Lightwave Communications LDX-3232 manual Setting Up the Precision Current Source

O P E R A T I O N

Operating a Laser in Constant Current (I) Mode

Setting Up the Precision Current Source

C H A P T E R 2

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 (IHBW) 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 IPD (PD current, µA), PPD (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, IPD, V, or PPD).

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).

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