Ipd Current Calibration - ILX Lightwave LDC-3926339 User Manual

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
5
C H A P T E R
Remote Calibration
6
7

IPD Current Calibration

This procedure is for remotely calibrating the laser I
measurement circuits. The internal calibration procedure sets the current to two
values; you must enter the resulting I
The GPIB commands use the nomenclature MDI, which means "Monitor Diode
Current", and is synonymous with "IPD".
1
2
3
Note: If this calibration value is to be measured and entered remotely via a GPIB
controlled DMM, the actual value of the current cannot be entered until the cal procedure is
ready to receive it.
4
5
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LDC-3926339
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(current in Amps).
For example: LASER:CAL:MEAS 513.9
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 cal procedure sets the output current to approximately 90% of its output 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 1 value is returned.
Enter the second measured current by sending the command LASER:CAL:MEAS
(current in Amps).
For example: LASER:CAL:MEAS 5350.7
After you have entered the second measured current, the internal calibration procedure
performs the calibration for the laser current setpoint, current measurement, and current
limit circuits. The calibration procedure sets the status to 2, indicating the calibration is
finished.
With the output off, connect the IPD calibration circuit, Figure 5.1 on page 68, to the laser
connector.
Determine R4 resistance with 4-wire resistance measurement. Connect DMM across R4.
Send the command LASER:CAL:MDI to begin the IPD current calibration.
The internal calibration procedure turns on the output and drives the laser current until the
PD current is approximately 20% 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
(photodiode monitor)
PD
current measured at both of these points.
PD