technical reference
59
SYNRAD OEM v40 Operator’s Manual Version 4
Controlling laser power
Warning
serious
personal
injury
Always use shielded cable when connecting your PWM Command
signal source to PWM Input / PWM Return inputs. In electrically-
noisy environments, long lengths of unshielded wire act like an
antenna and may generate enough voltage to trigger uncommanded
lasing.
Figure 4-3
Representative Firestar v40 waveforms
Firestar v40 lasers are designed to operate at Command signal base frequencies up to 25 kHz; however, the
choice of PWM frequency depends on the user’s specific application. In the majority of laser applications,
the UC-2000’s default Command signal frequency of 5 kHz has proven to work well. When considering
Command frequencies at 5 kHz or below, please review Marking/engraving operation later in this section.
For high-speed motion applications that cannot tolerate any ripple in the optical beam response, but still
need adjustable power levels, we recommend the use of higher PWM frequencies, up to 25 kHz maximum.
At 25 kHz, the laser’s optical beam response no longer follows the Command input and is very nearly a DC
value with just a small amount of ripple present.
Command signal
1
5.00 V M 50.0µs Ch1 1.24 V
Ch1
Typical optical output pulse (50% duty cycle at 5 kHz)
T
2
1
5.00 V M 50.0µs Ch1 1.24 V
Ch1
Typical optical output pulse (50% duty cycle at 3 kHz)
T
2
The modulated Command signal applied between Pin 9, PWM Input, and Pin 1, PWM Return, of the
User I/O connector on the Firestar v40 laser has three basic 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 Command 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
+0.8 VDC while the laser on voltage, typically 5 V, can range from +3.5 V to +6.7 VDC.
Base frequency, the second parameter, is the repetition rate of the PWM input signal. The standard base
frequency is 5 kHz, which has a period of 200 microseconds (µs). Maximum PWM frequency is 25 kHz.
