Synrad 48 Series - Operating Modes; Figure 3-8 PWM Command Signal Waveform

technical reference
311
Synrad
Series 48Series 48
Series 48Series 48
Series 48 operator’s manual
Controlling laser power
Signal amplitude is either logic low, corresponding to laser beam off, or logic high, corresponding to
beam on, using TTL- or CMOS-compatible voltage levels. The logic low (laser off) voltage, typically 0 V
can range from 0.0 V to +0.5 VDC while the logic high (laser on) voltage, typically 5 V, can range from
+3.5 V to +10 VDC. As a reference, the signal output for a UC-2000 Controller ranges from 0.0 V to
+0.5 VDC (laser off) and from +3.5 V to +5.0 VDC (laser on).
Base frequency 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 µs. Maximum PWM frequency is 20 kHz.
The third parameter, PWM duty cycle, is the percentage of the period that the Command signal is high.
If the Command signal’s amplitude (at 5 kHz) is high for 100 µs and low for 100 µs, it has a 50% duty
cycle; if the amplitude is high for 190 µs and low for 10 µs, it has a 95% duty cycle. Figure 3-8 illustrates
Command signal parameters.
5kHz Command Signal at 50% Duty Cycle 5kHz Command Signal at 95% Duty Cycle
100 µs
190 µs
200 µs
200 µs
0 VDC
5 VDC
Figure 3-8 PWM Command signal waveform
Operating modes
External control
In addition to controlling your Series 48 laser using a UC-2000 Controller, controlling the laser exter-
nally, without a UC-2000, is also possible. The two primary elements of laser control are gating, the
ability to turn the laser on and off at the appropriate times, and power, the ability to control the laser’s
output energy. Both gating and power can be handled by a device such as a personal computer, Program-
mable Logic Controller (PLC), or a function generator capable of sending PWM pulses at the proper
time (gating) and with the proper duty cycle (power) using TTL- or CMOS-compatible voltage levels.
The PWM input on Series 48 lasers consists of an optoisolated input LED. The PWM input frequency
can range from DC (0 Hz) to 20 kHz. Maximum current load for 48-1/48-2 lasers is 6 mA @ 5 VDC; for
48-5 dual-tube lasers, maximum current load is 12 mA @ 5 VDC. Table 3-2 shows minimum, maximum,
and nominal voltage levels for On and Off logic states.
Caution
possible
equipment
damage
Applying PWM Command pulses directly to the laser without first
sending tickle pulses, will cause unpredictable laser emission,
degrade optical rise time, and may lead to RF Driver failure.