Due to the
diffraction pattern caused by a slit, any lens (e.g. a
camera lens or the lens in the human eye) will cause a
diffraction pattern to occur in the image it makes. As
long as the diffraction angle is much less than the angle
one wishes to distinguish, this is not a problem.
However, the angular resolution of any lens is The diameter
of the lens is l. The factor 1.22 is a rather
arbitrary choice that is inspired by the shape of a
spherical lens pattern which can be written in spherical
bessel functions. Since these angles are very small, one
can replace sinq with q in the above formula. |