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Namely, a concerted emission of phonons can lead to coherent sound and an example of concerted phonon emission is the emission coming from quantum wells. This stands in similar paths with the laser where a coherent light can build up by the concerted stimulated emission of light from a lot of atoms. A SASER device transforms the electric ...
Coherence controls the visibility or contrast of interference patterns. For example, visibility of the double slit experiment pattern requires that both slits be illuminated by a coherent wave as illustrated in the figure. Large sources without collimation or sources that mix many different frequencies will have lower visibility. [4]: 264
For interference lithography to be successful, coherence requirements must be met. First, a spatially coherent light source must be used. This is effectively a point light source in combination with a collimating lens. A laser or synchrotron beam are also often used directly without additional collimation.
Finding a solution requires an iterative approach. Different algorithms have been applied for obtaining the control field such as the Krotov method. [27] A local in time alternative method has been developed, [28] where at each time step, the field is calculated to direct the state to the target. A related method has been called tracking [29]
Nevertheless, the intuitive pure-frequency heterodyne concept still holds perfectly for the wideband case provided that the signal and LO are mutually coherent. Crucially, one can obtain narrow-band interference from coherent broadband sources: this is the basis for white light interferometry and optical coherence tomography.
The white light source used to view these holograms should always approximate to a point source, i.e. a spot light or the sun. An extended source (e.g. a fluorescent lamp) will not reconstruct a hologram since its light is incident at each point at a wide range of angles, giving multiple reconstructions which will "wipe" one another out.
This reciprocal space diffraction image was taken by Ian Robinson's Group to be used in the reconstruction of a real space coherent X-ray diffraction image in 2007. Coherent diffractive imaging ( CDI ) is a "lensless" technique for 2D or 3D reconstruction of the image of nanoscale structures such as nanotubes, [ 1 ] nanocrystals, [ 2 ] porous ...
A turbulent flow is a flow regime in fluid dynamics where fluid velocity varies significantly and irregularly in both position and time. [3] Furthermore, a coherent structure is defined as a turbulent flow whose vorticity expression, which is usually stochastic, contains orderly components that can be described as being instantaneously coherent over the spatial extent of the flow structure.