Unconventional treatment of focal shift

[摘要] We present an unconventional approach for the explanation of focal shift behind a lens. It is based on the fact that, within the approximation of Fresnel diffraction, the intensity distributions in the conjugate planes of a lens are equal to their geometrical images. We show that the focus (position of highest intensity) is always shifted towards the lens. The results for a Gaussian beam and a uniform converging spherical wave are presented. (C) 1998 Elsevier Science B.V. All rights reserved.

[发布日期] 1998-12-01

[关键词] focal shift;Fourier optics;geometrical optics