Elenna, Camilla, Ryan. WP#12806 . IOT2L layout D1300357
Followup from the beam measurements taken last week 86962, while we still had the nominal ~115W through the PSL EOM. Elenna and I repeated these measurements today, now that the power through the EOM has been reduced to ~90W, see 86966, which appeared to improve the mode matching to the IMC. We see the beam has changed shape (now larger on IOT2L) since the power reduction.
We took the PSL input power down to ~100mW, locked out the rotation stage and then used the nano scan to take some beam profiles in the IMC REFL path on IOT2L.
| Location | D4 Sigma A1 Horizontal (um) | D4 Sigma A2 Vertical (um) | D4 Sigma A1 at 45deg (um) | D4 Sigma A2 at 45deg (um) |
| A: Profiler 11 1/2" upstream of IO_MCR_BS1 | 4922 | 4722 | 4731 | 4904 |
| B: Profiler 10 7/16" downstream of IO_MCR_BS1 (7" + 1 1/2" + 1 15/16") | 4992 | 4829 | 4953 | 4875 |
| C: Profiler 14 5/8" downstream of IO_MCR_BS1 (7" + 1 1/2" + 6 1/8") | 5187 | 4817 | 5050 | 4857 |
For positions B and C, we added a temporary steering mirror between IO_MCR_M7 and IO_MCR_L2. Distance between IO_MCR_BS1 and IO_MCR_M7 = 7"; Distance bewtween IO_MCR_M7 and temporary steering mirror = 1 1/2".
