Novanta 32-1 Laser, User Manual

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PWM signal
The modulated PWM signal applied to 32-1 lasers has three parameters: signal amplitude, base frequency,
and PWM duty cycle. By changing these parameters, you can command the beam to perform a variety of
marking, cutting, welding, or drilling operations.
The first PWM signal parameter, signal amplitude, is either logic low—corresponding to laser beam off, or
logic high—corresponding to beam on. The laser off voltage, typically 0 V, can range from 0.0 V to +0.5
VDC while the laser on voltage, typically 5 V, can range from +3.5 V to 10.0 VDC.
Base frequency, the second parameter, is the rate at which the amplitude is switched between its low and
high logic states. The standard base frequency is 5 kHz, which has a period of 200
μ
s. Maximum PWM
frequency is 20 kHz.
The third PWM signal parameter, PWM duty cycle, is the percentage of the period that the PWM signal is
high. If the PWM signal’s amplitude (at 5 kHz) is high for 100
μ
s and low for 100
μ
s, it has a 50% duty cycle;
if the amplitude is high for 190
μ
s and low for 10
μ
s, it has a 95% duty cycle. The following figure illustrates
PWM signal parameters while the following table lists PWM signal specifications.
Table 4-5 PWM signal specifications.
Figure 4-6 PWM signal waveform.
Warning: Serious Personal Injury
Always use shielded cable when connecting your PWM signal source to the laser’s PWM connections.
In electrically noisy environments, long lengths of unshielded wire act like an antenna and may
generate enough voltage to trigger un-commanded lasing.