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Presettings
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© 2012 Thorlabs
1.5 Presettings
1.5.1 Offset adjustment
Connect the photodiode and all other components of the complete system (the
photodiode must be in total darkness).
Switch on the PRO8000 (-4) / PRO800.
Select 10
A-range.
(Refer to chapter 2.2.7, "Setting the measurement range" on page 12)
Enter the channel menu to observe the photodiode current.
Adjust the offset with the offset potentiometer of the corresponding channel to
"zero".
(Refer to chapter 1.4, "Operating elements at the front of the module" on page 6)
NOTE:
When using photodiodes with a dark current higher than 1 nA only the
ground conductor of the photodiode is to be connected.
1.6 Connecting the photodiode
Photodiodes can be connected to the BNC jacks of an input with both polarities. The
outer conductor of the BNC jack is always grounded.
Both polarity settings of the PDA8000 (AG = "
a
node
g
round" and CG = "
c
athode
g
round") can be used depending on how the photodiode is connected to the BNC
jack.
If one of the connectors of the photodiode itself is connected to ground (e.g. as with
many housed laser diodes) this ground connector has to be connected to the outer
conductor of the BNC jack.
Only one of the polarity settings of the PDA8000 (AG or CG) will then be correct.
If in doubt, the correctly selected polarity yields a positive photo current on the
display.