Evan, Kiwamu, Stefan Tonight we left the PRMI locked, with a dither loop for ITMY, and a sqrt(POB18) gain scaling for MICH and PRC. The ring heater was set at 0.75W for both upper and lower heater (total of 1.5W). The heat was turned on at 09:13:38 UTC. The idea of this "low-heat" run is to keep the heating in a regime where the lens strength is roughly linear in the change in build-up. This should give us a good measurement of the lens-strength vs. time.
Here's the time evolution of the defocus of the test mass (single pass, thermal lens only, two different x-axis ranges) in response to a 1W step function in ring heater power at t=0s.