Optical Surface Diffraction and Improved Lateral Resolution


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Optical coherence plays an important role in the local field in the vicinity of surfaces where the incident and scatter field overlap (1). While phase differences are small in the optical nearfield, the longitudinal component in the nearfield leads to strong coupling with the scanning probe which limits quantitative optical surface imaging (2). At larger distances optical coherence leads to larger phase differences resulting in the formation of standing waves for counter propagating wave components. Depending on the magnitude of the angle of incidence (non-normal) the superimposed direct image and diffraction image separate in the image plane. This is due to the bilinear nature of the resulting field. The diffraction image is displaced in the direction of the incident beam and centered around the reflected beam direction. This opens the possibility to image surfaces at larger distance at high lateral resolution. The size of the region undisturbed by the diffraction image is found to depend on the angle of incidence and the image height. At larger distances the separation of direct and diffraction image is larger but the resolution of the direct image is reduced. In the intermediate distance range (several wavelengths off the surface) we can record objects of the size smaller than the distance between object and image plane at high lateral resolution. 1. B. Levine, A. Kulik and W. S. Bacsa, Phys. Rev. B 66, 233404, 2002 2. J. Fiurasek, B. Chernobrod, Y. Prior, I.S. Averbukh, Phys. Rev. B 63, 045420, 2001

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Journal: TechConnect Briefs
Volume: 3, Technical Proceedings of the 2005 NSTI Nanotechnology Conference and Trade Show, Volume 3
Published: May 8, 2005
Pages: 291 - 294
Industry sector: Sensors, MEMS, Electronics
Topic: Photonic Materials & Devices
ISBN: 0-9767985-2-2