I Pd Current Calibration - ILX Lightwave LDX-3200 Series User Manual

g. Input the second actual (measured) output current (as an <nrf value>) as in Step e.
h. Once the second actual I value is entered via the "LAS:LDI" command, the new calibration constants will be
calculated and stored into non-volatile memory. In low bandwidth calibration mode, the LDX-3200 Series
Current Source will also perform current limit calibration as indicated by the CURRENT LIMIT LED flashing.
The "OPC?" query may be used (after the "LAS:LDI" value is sent) to determine when the calibration is
completed. Or, wait about 2 seconds before continuing with other GPIB commands.
i. Turn the current source output off. Change the Mode to I
the LAS:IHBW command. Repeat the calibration procedure as described above.
I Current Calibration
PD
The following procedure is for calibrating the LASER I
feedback circuits for constant I
enters the actual value of the current, as measured by an external DMM. The LDX-3200 Series Current Source then
automatically calibrates the LASER feedback circuits.
Configure the Current Source in the following manner for the Laser Current Source calibration:
FUNCTION
LASER MODE
CAL PD
CURRENT LIMIT
I Set POINT
PD
a. With the LASER output off, connect a calibrated ammeter to the PD Anode output of the Laser Current
Source output connector (9 pin on rear panel), and connect the circuit of Figure 6.1 to the LASER and PD
outputs with the correct load resistor for the Current Source model you are calibrating (See Table 6.2).
b. Enter the "LAS:OUT ON" command to turn the LASER output on. Verify proper operation, i.e. the I
should be close to the set point, and the unit should not be in current limit (read the limit status via the
"LAS:COND?" query, bit 0).
c. Enter the "LAS:CAL:MDI" command to place the Current Source in its LASER Current Calibration mode.
The Current Source will increase the laser current output until the current at the PD monitor (I
equals the targeted set point.
d. After a few seconds, the Current Source will be ready for the actual I
"LAS:MDI <nrf value>" command. The measured value of the current should not be entered until the
Current Source is ready to receive it. The Current Source will be ready to receive the current value when,
after a "LAS:CAL:MDI?" query is sent, the response from the Current Source is "1".
e. Once the actual I
PD
the new calibration value. It will then set the output to approximately one-fourth (1/4) of the original current.
(For example, if the first calibration set point was 4000 µA, the second set point will be 1000 µA.) Then, it will
be ready to receive the second calibration value.
CALIBRATING THE LDX-3200 SERIES CURRENT SOURCE
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and constant P modes. When these values are reached and are stable, the user
PD PD
STATE
P (constant power)
set equal to zero
90% of FS (full scale of range)
80% of FS
value is entered via the "LAS:MDI <nrf value>" command, the Current Source will store
(high bandwidth constant current mode) with
HBW
constant current source. This procedure calibrates the
PD
PD
PAGE 8
GPIB COMMAND
LAS:MODE:MDP
LAS:CALMD
LAS:LIM:Ix
LAS:MDI
output
PD
) inputs
PD
current to be entered via the
CHPT 6