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Dependence of the focal shift on Fresnel number and f number

1982; Optica Publishing Group; Volume: 72; Issue: 6 Linguagem: Inglês

10.1364/josa.72.000770

2375-1037

Yajun Li,

Radio Astronomy Observations and Technology

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 f 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.