[Uchiyama, Washimi, Yokozawa, Ushiba]

Abstract:

We took photos of REFL and POP tables when PRFPMI was locked with OBSERVATION state.
Several ghost beams, which were not propery dumped, were found.
Also, the iris just after the periscope of REFL table seems clipping the REFL beam.
It's better to take time to check the each optical table again at some point.

Detail:

We took photos of POP and REFL table with camera, which can detect IR today (fig1-3: POP, fig4-8:REFL).
There are several beam spot on PDs, QPDs, and walls, which should be propery dumped.

We also found the iris just after the REFL periscope seems clipping the REFL beam.
So, it should be fixed soon.

Since the alignment could be changed due to the cooling, it would be better to check the optical path again for all optical tables.