5. Lenses & lens holder
5.7 Scheimpflug adjustment
What has to be done ?
The lens holder has to be adjusted so that the “sharp focus plane” of the projected im age falls together with the plane o f the screen
(Fp1→Fp2). This is achieved by changing the distance between the DMD plane and the lens plane (Lp1→Lp2). T he c loser the lens
plane com es to the DMD plane the further the sharp focus plane will be. It can sometimes happen that y ou won’t be able to get a
complete focused image on the screen due to a tilt (or swing) of the lens plane w ith respe ct to the DM D plane. This is also known
as Sheimpflug’s law. To solve this the lens plane mus t be placed parallel with the DMD plane. This ca n b e achieved by turning the
lens holder to remove the tilt (or swing) between lens plane and DMD plane (Lp3→Lp4).
SCREEN
DMD
Lp1
Lp2
Fp1
Fp2
SCREEN
DMD
Lp3
Lp4
Fp3
Fp4
(Scheimpflug)
Image 5-35
Scheimpflug principle
Scheimpflug principle
The "plane of sharp focus" can be changed so that any plane can be brought into sharp focus. W hen 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 s harp focus will also be tilted according to geometrical and
optical properties. The DMD plane, the principal lens pla ne and the s harp focus plane will intersect in a line below the
projector for downward lens tilt.
Scheimpflug adjustment points
4
1
2
3
d
D
c
C
A
a
B
b
Image 5-36
Scheimpflug adjustments
Indication on drawing Function
4 Locking nut
1, 2 and 3
Scheimp flug adjustment nuts
A, B, C and D Set screws
a, b, c and d lock n uts
1, 2 and 3 are adjustment points.
4 is a locking point and NOT used during Scheimpflug adjustment.
82
R5905963 PROMETHEUS SERIES 09/03/2015
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