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PG-200 Operation Manual
Version 2.D
Specifications
Maximum Pulse Separation:
500 µsec (see Figure 22)
Minimum Pulse Separation:
1 µsec
Input Impedance:
PG-200 compatible
Propagation Delay:
2 nsec (typical)
Typical Output Pulse Voltage:
200 V
Power Supply
The Pulse Combiner is automatic and has no user adjustments. It is provided with a
power supply with an IEC mains input that automatically adjusts for power mains
voltages of nominally either 120 V AC or 220 V AC, 50-60 Hz. The output of the supply
plugs into a mating connector on the back of the Pulse Combiner.
Operation
The Combiner is designed to work with high voltage pulses. Be sure both pulse
generators are switched off before connecting or disconnecting the system. Only use
known good, high-quality cables with appropriate BNC connectors. We recommend the
use of 50
cable (RG-58/U) .
Only connect the Combiner output to ICCDs having a high-impedance (1 M
)
termination. Do NOT use 50
terminators with the Pulse Combiner. ICCD Detectors
manufactured for use with the FG-100 Pulser have a 50
terminator and could be
damaged if connected to the Combiner’s output.
Operation of the Combiner is extremely simple and largely user transparent. Once the
cables are connected, all that is required is to turn on the power supply to the Combiner
and then the PG-200 Pulse Generators. From that point on, the Combiner works
automatically as previously described. Any remaining operating considerations apply
primarily to the PG-200s and are directed towards assuring that the gating pulses arrive
at the ICCD properly timed to gate the light input and so eliminate the influence of
background illumination. Thus the laser pulses define the exact timing, and the gate
pulses must be timed to bracket the laser pulses at the ICCD. One convenient way of
accomplishing this is to pretrigger the PG-200s to compensate for the system propagation
times. Another is to optically delay the light input to the ICCD using a fiber-optic cable.
Although the interval between pulse pairs may be arbitrarily long, the interval between
the end of the first pulse and the end of the second should not exceed 500 µsec (see
Figure 22). Also, there should be at least 1 µsec between the end of the first pulse and
the start of the second as shown. Pulses can be as narrow as 50 nsec or as long as 200
µsec. The Combiner introduces a slight loss in pulse rise time and a slight increase in
pulse width. Using the Combiner with the PG-200 pulse width set to 50 nsec the typical
rise time (optical turn-on at the ICCD) will be approximately 20 nsec and the typical fall
time 10 nsec (optical turn-off at the ICCD). Degraded operation is possible with pulses
narrower than 50 nsec.
WARNINGS
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