aLIGO LHO Logbook

H1 ISC

jenne.driggers@LIGO.ORG - posted 13:01, Thursday 06 October 2016 - last comment - 16:16, Thursday 06 October 2016(30272)

Laser power was too high - 60W was actually ~60W

So, apparently Peter went into the PSL this morning and adjusted the HWP to give us more power incident on the rotation stage. However, this was not communicated to commissioners / people in the control room, so the ISC_LOCK guardian was still requesting 60W. With the hardware change, this was actually giving us ~60W into the vacuum. Something in the ASC didn't like this, and we lost 2 locks after ~1 hour each, with something drifting away.

EDIT: I guess some commissioners did know that we were getting 60W and decided to try running with it, we just didn't think it would have such a deleterious effect on the ASC.

Comments related to this report

peter.king@LIGO.ORG - 16:16, Thursday 06 October 2016 (30279)

Link

The half waveplate before the IO EOM was adjusted to yield a maximum of 60W as displayed by the
Ops Overview MEDM screen.  Said activity was performed under the watchful gaze of the day operator,
who was also my interlocutor whilst the waveplate was adjusted.

So the power table looks like ...


  
     Requested power 
     Indicated power 
  
  
     60 
     59.7 
  
  
     50 
     54.5 
  
  
     40 
     43.5 
  
  
     25 
     27.4 
  
  
     2 
     2.2 
  


    For the record, turning the small adjustment knob clockwise as you look at the mount, increases
the power.


Peter & (the day time operator)