In many photonics and fiber-optics applications, the irradiance distribution in the very near field (<i>z</i>/<i>D</i> < 0.25) behind a circular or annular aperture is of interest. We present the results of detailed calculations of the irradiance distribution throughout the entire space behind an annular aperture. Included as a special case of the annular aperture is the circular aperture and the opaque circular disk. A log-log plot over many orders of magnitude in axial distance provides particular insight. The behavior throughout the Fresnel and Fraunhofer region is well known; however, we pay particular attention to the behavior in the near field. A variety of subtle effects in the near field are presented and discussed.
© 2002 Optical Society of America
(050.0050) Diffraction and gratings : Diffraction and gratings
(050.1220) Diffraction and gratings : Apertures
(050.1960) Diffraction and gratings : Diffraction theory
(260.0260) Physical optics : Physical optics
James E. Harvey and Andrey Krywonos, "Axial irradiance distribution throughout the whole space behind an annular aperture," Appl. Opt. 41, 3790-3795 (2002)