Faculté des sciences

Unconventional treatment of focal shift

Vokinger, Urs ; Dändliker, René ; Blattner, Peter ; Herzig, Hans-Peter

In: Optics Communications, 1998, vol. 157, no. 1-6, p. 218-224

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... Plus

Ajouter à la liste personnelle
    Summary
    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.