Due to a mistake in past CHETA models there is more astigmatism then expected on the tables and a change in beam size at the ITM. The astigmatism can be fixed by rotating L1 around the vertical axis and the beam size can be changed by movind L2 using the translation stage in each setup. Using a modified Fintrace model the required rotation angle and translation for each table as they are currently populated at LHO (0922, 0918) and LLO (0919, 0851) have been calculated and are shown below.
The tables below give the current astigmatism and then the angles and translations such that the x and y beamsize on the ITM is 52.7mm with no astigmatism.
This code is avaliable in the CHETA modelling repository.
| Unit | Current astig [mm] | Rotation angle of L1 [deg] | Translation [mm] | ITM wx [mm] | ITM wy [mm] |
| 0922 | -7.69 | 10.17 | -0.12 | 52.7 | 52.7 |
| 0918 | -4.02 | 11.84 | -12.89 | 52.7 | 52.7 |
| 0919 | -7.55 | 12.17 | 3.81 | 52.7 | 52.7 |
| 0851 | -5.76 | 11.13 | 3.73 | 52.7 | 52.7 |
Without translating of L2 astigmatism can be removed but the beam size is still unoptimised.
| Unit | Current atig [mm] | Angle [deg] | ITM wx [mm] | ITM wy [mm] |
| 0922 | -7.69 | 10.17 | 52.75 | 52.75 |
| 0918 | -4.02 | 11.18 | 55.39 | 55.39 |
| 0919 | -7.55 | 12.03 | 50.95 | 50.95 |
| 0851 | -5.76 | 11.24 | 51.80 | 51.80 |