Diffraction by Circular Apertures with a Ring-Shaped π-Phase Change

Expressions are given for the three-dimensional irradiance distribution of the error-free diffraction pattern by circular apertures with a ring-shaped π-phase change. Both the amplitude distribution in the focal plane and the irradiance distribution along the optical axis have been evaluated for a large number of cases. Some interesting results are discussed and illustrated graphically. The resolving power and focal depth are taken into considerations with these apertures. Finally, some experimental results are presented.