Parameters
wx : half width of the incident beam waist waist in the XZ plane
wy : half width of the incident beam waist waist in the YZ plane
lam : wavelength
fi1 : back focal length of the first lens
fi2 : back focal length of the second lens
wf : mode radius of the fiber optic
T : transmission coefficient at the entrance of the fiber optic
dx : lateral shift of the fiber optic along X axis
dy : lateral shift of the fiber optic along Y axis
dz : defocus of fiber optic
tiltx : tilt of the fiber optic around the X axis
tilty : tilt of the fiber optic around the Y axis
C : coupling ratio
zix : distance from the second lens to the waist in the XZ plane of the refacted beam (which is also the distance from the second lens to the fiber optic entrance without misalignments )