aLIGO LHO Logbook

H1 TCS (AWC, TCS)

daniel.vander-hyde@LIGO.ORG - posted 20:41, Sunday 03 February 2019 - last comment - 14:40, Monday 04 February 2019(46755)

SRM heater alignment attempt #2 (Yaw still clipping)

Satoshi, Danny

Continuing from our last attempt (alog 46692) we sought to finish this up by increasing our range in yaw without clipping on the SRM AR baffle but this still proved to be difficult. We first tried walking the beam using both upper and lower periscope mirrors and then resorted to shifting the table. After trying various configurations we decided to think about it more carefully before attempting again on Tuesday.

Comments related to this report

aidan.brooks@LIGO.ORG - 12:19, Monday 04 February 2019 (46760)

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Would it be possible to add more detail to this? What is the metric you're using to determine the alignment?

daniel.vander-hyde@LIGO.ORG - 14:40, Monday 04 February 2019 (46766)AWC, TCS

Link

The metric we are using is the amount of deflection we see on the AS_A and AS_B photodiodes (with the IFO in single bounce)

We are currently using the following method to align:

Make sure you are not clipping on the mirror apertures or baffles using the red alignment laser and can see the transmission of the red laser onto the SRM-HR baffle through the viewport adjacent to the Zn-Se viewport.
When scanning the back of the SRM with the CO2 you expect the CO2 to create a wedge as you get close enough to the ifo beam which corresponds to a strong deflection on the aforementioned PDs
If given enough range, you should be able to pass the CO2 over the ifo beam which would correlate to the behavior shown in the figure attached (I use yaw as the example).
Fine tune alignment to achieve State B.

Results:

We have used this method to achieve good centering in pitch.
In yaw, we see the behavior in State A (in the figure) but we start clipping on the SRM-AR baffle before we can start to see State B and State C.

Images attached to this comment