External Triggering And Fps - NORTHROP GRUMMAN Patara I User Manual

External Triggering and FPS

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The laser may be externally triggered using a TTL signal of 300 ns to 500 ns
duration. The signal may be input via the BNC connector labeled EXTERNAL
TRIGGER on the back of the eDrive controller.
Figure 4-14 illustrates the RF signal output to the Q-switch without first pulse
suppression (FPS) and the laser pulse train with the first giant pulse. If the peak
power of these giant pulses is high enough, it can cause the damage to the mirrors
and the laser crystals. The giant pulse forms when the lasing was stopped while
the pumping light is still on during the laser processing cycle. The amplitude of
the giant pulse is dependent on the non-lasing duration as well as the operating
current.
Figure 4-14. First Giant Pulse with FPS Disabled
CAUTION.
The FPS has to be enabled and parameters for FPS have to be set
properly. Failure to suppress the first giant pulse may cause the internal optical damage
as well as damage to the work piece.
For each type of laser processing, a particular operating current and pulse
repetition rate are needed. The giant pulse can be suppressed by enabling FPS and
setting the proper FPS parameters. For detailed information, please refer the
Configuring the Integrated AO Q-Switch RF Driver section in Chapter 3:
Operating Basics in the eDrive User Manual (CEO-UMAN-0001).
To set the FPS properly, use a photodiode detect with response time 1 ns and an
oscilloscope.
Chapter Four: Installation and Operation
38 Patara I and II Laser User Manual