Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel (415) 453 9955 ° Fax (415) 453 9956 ° www.berkeleynucleonics.com
The output stripline is marked with a + and -. The “+” side is the positive output
pulse, and the “-“ side of the stripline is the return. The laser diode anodes connect
to the “+” side of the stripline, and the laser diode cathode connects to the “-“ side.
A magnet is mounted to the housing to activate the magnetic reed switch.
The laser diode should be connected directly to the end of the stripline. If wire
interconnections are needed between the end of the stripline and the diode, they
should be kept as short as possible, preferably no more than 2” (5 cm) to minimize
interconnection inductance. Excessive inductance in the interconnections or laser
diode package may lead to ringing on the leading edge of the pulse waveform.
This ringing may be reduced or eliminated by lengthening the pulse rise time using
the variable rise time feature.
5.3 Gate Input
An input gate of +5 V ±1 V (CMOS) is required to gate on the PCO-6131.
Departure from these values can result in a loss of performance. This trigger
requirement is met by any high-quality low voltage pulse generator.
The gate signal should be connected to J2-8 using a 50
Ω
coaxial cable. The
shield of the coaxial cable should be connected to any one of the ground pins of
connector J2. To improve pulse fidelity, all connections should be as short as
possible.
The output pulse’s width and frequency follow the width and frequency of the input
gate. To generate a CW output, the gate should be held high.
5.4 Enable Input
The “enable” signal (J2-10) is used to enable and disable the output of the PCO-
6131. This input must be pulled TTL “High” to enable the driver. This input can be
connected to an interlock or key switch in the user’s system or may be controlled
by the system’s control computer.
When the driver is enabled but not pulsing, it dissipates a fixed amount of power
(see Section 5.5 below). Therefore, for optimum efficiency and minimum power
consumption, the driver should be disabled when not in use.
5.5 Output Current Setpoint Monitor
The output current setpoint monitor (J2 Pin 6) can be used to set the output
current flowing in the inductor prior to generating an output pulse. This allows the
user to set the current that will be applied to the diode, without applying power to
the diode. To set the current using the setpoint monitor, the PCO-6131 must be
enabled, while the gate input is held low.