Cao, Dan

After getting to NLN we found the phase camera path was causing a lot of scattering issues. Tonight we think we have fixed all or most of it. The main issue was that the realignment of the interferometer caused the POP beam to fall off of the 1811 we are using, this was scattering all over the table and caused all the low frequency scatter. The smaller lines around 300Hz were from a lens I hadn't screwed down. Additionally we installed a 90:10 beamsplitter to dump most of the POP light into the black glass beam dump, as at full power there is way too much for the camera anyway. We borrowed a flip mirror from the TCS cupboard that we can drive with a 5V signal to dump the rest of the path after the beamsplitter if any new issues arise, although we will have to sort out a channel for it tomorrow.

As it looks much better I have left the phase camera path open and maybe some shaking tests will get done tomorrow.

Leaving for the night, IFO is locked in nominal low noise.