نتایج جستجو برای: light coherence
تعداد نتایج: 463424 فیلتر نتایج به سال:
We report, what is to our knowledge, the first experimental realization of partially coherent bottle beams. It is shown that partially coherent bottle beams can be achieved by the focusing of partially coherent light with an axicon-lens system. The influence of the spatial coherence of the incident partially coherent light and other parameters, such as the radius of the limiting aperture of the...
Dynamic low-coherence interferometry was used to measure Brownian motion of submicrometer particles within highly scattering media. Strong rejection of multiply scattered light was obtained by combination of a coherence gate with a confocal microscope, thus allowing particle characterization methods generally reserved for optically dilute materials to be applied to optically concentrated suspen...
The idea that quantum-mechanical phenomena can play nontrivial roles in biology has fascinated researchers for a century. Here we review some examples of such effects, including light-harvesting in photosynthesis, vision, electronand proton-tunneling, olfactory sensing, and magnetoreception. We examine how experimental tests have aided this field in recent years and discuss the importance of de...
A coherence-controlled holographic microscope (CCHM) enables quantitative phase imaging with coherent as well as incoherent illumination. The low spatially coherent light induces a coherence gating effect, which makes observation of samples possible also through scattering media. The paper describes theoretically and simulates numerically imaging of a two-dimensional object through a static sca...
Abstract Speckle is maybe the most fundamental interference effect of light in disordered media, giving rise to fascinating physical phenomena and cutting edge applications. While speckle formed outside a sample easily measured analysed, true bulk speckle, as inside random difficult investigate directly due obvious issue access. Furthermore, its proper theoretical description poses enormous cha...
This paper attempts to reconcile conflicting points of view of laboratory physicists and coherence theorists on correlation-induced spectral changes arising from the partial coherence of primary and secondary light sources. It is shown that, under normal laboratory conditions and in the Fraunhofer approximation, the directional spectrum of light does not change on propagation in free space, and...
We put forward a theory on the optical force exerted upon a dipolar particle by a stationary and ergodic partially coherent light field. We show through a rigorous analysis that the ensemble averaged electromagnetic force is given in terms of a partial gradient of the space-variable diagonal elements of the coherence tensor. Further, by following this result we characterize the conservative and...
Visible-light optical coherence tomography (vis-OCT) is an emerging imaging modality, providing new capabilities in both anatomical and functional imaging of biological tissue. It relies on visible light illumination, whereas most commercial and investigational OCTs use near-infrared light. As a result, vis-OCT requires different considerations in engineering design and implementation but bring...
Natural and artificial light-harvesting processes have recently gained new interest. Signatures of long-lasting coherence in spectroscopic signals of biological systems have been repeatedly observed, albeit their origin is a matter of ongoing debate, as it is unclear how the loss of coherence due to interaction with the noisy environments in such systems is averted. Here we report experimental ...
Measurements of the spatial and temporal coherence of single, femtosecond x-ray pulses generated by the first hard x-ray free-electron laser, the Linac Coherent Light Source, are presented. Single-shot measurements were performed at 780 eV x-ray photon energy using apertures containing double pinholes in "diffract-and-destroy" mode. We determined a coherence length of 17 μm in the vertical dir...
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