Berlin 2005 – scientific programme

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O: Oberflächenphysik

O 22: Rastersondentechniken I

O 22.9: Talk

Saturday, March 5, 2005, 12:45–13:00, TU EB407

Measurement of the near-field distribution of a wave guide with sub-wavelength aperture on a macroscopic scale — •Oliver Schimek, Georgios Ctistis, Jens J. Paggel, and Paul Fumagalli — Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin

The optical near-field is a very useful and interesting experimental tool, which in scalar diffraction theory is well known and widely understood. Scalar diffraction theory however does not include polarization. Very little is known about polarization in the near-field. Also no direct measurement of the field distribution has been presented yet. On the other hand, theoreticians presented a large amount of calculations describing the near-field for a better understanding of the gained experimental results in scanning near-field optical microscopy. We present here our results on the measurements of the near-field of microwaves directed through a wave guide and a sub-wavelength aperture. We used a standard klystron with a wavelength of 3.3 cm and an aluminium tube as wave guide as well as differently shaped apertures. We measured the field intensity in two polarisation directions, its dependence from aperture size, and distance from the aperture. These results are compared with theoretical predictions.