E. Diffraction in Far Field Approximation

If the optical wavelength is a linear function of the coordinates of the points in the plane of the aperture and the plane of the projection, one can apply the so called FRAUNHOFER Far Field Approximation. There are many examples for such a case. E.g. the source and the projection planes are far away from the aperture. Another possibility would be the use of lenses. In the following section only the former situation (source and projection planes are in the far field) is considered.