Fundamentals Of Operation; Operating A Laser In Constant Current (I) Mode; Setting Up The Precision Current Source - ILX Lightwave LDX-32420 User Manual

Fundamentals of Operation

This section describes fundamentals of operation for your LDX-32420 in two
operating modes: Constant Current (I) and Constant Power (P).
• [ square brackets ]: the equivalent remote commands for the front panel instructions listed.

Operating a Laser in Constant Current (I) Mode

Suppose you want to run the instrument in Constant Current, low bandwidth
mode, with a setpoint of 7.5 A and a current limit of 8 A. This particular mode uses
a low-pass filter on the laser drive current output to reduce noise. In this mode a
modulation input of up to 10 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

Configure the display so that it reads laser current in A [LASer:DISplay:LDI]. Press
and release the SELECT switch in the DISPLAY section of the front panel until the
A enunciator is lit. The (DISPLAY) SELECT switch is also used to select the I
(PD current, µA) [LAS:DIS:MDI], P
(forward voltage, V) measurement [LAS:DIS:LDV] or setpoint [LAS:DIS:SET]
display modes. When the setpoint mode is active, the corresponding enunciator
will flash to indicate setpoint mode. The display defaults to the measurement
mode.
01_10
Refer to Chapter 4 for more information.
Set the LDX-32420 in Constant Current, low bandwidth
mode by selecting I in the MODE section of the front panel
[LASer:MODE:ILBW]. 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) [LASer:MODE:ILBW], photodiode power (P)
[LASer:MODE:MDP], or high bandwidth current (I
[LASer:MODE:IHBW] control modes.
Next, in the RANGE section set the current source range by
selecting the 10 A range indicated by the accompanying
LED [LASer:RANge LOW]. 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:OUTput OFF] in order to change ranges.
O P E R A T I O N
Fundamentals of Operation
(laser power, mW) [LAS:DIS:MDP], or V
PD
2
C H A P T E R
)
HBW
PD
19
LDX-32420
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