Renishaw XL-80 - Common Causes of Laser Destabilisation

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Common causes of laser destabilisation
Back reections
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
reected back into the output beam aperture of the laser shutter, the detection
circuitry can be confused as the reected 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 reected
from the centre of the retroreector. The loss of stability is temporary and the
laser will restabilise once the reection is removed.
Ambient temperature change
If the XL laser has been kept in a cold place (for example, stored in the boot
of a car overnight in winter) and is 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 stabilises at a lower temperature than if it had been kept
in the working environment� If the ambient temperature around the tube
increases signicantly (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 rst 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�
XL-80 Hardware