Book contents
- Frontmatter
- Contents
- Preface to the first edition
- Preface to the second edition
- 1 Introduction
- 2 Theoretical foundations
- 3 Propagation and focusing of optical fields
- 4 Resolution and localization
- 5 Nanoscale optical microscopy
- 6 Localization of light with near-field probes
- 7 Probe–sample distance control
- 8 Optical interactions
- 9 Quantum emitters
- 10 Dipole emission near planar interfaces
- 11 Photonic crystals, resonators, and cavity optomechanics
- 12 Surface plasmons
- 13 Optical antennas
- 14 Optical forces
- 15 Fluctuation-induced interactions
- 16 Theoretical methods in nano-optics
- Appendix A Semi-analytical 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 functions
- Index
- References
4 - Resolution and localization
Published online by Cambridge University Press: 05 November 2012
- Frontmatter
- Contents
- Preface to the first edition
- Preface to the second edition
- 1 Introduction
- 2 Theoretical foundations
- 3 Propagation and focusing of optical fields
- 4 Resolution and localization
- 5 Nanoscale optical microscopy
- 6 Localization of light with near-field probes
- 7 Probe–sample distance control
- 8 Optical interactions
- 9 Quantum emitters
- 10 Dipole emission near planar interfaces
- 11 Photonic crystals, resonators, and cavity optomechanics
- 12 Surface plasmons
- 13 Optical antennas
- 14 Optical forces
- 15 Fluctuation-induced interactions
- 16 Theoretical methods in nano-optics
- Appendix A Semi-analytical 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 functions
- Index
- References
Summary
Localization refers to the precision with which the position of an object can be defined. 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 then found that this limit is not as strict as assumed and that access to evanescent modes of the spatial spectrum offers a direct route to overcome the diffraction limit. However, further critical analysis of the diffraction limit revealed that “super-resolution” can also be obtained by pure far-field imaging under certain constraints. 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 and ky.
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- Information
- Principles of Nano-Optics , pp. 86 - 130Publisher: Cambridge University PressPrint publication year: 2012
References
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