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©1990-2002 J.Paul Robinson, Purdue University
Numerical Aperture
•Resolving power is directly related to numerical aperture.
•The higher the NA the greater the resolution
•Resolving power:
The ability of
an objective to resolve two distinct lines very close together
NA = n sin m
–(n=the lowest refractive index between the object and first objective element) (hopefully 1)
– m
is 1/2 the angular aperture of the objective
