Chapter 3 Usage of Components
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3.10.4 Using an Objective with a Diaphragm
When performing DF microscopy, use of an objective
with diaphragm allows numerical aperture (NA)
adjustment of the objective according to the NA of
the DF condenser.
Operation:
Check the minimum NA of the DF condenser, and
then adjust the diaphragm adjusting ring so that
the NA of the objective is smaller than the
minimum NA.
Display:
Check the numerical aperture using the gradua-
tions on the diaphragm adjusting ring.
Example of an objective with a diaphragm
“Iris” mark
Diaphragm
adjusting ring