Regensburg 2004 – scientific programme
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O: Oberflächenphysik
O 28: Postersitzung (Elektronische Struktur, Grenzfläche fest-flüssig, Halbleiteroberflächen und -grenzflächen, Magnetismus und Symposium SYXM, Methodisches, Nanostrukturen, Oberflächenreaktionen, Teilchen und Cluster, Zeitaufgelöste Spektroskopie)
O 28.47: Poster
Wednesday, March 10, 2004, 16:00–19:00, Bereich C
Self-imaging observed on colloid crystals and Fischer projection patterns — •Manuel Gonçalves and Othmar Marti — Department of Experimental Physics, University of Ulm, D-89069 Ulm, Germany
The self-imaging phenomenon in optical systems is known since the Talbot effect was discovered in the 19th century. The Talbot effect is generated by the interference of the incoming light from a diffraction array of apertures of size a that takes place near the array (Fresnel zone). In general, a ≫ λ.
Apertures separated by a distance d, when illuminated by a coherent and plane wave of wavelength λ produce self-images at distances dT = ν 2 d2 / λ , for ν = 1, 2, … [1],[2].
We have observed that arrays of colloidal crystals of polystyrene spheres with diameter of few µm produce self-images, at distances of several tenths of µm. The theoretical Talbot length is compared with the measured distances for self-images, for different illumination modes of coherent light.
A discussion of the multiple scattering and diffraction of light by a regular array of colloidal particles is introduced and analyzed.
[1] K. Patorski, in Prog. Opt. XXVII, Elsevier, 1989.
[2] A. Lohmann and J. A. Thomas, Appl. Opt., 29 29, 4337–4340.