Keithley 2520, User Manual, Page: 72 / 329

3-12 Basic Operation Model 2520 User’s Manual
Configuring measurements
Follow the general procedures below to set the range and polarity for both laser diode and
photodiode measurements.
NOTE
The pulse width setting affects not only the source, but the measurement as well.
The larger the pulse width, the more A/D samples that will be averaged to gener-
ate a measurement, which decreases noise, but increases test time. In the DC
mode, the pulse width setting effectively becomes the aperture (sample time) for
the entire measurement.
Configuring laser diode measurements
1. Press CONFIG then LASER V
L
to access the laser diode measurement configura-
tion menu.
2. Choose POLARITY, then press ENTER.
3. Select POSITIVE or NEGATIVE as desired, then press ENTER ( Figure 3-3 ).
4. Press the LASER V
L
key.
5. Use the RANGE ▲ and
▼
keys to select the desired measurement range (5V or
10V). Use the lowest range possible for best accuracy.
Configuring photodiode measurements
1. Press CONFIG then either DETECTOR 1 I
PD
or DETECTOR 2 I
PD
to access the
photodiode measurement configuration menu.
2. Choose POLARITY, then press ENTER.
3. Select POSITIVE or NEGATIVE as desired, then press ENTER ( Figure 3-4 ).
4. Press the DETECTOR 1 I
PD
or DETECTOR 2 I
PD
key.
5. Use the RANGE
▲
and ▼ keys to select the desired measurement range (10mA,
20mA, 50mA, or 100mA). Use the lowest range possible for best accuracy.
6. Repeat steps 1 through 6 for the other photodiode detector channel.