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MIF (ASC)
hirose.chiaki - 7:57 Friday 25 November 2022 (23026) Print this report
Measurement of stability to sensing matrix of Yarm

Tanaka, Hirose

We have measured stability of sensing matrix of Yarm since 20th Nov. (I'm so sorry for missing to post klog.)
The purpose is to research the effects of birefringence by measuring the stability of the sensing matrices due to changes in the beam spot of ITMY.
How to measure is following.

  1. Yarm is turn to IR lock.
  2. Loop (DCQPDs of TMSY ->IY, EY) is turned on.
  3. Record and offroad good oplev of IY, EY.
    →　To adjust the optical axis to the same optical axis each time to start measurement.
  4. Loop (DCQPDs of TMSY ->IY, EY) is turned off and OLDAMP (from TM to MN) is turned on. (For detail is klog22972)
    →　Now TMSY returns more noise than OLDAMP because it is not covered. After setting GOOD OPLEV, switch to OLDAMP control.
  5. ADS(TMSY->IMMT2,PR2) is turned on. Wait for ADS to settle.
  6. We measure the sensing matrix with excitation applied to each degree of freedom by diaggui at frequency higher than the ADS control band.
    →　Once the incident optical axis and the resonator axis are aligned, we measure the sensing matrix centered on that position.
  7. Change the beam position by changing the oprev set point, then measure like step6.

We will post the results later.

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hirose.chiaki - 10:40 Friday 02 December 2022 (23087) Print this report

I summarized the results of the sensing matrix.
We did measurement of Sensing matrix in 22, 23, 24, and 28 Nov.
Shift ±4 mm of PIT, YAW direction on ITMY beam spot (add to the set point: PIT's IY, EY by 2 urad: YAW's IY, EY by ±2 urad) from the determined center.
Good oplev of center : following the figure in klog23026.
Good oplev of center on 28th is changing from this work(klog23069), It is possible that the center from the previous day and the center on the 28th may be misaligned.
Replacement of signal generators(klog23008) has reduced the value of the WFS signal.

22th : center, PIT+4mm : IMMT2, PR2
23th : center : IMMT2,PR2,EY
24th : center, YAW±4mm : IY, EY, PR2, IMMT2 (also PR2 and IMMT2 on AS_WFS)
28th : Yaw ±4mm : PR2, IMMT2
We measured the degrees of freedom of each of these three times.
We originally wanted to measure three times on different dates,
but the number of measurements is not enough due to the high volume of measurements and the time it takes for the ADS to stabilize.
Also, PIT-4mm has not yet been measured.

  • The three data fluctuations are large relative to the error calculated from the coherence.
  • The ratio of the two QPD results has not changed significantly in the day-to-day measurements.
    In case the sensing matrices are fluctuating, I will set a larger phase margin for the ASC filter.

Sensing matrix : /user/Commissioning/data/ASC/2022/REFL_WFS/202211{22,23,24,28}/{center,p4mm_PIT, m_4mm_PIT, p4mm_YAW, m4mm_PIT}/TF_ASC_Yarm_REFLWFS_OVLEV_{mirrors}_{P,Y}{,_2,_3}.xml　->I haven't been able to organize some of the files.

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