© 2018 Thorlabs
3 Operating the ITC4000 Series
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3.8 QCW Pulse Settings
The Quasi Continuous Wave (QCW) mode allows the laser output to be pulsed with an internal
or an external trigger source. All necessary pulse parameters can be set in the QCW pulse set-
tings menu.
QCW Mode
Off
sets the ITC4000 to "CW" (continuous wave) mode. This is the default setting.
On
enables the "QCW" (quasi continuous wave) mode.
Changes in the state of the QCW mode (On/Off) are only possible if the laser output is
switched off.
The QCW mode can only be enabled in constant current mode. Otherwise the error message
"Wrong LD Source Operating Mode" will be shown. In this case please set the LD operating
mode to constant current. (please refer to section
Setting the LD source parameters
)
Trigger Source
This parameter specifies the QCW pulse trigger source.
Internal
: current pulses are generated regularly with the specified period / frequency.
External
: a single current pulse is generated each time a rising edge is detected at the QCW
Pulse input (R2) at the rear of the unit.
The parameters shown in the QCW pulse settings menu are dependent on the trigger source
used. The upper screenshot shows the parameters for internal triggering.
QCW pulse diagram
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