fully open and the LLCV bypass valve 1/2 turn open.

Flow was noted after 26 seconds, LLCV valve was closed immediately after, but the exhaust bypass valve was left open (per Kyle's aLOG)

Keita Daniel

With the most recent modifications we were finally able to engage the new outer loop ISS. The gain slider was at 10 dB with 2 W input power. We increased the power to 50 W, while running the feedforward correction for the AC coupling loop. This gave us an ISS with a ugf around 300 Hz. Increasing the gain further will require more loop shaping to avoid internal saturations.

The first attached plot shows the PSD at 50 W with the servo engaged, whereas the black reference trace is with the servo off.

The second attached plot shows the power up transition—indicating that the feedforward works pretty well.

Morning meeting

- We had a nice lock last nice.

- PSL chiller swap planned

Activities (all time in UTC)

14:45 Chris in LVEA collecting ext cords not in use (1-2 hrs -- safety audit work)

15:47 ISS work (Daniel, Keita)

16:36 Fil + Elizabeth to MY

16:49 Fil + Elizabeth back

          Fil to LVEA woring by PSL rack (ISS chasis pull out)

~17:15 ISS work done. PSL begin chiller swap

17:33 Rebooting framewriter1 (Dave, Jim)

18:01 framewriter1 back, restarting ISS model + DAQ

18:14 Fil going back to LVEA

18:33 PSL done

18:35 Jason to LVEA toggling noise eater

18:36 Fil out

19:09 Jason resetting noise eater (again)

21:07 Dick, Betsy to MY

21:20 Sheila to LVEA HAM6 area

21:40 Betsy+Dick back

22:02 Gerado to CP3

22:06 Fil to LVEA by PSL rack (ISS chasis work)

22:15 oaf ADC/DAC error. Dave restarted the model in time to save TCS.

22:36 Fil back

22:39 Dick to CER

OpLev trends from the past week. FAMIS #4692

Fil Keita Daniel

At 50 W input power we are now saturating the amplifier stage, since there is too much whitening upfront and the compensation is after the gain. We moved the 20 Hz/380 Hz compensation to the transimpedance board to give us more headroom. Continuing from alog 29527 and alog 29293 we changed:

1. C26 was changed to a 33nF in series to 10K on the transimpedance board (4x channels on 2x boards). This gives a pole at 21 Hz and a zero at 483 Hz. This also eliminated one of the 15.4 kHz poles.
2. R49 was removed from the servo board to disable the second compensation stage and make it unity gain.

Some changes were made to the front-end model to change the polarity of the 0.1 Hz switches and to add filter modules to the PD readbacks. This allows adding anti-whitening filters. Since the AC readbacks now have a DC gain of 1, we don't need the dedicated DC readouts anymore.

Attached is the transfer function of one of the transimpedance PD chains.

After finding that the ISS 2nd loop pitch and yaw signals are swapped, and inverted wrt im4 trans (my first look at qpds downstream of the IMC, alog 29542), I've looked at four qpds downstream of the IMC for signal consistancy - IM4 Trans, ISS 2nd Loop, POPA, and POPB.

What I found:

• plot 1: im4 trans yaw, iss2 pitch (inverted), popa yaw, and popb yaw - consistant
• plot 2: im4 trans pitch (doubled), iss2 yaw (inverted), popa pitch (inverted), and popb pitch - first 3 consistant, popb pitch is not a good match
• plot3:  im4 trans pitch (doubled), iss2 yaw (inverted), popa pitch (inverted), and popb pitch (inverted) - first 3 consistant, popb pitch (inverted) is closer, but still not a good match
• plot4: im4 trans yaw, iss2 pitch (inverted), popa yaw, popb yaw, and popb pitch - popb pitch is a pretty good fit for yaw

Attached is a two hour second-trend plot of the DAC drive  for the TCS ITMX temperature setpoint and the chiller water flow rate (which shows when the chiller tripped). The data is from Wednesday night, 10pm to midnight PDT.

At 22:42 PDT the IOP stopped driving the DAC outputs (presumably due to a FIFO error) with the user supplied signals and instead outputted zero volts.

At 23:32 PDT the chlller tripped (+50mins later)

Nutsinee says that the nominal driving temperature is around 20C, the trip point is 15C, and the maximum temperature rate-of-change is 0.1C/minute. The transition from 20C to 15C would then take 50 minutes, which agrees with the timing seen on Wednesday.

