Lightwave Communications manual Remote Calibration of the LDX-3232 Current Source, Gpib Command

CA LI BRATION AND TR OUBLESHOOTING

Remote Calibration of the LDX-3232 Current Source

C H A P T E R 6

Remote Calibration of the LDX-3232 Current Source

The LDX-3232 Current Sources can be calibrated remotely via the GPIB Interface. All of the required calibration commands are listed in Table 4.1 in Chapter 4. The procedures below are general guidelines for writing a program to calibrate your instrument.

Note: The operation complete flag (bit 0 of the Standard Event Status Register) may be used to trigger a service request. This type of interrupt is enabled by setting bit 0 of the Service Request Enable register (via the *ESE command) and bit 5 of the Service Request Enable register (via the *SRE command). Service request (SRQ) handling depends on your GPIB hardware. Refer to your GPIB user's manual for details.

After a calibration value is entered, the *OPC? query may be used to determine when the calibration sequence is done. However, the *OPC, *WAI command, or *OPC? query should not be issued until after the expected calibration value is entered, or the system will "hang". This happens because the LDX-3232 Current Source will wait indefinitely for an input, yet not allow any input until the calibration is finished.

Current Source Calibration

There are three calibration adjustments required for the LDX-3232 Current Source. They are calibration of the constant current source for both bandwidths and ranges, calibration of the laser voltage measurement, and calibration of the constant light power (IPD) feedback circuits.

The LDX-3232 Current Source implements a two-point calibration for the current source. Two currents (approximately 20% and 80% of FS) are applied to a test load, and the resulting actual currents are fed back (by the user) to the current source. The laser current source calibration program uses the two sets of data to calculate new calibration constants. These calibration constants are used to set the actual current of the current source.

The following procedure is for calibrating each range of the current source. Start with the low range. After calibration is complete in this range, switch to the high range and repeat the procedure.

Configure the current source in the following manner for the laser current source calibration:

Function	State	GPIB COMMAND
LASER MODE	I (constant current low bandwidth)	LAS:MODE:ILBW
RANGE	Low (lowest per instrument model)	LAS:RAN x
LIMIT	90% of FS (full scale of range)	LAS:LIM:Ix
SETPOINT	80% of FS	LAS:LDI

04_06 LDX-3232 95