15
2. The purpose of the second stage of alignment
is to manually adjust the detector so as to align
the centre of the beam as closely as possible
with the centre of the refl ector.
Turn one of the thumbwheels until one of the
LEDs starts fl ashing. It does not matter whether
you pan or tilt fi rst or which way you turn the
thumbwheel (Figs 18 to 20 assume that pan-
ning is carried out fi rst).
If turning one way does not cause either of the
LEDs to fl ash, turn the thumbwheel the other
way.
3. If the amber LED illuminates, turn the
thumbwheel the other way until either the red
LED starts to fl ash (beam now close to centre)
or neither LED fl ashes (beam is in the centre).
Keep turning until the amber LED fl ashes then
stop turning (Fig 18). Go to step 5.
4. If the red LED fl ashes, wait until it stops and then
turn a few steps more in the same direction. If
the red LED fl ashes between steps, wait until it
stops. Keep turning until the amber LED fl ashes
then stop turning (Fig 18). Go to step 5.
5. Turn the thumbwheel back, counting the
number of turns as you go, until the amber
LED starts fl ashing again and stop (Fig 19). If
the red LED fl ashes at any point, wait until it
goes out before going on.
6. Change the direction of turn of the
thumbwheel again and turn half the number
of steps counted (Fig 20). If the red LED fl ashes
at any point, wait until it goes out before going
on.
7. Now turn the other thumbwheel and carry
out the steps described in points 3 to 6. Figs
21 and 22 correspondingly show the tilting
movement.
8. At the end of the panning and tilting align-
ment procedures the centre of the beam
should be projected onto the centre of the
refl ector, as shown in Fig 23. The LEDs will not
be illuminated.
The
refl ective beam detector is now aligned
and ready for fi nal checks.
AMBER
LED
FLASHES
NOTE
NUMBER
OF
TURNS
UNTIL
AMBER
LED
FLASHES
AGAIN
TURNING
BACK
HALF
THE
NUMBER
OF
TURNS
PUTS
THE
BEAM
AT
THE
CENTRE
OF
THE
VERTICAL
LINES
Fig 18
Fig 19
Fig 20 no
LED
fl ashes
Fig 21
Fig 22
Fig 23 Detector aligned
IMAGINARY LINES
INDICATE LED FLASH
BOUNDARIES
