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Laser Optimization
© 2019 Cutting Edge Optronics
11. If the laser is still not within 5% of the original power or is not stable, repeat
the steps in Laser Optimization and HR/HM Alignment until there is no
significant performance improvement.
12. If the laser power can't be restored to the specification, or the laser is not
stable, then the Walking the Cavity procedure can be tried.
1. Turn the laser to operate at normal output power. Check the settings of the
diode power supply operating current, chiller temperature, and TEC controller
temperature.
2. Check the performance with all operating parameters set to the values on the
ATP test report data summary.
3. Make sure that the flow rate is 1.4 – 1.5 gpm and the temperature of the chiller
matches results from the original test report. The coolant flow rate and
temperature have a significant impact on the laser performance.
4. Run the laser for a minimum of 1 hour and wait for the laser to reach thermal
stabilization.
Both the laser bench temperature and environmental temperature significantly
impact the laser power. Wait for the laser to be thermally stabilized before
attempting any adjustment.
5. Peak up the laser power by tuning the temperature of the TEC controller. Do
not adjust TEC in more than .2°C increments. Adjusting TEC at full power
can cause optical damage to the SHG crystal.
The phase matching of the SHG crystal is crucial for the laser. This is achieved by
setting the proper temperature on the SHG crystal, which is controlled by the TEC
controller.
Figure 3-4 illustrates an example of the dependency of power and pulse-to-pulse
instability of the laser to the SHG crystal temperature. As shown in the example,
the midpoint of the temperature band is around 28.5 ºC; the midpoint of the
temperature band is the normal operating temperature. The laser may have peak
power at 29.3 ºC in this example, but a small temperature change on the SHG
crystal could result in a power fluctuation.
Chapter 3: Tuning and Testing Procedures
43
Patara II and Iklwa II Service Manual
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