M. Todd, E. Capote, C. Compton, S. Dwyer
After the vent, beam profiles were taken at REFL and POP (single-bounce) which are of interest to modeling efforts to gain some confidence in model parameters. Using a-la-mode to model the beam throughout the IFO and compare it to the measurements, we are able to confirm most of the parameters in the finesse yamlfile for the IFO model. See Figure 1 and Figure 2 for measured profiles of REFL and POP compared to the model beam parameters.
Now that we have more confidence in the model, we feel more comfortable looking at figures of merit that the model can provide -- such as the beam overlaps of different modes. Of particular interest was the input beam overlap with the PRC and ARM eigenmodes -- it seems the input beam is not super well mode-matched the PRC.
| Mode1 | Mode2 | Overlap: v, h [%] |
|---|---|---|
| Input beam [IMC] | PRCx | 94.98 , 97.00 |
| Input beam [IMC] | PRCy | 96.99 , 98.32 |
| Input beam [IMC] | ARMx | 98.57 , 98.91 |
| Input beam [IMC] | ARMy | 99.03 , 99.31 |
| PRCx | ARMx | 96.71 , 98.11 |
| PRCy | ARMy | 97.96 , 98.87 |
There are plenty of interesting figures of merit that we can calculate using this model that help us understand more about the mode-matching state of our interferometer, and hopefully inform steps to correct mismatch.
The code used in this modeling is held in the 'ligo-commissioning-modeling' repo folder:
