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XL laser system
XL-80 hardware XL-80 applications
Common causes of laser destabilisation
Back reflections
The feedback circuit which controls the heater, and thus stabilises the laser, is
based on monitoring the output beam from the laser tube. If the laser beam is
reflected back into the output beam aperture of the laser shutter, the detection
circuitry can be confused as the reflected beam will interfere with the outgoing
beam. This will lead to a loss of stability of the laser.
This is most likely to occur during system alignment, either due to the beam being
misdirected back into the laser or the outgoing beam being reflected from the
centre of the retro-reflector. The loss of stability is temporary and the laser will
restabilise once the reflection is removed.
Ambient temperature change
If the XL laser has been kept in a cold place, e.g stored in the boot of a car
overnight in winter, and is then taken into a warm factory to be used, the laser
may become unstable. When the laser is switched on, the temperature of the laser
tube will stabilise at a lower temperature than it would if it had been kept in the
working environment. Thus if the ambient temperature around the tube increases
significantly, due to self heating and an increase in the ambient room temperature,
the heater current may reduce to zero and the laser will become unstable.
If you encounter this problem, it can be overcome as follows:
1. Turn off the laser at least 15 minutes after the laser has first stabilised.
2. Wait a few seconds.
3. Turn on the laser.
4. Wait while the laser goes through a second preheat cycle and restabilises
at a higher tube temperature.
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