Front Panel Operation; Front Panel Operation; Operating A Laser In Constant Current, "I" Mode; Operating A Laser In Constant Current, "I" Mode - ILX Lightwave LDX-3200 Series User Manual

FRONT PANEL OPERATION

This section describes fundamentals of operation for your LDX-3200 Series Precision Current Source in two
operating modes, Constant Current (I), and Constant Power (P).

The Display

underneath the display indicate control errors and are explained in the section titled "ERROR INDICATORS". All
laser control parameters are displayed on this digital display with the appropriate annunciator illuminated.

OPERATING A LASER IN CONSTANT CURRENT, "I" MODE

Suppose you have an LDX-3220 and you want to run the instrument in Constant Current, low bandwidth mode, with
a set point of 150 mA and a current limit of 175 mA. This particular mode uses a low-pass filter on the laser drive
current output to significantly reduce noise. In this mode a modulation input of up to 15 kHz may be used, via the
front panel MOD EXTERNAL connector. Follow the instructions below in the sequence presented.

Setting Up the Precision Current Source

Set the LDX-3200 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
Next, in the RANGE section 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 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
(photodiode current, µA), P
I
PD
modes. When the set point mode is active, the corresponding annunciator will flash to indicate set point rather than
measurement display.
To just view the set point, 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.
HOW TO OPERATE YOUR LDX-3200
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The digital display is used to show control parameters such as laser
drive current (mA), laser current limit (mA), laser forward voltage (V),
voltage limit (V), monitor photodiode current (µA), and laser optical
power (mW) in both set point and measurement modes. It will also
display error codes that relate to LASER operation. Error indicators
(laser power, mW), or V (forward voltage, V) measurement or set point display
PD
PAGE
) control modes.
HBW
5
CHPT 2