keita.kawabe@LIGO.ORG - posted 19:44, Thursday 05 July 2012 - last comment - 21:31, Thursday 05 July 2012(3343)
Faraday replacement (Jax, Alberto, Dick, Keita)
We replaced the green Faraday due to clipping problem.
We've already aligned the injection path (i.e. the beam goes to the TMS and the QPDs are centered) but we need to work on the PDH and WFS path tomorrow.
Comments related to this report
keita.kawabe@LIGO.ORG - 21:31, Thursday 05 July 2012 (3344)
First picture is the beam with the original Faraday. You can easily see some really ugly lines. According to Alberto and Dan, this gets uglier when the beam is centered in the Faraday, so it was aligned closer to the Faraday edge. Combined with large TM motion, this caused a serious clipping problem.
The second picture is with the new Faraday taken at the same position. No apparent ugliness here. If you look closely you can tell that there's some funny stuff still there at the top (it would become more apparent in the far field), but this is much better than before. We expect that the clipping problem will be gone, though the large TM motion is still a problem on its own.
Before/After picture
First picture is the beam with the original Faraday. You can easily see some really ugly lines. According to Alberto and Dan, this gets uglier when the beam is centered in the Faraday, so it was aligned closer to the Faraday edge. Combined with large TM motion, this caused a serious clipping problem.
The second picture is with the new Faraday taken at the same position. No apparent ugliness here. If you look closely you can tell that there's some funny stuff still there at the top (it would become more apparent in the far field), but this is much better than before. We expect that the clipping problem will be gone, though the large TM motion is still a problem on its own.