ILX Lightwave LDX-32420 User Manual page 37

2
C H A P T E R
To view the setpoint, press and hold down the display SELECT switch for two or
more seconds. When the SELECT switch is released the measurement mode will
be restored.
At this point the LDX-32420 is in Constant Current Mode, (I), in the 10A range,
and the display is reading in A. Next, we need to adjust the setpoint of the laser
current source.
To adjust the setpoint of the current source to 7.5 A, turn the adjust knob
clockwise to increase the setpoint; counterclockwise to decrease the value
[LAS:LDI: 7.5]. When the adjust knob is turned, the LDX-32420 automatically
changes to setpoint mode indicated by the flashing annunciator. Adjust the
setpoint to 7.5 A. After an adjustment has been made, and the adjust knob is
released, the setpoint mode will time out in three seconds. The current set point
value will be updated and the display will revert to the original measurement
display mode (I, I
The instrument is still not ready to turn on the laser. One of the laser protection
features our precision current sources offer is a fully independent hardware
current limit. The current limit protects your laser by never allowing the laser drive
current to exceed the limit independent of the setpoint and the output control
mode (Constant Current or Constant Power).
To set the current source limit, use the SELECT
push button in the PARAMETER section of the
front panel to select LIM I. Press the
(PARAMETER) SET push button and rotate the
adjust knob to vary the limit setpoint value. Set
the limit to 8 A [LASer:LIMit:ILOW 8]. After three
seconds, the new limit 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 LASER output is enabled.
An additional feature of the LDX-32420 instrument is an adjustable voltage limit.
This allows an extra level of laser protection in the event of an intermittent open
circuit.
20
 LDX-32420
O P E R A T I O N
Operating a Laser in Constant Current (I) Mode
, V, or P
PD
).
PD