Boundary diffraction wave theory of plane waves diffracted at an annular aperture

Starting from the Maggi-Rubinowic theory of the boundary diffraction wave and Helmhotz-Kirchhoff integral theorem,the diffraction integral formula of plane waves diffracted at an annular aperture is derived.The diffraction at a circular aperture and a circular screen,as well as the axial field distribution is treated as the special cases of our general result.The characteristics of axial intensity distribution of the diffracted field are analyzed.Numerical examples show that the results obtained by means of the formula given in this paper are in good agreement with the direct numerical integration of the Kirchhoff integral formula.In the near field there are noticeable discrepancies between our formula and the Rayleigh diffraction integral.