A special procedure was developed
for aligning the mirrors. This procedure is based on the
ray-tracing for the optimized mirror positions.
The alignment scheme is presented in Fig. 10.
).
A second spot on the screen
indicates the position of the reflected light
( 
).
and
will be
on the center line of the screen.
This ensures that the mirror surface
is perpendicular to the segment median plane.
to the middle plane
is calculated as a function of the
distance from
to the middle plane for the optimized
mirror position, and stored in an alignment table.
can be adjusted according to the alignment table.
) ,
which is covered by another screen.
The ``theoretical position'' of
with respect to the center of WC window is also stored
in the alignment table as a function of the
distance from
to the middle plane.
As was shown in chapter 4.2 the deviation of
position should not exceed a few millimeters.
The center of the spot can be defined with an accuracy of
mm for the light reflected off the elliptical
part of mirror, and
mm for light reflected off the flat part.
