Using Interlock 2; Interlock 2 Usage Example; Modulating The Laser Current Source - ILX Lightwave LDX-32420 User Manual

5
C H A P T E R

Using Interlock 2

The Interlock 2 connection is designed to allow an external emergency input
signal to turn the current output off. The interlock is TTL compatible and
configured to be normally high. The BNC interlock connection, when left
unconnected, is pulled to a logic high with a 100 k resistor. High values (+5 V)
will keep the current source in the operational state, while low values (0 V) forces
the output off. Once the BNC interlock is low, the output will stay off until the
interlock is high again, and you re-enable the output.

Interlock 2 Usage Example

When using the LDX-32420 Current Source to drive a temperature controlled
laser diode, Interlock 2 can be used to accept an error signal from the laser diode
temperature controller unit. Linking the LDX-32420 Current Source to a
temperature controller* with the ability to signal when its temperature control has
gone outside of some tolerance window will allow the LDX-32420 to safely
disable the current source output before thermal damage occurs to the laser
diode.
*The ILX Lightwave LDT-5900 series of temperature controllers include an output
BNC connector that is compatible with the BNC interlock feature of the LDX-
32420. The output BNC connector of the LDT-5900 has a TTL compatible output
signal that will signal when the temperature control has gone outside of a
programmable temperature window. For more information about the LDT-5900
series of temperature controllers, go to www.ilxlightwave.com.

Modulating the Laser Current Source

The LDX-32420 Current Source allows a modulated signal to be superimposed on
the source output current. The allowable bandwidth of the modulated analog
signal, defined as the 3 dB roll off point, is dependent on the output current range
and the mode (constant current low/high bandwidth). See the section, LASER
CURRENT SOURCE SPECIFICATIONS, in Chapter 1 for external analog
modulation bandwidth specifications.
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 LDX-32420
FU N C T I O N S A N D FE A T U R E S
Using Interlock 2