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6.7 Scheimpflug adjustment
What has to be done ?
The lens holder has to be adjusted so that the "sharp focus plane" of the projected image falls together with
the plane of the screen (Fp1→Fp2). This is achieved by changing the distance between the DMD plane and
the lens plane (Lp1→Lp2). The closer the lens plane comes to the DMD plane the further the sharp focus
plane will be. It can sometimes happen that you won't be able to get a complete focused image on the screen
due to a tilt (or swing) of the lens plane with respect to the DMD plane. This is also known as Sheimpflug's law.
To solve this the lens plane must be placed parallel with the DMD plane. This can be achieved by turning the
lens holder to remove the tilt (or swing) between lens plane and DMD plane (Lp3→Lp4).
Image 6-22: Scheimpflug principle
Scheimpflug principle
The "plane of sharp focus" can be changed so that any plane can be brought into sharp focus.
When the DMD plane and lens plane are parallel, the plane of sharp focus will also be parallel to
these two planes. If, however, the lens plane is tilted with respect to the DMD plane, the plane of
sharp focus will also be tilted according to geometrical and optical properties. The DMD plane, the
principal lens plane and the sharp focus plane will intersect in a line below the projector for
downward lens tilt.
Scheimpflug adjustment points
A
a
1
4
D
Image 6-23: Scheimpflug adjustments
Indication on drawing
1, 2 and 3
4
A, B, C and D
a, b, c and d
1, 2 and 3 are adjustment points.
B
b
2
3
c
d
C
Function
Scheimpflug adjustment nuts
Locking nut
Set screws
lock nuts
Lenses & lens holder
R5906897 /02
Prometheus III
75
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