In: Physics
Explain what the diffraction limit is and how it is connected to the spatial resolution of an optical system. Is it possible to resolve features smaller than the diffraction limit? Can you resolve 100 nm features using an optical microscope? How about 100 pm?
When lens is used in an optical instrument and the lens is well
corrected for abberations,The light rays must be focused at one
point. But, due to diffraction the light is focused into a finite
area. It can be discussed as a plane wave incident on a convex lens
after passing through a circular apperature. A diffraction pattern
is formed and the central maxima has a radius of
where f is focal length and a is the diameter of apperature and v
is the image distance. objects that form an image closer than this
will not be resolved
corressponding min. seperation between objects=
here m is magnification of microscope
for general microscope has magnifiaction of 1000
and wavelength be 500 nm and v = 0.1 m
we get the limit as 2.4 nm
so objects with seperation of 2.4 nm cannot be viewed
so we can resolve features in the range of 100 nm but not 100 pm