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Journal of the Optical Society of America A

Journal of the Optical Society of America A


  • Vol. 16, Iss. 8 — Aug. 1, 1999
  • pp: 1936–1946

Influence of secondary tip shape on illumination-mode near-field scanning optical microscopy images

Lee J. Richter, Claire E. Jordan, Richard R. Cavanagh, Garnett W. Bryant, Ansheng Liu, Stephan J. Stranick, Christine D. Keating, and Michael J. Natan  »View Author Affiliations

JOSA A, Vol. 16, Issue 8, pp. 1936-1946 (1999)

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We report illumination-mode near-field optical microscopy images of individual 80–115-nm-diameter Au particles recorded with metal-coated fiber probes. It is found that the images are strongly influenced by the metal-coating thickness. This dependence is consistent with theoretical models, which are in good agreement with the experimental images. Probes with thick coatings (∼λ/2) produce images consisting of three extrema, owing to a resonancelike polarization of the probe end. Probes with thinner coatings generally produce simpler images. However, in some cases the images contain wavelike structures that are due to interference between direct radiation from the tip and propagating tip fields scattered by the particles.

© 1999 Optical Society of America

OCIS Codes
(180.0180) Microscopy : Microscopy
(290.5850) Scattering : Scattering, particles

Original Manuscript: January 5, 1999
Revised Manuscript: March 25, 1999
Manuscript Accepted: March 25, 1999
Published: August 1, 1999

Lee J. Richter, Claire E. Jordan, Richard R. Cavanagh, Garnett W. Bryant, Ansheng Liu, Stephan J. Stranick, Christine D. Keating, and Michael J. Natan, "Influence of secondary tip shape on illumination-mode near-field scanning optical microscopy images," J. Opt. Soc. Am. A 16, 1936-1946 (1999)

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  9. Certain commercial equipment, instruments, or materials are identified in this paper to specify adequately the experimental procedure. In no case does such identification imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the equipment or the materials identified are necessarily the best available for the purpose.
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  12. Adjustments of ±30% of a typical dither drive amplitude ±3% off the tip resonance frequency and minimizing the shear-force damping are common optimization routes after tip exchange.
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  15. Although unlikely, it is possible that the metal coating and the glass face lie exactly in the same plane, resulting in no topographic contrast for the aperture.
  16. Small sample features will provide the highest-fidelity images of the probe.
  17. No attempt was made to deconvolve the sample asperity responsible for the topographic contrast. Thus the tabulated base width is an upper limit on the true width of the probe, and the tabulated aperture ID is a lower limit on the true aperture ID.
  18. Information about the model is available from A. Liu, G. W. Bryant, L. J. Richter, S. J. Stranick, National Institute of Standards and Technology, Gaithersburg, Maryland 20899.
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  21. We note that the three-extrema structure cannot be attributed to the weak oscillations in the calculated Y line scans for thin coatings in Fig. 9. The calculated separation between the first maxima in the Y line scans is much larger than observed (∼700 nm), and the calculated maxima appear along the wide dimension of the central minimum, not as observed along the narrow dimension.
  22. C. Obermüller, K. Karrai, “Far field characterization of diffracting circular apertures,” Appl. Phys. Lett. 67, 3408–3410 (1995). [CrossRef]

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