The plot shows that after the chiller tripped, the control room was alerted of the problem, the front end was restarted and the chiller was reset within 10 minutes.

Clearly if the verbal alert system warned the control room at the time the DAC output went to zero, in this failure mode we will have plenty of time to restart the OAF IOP model and recover chiller operations.

P. King, J. Bartlett, J. Oberling

We swapped the PSL chillers for the backup in an effort to isolate the recent laser tripping issues.  The laser is now back up and running.

Operating hours for the chillers, as reported by the chillers themselves and the chiller MEDM screen, are:

There is a difference between the chillers and MEDM because the MEDM screen gets its info from the PSL Beckhoff PC, which uses its own internal counter to track the chiller hours instead of the hours recorded by the chillers themselves; we currently do not know a safe way to reset this Beckhoff counter.

I wrote a simple interface to download data from the Tektronix network/web-enabled oscilloscopes (TDS3034B and (presumably) the like).  You can use it to download a single data file, or download data periodically:

jameson.rollins@opsws8:~ 0$ readlink -f $(which tektronix)
/opt/rtcds/userapps/trunk/sys/common/src/python/tektronix.py
jameson.rollins@opsws8:~ 0$ tektronix -h
usage: tektronix [-h] <command> ...

Interact with Tektronix oscilloscope over the network.

positional arguments:
  <command>
    download  Download data from scope periodicially

optional arguments:
  -h, --help  show this help message and exit

Use environment variable HOST to specify network address.
(default: 10.22.10.51)
jameson.rollins@opsws8:~ 0$ tektronix download -h
usage: tektronix download [-h] [-c CHANNEL] [outdir] [count] [period]

Download data from scope periodicially

Data will be saved in a two-column (time,voltage), comma-separated CSV
file named "<time>.dat", where <time> is an ISO-formatted timestamp of
the local time of the data snapshot.

NOTE: data takes about 30 seconds to download, so period should not be
less than 30 seconds.

positional arguments:
  outdir                directory to store timestamped data ['.']
  count                 number of downloads (0=Inf) [1]
  period                time between downloads in seconds [60]

optional arguments:
  -h, --help            show this help message and exit
  -c CHANNEL, --channel CHANNEL
                        channel to download ['ch1']
jameson.rollins@opsws8:~ 0$ tektronix download
output directory: /ligo/home/jameson.rollins
fetching 2016-09-09T11:16:31.747247.dat ...done (in 29.959158s).
jameson.rollins@opsws8:~ 0$

Jenne, Matt, Patrick, Sheila, Stefan, Kiwamu,

We tried two different differential CO2 settings today at 20W to see if we can improve the imbalanced RF sidebands (29535). One of the two tests was already reported by Jenne et al. on 29553.

According to the tests, the addition of a 10 uD single-pass substrate defocus to the X compensation plate seems to balance the amplitude of the upper and lower 45 MHz sidebands.

[Settings]

• Locked at 20 W
• CO2X  200 mW ->  1 W
• CO2Y  stayed at 0 W

The interferometer arrived at a 20 W lock at 22:53 local. We then added a 800 mW of laser power on to CO2X, resulting in a 1 W CO2 power at 22:55:40. As opposed to the previous test (29535), we did not change CO2Y this time and therefore it stayed at 0 W.

The measurement finished at 23:15 and we set CO2X to 700 mW. We then increased the PSL power to 50 W while maintaining the same lock.

[Results]

As expected from the previous test, the imbalance of the 45 MHz RF sidebands, as seen by the optical spectrum analyzer, was improved by this action. After roughly 20 min, we reached a point where the upper and lower sidebands almost had the same amplitude. HWSX was functioning at the beginning of the test (for 10 minutes or so), but then unfortunately started showing some meaningless signals. We have no idea why. Nevertheless, we were able to extrapolate where we would be in terms of the substrate defocus based on the initial rise. It looks like that an additional 20 uD double-pass (= 10 uD single pass) is the good defocus value for ITMX in order to get balanced upper and lower 45 MHz sidebands. A 10 uD single-pass defocus corresponds to a 400 mW CO2 laser on the X compensation plate in equilibrium [assuming a 25 uD/W actuation coefficient (single-pass), 28799].

The attached is a screenshot of OSA outputs in which scans from different time are overlaid. It is clear that the imbalance improved as time elapsed.

On the other hand, the frequency noise coupling became worse by a factor of a few comparing to the initial coupling value at 900 Hz. It did not experience a sign change. Not sure what this means.