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VIS (SR2)
terrence.tsang - 21:06 Wednesday 22 May 2019 (8945) Print this report
SR2 residual motion measurement - succeed

With the combination of fine OL diagonalization (suppressed L motion to ~ 0.5 - 0.6 µm/s) and further improving OL wind shield, I successfully made a measurement that would prove that the SR2 satisfies the lock-acquistion phase requirements (almost satisfy observation phase requirements) (in particular longitudinal rms velocity). Here are the results:

Residual displacement (Lock-acqusition and Observation phase)
  Requirement Preliminary result
Longitudinal 0.4 µm 0.436 µm
Pitch 1 µrad 0.201 µrad
Yaw 1 µrad 0.360 µrad

 

Residual velocity (Lock-acqusition and Observation phase)
  Requirement Preliminary result
Longitudinal 0.5 µm/s 0.448 µm/s
Pitch / ~0.39 µrad/s
Yaw/ / ~0.31 µrad/s

The only requirement that hasn't been met is the longitudinal residual displacement for observation phase. It is limited by the microseismic peaks at 0.2 - 0.5 Hz and an anonymous peak at 0.4 Hz. 

Comments to this report:
terrence.tsang - 9:37 Thursday 23 May 2019 (8949) Print this report

In the morning, while it's still quiet in the mine, I measured residual motion again. And, I would declare that, with all local control systems on, the SR2 satisfies the residual motion requirements for lock-acquisition phase and observation phase. Results will be presented in the type B paper.

Residual displacement (Lock-acqusition and Observation phase)

 
  Requirement Preliminary result
Longitudinal 0.4 µm 0.358 µm
Pitch 1 µrad 0.177 µrad
Yaw 1 µrad 0.405 µrad

 

Residual velocity (Lock-acqusition and Observation phase)
  Requirement Preliminary result
Longitudinal 0.5 µm/s 0.379 µm/s
Pitch / 0.425 µrad/s
Yaw/ / 0.414 µrad/s
 
Images attached to this comment
kiwamu.izumi - 4:17 Friday 24 May 2019 (8958) Print this report

Hi Terrence,

Nice work! By they way, I have a question for you --- how did you derive all those requirements for lock acquisition? If SR2 needs to be as quiet as 1 urad in angle, does this mean that SR3 then has to be 0.125 urad or smaller due to the fact that the beam size is larger by a factor of 8 on SR3?

ayaka.shoda - 13:19 Friday 24 May 2019 (8963) Print this report
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