technical reference
62
SYNRAD OEM v40 Operator’s Manual Version 4
Controlling laser power
Marking/engraving operation
When the delay between the end of one PWM Command signal pulse and the beginning of the next
PWM pulse exceeds 200 microseconds (less than or equal to 5 kHz), Firestar’s on-board tickle generator
sends a tickle pulse to maintain plasma ionization in the tube. Because the on-board tickle generator can
not anticipate when the next PWM Command pulse will arrive, the tickle pulse (which typically lasts for
2–6 µs depending on the laser) can eectively merge with a PWM signal that follows closely afterwards.
When the PWM pulse that follows is short, causing the tickle pulse to become a signicant fraction of the
PWM pulse duration, then the tickle pulse eectively substantially increases the length of the PWM pulse
it has merged with. For subtle marking applications on sensitive, low threshold materials this lengthened
PWM pulse may aect mark quality.
While this situation can occur when using PWM Command signal frequencies of 5 kHz and less, it is im-
portant to note that it isn’t the Command signal frequency itself that is the determining factor but rather
this behavior happens only when the o time between PWM pulses exceeds 200 microseconds.
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