High definition aperture probes for near-field optical microscopy fabricated by focused ion beam milling

J.A. Veerman, A.M. Otter, L. Kuipers, N.F. van Hulst

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We have improved the optical characteristics of aluminum-coated fiber probes used in near-field scanning optical microscopy by milling with a focused ion beam. This treatment produces a flat-end face free of aluminum grains, containing a well- defined circularly-symmetric aperture with controllable diameter down to 20 nm. The polarization behavior of the tips is circularly symmetric with a polarization ratio exceeding 1:100. The improved imaging characteristics are demonstrated by measuring single molecule fluorescence. Count rates increase more than o­ne order of magnitude over unmodified probes, and the molecule images map a spatial electric field distribution of the aperture in agreement with calculations. (C) 1998 American Institute of Physics.
Original languageUndefined
Pages (from-to)3115-3117
Number of pages3
JournalApplied physics letters
Issue number24
Publication statusPublished - 1998


  • METIS-128616
  • IR-23817

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