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Document #7650-0004 Rev C2. © Copyright 2019 Directed Energy, Inc. All rights reserved.
Introduction
Description
The PCX-7420 is a pulsed current source designed to drive laser diodes, bars,
and arrays. It delivers current pulses from 0 A to 21.5 A with up to 375 W of total
output power. An internal trigger source provides pulse repetition frequencies from
40 Hz to 100 kHz. The external trigger function allows operation at frequencies
from single-shot to 1 MHz.
The bias current amplitude, the main output current amplitude, the bias pulse
width, the main pulse width, the trigger source, and the trigger frequency are
adjustable from the front panel touch screen or by computer control via RS232,
USB, or Ethernet interface.
The bias feature allows the PCX-7420 to deliver the current pulse in two steps.
The first step—the bias pulse—starts before the intended trigger time and is
adjusted to supply enough current to set the diode just below the lasing point. This
minimizes the diode’s response time to the main pulse. The bias pulse amplitude
is adjustable from 0 A to 5.8 A and its width is adjustable from 0 ms to 25 ms.
The main pulse current adds to the bias current and energizes the diode at the
intended time. The main pulse current is adjustable from 0 A to 15.7 A and its
width is adjustable from 50 ns to 5 ms.
Note: The total current output pulse is always the sum of the bias pulse current
and the main pulse current, even if the bias pulse width is set to zero. Consider
both the bias output current and the main output current when planning the total
output current.
The PCX-7420 can be triggered internally or externally, and it can be readily
synchronized with other devices via the Sync output signal on the front panel. The
input termination impedance for both the external trigger and the external bias
trigger is selectable for either 50 Ω or 10000 Ω. The Sync signal logic amplitude is
0 V and +5 V. The rising edge corresponds to the rising edge of the main output
current pulse. The delay between the sync output signal and the main output
current pulse is 5 ns to 15 ns.