The behavior along the axis of the intensity arising from the diffraction of a uniform, converging spherical wave at a circular aperture is studied on the basis of the theory of the boundary-diffraction wave. The results are used to determine the location of the principal intensity maximum and to elucidate the dependence of the focal shift both on the Fresnel number and on the ƒ number of the focusing geometry. Analytic as well as numerical results are obtained. Comparison with microwave experiments of Farnell [Can. J. Phys. 36, 935 (1958)] is also made.
© 1982 Optical Society of America
Yajun Li, "Dependence of the focal shift on Fresnel number and ƒ number," J. Opt. Soc. Am. 72, 770-774 (1982)