Beam position based on exciting the pitch(yaw) DOF and then changing P2L(Y2L) gain to minimize the peak. Both measurements use a sign convention that is consistent with UR coil values. The Dec 2013 alpha numbers are as posted, however the beam distance numbers have been recalculated. In Dec 2013 the conversion from alpha to mm was 37.5mm/alpha, and the current conversion is 42.2mm/alpha.
| 13 Dec 2013 | 21 Mar 2017 | change | |||
| alpha | beam distance from center, mm | alpha | beam distance from center, mm | mm | |
| MC1 pitch | -0.043 | +1.81 | -0.057 | +2.42 | +0.6 |
| MC1 yaw | +0.029 | +1.22 | +0.089 | +3.76 | +2.5 |
| MC2 pitch | -0.062 | +2.62 | -0.183 | +7.72 | +5.1 |
| MC2 yaw | -0.048 | -2.03 | -0.020 | -0.084 | +1.2 |
| MC3 pitch | +0.041 | -1.73 | -0.051 | +2.15 | +3.9 |
| MC3 yaw | -0.052 | -2.19 | -0.135 | -5.70 | -3.5 |
The animation that's attached shows the ideal IMC alignment in a dashed magenta line, the Dec 2013 alignment in red, and the Mar 2017 alignment in blue. Green markers show the optics, squares are MC1, triangles are MC2, and circles are MC3.
The lines and markers accurately represent the optics and the beam changes, but are not to scale. I altered some numbers to make the changes visible in this animation.
| 13 Dec 2013 | 21 Mar 2017 | change | |||
| alpha | beam distance from center, mm | alpha | beam distance from center, mm | mm | |
| MC2 yaw | -0.048 | -2.03 | -0.020 |
-0.84 |
+1.2 |