Laser Forward Voltage Measurement Calibration - ILX Lightwave LDC-3926339 User Manual

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Laser Forward Voltage Measurement Calibration

This procedure is for remotely calibrating the laser forward voltage (LDV)
measurement circuit. The internal calibration procedure sets the current to two
values; you must measure and enter the forward voltage at both of these points.
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Note: If this calibration value is to be measured and entered remotely via a GPIB
controlled DMM, for example, the actual value of the current should not be entered until the
cal procedure is ready to receive it.
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C A L I B R A T I O N A N D T R O U B L E S H O O T I N G
in µAmps).
For example: LASER:CAL:MEAS 981.234
The internal calibration procedure stores the actual measured value and briefly changes
its measurement status to 0 to indicate that it is not yet ready for another measurement.
This occurs each time a new measurement is entered.
The controller drives the laser current until the PD current is approximately 60% of full
range. Allow the current to settle for at least 10 seconds.
Send the query LASER:CAL:STATUS? to make sure the internal calibration procedure is
ready for a measurement.
The calibration procedure is ready for a measurement if it returns the value 1. Query the
status until the value that is returned is 1.
Enter the measured current in µA by sending the command LASER:CAL:MEAS (current
in µAmps).
For example: LASER:CAL:MEAS 2986.123
After you have entered the second measured photodiode current, the internal calibration
procedure performs the calibration for the photodiode current measurement circuit. The
calibration procedure sets the status to 2, indicating the calibration is finished.
With the output off, connect a 1 Ω, 50 W resistor across the laser output terminals (Laser
Anode, pin A3, and Laser Cathode, pin A2).
Connect a calibrated voltmeter across the load resistor.
Send the command LASER:CAL:LDV to begin the LDV measurement calibration.
The internal calibration procedure begins by setting the laser output current to
approximately 25% of its full range. Allow the current to settle for at least 10 seconds.
Send the query LASER:CAL:STATUS? to make sure the internal calibration procedure is
ready for a measurement.
The calibration procedure is ready for a measurement if it returns the value 1. Query the
status until the value that is returned is 1.
Enter the measured voltage in Volts (V) by sending the command LASER:CAL:MEAS
<voltage in V>.
For example: LASER1:CAL:MEAS 1.40
The calibration procedure sets the output current to approximately 75% of its output
range. Allow the current to settle for at least 10 seconds.
C H A P T E R
Remote Calibration
LDC-3926339
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