Continuum Surelite EX 10, Operation And Maintenance Manual

Page: 89 / 114

Section 6: Troubleshooting
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Figure 53 Flashlamp rise – free-
running pulse
Figure 54 Flashlamp rise – further
adjustment required
Note: To eliminate the free-running, adjustments to the polarization optics
need to be made.
11. At this time make a small adjustment to the
vertical axis of the Pockels cell through the
vertical adjustment access hole located at the
top of the Pockels cell mount.
12. Note the vertical amplitude of the scope
display. If it becomes less, then the previous
adjustment was made in the correct direction.
13.
Continue to adjust the vertical axis until the amplitude of the trace is as small as
possible or until the free-running stops.
If
the free-running stops, then go on to step
16.
14. Now follow the same procedure as in steps 12
and 13, only this time adjust the horizontal
axis located on the lower corner of the
Pockels cell mount.
15. Continue these adjustments until the free-running has been eliminated.
16. Close the intracavity shutter and increase the pump voltage by 100 V.
CAUTION!
Do not exceed 1.8 kV unless otherwise instructed
to do so by a Continuum representative.
17. Open the intracavity shutter and look at the oscilloscope to see if the laser is free-
running.
18. If the laser is in a free-running state, then repeat steps 11 through 15 while at this
higher pump voltage.
Note : Once the oscillator optics are properly adjusted, passive free-running should
not occur until the pump voltage has exceeded 100 V above the normal operating
level. In many cases this voltage “ buffer” will be even greater than 100 V.
19. Once the “ buffer” voltage is ~100 V, return the pump voltage to its normal level. (See
QA chart in front of the manual immediately following the title page.)
Note : After completing the free-running test procedure, it is very important to
check the oscillator alignment once again. Any movement of the Pockels cell may
cause a misalignment, requiring a back mirror adjustment (see page 6-6).
Flashlamp voltage adjustment
It is common for flashlamps to last 20-30 million shots, but during that time the efficiency of
the lamps will decline. Initially, it is possible to compensate for the decline by increasing
pump voltage. However, after a point, the thermal loading on the YAG rod will adversely