ILX Lightwave LDX-3200 Series User Manual page 107

Next, set the current source range by selecting the 200 mA range indicated by the
accompanying LED. You will need to press the select push button twice to change the range.
It must be pressed twice quickly (within less than 1 second) to switch between modes, and the
current source output must be off (MODE ON indicator unlit) in order to change ranges.
The limit clamp function for DC output current applies to the modulated current as well protecting your laser in any
mode. To accomplish setting the current source limit, use the (PARAMETER) SELECT push button LIM I. Press the
(PARAMETER) SET push button and rotate the adjust knob. Set the limit to 175 mA. Once the (PARAMETER) SET
push button is released, the new parameter value is stored in non-volatile memory.
When the laser current limit is reached, the CURRENT LIMIT error indicator flashes. The current limit setting is
independent of the voltage drop of the device connected to the laser output, and therefore, no dummy load is
required for precise adjustment of the current limit. Furthermore, since the current limit circuitry is fully independent
of the main current control, the current limit can be adjusted safely, even while the current source output is active.
Now you are ready to modulate the laser injection current. To enable the Current Source output, press the push
button labeled (MODE) OUTPUT. The accompanying LED labeled ON will illuminate indicating that the laser current
source's output is enabled. The instrument will drive the current source to the value set by the corresponding MODE
set point. Turn on the function generator (modulation source) to inject the modulation signal.
To disable the output, press the OUTPUT push button again. When the LDX-3200 current output is off, an internal
short is placed across the output. This short will prevent the modulation signal from reaching the LED in our example
experiment. Thus, it is safe to disconnect the test device (LED) when the LDX-3200's output is off, regardless of the
presence of the modulation signal.
FUNCTIONS AND FEATURES
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