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Van Cittert–Zernike Theorem
The van Cittert–Zernike theorem, named after physicists Pieter Hendrik van Cittert and Frits Zernike, is a formula in coherence theory that states that under certain conditions the Fourier transform of the intensity distribution function of a distant, incoherent source is equal to its complex visibility. This implies that the wavefront from an incoherent source will appear mostly coherent at large distances. Intuitively, this can be understood by considering the wavefronts created by two incoherent sources. If we measure the wavefront immediately in front of one of the sources, our measurement will be dominated by the nearby source. If we make the same measurement far from the sources, our measurement will no longer be dominated by a single source; both sources will contribute almost equally to the wavefront at large distances. This reasoning can be easily visualized by dropping two stones in the center of a calm pond. Near the center of the pond, the disturbance created ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Coherence Theory (optics)
In physics, coherence theory is the study of optical effects arising from partially coherent light and radio sources. Partially coherent sources are sources where the coherence time or coherence length are limited by bandwidth, by thermal noise, or by other effect. Many aspects of modern coherence theory are studied in quantum optics. The theory of partial coherence was awoken in the 1930s due to work by Pieter Hendrik van Cittert and Frits Zernike. Topics in coherence theory * * Mutual coherence function * * * * * * * See also * Nonclassical light * Optical coherence tomography Optical coherence tomography (OCT) is a high-resolution imaging technique with most of its applications in medicine and biology. OCT uses coherent near-infrared light to obtain micrometer-level depth resolved images of biological tissue or oth ... References * Eugene Hecht and Alfred Zajac, ''Optics'', (1974) Addison-Wesley Publishing, Reading, Massachusetts . ''(Chapter 12 provides an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
