Reports until 13:24, Tuesday 29 November 2022
H1 TCS
camilla.compton@LIGO.ORG - posted 13:24, Tuesday 29 November 2022 - last comment - 09:34, Wednesday 30 November 2022(66077)
Slow ITM dither to check HWS calibration.
Mitchell, Dan, Camilla. 
Repeating Aidan's 52513, we put a very slow 0.005Hz +/-10urad dither on H1:SUS-ITM{X,Y}_M0_OPTICALIGN_{P,Y}_EXCMON using awggui.  
At 11:20am, we tried a 0.2Hz but the HWS code only calculates at 1Hz so this was too fast. 
Plots attached for YAW and PIT. You can see that ITMX YAW and ITMX PIT and YAW is coupling into the ETMs.
Images attached to this report
Comments related to this report
mitchell.schiworski@LIGO.ORG - 15:13, Tuesday 29 November 2022 (66088)
Link 

Processed the data from this test (see attached plots) to estimate the magnification according to how it was done in the above mentioned ALOG (I think). Results show quite a bit of astigmatism in both the ETM and ITM HWS, but there is roughly the same amount in each. The current set magnifications for both is the default value of 17.5.

The origins for each Hartmann may not be correct which could explain why these results look strange?

Summary:
HWS-ITMX:
  Magnification x: 15.7
  Magnification y: 12.0
  Ratio x/y: 1.31
  Ratio y/x: 0.76

HWS-ITMY:
  Magnification x: 12.9
  Magnification y: 17.8
  Ratio x/y: 0.72
  Ratio y/x: 1.38
Images attached to this comment
mitchell.schiworski@LIGO.ORG - 16:58, Tuesday 29 November 2022 (66095)
Link 

Have followed up and applied quadratic fits to the ITMX/ITMY ring heater test done a month ago. In these tests only the ring heaters were left on for a period of 5 hours, the deformation seen by the HWS should be approximately quadratic and the same in x/y assuming no astigmatism in the hartmann optics.

The results are summarized in the attached images.

ITMX Quadratic fits:
   x slice: -1.54e9*x**2 + 4.14e5*x + 3.42e4
   y slice: -1.49e9*x**2 + 1.27e6*x + 3.31e4
   quad x / quad y : 1.03
   quad y / quad x : 0.97
ITMY Quadratic fits:
   x slice: -1.86e9*x**2 + 2.85e5*x + 6.29e4
   y slice: -1.68e9*x**2 + 1.39e5*x + 6.04e4
   quad x / quad y : 1.11
   quad y / quad x : 0.90

Avg quad ITMX / Avg. quad ITMY: = 1.52/1.77 = 0.86
Avg quad ITMY / Avg. quad ITMX: = 1.77/1.52 = 1.16

These results seem more reasonable, and imply only a 3-10% astigmatism in the magnification in the ITMX/IMTY HWS (if the ratio of the quadratic terms in the fits is the correct metric).
Images attached to this comment
mitchell.schiworski@LIGO.ORG - 18:51, Tuesday 29 November 2022 (66099)
Link 

For future reference, I will attach the python scripts used to process the Hartmann magnification measurement/calibration and to perform the quadratic fit to the ringheater test.

In each script you will only need to modify the specified GPS times and which HWS to use, and the rest will be processed automatically.
Non-image files attached to this comment
mitchell.schiworski@LIGO.ORG - 19:22, Tuesday 29 November 2022 (66100)
Link 

Data from another much longer ring heater test from April 2022 shows similar behaviour in HWS-ITMY (data from ITMX was bad due to misalignment).

ITMY Quadratic fits:
   x slice: -1.43e9*x**2 + 1.39e5*x + 4.11e4
   y slice: -1.28e9*x**2 + 7.78e5*x + 3.89e4
   quad x / quad y : 1.12
   quad y / quad x : 0.90
Images attached to this comment
aidan.brooks@LIGO.ORG - 20:01, Tuesday 29 November 2022 (66101)
Link

The magnification of the HWS images can also be estimated directly from the shape of the shadows in the intensity distribution. Measurements of the ITMY intensity distribution earlier this year are close to what is predicted with magnifcation of 17x. A closer look at this is definitely recommended.

aidan.brooks@LIGO.ORG - 09:34, Wednesday 30 November 2022 (66103)
Link

Analysis of the uniformity of the Ring Heaters is given in: https://dcc.ligo.org/LIGO-T1000727. There is some small astigmatism predicted. The document quotes it in absolute Zernike values - annoyingly the spherical power component is not also given (might be possible to back it out).