Abe, Marc (with help of Michael and Yuhang to safely move the spare ETMY)

First we removed the spare ETMY.

Then, we used the razor blade and high power power meter connected to the lock-in amplifier DC to check the pump beam angle of incidence in vertical and horizontal planes. (analysis to follow)

We installed the surface reference sample and got R ~15.7 /W without tuning the alignment.

We tuned the alignment and got R_surface = 18.537 /W with Z_translationStage = 42 mm and Z_IU = 66 mm.

We also measured R_bulk = 0.6703 cm/W.

We reinstalled the spare ETMY with the 2 ears flat (ie same configuration as in entry 2755.

We tuned Z_IU to 5.4 mm taking into account the thickness after repolishing (14.3 cm instead of 15 cm).

We started to look for the 2 surfaces signal increasing the input pump power from 2W to about 7W (in transmission of the spare ETMY).

At that point we may have seen the expected signal with median and average filters order 10 but because the step size was 0.2mm we could not clearly see them.

For reference, the last time that the spare ETMY absorption has been measured the input pump power was about 10 W (see for example entry 1601)

As it was getting late on Christmas eve we stopped there and will start absorption measurement on monday.