184
pression of spatial lines which form together a spatial (floating)
surface.
With the help of a spindle, which can be operated conveniently
by a knob on the left side of the table, the surface can be translated
towards and away from the observer, so that its stereoscopic
picture intersects the visual stereomodel at different heights.
The (Z-)displacement of the surface can be read off from a scale
with the help of a conveniently placed mirror. In the basic position
of the surface, the optical distance from the eyes is about 300 mm,
which is identical to that of the photographs from the eyes. There
fore in this position both the surface and the photographs are
simultaneously in focus. From its basis position the surface can be
displaced by about 30 mm, giving a Z-range of 10% of the
mean flying height above ground.
Fig. 1.
