Luke, Deepak, Cheryl, Alex, Rodica

Last week we finished assembling and aligning the IO Faraday isolator on the H1 PSL table. A little more ghost beam hunting is needed, but once all the stray light is contained, the system is ready for high power testing. Without the DKDP crystal yet installed the isolation is 47.8-49 dB, with 96-98% in the returned REFL beam (98-99% transmission assuming equal losses in forward and backward directions) for 500 mW to 9 W incident power. The forward extinction (incident to forward rejected) is >30 dB, and could be improved even further with some more careful finetuning.

The following steps are suggested for high power testing:

- quantify the power in all ghost beams and make sure they are blocked properly

- measure and finetune isolation / transmission up to 150 W without / with DKDP

- measure thermal lensing

The water cooled power meter needs to be moved to measure the powers in REFL and incident beams. Also, it helps if two low power Ophir power meters are used to simultaneusly check isolation and transmission. 

Thanks to everyone at LHO for their great help and support with this!