OPERATION
Front Panel Operation
38 LDX-36000 Series
CHAPTER 3
QCW-Pulse Mode
QCW-Pulse mode is selected by pressing the
QCW Mode Select button (Figure 3.10) until the
PULSE LED is illuminated. In this mode, all
pulse parameters are configurable either via
GPIB or from the front panel. The pulse
parameters of pulsewidth, duty cycle percentage
and/or frequency may be set from the front panel
controls shown in Figure 3.6. When the output is
enabled, the output pulses run asynchronously
to any trigger input that may be connected to the
instrument.
Figure 3.13 QCW Mode Box
Limit cable length to 6 feet (1.83 m) to comply with CE testing standards
Constant Duty Cycle vs. Constant Frequency
Because the QCW parameters of pulsewidth, frequency and duty cycle are
interrelated, adjusting one parameter will simultaneously affect the other
parameters. This dependency can be problematic if one is attempting to, for
example, control the power loading of the laser while still being able to vary
pulsewidth. The solution to this application is to operate with a constant duty
cycle.
It may be true instead that the test being run requires an output whose frequency
or pulse period does not change with pulsewidth. In this case, the preferred
operational mode would be constant frequency. Information on how to specify
either of these modes is given below.
Pressing the left P
w
button changes Display 2 to show pulsewidth setpoint in
milliseconds. The Const % LED below Display 2 is illuminated. Pulsewidth is
adjusted by pressing the Adjust button and then rotating the Adjust knob within
three seconds. The new pulsewidth value will be stored in nonvolatile RAM after a
three second timeout. If either P
w
button is pressed while in CW mode, the
display will be blanked out with dashes.
Pressing the % button displays the current duty cycle setpoint as a percentage on
Display 2. The Const % LED is illuminated. If the Adjust button is pressed and
the Adjust knob rotated within three seconds, the duty cycle may be changed.
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