Book contents
- Frontmatter
- Contents
- Preface
- 1 Introduction
- 2 Theoretical foundations
- 3 Propagation and focusing of optical fields
- 4 Spatial resolution and position accuracy
- 5 Nanoscale optical microscopy
- 6 Near-field optical probes
- 7 Probe–sample distance control
- 8 Light emission and optical interactions in nanoscale environments
- 9 Quantum emitters
- 10 Dipole emission near planar interfaces
- 11 Photonic crystals and resonators
- 12 Surface plasmons
- 13 Forces in confined fields
- 14 Fluctuation-induced interactions
- 15 Theoretical methods in nano-optics
- Appendix A Semianalytical derivation of the atomic polarizability
- Appendix B Spontaneous emission in the weak coupling regime
- Appendix C Fields of a dipole near a layered substrate
- Appendix D Far-field Green's functions
- Index
4 - Spatial resolution and position accuracy
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface
- 1 Introduction
- 2 Theoretical foundations
- 3 Propagation and focusing of optical fields
- 4 Spatial resolution and position accuracy
- 5 Nanoscale optical microscopy
- 6 Near-field optical probes
- 7 Probe–sample distance control
- 8 Light emission and optical interactions in nanoscale environments
- 9 Quantum emitters
- 10 Dipole emission near planar interfaces
- 11 Photonic crystals and resonators
- 12 Surface plasmons
- 13 Forces in confined fields
- 14 Fluctuation-induced interactions
- 15 Theoretical methods in nano-optics
- Appendix A Semianalytical derivation of the atomic polarizability
- Appendix B Spontaneous emission in the weak coupling regime
- Appendix C Fields of a dipole near a layered substrate
- Appendix D Far-field Green's functions
- Index
Summary
Position accuracy refers to the precision with which an object can be localized in space. Spatial resolution, on the other hand, is a measure of the ability to distinguish two separated point-like objects from a single object. The diffraction limit implies that optical resolution is ultimately limited by the wavelength of light. Before the advent of near-field optics it was believed that the diffraction limit imposes a hard boundary and that physical laws strictly prohibit resolution significantly better than λ/2. It was found that this limit is not as strict as assumed and that various tricks allow us to access the evanescent modes of the spatial spectrum. In this chapter we analyze the diffraction limit and discuss the principles of different imaging modes with resolutions near or beyond the diffraction limit.
The point-spread function
The point-spread function is a measure of the resolving power of an optical system. The narrower the point-spread function the better the resolution will be. As the name implies, the point-spread function defines the spread of a point source. If we have a radiating point source then the image of that source will appear to have a finite size. This broadening is a direct consequence of spatial filtering. A point in space is characterized by a delta function that has an infinite spectrum of spatial frequencies kx, ky. On propagation from the source to the image, high-frequency components are filtered out.
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- Principles of Nano-Optics , pp. 89 - 133Publisher: Cambridge University PressPrint publication year: 2006
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