38
POSSIBLE CAUSE:
External cooling water has frequent and large pressure fluctuations.
REMEDY:
Check external cooling water for pressure fluctuations. Install pressure regulator set at 20 psi
if necessary.
SYMPTOM #6: Q-switch BUT Reduction Changes (slowly) by more than 10% after external
cooling water is flowing.
POSSIBLE CAUSE:
Etalon effects from various coated and uncoated surfaces within the resonator.
REMEDY:
With the Mode Switch in MANUAL, change the Laser Frequency Potentiometer (located on
top of the laser head) while observing the reduction in Q-switch BUT. As the seed laser is
tuned in and out of resonance with the host, if the Q-switch BUT periodically changes from
a large BUT to a smaller BUT, some element within the host cavity is acting as an etalon.
This should be tracked down and corrected by tilting the element off axis. This would
happen every 5 to 25 resonances of the seeder with the host, and is not to be confused with
the mode hopping of the seed laser which happens after more than 100 resonances or >1cm
-1
of seed laser tuning.
SYMPTOM #7: No output from the seed laser.
POSSIBLE CAUSE:
Laser diode has reached the end of its life or the seeder NPRO has misaligned.
REMEDY:
The unit must be returned to Lightwave for repair.