sheila.dwyer@LIGO.ORG - posted 00:20, Thursday 27 March 2014 - last comment - 10:58, Thursday 27 March 2014(11025)
Red arm losses
Valera called and asked for a measurement of the arm losses. I used REFL_AIR, meaured 0 counts when the IMC was unlocked, 1.539 when the arm was locked with ALS off resonance, and 1.471 when the arm was locked on resonance. The IR trans power was only 70% of the nominal, so the arm was not well aligned and this only gives us an upper limit on the losses, which is 159ppm, assuming the ITM transmission is 1.4%.
A more accurate measurement shoud probably be done.
Correction: This is really a lower limit, anyway not a very good one.