53
Centration of Xe or Hg gas discharge lamps
n.b.!
Never look straight into the light path!
Remember the risk of glare when switching to
the BF or Smith reflector!
Move the reflection of the discharge arc to the
side or entirely out of the light path by adjusting
the centring screws on the back of the lamp-
housing (70.2, 3, 4).
Focus the direct image of the arc with the collec-
tor adjustment (70.6)
Caution:
Use the neutral density filter to reduce the
intensity of the discharge arc image on the
centration areas due to the risk of glare dam-
aging the eyes.
Centre the arc images as follows:
Hg 50 W mercury lamp
Using the centring buttons (70.1, 70.5) move the
direct image of the arc to the right or left of an
imaginary line through the middle of the centrati-
on area (71a, b). Then focus the reflection (70.3)
and, using the centring buttons of the mirror
adjustment (70.2, 4), move the reflection until it is
symmetrical with the direct image (71c).
Hg 100 W and Xe 75 W lamps
Using the centring buttons (70.1, 5) move the
direct image of the arc to the middle of the cen-
tration area, with the bright tip of the arc, the
focal spot of the cathode, just off centre.
Then focus the reflection (70.3) and, using the
centring buttons of the reflector adjustment,
move the reflection until it is symmetrical with the
direct image (71a, b, c).
The V-shaped emissions of the arcs of the direct
image and the reflection can be superimposed.
Caution:
The bright tip of the light arcs, the focal spots
of the cathode, must never be projected on
top of one another, as there is then a risk of
explosion due to overheating.
Replace spent burners in good time and dispose
of in an environmentally compatible way.
Open lamphousing only after cooling and dis-
connection from the mains.
Wear gloves and mask if using Xe lamps.
Hg lamps will reach their full intensity only after a
few minutes, they do not ignite when hot.
Fig. 71
Schematic diagram of the lamp centration in lamp-
housing 106Z (in reality the lamp images are not as sharp)
a
direct lamp image, focused, but decentred
b
direct lamp image in correct position
c
indirect and direct lamp image in correct position
a
12V
100W
halogen
lamps
Hg
50 W
Hg
75 W
Hg
100 W
lamps
b
c
