- ILX Lightwave Corporation User's Guide High Compliance Current Source LDX-3232

OPERATION

Operating a Laser in Constant Current (I) Mode

04_06 LDX-3232 15

CHAPTER 2

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Setting Up the Precision Current Source

Set the LDX-3232 in Constant Current, low bandwidth mode

by selecting I in the MODE section of the front panel. Do this

by toggling the SELECT push button until the I indicator is

illuminated. Repeatedly pressing the (MODE) SELECT

switch cycles through the current (I), light power (P), or

high-bandwidth current (I

HBW

) control modes.

Next, in the RANGE section set the current source range by

selecting the 2000 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 ranges, and the

LASER output must be off (LASER MODE ON indicator

unlit) in order to change ranges.

Configure the display so that it reads laser current in mA. Press and release the

SELECT switch in the DISPLAY section of the front panel until the mA annunciator

is lit. The (DISPLAY) SELECT switch is also used to select the I

(PD current,

µA), P

(laser power, mW), or V (forward voltage, V) measurement or setpoint

display modes. When the setpoint mode is active, the corresponding annunciator

will flash to indicate setpoint rather than measurement display.

To only view the setpoint, press and hold down the display SELECT switch for two

or more seconds. When the SELECT switch is released the previous

measurement mode will be restored.

At this point the LDX-3232 is in Constant Current Mode, (I), in the 2000 mA range,

and the display is reading in mA. Next, we need to adjust the setpoint of the laser

current source.

To adjust the setpoint of the current source to 1500 mA, turn the adjust knob to

vary the setpoint. When the adjust knob is turned, the LDX-3232 automatically

changes to setpoint mode indicated by the flashing annunciator. Adjust the

setpoint to 1500 mA. After an adjustment has been made, and the adjust knob is

released, the setpoint mode will time out in three seconds. The display will revert

to the original measurement display mode (I, I

, V, or P

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).