The HWS on ITMX was running during last night's 1 hour lock. It saw a lens of ~6 micro-diopters (double-passed) form while the IFO was locked. The transient data is in the attached plot.
HWSY is not currently operational.
At the moment, I can't reliably estimate the absorption coefficient, but the absorbed power is about 1.06 mW per micro-diopter (double-passed), so roughly 6mW of power was absorbed.
If I go with 2W requested from the PSL rotation stage and do the same calculation we did at LLO:
2W (input power) * 30 (recycling gain) * 0.5 (beam splitter) * 286 (arm cavity gain) = 8.6kW stored arm power,
which yields
~700 parts per billion absorption in ITMX coating
I would definitely take this number with a healthy grain of salt ... I'd still like to run some diagnostics on the ITMX HWS following yesterday's code update.
(Also, the data in the attached plot was rescaled in dataviewer, by 0.00326, to what is currently displayed to account for the fact that the HWS magnification was set to 1x at the time of this measurement, rather than 17.5x. The spherical power scales as 1/M^2 = 1/17.5^2 = 0.00326).
I've added this data to the TCS actuator couplings document on the DCC.
I've calculated the stored arm power from last night's lock as 11.5kW (As calculated in post 16579).
Using this number instead of 8.6kW approximated from livingston's numbers, this brings the estimate of absorption in the ITMX coating to 520 parts per billion.