Following the same idea as elog 28442, here is a script for moving the beam spot position on PRM (prmspotmove.py).
It monitors IM3 slides, and moves IM4, PRM and PR2 sliders in such a way the the beam spot positions on PR2 and PR3 don't change.
The script was tuned in INPUT_ALIGN (for IM4 and PR2 matrix elements) and PRM_ALIGN (for PRM matrix elements).
Matrix elements (in rad /rad IM3)
pitIM3toPR2=+0.0022;
yawIM3toPR2=+0.0055;
pitIM3toIM4=-1.3;
yawIM3toIM4=+0.92;
pitIM3toPRM=-0.009;
yawIM3toPRM=+0.031;
Also attached is the python script used for finding the matrix element, getMx.py.
Here is the theoretical matrix for this move (note that signs will vary for pitch and yaw):
IM4/IM3=-1.022385686091801*tim3;
PR2/IM3=0.069871106113604*tim3;
PRM/IM3=-0.350788523435222*tim3;
This was calculated with the following data (in meters):
RPRM=-11;
RPR2=-4.555;
RPR3=36.0;
RITM=1939;
LPRM=16.6128;
LPR2=16.1551;
LPR3=24.88797;
LARM=3994.5;
LIM4=0.413;
LIM3=1.17;
n=1.45;
f=-RITM/(n-1); # thin lens approximation
fm=-RPRM/(n-1); # thin lens approximation