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depth of focus is limiting the tilt of the 
of a three-dimensional test field with 
optimal (see fig. 2). On top of the "U" 
information and instead of the object, a 
control. 
object against the optical axis and the use 
the shape of an U has been found as 
a reseau grid is used as 3D-control point 
reseau below the U is used for vertical 
fig 1 stereo microscope 
Caused by the small view angle, the elements of interior orientation are highly 
correlated. But the determined object coordinates inside the three-dimensional are 
not influenced by this. 
fig. 3 geometric condition of stereo microscope