While Gautam is working the restoration of Yarm ASS, I worked on Xarm.
Basically, I have changed the oscillator freqs and amps so as to have linear signals to the misalignment of the mirrors.
Also reduced the complexity of the input/output matrices to avoid any confusion.
Now the ITM dither takes care of the ITM alignment, and the ETM dither takes care of the ETM alignment.
The cavity alignment servos (4dofs) are running fine although the control band widths are still low (<0.1Hz).
The ETM spot positions should be controlled by the BS alignment, but it seems that these loops have suspicion about the signal quality.
While Gautam wa stouching the input TTs, we occasionally saw anomalously high transmission of the arm cavities (~1.2).
We decided to use this beam as this could have indicated partial clipping of the beam somewhere in the input optics chain.
Then the arm cavity was aligned to have reasonably high transmission for the green beam. i.e. Use the green power mon PD as a part of the alignment reference.
This resulted very stable transmission of both the IR and green beams. We liked them. We decide to use this a reference beam at least for now.
Attachment1: GTRX image at the end of the work.
Attachment2: ASSX screen shot
Attachment3: ASSX servo screen shot
Attachment4: Green ASX servo screen shot
Attachment 5: Screen shot of the ASS X strip tool
Attachment 6: Screen shot of the ASS X input matrix
Attachment 7: Screen shot of the ASS X output matrix |